Polymers

2022

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13 pages, 2505 KiB

Open AccessArticle

Hair Growth-Promoting Activities of Glycosaminoglycans Extracted from the Tunics of Ascidian (Halocynthia roretzi)

by Therese Ariane N. Neri, Grace N. Palmos, Shin Young Park, Tae Sung Jung and Byeong-Dae Choi

Polymers 2022, 14(6), 1096; https://doi.org/10.3390/polym14061096 - 9 Mar 2022

Cited by 6 | Viewed by 3415

Abstract

Throughout the ages, hair has had psychological and sociological importance in framing the personality and general appearance of an individual. Despite efforts to solve this problem, no groundbreaking measures have been proposed. Glycosaminoglycans (GAGs) and associated proteoglycans have important functions in homeostatic maintenance [...] Read more.

Throughout the ages, hair has had psychological and sociological importance in framing the personality and general appearance of an individual. Despite efforts to solve this problem, no groundbreaking measures have been proposed. Glycosaminoglycans (GAGs) and associated proteoglycans have important functions in homeostatic maintenance and regenerative processes of the skin. However, little is known about the role of these molecules in the regulation of the hair follicle cycle. Three fractions (F1, F2 and F3) were obtained after separation and purification of GAGs from ascidian tunics. F1 was observed to contain a small amount of amino sugar while high contents of galactose and N-acetylglucosamine were noted in F2 and F3. 2-acetamido-2-deoxy-3-O-(β-D-gluco-4-enepyranosyluronic acid)-6-O-sulfo-D-galactose (∆Di-6S) and 2-acetamido-2-deoxy-3-O-(β-D-gluco-4-enepyranosyluronic acid)-4-O-sulfo-D-galactose (∆Di-4S) were the main disaccharide components. F3 exhibited the highest proliferation activity on human follicle dermal papilla (HFDP) cells. In addition, mixed samples (FFM) of F2 and F3 at different concentrations showed peak activities for five days. After cell culture at a concentration of 10 mg/mL and dihydrotestosterone (DHT), the inhibition effect was higher than that for Minoxidil. Application of 10 mg of FFM to the hair of mice for 28 days resulted in a hair growth effect similar to that of Minoxidil, a positive control. Full article

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2021

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14 pages, 24427 KiB

Open AccessArticle

Microencapsulation of a Pseudomonas Strain (VUPF506) in Alginate–Whey Protein–Carbon Nanotubes and Next-Generation Sequencing Identification of This Strain

by Fariba Fathi, Roohallah Saberi Riseh, Pejman Khodaygan, Samin Hosseini and Yury A. Skorik

Polymers 2021, 13(23), 4269; https://doi.org/10.3390/polym13234269 - 6 Dec 2021

Cited by 30 | Viewed by 3313

Abstract

Alginate is a common agent used for microencapsulation; however, the formed capsule is easily damaged. Therefore, alginate requires blending with other biopolymers to reduce capsule vulnerability. Whey protein is one polymer that can be incorporated with alginate to improve microcapsule structure. In this [...] Read more.

Alginate is a common agent used for microencapsulation; however, the formed capsule is easily damaged. Therefore, alginate requires blending with other biopolymers to reduce capsule vulnerability. Whey protein is one polymer that can be incorporated with alginate to improve microcapsule structure. In this study, three different encapsulation methods (extrusion, emulsification, and spray drying) were tested for their ability to stabilize microencapsulated Pseudomonas strain VUPF506. Extrusion and emulsification methods enhanced encapsulation efficiency by up to 80% and gave the best release patterns over two months. A greenhouse experiment using potato plants treated with alginate–whey protein microcapsules showed a decrease in Rhizoctonia disease intensity of up to 70%. This is because whey protein is rich in amino acids and can serve as a resistance induction agent for the plant. In this study, the use of CNT in the ALG–WP system increased the rooting and proliferation and reduced physiological complication. The results of this study showed that the technique used in encapsulation could have a significant effect on the efficiency and persistence of probiotic bacteria. Whole genome sequence analysis of strain VUPF506 identified it as Pseudomonas chlororaphis and revealed some genes that control pathogens. Full article

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14 pages, 2202 KiB

Open AccessArticle

Thermal Properties of Plasticized Cellulose Acetate and Its β-Relaxation Phenomenon

by Rafael Erdmann, Stephan Kabasci and Hans-Peter Heim

Polymers 2021, 13(9), 1356; https://doi.org/10.3390/polym13091356 - 21 Apr 2021

Cited by 30 | Viewed by 6180

Abstract

Cellulose acetate (CA), an organic ester, is a biobased polymer which exhibits good mechanical properties (e.g., high Young’s modulus and tensile strength). In recent decades, there has been significant work done to verify the thermal and thermomechanical behaviors of raw and plasticized cellulose [...] Read more.

Cellulose acetate (CA), an organic ester, is a biobased polymer which exhibits good mechanical properties (e.g., high Young’s modulus and tensile strength). In recent decades, there has been significant work done to verify the thermal and thermomechanical behaviors of raw and plasticized cellulose acetate. In this study, the thermomechanical properties of plasticized cellulose acetate—especially its β

β

-relaxation and activation energy—were investigated. The general thermal behavior was analyzed and compared with theoretical models. The study’s findings could be of special interest, due to the known β

β

-relaxation dependency of some polymers regarding mechanical properties—which could also be the case for cellulose acetate. However, this would require further investigation. The concentration of the plasticizers—glycerol triacetate (GTA) and triethyl citrate (TEC)—used in CA ranged from 15 to 40 wt%. DMTA measurements at varying frequencies were performed, and the activation energies of each relaxation were assessed. Increasing plasticizer content first led to a shift in β

β

-relaxation temperature to highervalues, then reached a maximum before declining again at higher concentrations. Furthermore, the activation energy of the β

β

-relaxation constantly rose with increases in plasticizer content. The trend in the β

β

-relaxation temperature of the plasticized CA could be interpreted as a change in the predominant phase of the overlapping β

β

-relaxation of the CA itself and the α

α^{'}

-relaxation of the plasticizer—which appears in the same temperature range. The plasticizer used (GTA) demonstrated a higher plasticization efficiency than TEC. The efficiencies of both plasticizers declined with increasing plasticizer content. Additionally, both plasticizers hit the saturation point (in CA) at the lowest studied concentration (15 wt%). Full article

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2020

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15 pages, 3878 KiB

Open AccessArticle

Comparison of Polysaccharides as Coatings for Quercetin-Loaded Liposomes (QLL) and Their Effect as Antioxidants on Radical Scavenging Activity

by Manuel Román-Aguirre, César Leyva-Porras, Pedro Cruz-Alcantar, Alfredo Aguilar-Elguézabal and María Zenaida Saavedra-Leos

Polymers 2020, 12(12), 2793; https://doi.org/10.3390/polym12122793 - 26 Nov 2020

Cited by 16 | Viewed by 2624

Abstract

Liposomes are microstructures containing lipid and aqueous phases employed in the encapsulation and delivery of bioactive agents. Quercetin-loaded liposomes (QLLs) were coated with three different polysaccharides and then tested as radical scavengers. Lactose (LCQLL), chitosan (CCQLL), and inulin (ICQLL) were employed as coating [...] Read more.

Liposomes are microstructures containing lipid and aqueous phases employed in the encapsulation and delivery of bioactive agents. Quercetin-loaded liposomes (QLLs) were coated with three different polysaccharides and then tested as radical scavengers. Lactose (LCQLL), chitosan (CCQLL), and inulin (ICQLL) were employed as coating materials. Particle size determined by light scattering, showed primary size of 200 nm for all samples, while a secondary particle size of 600 nm was observed for CCQLL. Scanning electron microscopy (SEM) evidenced particle aggregation with the addition of the polysaccharide coating. Transmission electron microscopy (TEM) revealed the layered microstructure of liposomes composed of at least two layers, and primary particle size below 100 nm. QLL showed higher antioxidant activity than the coated liposomes. This behavior was attributed to the chemical interaction between quercetin and the corresponding coating polysaccharide in the layered structure, which traps the quercetin and keeps it unavailable for radical scavenging. From the three polysaccharides, lactose showed a better performance as coating material in the antioxidant activity, which suggested that the smaller size of the disaccharide molecule resulted in a faster releasing of the quercetin in the solution. Thus, LCQLL is an advantageous way to deliver quercetin for antioxidant purposes, where the low stability in delivered media of quercetin loaded liposomes is commonly compromised. Full article

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20 pages, 4480 KiB

Open AccessArticle

Hyaluronan-Arginine Interactions—An Ultrasound and ITC Study

by Adam Jugl and Miloslav Pekař

Polymers 2020, 12(9), 2069; https://doi.org/10.3390/polym12092069 - 12 Sep 2020

Cited by 7 | Viewed by 2745

Abstract

High-resolution ultrasound spectroscopy and isothermal titration calorimetry were used to characterize interactions between hyaluronan and arginine oligomers. The molecular weight of arginine oligomer plays an important role in interactions with hyaluronan. Interactions were observable for arginine oligomers with eight monomer units and longer [...] Read more.

High-resolution ultrasound spectroscopy and isothermal titration calorimetry were used to characterize interactions between hyaluronan and arginine oligomers. The molecular weight of arginine oligomer plays an important role in interactions with hyaluronan. Interactions were observable for arginine oligomers with eight monomer units and longer chains. The effect of the ionic strength and molecular weight of hyaluronan on interactions was tested. In an environment with increased ionic strength, the length of the arginine oligomer was crucial. Generally, sufficiently high ionic strength suppresses interactions between hyaluronan and arginine oligomers, which demonstrated interactions in water. From the point of view of the molecular weight of hyaluronan, the transition between the rod conformation and the random coil conformation appeared to be important. Full article

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13 pages, 2140 KiB

Open AccessArticle

Effect of Cellulose Solvents on the Characteristics of Cellulose/Fe₂O₃ Hydrogel Microspheres as Enzyme Supports

by Saerom Park, Yujin Oh, Dahun Jung and Sang Hyun Lee

Polymers 2020, 12(9), 1869; https://doi.org/10.3390/polym12091869 - 19 Aug 2020

Cited by 11 | Viewed by 3488

Abstract

Cellulose hydrogels are considered useful biocompatible and biodegradable materials. However, as few cellulose-dissolving solvents can be used to prepare cellulose hydrogel microspheres, the use of unmodified cellulose-based hydrogel microspheres for enzyme immobilization remains limited. Here, we prepared cellulose/Fe₂O₃ hydrogel microspheres [...] Read more.

Cellulose hydrogels are considered useful biocompatible and biodegradable materials. However, as few cellulose-dissolving solvents can be used to prepare cellulose hydrogel microspheres, the use of unmodified cellulose-based hydrogel microspheres for enzyme immobilization remains limited. Here, we prepared cellulose/Fe₂O₃ hydrogel microspheres as enzyme supports through sol-gel transition using a solvent-in-oil emulsion. Cellulose-dissolving solvents including 1-ethyl-3-methylimidazolium ([Emim][Ac]), an aqueous mixture of NaOH and thiourea, tetrabutylammonium hydroxide, and tetrabutylphosphonium hydroxide were used to prepare regular shaped cellulose/Fe₂O₃ microspheres. The solvent affected microsphere characteristics like crystallinity, hydrophobicity, surface morphology, size distribution, and swelling properties. The immobilization efficiency of the microspheres for lipase was also significantly influenced by the type of cellulose solvent used. In particular, the lipase immobilized on cellulose/Fe₂O₃ microspheres prepared using [Emim][Ac] showed the highest protein loading, and its specific activity was 3.1-fold higher than that of free lipase. The immobilized lipase could be simply recovered by a magnet and continuously reused. Full article

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21 pages, 4519 KiB

Open AccessArticle

Structural Features of Three Hetero-Galacturonans from Passiflora foetida Fruits and Their in Vitro Immunomodulatory Effects

by Ya Song, Peng Wen, Huili Hao, Minqian Zhu, Yuanming Sun, Yuxiao Zou, Teresa Requena, Riming Huang and Hong Wang

Polymers 2020, 12(3), 615; https://doi.org/10.3390/polym12030615 - 8 Mar 2020

Cited by 15 | Viewed by 3422

Abstract

Passiflora foetida is a horticultural plant and vital traditional Chinese herbal medicine. In our previous study, the characterization and immuno-enhancing effect of fruits polysaccharide 1 (PFP1), a water-eluted hetero-mannan from wild Passiflora foetida fruits, were investigated. Herein, another three salt-eluted novel polysaccharides, namely [...] Read more.

Passiflora foetida is a horticultural plant and vital traditional Chinese herbal medicine. In our previous study, the characterization and immuno-enhancing effect of fruits polysaccharide 1 (PFP1), a water-eluted hetero-mannan from wild Passiflora foetida fruits, were investigated. Herein, another three salt-eluted novel polysaccharides, namely PFP2, PFP3, and PFP4, were obtained and structurally characterized. The results showed that PFP2, PFP3, and PFP4 were three structurally similar hetero-galacturonans with different molecular weights of 6.11 × 10⁴, 4.37 × 10⁴_, and 3.48 × 10⁵ g/mol, respectively. All three of these hetero-galacturonans are mainly composed of galacturonic acid, galactose, arabinose (75.69%, 80.39%, and 74.30%, respectively), and other monosaccharides including mannose, fucose, glucose, ribose, xylose, and glucuronic acid (24.31%, 19.61, and 25.70%, respectively), although differences in their backbone structure exist. Additionally, immunomodulatory assay indicated that the three hetero-galacturonans possess the ability to promote the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) in RAW264.7 macrophages in a concentration-dependent manner (p < 0.05). Especially, PFP3 displayed a stronger enhancing effect than PFP2 and PFP4 at the minimum effective concentration. Therefore, the results suggested that the obtained three salt-eluted hetero-galacturonans, especially PFP3, could be utilized as immunomodulatory effectivity ingredients in nutritional/pharmaceutical industries. Full article

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13 pages, 1696 KiB

Open AccessArticle

Efficient Extraction and Structural Characterization of Hemicellulose from Sugarcane Bagasse Pith

by Yitong Xie, Xin Guo, Zhiyu Ma, Jingwei Gong, Haisong Wang and Yanna Lv

Polymers 2020, 12(3), 608; https://doi.org/10.3390/polym12030608 - 6 Mar 2020

Cited by 37 | Viewed by 5205

Abstract

The aim of this study was to investigate the ultrasound-assisted alkaline extraction process and structural properties of hemicellulose from sugarcane bagasse pith. Response surface model (RSM) was established in order to optimize the extraction conditions for the highest hemicellulose yield based on the [...] Read more.

The aim of this study was to investigate the ultrasound-assisted alkaline extraction process and structural properties of hemicellulose from sugarcane bagasse pith. Response surface model (RSM) was established in order to optimize the extraction conditions for the highest hemicellulose yield based on the single-factor experiments. A maximum total hemicellulose yield of 23.05% was obtained under the optimal conditions of ultrasonic treatment time of 28 min, KOH mass concentration of 3.7%, and extraction temperature of 53 °C, and it evidently increased 3.24% compared without ultrasound-assisted extraction. The obtained hemicellulose was analyzed by Fourier transform infrared (FT-IR) spectroscopy. The monosaccharide composition and average molecular weight of hemicellulose were characterized by using ion chromatography (IC) and gel permeation chromatography (GPC). The results indicated that xylose was dominant component in water-soluble hemicellulose (WH, 69.05%) and alkali-soluble hemicellulose (AH, 85.83%), respectively. Furthermore, the monosaccharides (otherwise xylose) and uronic acids contents of WH were higher than that of AH. Weight average molecular weight of WH was 29923 g/mol, lower than that of AH (74,872 g/mol). These results indicate that ultrasonic-assisted alkaline extraction is an efficient approach for the separation of hemicellulose from sugarcane bagasse pith. Full article

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15 pages, 5164 KiB

Open AccessArticle

Xanthan Gum–Konjac Glucomannan Blend Hydrogel for Wound Healing

by Andreia Alves, Sónia P. Miguel, André R.T.S. Araujo, María José de Jesús Valle, Amparo Sánchez Navarro, Ilídio J. Correia, Maximiano P. Ribeiro and Paula Coutinho

Polymers 2020, 12(1), 99; https://doi.org/10.3390/polym12010099 - 4 Jan 2020

Cited by 81 | Viewed by 10887

Abstract

Hydrogels are considered to be the most ideal materials for the production of wound dressings since they display a three-dimensional structure that mimics the native extracellular matrix of skin as well as a high-water content, which confers a moist environment at the wound [...] Read more.

Hydrogels are considered to be the most ideal materials for the production of wound dressings since they display a three-dimensional structure that mimics the native extracellular matrix of skin as well as a high-water content, which confers a moist environment at the wound site. Until now, different polymers have been used, alone or blended, for the production of hydrogels aimed for this biomedical application. From the best of our knowledge, the application of a xanthan gum–konjac glucomannan blend has not been used for the production of wound dressings. Herein, a thermo-reversible hydrogel composed of xanthan gum–konjac glucomannan (at different concentrations (1% and 2% w/v) and ratios (50/50 and 60/40)) was produced and characterized. The obtained data emphasize the excellent physicochemical and biological properties of the produced hydrogels, which are suitable for their future application as wound dressings. Full article

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2019

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17 pages, 1821 KiB

Open AccessArticle

Synthesis and Physicochemical Characterization of Undecylenic Acid Grafted to Hyaluronan for Encapsulation of Antioxidants and Chemical Crosslinking

by Gloria Huerta-Ángeles, Martina Brandejsová, Kateřina Kopecká, František Ondreáš, Tomáš Medek, Ondrej Židek, Jaromír Kulhánek, Hana Vagnerová and Vladimir Velebný

Polymers 2020, 12(1), 35; https://doi.org/10.3390/polym12010035 - 24 Dec 2019

Cited by 16 | Viewed by 4348

Abstract

In this work, a new amphiphilic derivative made of 10-undecylenic acid grafted to hyaluronan was prepared by mixed anhydrides. The reaction conditions were optimized, and the effect of the molecular weight (Mw), reaction time, and the molar ratio of reagents was explored. Using [...] Read more.

In this work, a new amphiphilic derivative made of 10-undecylenic acid grafted to hyaluronan was prepared by mixed anhydrides. The reaction conditions were optimized, and the effect of the molecular weight (Mw), reaction time, and the molar ratio of reagents was explored. Using this methodology, a degree of substitution up to 50% can be obtained. The viscosity of the conjugate can be controlled by varying the substitution degree. The physicochemical characterization of the modified hyaluronan was performed by infrared spectroscopy, Nuclear Magnetic Resonance, Size-Exclusion Chromatography combined with Multiangle Laser Light Scattering (SEC-MALLS), and rheology. The low proton motility and self-aggregation of the amphiphilic conjugate produced overestimation of the degree of substitution. Thus, a novel method using proton NMR was developed. Encapsulation of model hydrophobic guest molecules, coenzyme Q10, curcumin, and α-tocopherol into the micellar core was also investigated by solvent evaporation. HA-UDA amphiphiles were also shown to self-assemble into spherical nanostructures (about 300 nm) in water as established by dynamic light scattering. Furthermore, HA-UDA was crosslinked via radical polymerization mediated by ammonium persulphate (APS/TEMED). The cross-linking was also tested by photo-polymerization catalyzed by Irgacure 2959. The presence of the hydrophobic moiety decreases the swelling degree of the prepared hydrogels compared to methacrylated-HA. Here, we report a novel hybrid hyaluronan (HA) hydrogel system of physically encapsulated active compounds and chemical crosslinking for potential applications in drug delivery. Full article

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14 pages, 3243 KiB

Open AccessArticle

Physicochemical Characterization and Immunomodulatory Activity of a Novel Acid Polysaccharide from Solanum muricatum

by Heng Yue, Qianqian Xu, Xianheng Li, Jeevithan Elango, Wenhui Wu and Jianfeng Xu

Polymers 2019, 11(12), 1972; https://doi.org/10.3390/polym11121972 - 30 Nov 2019

Cited by 6 | Viewed by 2866

Abstract

To investigate the structure and immunomodulatory activity of polysaccharide from Solanum muricatum, a novel acid polysaccharide named SMP-3a was purified from Solanum muricatum pulp through DEAE-52 cellulose column and Sephadex G-200 chromatography. Monosaccharide composition analysis showed that SMP-3a was mainly composed of [...] Read more.

To investigate the structure and immunomodulatory activity of polysaccharide from Solanum muricatum, a novel acid polysaccharide named SMP-3a was purified from Solanum muricatum pulp through DEAE-52 cellulose column and Sephadex G-200 chromatography. Monosaccharide composition analysis showed that SMP-3a was mainly composed of rhamnose, arabinose, galactose, and galacturonic acid with the molar ratio of 1.09:2.64:1.54:1. The average molecular weight was found to be 227 kDa by high performance gel permeation chromatography (HPGPC). Thermal studies revealed the SMP-3a was a thermally stable polymer. Based on the results of methylation and NMR analysis, the backbone chain of SMP-3a was composed of →2)-α-l-Rhap-(1→, →4)-α-d-GalpA-(1→ and →4)-α-d-Galp-(1→. The side chain was consisted of α-l-Araf-(1→ and →5)-α-l-Araf-(1→. Immunomodulatory assay indicated that SMP-3a could significantly promote the proliferation of macrophages and stimulate the secretion of cytokines, including TNF-α, IL-1β, and IL-6. Our results suggested that SMP-3a could be used as a novel potential immunomodulatory agent in functional food. Full article

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18 pages, 2261 KiB

Open AccessArticle

Potato Starch Hydrogels Produced by High Hydrostatic Pressure (HHP): A First Approach

by Dominique Larrea-Wachtendorff, Gipsy Tabilo-Munizaga and Giovanna Ferrari

Polymers 2019, 11(10), 1673; https://doi.org/10.3390/polym11101673 - 14 Oct 2019

Cited by 36 | Viewed by 5042

Abstract

Starch-based hydrogels have received considerable interest due to their safe nature, biodegradability and biocompatibility. The aim of this study was to verify the possibility of producing natural hydrogels based on potato starch by high hydrostatic pressure (HHP), identifying suitable processing conditions allowing to [...] Read more.

Starch-based hydrogels have received considerable interest due to their safe nature, biodegradability and biocompatibility. The aim of this study was to verify the possibility of producing natural hydrogels based on potato starch by high hydrostatic pressure (HHP), identifying suitable processing conditions allowing to obtain stable hydrogels, as well as to characterize structural and mechanical properties of these products. Sieved (small size granules and medium size granules) and unsieved potato starch samples were used to prepare aqueous suspensions of different concentrations (10–30% w/w) which were processed at 600 MPa for 15 min at different temperatures (25, 40 and 50 °C). Products obtained were characterized by different techniques (light and polarized microscopy, Fourier transform infrared spectroscopy (FTIR), rheology and differential scanning calorimetry (DSC)). Results obtained so far demonstrated that potato starch suspensions (20% starch–water concentration (w/w)) with granules mean size smaller than 25 µm treated at 600 MPa for 15 min and 50 °C showed a complete gelatinization and gel-like appearance. Potato HHP hydrogels were characterized by high viscosity, shear-thinning behavior and a highly structured profile (G’ >> G’’). Moreover, their FTIR spectra, similarly to FTIR profiles of thermal gels, presented three absorption bands in the characteristic starch-gel region (950–1200 cm⁻¹), whose intensity increased with decreasing the particle size and increasing the processing temperature. In conclusion, potato starch hydrogels produced by HHP in well-defined processing conditions exhibited excellent mechanical properties, which can be tailored according to the requirements of the different applications envisaged. Full article

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17 pages, 2545 KiB

Open AccessArticle

Sugar Alcohol-Based Deep Eutectic Solvents as Potato Starch Plasticizers

by Magdalena Zdanowicz, Piotr Staciwa, Roman Jędrzejewski and Tadeusz Spychaj

Polymers 2019, 11(9), 1385; https://doi.org/10.3390/polym11091385 - 23 Aug 2019

Cited by 36 | Viewed by 5171

Abstract

The aim of this work was to prepare sugar alcohol-based deep eutectic solvents (DES) and test them as starch plasticizers. Thermoplastic starch (TPS) films were obtained via a simple and convenient thermocompression method. Influence of starch/DES premixtures conditioning (preheating, storage time) on TPS [...] Read more.

The aim of this work was to prepare sugar alcohol-based deep eutectic solvents (DES) and test them as starch plasticizers. Thermoplastic starch (TPS) films were obtained via a simple and convenient thermocompression method. Influence of starch/DES premixtures conditioning (preheating, storage time) on TPS properties was investigated. TPS/sorbitol (S)-based DES exhibited similar tensile strength (TS) (8.6 MPa) but twice higher elongation at the break (ε) (33%) when compared with TPS plasticized only with S. Extra treatment, i.e., heating or prolonged storage time, facilitated starch/DES plasticizing. Starch with selected DES was also extruded and the influence of preconditioning and extrusion rotational speed were subsequently studied on thermocompressed films. Extrusion at 100 rpm led to films with TS up to ca. 10 MPa and ε up to 52%. Some differences in film samples morphology obtained via two processing methods were observed. X-ray diffractograms revealed that extruded samples exhibited a V-type peak at 18.2°, with intensity depending on plasticizer total molecular size. Applied techniques (mechanical tests, XRD, Dynamic Mechanical Analysis (DMA), FTIR-Attenuated Total Reflection (ATR), and moisture sorption) indicated that S-based DES forms stronger interactions with starch than glycerol (G) only used as conventional plasticizer, thus leading to better mechanical properties and inhibited tendency to starch recrystallization (studied up to one year). Full article

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15 pages, 3672 KiB

Open AccessArticle

Neutral Polysaccharide from the Leaves of Pseuderanthemum carruthersii: Presence of 3-O-Methyl Galactose and Anti-Inflammatory Activity in LPS-Stimulated RAW 264.7 Cells

by Vo Hoai Bac, Berit Smestad Paulsen, Le Van Truong, Andreas Koschella, Tat Cuong Trinh, Christian Winther Wold, Suthajini Yogarajah and Thomas Heinze

Polymers 2019, 11(7), 1219; https://doi.org/10.3390/polym11071219 - 22 Jul 2019

Cited by 6 | Viewed by 4731

Abstract

Pseuderanthemum carruthersii (Seem.) Guillaumin is a native tree in Vietnam. The water extract of the leaves from this tree gives a highly viscous product that has been used to heal wounds and treat inflammations. Our previous studies showed that the leaves of P. [...] Read more.

Pseuderanthemum carruthersii (Seem.) Guillaumin is a native tree in Vietnam. The water extract of the leaves from this tree gives a highly viscous product that has been used to heal wounds and treat inflammations. Our previous studies showed that the leaves of P. carruthersii have a high content of polysaccharides. In this study, the structure and influence of the neutral polysaccharide from Pseuderanthemum carruthersii (PCA1) on lipopolysaccharide (LPS)-stimulated RAW264.7 cells were investigated. The PCA1 isolated from P. carruthersii is a galactan-type polysaccharide, containing galactose (77.0%), 3-O-methyl galactose (20.0%), and arabinose (3.0%). Linkage analysis of PCA1 showed that both the 3-O-methyl galactose and galactose were 1,4-linked. The presence of 3-O-methyl galactose units as part of the polysaccharide is important and can be used as a chemotaxonomic marker. The molecular weight of the PCA1 was 170 kDa. A PCA1 concentration of 30–40 μg/mL strongly inhibited TNFα, IL-1β, and IL-6 inflammatory cytokine production, and reactive oxygen species (ROS) release. PCA1 had inhibitory activities on pro-inflammatory cytokine and ROS release in LPS-stimulated mouse macrophages in vitro through MAPK signaling. Full article

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9 pages, 1994 KiB

Open AccessReview

Xylans of Red and Green Algae: What Is Known about Their Structures and How They Are Synthesised?

by Yves S.Y. Hsieh and Philip J. Harris

Polymers 2019, 11(2), 354; https://doi.org/10.3390/polym11020354 - 18 Feb 2019

Cited by 55 | Viewed by 6148

Abstract

Xylans with a variety of structures have been characterised in green algae, including chlorophytes (Chlorophyta) and charophytes (in the Streptophyta), and red algae (Rhodophyta). Substituted 1,4-β-d-xylans, similar to those in land plants (embryophytes), occur in the cell wall matrix of advanced [...] Read more.

Xylans with a variety of structures have been characterised in green algae, including chlorophytes (Chlorophyta) and charophytes (in the Streptophyta), and red algae (Rhodophyta). Substituted 1,4-β-d-xylans, similar to those in land plants (embryophytes), occur in the cell wall matrix of advanced orders of charophyte green algae. Small proportions of 1,4-β-d-xylans have also been found in the cell walls of some chlorophyte green algae and red algae but have not been well characterised. 1,3-β-d-Xylans occur as triple helices in microfibrils in the cell walls of chlorophyte algae in the order Bryopsidales and of red algae in the order Bangiales. 1,3;1,4-β-d-Xylans occur in the cell wall matrix of red algae in the orders Palmariales and Nemaliales. In the angiosperm Arabidopsis thaliana, the gene IRX10 encodes a xylan 1,4-β-d-xylosyltranferase (xylan synthase), and, when heterologously expressed, this protein catalysed the production of the backbone of 1,4-β-d-xylans. An orthologous gene from the charophyte green alga Klebsormidium flaccidum, when heterologously expressed, produced a similar protein that was also able to catalyse the production of the backbone of 1,4-β-d-xylans. Indeed, it is considered that land plant xylans evolved from xylans in ancestral charophyte green algae. However, nothing is known about the biosynthesis of the different xylans found in chlorophyte green algae and red algae. There is, thus, an urgent need to identify the genes and enzymes involved. Full article

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14 pages, 4151 KiB

Open AccessEditor’s ChoiceArticle

Antimony Removal from Water by a Chitosan-Iron(III)[ChiFer(III)] Biocomposite

by Byron Lapo, Hary Demey, Tanya Carchi and Ana María Sastre

Polymers 2019, 11(2), 351; https://doi.org/10.3390/polym11020351 - 18 Feb 2019

Cited by 25 | Viewed by 5184

Abstract

The presence of antimony(III) in water represents a worldwide concern, mainly due to its high toxicity and carcinogenicity potential. It can be separated from water by the use of sustainable biopolymers such as chitosan or its derivatives. The present study applied chitosan modified [...] Read more.

The presence of antimony(III) in water represents a worldwide concern, mainly due to its high toxicity and carcinogenicity potential. It can be separated from water by the use of sustainable biopolymers such as chitosan or its derivatives. The present study applied chitosan modified with iron(III) beads to Sb(III) removal from aqueous solutions. The resulting material performed with a high adsorption capacity of 98.68 mg/g. Material characterization consisted of Raman spectroscopy (RS), X-ray diffraction (XRD), scanning electron microscope observations (SEM-EDX), Fourier transform infrared spectroscopy (FTIR) and point of zero charge (pH_pzc). The adsorption study included pH study, effect of initial concentration, kinetics, ion effect, and reusability assessment. The RS, XRD, and FTIR results indicated that the main functional groups in the composite were related to hydroxyl and amino groups, and iron oxyhydroxide species of α-FeO(OH). The pH_pzc was found to be 7.41. The best adsorption efficiency was set at pH 6. The equilibrium isotherms were better fitted with a non-linear Langmuir model, and the kinetics data were fitted with a pseudo-second order rate equation. The incorporation of iron into the chitosan matrix improved the Sb(III) uptake by 47.9%, compared with neat chitosan (CS). The material did not exhibit an impact in its performance in the presence of other ions, and it could be reused for up to three adsorption–desorption cycles. Full article

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18 pages, 2266 KiB

Open AccessEditor’s ChoiceArticle

Sorption and Desorption Studies of Pb(II) and Ni(II) from Aqueous Solutions by a New Composite Based on Alginate and Magadiite Materials

by Keltoum Attar, Hary Demey, Djamila Bouazza and Ana Maria Sastre

Polymers 2019, 11(2), 340; https://doi.org/10.3390/polym11020340 - 15 Feb 2019

Cited by 49 | Viewed by 4943

Abstract

A new composite material based on alginate and magadiite/Di-(2-ethylhexyl) phosphoric acid (CAM-D2EHPA) was successfully prepared by previous impregnation of layered magadiite with D2EHPA extractant, and then immobilized into the alginate matrix. Air dried beads of CAM-D2EHPA were characterized by FTIR and SEM–EDX techniques. [...] Read more.

A new composite material based on alginate and magadiite/Di-(2-ethylhexyl) phosphoric acid (CAM-D2EHPA) was successfully prepared by previous impregnation of layered magadiite with D2EHPA extractant, and then immobilized into the alginate matrix. Air dried beads of CAM-D2EHPA were characterized by FTIR and SEM–EDX techniques. The sorbent was used for the separation of lead and nickel from nitrate solutions; the main parameters of sorption such as contact time, pH of the solution, and initial metal concentration were studied. The beads recovered 94% of Pb(II) and 65% of Ni(II) at pH 4 from dilute solutions containing 10 mg L⁻¹ of metal (sorbent dosage, S.D. 1 g L⁻¹). The equilibrium data gave a better fit using the Langmuir model, and kinetic profiles were fitted using a pseudo-second order rate equation. The maximum sorption capacities obtained (at pH 4) were 197 mg g⁻¹ and 44 mg g⁻¹ for lead and nickel, respectively. The regeneration of the sorbent was efficiently carried out with a dilute solution of HNO₃ (0.5 M). The composite material was reused in 10 sorption–elution cycles with no significant differences on sorption uptake. A study with synthetic effluents containing an equimolar concentration of both metals indicated a better selectivity towards lead ions. Full article

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12 pages, 2101 KiB

Open AccessArticle

Comparisons of Functional Properties of Polysaccharides from Nostoc flagelliforme under Three Culture Conditions

by Shi-Gang Shen, Ya-Hui Lin, Dong-Xue Zhao, Yi-Kai Wu, Rong-Rong Yan, Hua-Bing Zhao, Zhi-Lei Tan, Shi-Ru Jia and Pei-Pei Han

Polymers 2019, 11(2), 263; https://doi.org/10.3390/polym11020263 - 4 Feb 2019

Cited by 23 | Viewed by 4190

Abstract

Nostoc flagelliforme is an edible cyanobacterium with excellent food and herbal values. It has been used as food in China for more than 2000 years. Many studies have been focused on improving the yield and bioactivity of Nostoc flagelliforme polysaccharides although these have [...] Read more.

Nostoc flagelliforme is an edible cyanobacterium with excellent food and herbal values. It has been used as food in China for more than 2000 years. Many studies have been focused on improving the yield and bioactivity of Nostoc flagelliforme polysaccharides although these have ignored the functional properties. In this study, we extracted and purified three polysaccharides (WL-CPS, NaCl-CPS and Glu-CPS) from Nostoc flagelliforme under normal, salt stress and mixotrophic culture conditions, respectively, in order to change the physicochemical properties of polysaccharides with the aim of obtaining better functional properties. Both salt stress and mixotrophic culture conditions increased the specific yield of polysaccharides. Their functional properties were comparatively investigated and the results showed that NaCl-CPS exhibited the highest emulsification activity and flocculation capability, which was also higher than that of some commercial products. In contrast, Glu-CPS exhibited the highest water and oil holding capacities, foaming property, intrinsic viscosity and bile acids binding capacity. Our results indicated that both NaCl-CPS and Glu-CPS could be considered to be functional polysaccharides according to their respective characteristics, which have great potential in numerous applications, such as food, pharmaceutical, cosmetic, chemical and mineral industries. These findings also demonstrated the potential application of the proper regulation of culture conditions in the development of polysaccharides with desired functional properties. Full article

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11 pages, 2273 KiB

Open AccessArticle

Solubility Difference between Pectic Fractions from Creeping Fig Seeds

by Ri-si Wang, Xiao-hong He, Hong Lin, Rui-hong Liang, Lu Liang, Jun Chen and Cheng-mei Liu

Polymers 2019, 11(1), 159; https://doi.org/10.3390/polym11010159 - 17 Jan 2019

Cited by 10 | Viewed by 4884

Abstract

Crude water-extracted pectin (WEP) isolated from creeping fig seeds were mainly fractionated into WEP-0.3 and WEP-0.4 fractions. Fractions were confirmed to be nonstarch, nonreducing sugars, nonpolyphenols and protein-unbounded acidic polysaccharides. Interestingly, a significant difference in solubility was found between WEP-0.3 (higher solubility than [...] Read more.

Crude water-extracted pectin (WEP) isolated from creeping fig seeds were mainly fractionated into WEP-0.3 and WEP-0.4 fractions. Fractions were confirmed to be nonstarch, nonreducing sugars, nonpolyphenols and protein-unbounded acidic polysaccharides. Interestingly, a significant difference in solubility was found between WEP-0.3 (higher solubility than WEP) and WEP-0.4 (remarkably insoluble), which was consistent with the amorphous and porous sponge-like structure of WEP-0.3 as well as the crystalline and dense rod-like state of WEP-0.4. However, the result of the FT-IR spectra was contradicted by the solubility of WEP-0.4, which possessed the lowest degree of methoxylation and ought to possess the highest solubility. Through mineral analysis, a considerably high content of Ca²⁺ was found in WEP-0.4, suggesting that the low solubility of WEP-0.4 was probably attributable to the formation of microgels during dialysis. Therefore, metal divalent cations in the dialysate were suggested to be depleted for the dialysis of low methoxyl pectin. Full article

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17 pages, 3312 KiB

Open AccessArticle

Long Term and Large-Scale Continuous Studies on Zinc(II) Sorption and Desorption on Hybrid Pectin-Guar Gum Biosorbent

by Agata Jakóbik-Kolon, Joanna Bok-Badura, Andrzej Milewski and Krzysztof Karoń

Polymers 2019, 11(1), 96; https://doi.org/10.3390/polym11010096 - 8 Jan 2019

Cited by 14 | Viewed by 3239

Abstract

Pectin-guar gum biosorbent was tested for zinc(II) ions removal in column process. Sorption–desorption experiments were performed in laboratory and at larger scale. The breakthrough and elution curves were obtained for various conditions. The Bed Depth Service Time model was tested for utility in [...] Read more.

Pectin-guar gum biosorbent was tested for zinc(II) ions removal in column process. Sorption–desorption experiments were performed in laboratory and at larger scale. The breakthrough and elution curves were obtained for various conditions. The Bed Depth Service Time model was tested for utility in data estimation. Possibility of sorbent reuse and its lifetime was examined in 20 repeated sorption–desorption cycles. Finally, tests were repeated for real wastewater from galvanizing plant, giving satisfactory results. The effectiveness of Zn(II) sorption happened to be dependent on process parameters; tests have proved that it increased with increasing bed height and with decreasing flow rate or grain size. For an initial zinc concentration of 30 mg/L, even 2096 mL of zinc solution could be purified in small scale experiment (2 g of fine grain sorbent and flow rate 60 mL/h) or 5900 L in large-scale (16 kg of large grain sorbent and flow rate 45 L/h). This allowed for 40-fold or 49-fold zinc increases in concentration in one sorption–desorption cycle. The most successful results are meant that at least 20 sorption–desorption cycles could be performed on one portion of biosorbent without loss of its effectiveness, large-scale tests for real wastewater from galvanizing plant gave satisfactory results, and that the form and mechanical stability of our sorbent is suitable for column usage with flow rates applicable in industry. Full article

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14 pages, 3246 KiB

Open AccessArticle

The First Synthesis of Periodic and Alternating Glycopolymers by RAFT Polymerization: A Novel Synthetic Pathway for Glycosaminoglycan Mimics

by Masahiko Minoda, Tomomi Otsubo, Yohei Yamamoto, Jianxin Zhao, Yoshitomo Honda, Tomonari Tanaka and Jin Motoyanagi

Polymers 2019, 11(1), 70; https://doi.org/10.3390/polym11010070 - 5 Jan 2019

Cited by 9 | Viewed by 4748

Abstract

This study concerned the controlled synthesis of periodic glycopolymers by reversible addition-fragmentation chain transfer (RAFT) copolymerization. To this end, maltose- and lactose-substituted vinyl ethers (MalVE and LacVE, respectively) and maltose-substituted maleimide (MalMI) were newly synthesized. RAFT copolymerization of MalVE and ethyl maleimide (EtMI) [...] Read more.

This study concerned the controlled synthesis of periodic glycopolymers by reversible addition-fragmentation chain transfer (RAFT) copolymerization. To this end, maltose- and lactose-substituted vinyl ethers (MalVE and LacVE, respectively) and maltose-substituted maleimide (MalMI) were newly synthesized. RAFT copolymerization of MalVE and ethyl maleimide (EtMI) (monomer feed ratio: MalVE:EtMI = 1:1) afforded periodic glycopolymers (poly(MalVE-co-EtMI)) consisting of major parts of alternating structure (-(MalVE-EtMI)_n-) and a small part of consecutive sequences of EtMI (–EtMI-EtMI-). Occurrence of the latter sequences was caused by the homopolymerizability of maleimide under the present polymerization condition, and the formation of the consecutive sequences of EtMI was successfully suppressed by varying the monomer feed ratio. RAFT copolymerization of LacVE and EtMI was also found to proceed and similarly yielded periodic glycopolymers (poly(LacVE-co-EtMI)). Moreover, RAFT copolymerization of LacVE and MalMI (monomer feed ratio: LacVE:MalMI = 1:1) was performed to give copolymers (poly(LacVE-co-MalMI)) having composition ratio of LacVE/MalMI ≈ 36/64. The resultant periodic glycopolymers poly(MalVE-co-EtMI) and poly(LacVE-co-EtMI) were subjected to lectin binding assay using concanavalin A and peanut agglutinin, exhibiting the glycocluster effect. Moreover, these glycopolymers obtained from the copolymerization of VE and MI were found to be non-cytotoxic. Full article

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2018

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18 pages, 2924 KiB

Open AccessArticle

Molecular Mechanism of Xylogenesis in Moso Bamboo (Phyllostachys edulis) Shoots during Cold Storage

by Changtao Li, Lingling Xuan, Yuming He, Jie Wang, Hui Zhang, Yeqing Ying, Aimin Wu, Antony Bacic, Wei Zeng and Lili Song

Polymers 2019, 11(1), 38; https://doi.org/10.3390/polym11010038 - 27 Dec 2018

Cited by 11 | Viewed by 4957

Abstract

A bamboo shoot is the immature stem of the woody grass and a nutritious and popular vegetable in East Asia. However, it undergoes a rapid xylogenesis process right after harvest, even being stored in a cold chamber. To investigate the molecular regulation mechanisms [...] Read more.

A bamboo shoot is the immature stem of the woody grass and a nutritious and popular vegetable in East Asia. However, it undergoes a rapid xylogenesis process right after harvest, even being stored in a cold chamber. To investigate the molecular regulation mechanisms of xylogenesis in Moso bamboo (Phyllostachys edulis) shoots (MBSes) during cold storage, the measurement of cell wall polymers (cellulose, hemicellulose, and lignin) and related enzyme activities (phenylalanine ammonia lyase (PAL), cinnamyl alcohol dehydrogenase (CAD), peroxidase (POD), and xylan xylosyltransferase (XylT)) and transcriptomic analysis were performed during cold storage. It was noticed that cellulose and lignin contents increased, while hemicellulose content exhibited a downward trend. PAL, CAD, and POD activity presented an upward trend generally in MBS when stored at 4 °C for 16 days. XylT activity showed a descending trend during the stages of storage, but slightly increased during the 8th to 12th days after harvest at 4 °C. Transcriptomic analysis identified 72, 28, 44, and 31 functional unigenes encoding lignin, cellulose, xylan biosynthesis enzymes, and transcription factors (TFs), respectively. Many of these secondary cell wall (SCW)-related genes showed higher expression levels in the later period of cold storage. Quantitative RT-PCR analysis of the selected genes conformed to the expression pattern. Our study provides a comprehensive analysis of MBS secondary wall biosynthesis at the molecular level during the cold storage process. The results give insight into the xylogenesis process of this economically important vegetable and shed light on solving this problem of the post-harvest industry. Full article

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15 pages, 4114 KiB

Open AccessArticle

Effect of an Atmospheric Pressure Plasma Jet on the Structure and Physicochemical Properties of Waxy and Normal Maize Starch

by Yaping Zhou, Yizhe Yan, Miaomiao Shi and Yanqi Liu

Polymers 2019, 11(1), 8; https://doi.org/10.3390/polym11010008 - 21 Dec 2018

Cited by 43 | Viewed by 5605

Abstract

In present study, a novel physical modification of waxy maize starch (WMS) and normal maize starch (NMS) was investigated by using an atmospheric pressure plasma jet (APPJ) treatment. The effect on the structure and physicochemical properties of both starches was demonstrated by treatment [...] Read more.

In present study, a novel physical modification of waxy maize starch (WMS) and normal maize starch (NMS) was investigated by using an atmospheric pressure plasma jet (APPJ) treatment. The effect on the structure and physicochemical properties of both starches was demonstrated by treatment with a 5% starch suspension (w/w) with APPJ for short periods of time (1, 3, 5, or 7 min). The pH of WMS and NMS was decreased after APPJ treatment from 5.42 to 4.94, and 5.09 to 4.75, respectively. The water-binding capacity (WBC) (WMS: 105.19%–131.27%, NMS: 83.56%–95.61%) and swelling volume (SV) (WMS: 2.96 g/mL–3.33 g/mL, NMS: 2.75 g/mL–3.05 g/mL) of the starches were obviously increased by APPJ treatment. The surfaces of starch granules were wrecked, due to plasma etching. No changes in the crystalline types of both starches were observed. However, the relative crystallinities (RCs) of WMS and NMS were reduced from 46.7% to 42.0%, and 40.1% to 35.7%, respectively. Moreover, the short-range molecular orders of both starches were slightly reduced. In addition, APPJ treatment resulted in lower gelatinization temperature and enthalpies. Therefore, APPJ provides a mild and green approach to starch modification, showing great potential for applications in the food and non-food industry. Full article

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23 pages, 3429 KiB

Open AccessReview

Polysaccharide Based Scaffolds for Soft Tissue Engineering Applications

by Sanjay Tiwari, Rahul Patil and Pratap Bahadur

Polymers 2019, 11(1), 1; https://doi.org/10.3390/polym11010001 - 20 Dec 2018

Cited by 113 | Viewed by 9150

Abstract

Soft tissue reconstructs require materials that form three-dimensional (3-D) structures supportive to cell proliferation and regenerative processes. Polysaccharides, due to their hydrophilicity, biocompatibility, biodegradability, abundance, and presence of derivatizable functional groups, are distinctive scaffold materials. Superior mechanical properties, physiological signaling, and tunable tissue [...] Read more.

Soft tissue reconstructs require materials that form three-dimensional (3-D) structures supportive to cell proliferation and regenerative processes. Polysaccharides, due to their hydrophilicity, biocompatibility, biodegradability, abundance, and presence of derivatizable functional groups, are distinctive scaffold materials. Superior mechanical properties, physiological signaling, and tunable tissue response have been achieved through chemical modification of polysaccharides. Moreover, an appropriate formulation strategy enables spatial placement of the scaffold to a targeted site. With the advent of newer technologies, these preparations can be tailor-made for responding to alterations in temperature, pH, or other physiological stimuli. In this review, we discuss the developmental and biological aspects of scaffolds prepared from four polysaccharides, viz. alginic acid (ALG), chitosan (CHI), hyaluronic acid (HA), and dextran (DEX). Clinical studies on these scaffolds are also discussed. Full article

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13 pages, 2485 KiB

Open AccessArticle

Dynamic High-Pressure Microfluidization-Treated Pectin under Different Ethanol Concentrations

by Cheng-Mei Liu, Lu Liang, Xi-Xiang Shuai, Rui-Hong Liang and Jun Chen

Polymers 2018, 10(12), 1410; https://doi.org/10.3390/polym10121410 - 19 Dec 2018

Cited by 17 | Viewed by 4789

Abstract

We previously reported that dynamic high-pressure microfluidization (DHPM) can degrade pectin in aqueous solution. In this study, we further investigated the effect of DHPM on pectin in water-ethanol systems. In the absence of DHPM treatment, it was found that pectin exhibited increased average [...] Read more.

We previously reported that dynamic high-pressure microfluidization (DHPM) can degrade pectin in aqueous solution. In this study, we further investigated the effect of DHPM on pectin in water-ethanol systems. In the absence of DHPM treatment, it was found that pectin exhibited increased average particle size and unchanged average molecular weight, but a decline in reducing-sugar-ends content with the increase of ethanol concentrations (0–10% v/v). These results indicated that the addition of ethanol induced aggregation of pectin. During DHPM treatment, pectin underwent disaggregation and degradation under all measured ethanol concentrations. Disaggregation was enhanced but degradation was weakened with the increase of ethanol concentration. FT-IR and UV spectra indicated that demethylation but no β-elimination occurred in the water-ethanol system during DHPM. Finally, the mechanism of DHPM-induced disaggregation and degradation of pectin under a water-ethanol system was updated. This work may help us to find a suitable condition for reducing the degradation of pectin during the process of homogenization. Full article

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31 pages, 726 KiB

Open AccessReview

Biological Activity and Pharmacological Application of Pectic Polysaccharides: A Review

by Salima T. Minzanova, Vladimir F. Mironov, Daria M. Arkhipova, Anna V. Khabibullina, Lubov G. Mironova, Yulia M. Zakirova and Vasili A. Milyukov

Polymers 2018, 10(12), 1407; https://doi.org/10.3390/polym10121407 - 19 Dec 2018

Cited by 215 | Viewed by 13195

Abstract

Pectin is a polymer with a core of alternating α-1,4-linked d-galacturonic acid and α-1,2-l-rhamnose units, as well as a variety of neutral sugars such as arabinose, galactose, and lesser amounts of other sugars. Currently, native pectins have been compared [...] Read more.

Pectin is a polymer with a core of alternating α-1,4-linked d-galacturonic acid and α-1,2-l-rhamnose units, as well as a variety of neutral sugars such as arabinose, galactose, and lesser amounts of other sugars. Currently, native pectins have been compared to modified ones due to the development of natural medicines and health products. In this review, the results of a study of the bioactivity of pectic polysaccharides, including its various pharmacological applications, such as its immunoregulatory, anti-inflammatory, hypoglycemic, antibacterial, antioxidant and antitumor activities, have been summarized. The potential of pectins to contribute to the enhancement of drug delivery systems has been observed. Full article

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13 pages, 3541 KiB

Open AccessArticle

Solid-Phase Synthesis of Cellulose Acetate Butyrate as Microsphere Wall Materials for Sustained Release of Emamectin Benzoate

by Aimin Huang, Xuanhai Li, Xingtang Liang, Yanjuan Zhang, Huayu Hu, Yanzhen Yin and Zuqiang Huang

Polymers 2018, 10(12), 1381; https://doi.org/10.3390/polym10121381 - 13 Dec 2018

Cited by 32 | Viewed by 5824

Abstract

Emamectin benzoate (EB), a widely used pesticide, is prone to decomposition by ultraviolet light and suffers from the corresponding loss of efficacy. The timed release of EB based on microspheres is one of the effective methods to solve this issue. As a non-toxic [...] Read more.

Emamectin benzoate (EB), a widely used pesticide, is prone to decomposition by ultraviolet light and suffers from the corresponding loss of efficacy. The timed release of EB based on microspheres is one of the effective methods to solve this issue. As a non-toxic cellulose ester, cellulose acetate butyrate (CAB) is regarded as one of the best wall-forming materials for microcapsules with a good controlled release performance. Herein, two methods—mechanical activation (MA) technology and a conventional liquid phase (LP) method—were employed to synthesize different CABs, namely CAB-MA and CAB-LP, respectively. The molecular structure, rheological property, and thermal stability of these CABs were investigated. The two CABs were used to prepare microspheres for the loading and release of EB via an o/w (oil-in-water) solvent evaporation method. Moreover, the performances such as drug loading, drug entrapment, and anti-photolysis of the drug for these microspheres were studied. The results showed that both CABs were available as wall materials for loading and releasing EB. Compared with CAB-LP, CAB-MA presented a lower molecular weight and a narrower molecular weight distribution. Moreover, the MA method endowed the CAB with more ester substituent groups and less crystalline structure in comparison to the LP method, which had benefits including pelletizing and drug loading. Full article

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12 pages, 2757 KiB

Open AccessArticle

Changes in the Structure and Digestibility of Wrinkled Pea Starch with Malic Acid Treatment

by Miaomiao Shi, Qunyu Gao and Yanqi Liu

Polymers 2018, 10(12), 1359; https://doi.org/10.3390/polym10121359 - 7 Dec 2018

Cited by 25 | Viewed by 4224

Abstract

Resistant starch has gradually become a popular food component due to its beneficial physiological effects and heat resistance during processing. In this study, the structure, reaction mechanism, and digestibility of wrinkled pea starch with malic acid and heat–moisture treatment (HMT) are investigated. The [...] Read more.

Resistant starch has gradually become a popular food component due to its beneficial physiological effects and heat resistance during processing. In this study, the structure, reaction mechanism, and digestibility of wrinkled pea starch with malic acid and heat–moisture treatment (HMT) are investigated. The degree of substitution (DS) of malate starch, HMT-malate starch, and malate-HMT starch was 0.164, 0.280, and 0.146, respectively. Malate starch remained in its complete particle form and pronounced birefringence was displayed. However, the malate-HMT starch sample was almost completely broken into pieces and lost the polarized cross. All modified starch samples had a decreased swelling power and a new peak at 1731–1741 cm⁻¹ shown by FTIR. From the ¹³C CP/MAS NMR (Cross Polarizatio/Magic Angle Spinning Nuclear Magnetic Resonance) spectra, all the modified starches had extra peaks at 38.5 ppm and 172.8 ppm. After esterification treatment, the resistant starch (RS) and slowly digestible starch (SDS) content of starch samples increased dramatically. The higher content of RS and lower enzymatic hydrolysis rate of the malate starch could be used to produce low-calorie foods and have potential health benefits. Full article

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17 pages, 795 KiB

Open AccessArticle

The Drop-in-Drop Encapsulation in Chitosan and Sodium Alginate as a Method of Prolonging the Quality of Linseed Oil

by Szymon Mania, Robert Tylingo and Anna Michałowska

Polymers 2018, 10(12), 1355; https://doi.org/10.3390/polym10121355 - 6 Dec 2018

Cited by 11 | Viewed by 3388

Abstract

Nowadays, the encapsulation of sensitive products by various techniques has become popular as a promising preservation method. In particular, this applies to oils with a high content of unsaturated fatty acids and a high susceptibility to deterioration. This work presents the possibility of [...] Read more.

Nowadays, the encapsulation of sensitive products by various techniques has become popular as a promising preservation method. In particular, this applies to oils with a high content of unsaturated fatty acids and a high susceptibility to deterioration. This work presents the possibility of using a chitosan and sodium alginate in the form of a hydrogel membrane to protect food ingredients such as linseed oil, which is stored in an aquatic environment. The obtained results showed the high efficiency of the coaxial method encapsulation, which did not affect the quality of the oil measured after encapsulation. The greatest protective effect was observed in the linseed oil–chitosan membrane system, in which the primary and secondary oxidation products content were 88% and 32% lower than in the control sample, respectively. The smallest changes of the fatty acid profile, conjugated dienes, and trienes were observed in the chitosan capsules with linseed oil compared to the control sample. Full article

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10 pages, 3404 KiB

Open AccessArticle

Reversible Stability of Emulsion and Polymer Latex Controlled by Oligochitosan and CO₂

by Liang Li, Na Guo, Xiao Zhang, Wen Ou, Shengcai Yang, Xin Su and Yujun Feng

Polymers 2018, 10(12), 1352; https://doi.org/10.3390/polym10121352 - 6 Dec 2018

Cited by 6 | Viewed by 4197

Abstract

The addition of salt to a colloid solution ensures that emulsions can be easily separated into two phases and that polymer latexes can be coagulated. The switchable stability of emulsions and polymer latexes would improve the properties for their current applications. A switchable [...] Read more.

The addition of salt to a colloid solution ensures that emulsions can be easily separated into two phases and that polymer latexes can be coagulated. The switchable stability of emulsions and polymer latexes would improve the properties for their current applications. A switchable process of salt addition can be achieved using CO₂ and switchable water, and it is a novel, benign approach to achieving a switchable ionic strength in an aqueous solution. However, the problem associated with switchable water is that its additives are all synthetic tertiary amines, most of which are harmful to human beings and the environment. Oligochitosan, as a natural product, can also be used as a switchable water additive. In this paper, a new switchable water system using oligochitosan to change the ionic strength was explored for use in several potential industrial applications. The conductivity of the aqueous solution of oligochitosan (0.2 wt.%) was switched from 0.2 to 331 μS/cm through the addition and removal of CO₂. Oligochitosan and CO₂ were successfully utilized to reversibly break a crude oil emulsion. Polystyrene (PS) latexes could also be reversibly destabilized; the zeta potential of the PS latex changed between −5.8 and −45.2 mV in the absence and presence of CO₂ after oligochitosan was dissolved in the PS latex. The use of oligochitosan is a more environmentally friendly means for reversibly separating colloid solutions. Full article

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15 pages, 26080 KiB

Open AccessArticle

Mixed Membranes Comprising Carboxymethyl Cellulose (as Capping Agent and Gas Barrier Matrix) and Nanoporous ZIF-L Nanosheets for Gas Separation Applications

by Fang Zhang, Jing Dou and Hui Zhang

Polymers 2018, 10(12), 1340; https://doi.org/10.3390/polym10121340 - 4 Dec 2018

Cited by 59 | Viewed by 7068

Abstract

Two-dimensional metal–organic framework (MOF) nanosheets with molecular sieving properties and unique dimensional advantages are highly desired as polymer fillers for gas separation applications. Regarding polymer-supported MOF membranes, it is crucial to enhance the adhesion between the polymeric substrate and the MOF component and [...] Read more.

Two-dimensional metal–organic framework (MOF) nanosheets with molecular sieving properties and unique dimensional advantages are highly desired as polymer fillers for gas separation applications. Regarding polymer-supported MOF membranes, it is crucial to enhance the adhesion between the polymeric substrate and the MOF component and avoid MOF particle agglomeration. In this study, hydrophobic, embedded nanoporous nanosheets of a 2D zeolitic imidazolate framework synthesized using zinc salt and 2-methylimidazole (Hmim) aqueous solution (ZIF-L) were incorporated into a carboxymethyl cellulose (CMC) solution to form a steady mixed aqueous suspension through one-step solution blending. This prepared the composite membranes with a fine dispersion of ZIF-L nanosheets (up to loadings of 52.88 vol %) and good adhesion within the highly dense structural CMC matrix due to the strong interactions between ZIF-L and CMC, as confirmed by FTIR, Zeta potential, XPS, and SEM analysis. The potential advantages of CMC over classic polymer matrices used for gas separation mainly include: (a) Good interaction, (b) high dispersion of ZIF-L nanosheets, (c) the gas barrier nature of the CMC membrane, and (d) a facile water-based synthetic process. Based on the molecular sieving effect of ZIF-L and the gas barrier nature of the CMC matrix, gas permeation tests (H₂, CO₂, N₂, CH₄) of the mixed membrane showed a great improvement in gas selectivities compared with the CMC membrane and the reported pure ZIF membranes. Full article

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21 pages, 4768 KiB

Open AccessArticle

Isothermal Adsorption Properties for the Adsorption and Removal of Reactive Blue 221 Dye from Aqueous Solutions by Cross-Linked β-Chitosan Glycan as Acid-Resistant Adsorbent

by Chih-Wei Chiu, Ming-Tsung Wu, Jimmy Chi-Min Lee and Ting-Yu Cheng

Polymers 2018, 10(12), 1328; https://doi.org/10.3390/polym10121328 - 30 Nov 2018

Cited by 20 | Viewed by 4840

Abstract

Dye effluent causes serious pollution and damage to the environment and needs a series of treatments before it can be discharged. Among the numerous effluent treatment methods, adsorption is the simplest and does not cause secondary pollution. Bio-adsorbents are especially advantageous in the [...] Read more.

Dye effluent causes serious pollution and damage to the environment and needs a series of treatments before it can be discharged. Among the numerous effluent treatment methods, adsorption is the simplest and does not cause secondary pollution. Bio-adsorbents are especially advantageous in the treatment of low-concentration dye effluent. In this study, the adsorption and removal capacities of unmodified α- and β-chitosan and modified β-chitosan (β-chitosan cross-linked with triethylenetetramine, BCCT) on C.I. Reactive Blue 221 (RB221) dye were compared. The experiments were performed on the adsorption of the RB221 dye by unmodified α- and β-chitosan and cross-linkage–modified BCCT at different temperatures and for different durations, which are presented along with the relevant adsorption kinetics calculations. According to the results, as the temperature increased from 303 to 333 K, the initial adsorption rates of the adsorbents, α-chitosan, β-chitosan, and BCCT, for the RB221 dye, changed from 1.01 × 10², 4.74 × 10², and 1.48 × 10⁶ mg/g min to 5.98 × 10⁴, 4.23 × 10⁸, and 1.52 × 10¹³ mg/g min, respectively. BCCT thus showed the best adsorption for the dye at all temperatures from the Elovich model. These results confirmed the successful introduction of a polyaminated and cross-linked extended structure as a modification for the BCCT adsorbent, which makes it resistant to acid hydrolysis and gives it the functional amine group for dye adsorption, thereby promoting the ability of BCCT to adsorb dyes under strongly acidic conditions. The compound synthesized in this study is expected to be a good choice in the future for purifying strongly acidic effluent containing anionic organic dyes. Full article

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12 pages, 21189 KiB

Open AccessArticle

Isothermal Crystallization and Rheology Properties of Isotactic Polypropylene/Bacterial Cellulose Composite

by Bo Wang, Fu-hua Lin, Xiang-yang Li, Zhong-wei Zhang, Xiao-rong Xue, Si-xiao Liu, Xu-ran Ji, Qian Yu, Zheng-qiu Yuan, Xin-de Chen and Jun Luo

Polymers 2018, 10(11), 1284; https://doi.org/10.3390/polym10111284 - 18 Nov 2018

Cited by 26 | Viewed by 3968

Abstract

Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were [...] Read more.

Bacterial cellulose (BC) is a new kind of cellulose with great potential in enhancing preparation of isotactic Polypropylene (iPP) composites, which have been found with excellent performance. However, the interface compatibility between BC and iPP is poor. In this study, iPP/BC composites were prepared by solution mixing. Esterification modified BC (CO) and Maleic anhydride grafted polypropylene (MAPP) added as a compatibilizer was both used to improve the interfacial compatibility of the iPP/BC composites. The rheology and isothermal crystallization behavior of the composites was tested and discussed. The result shows that the complex viscosity and storage modulus of the composite significantly increase in the rule iPP, iPP/BC2, iPP/CO2, and M-iPP/BC3, which indicates that the compatibility of the composite increases as this rule. According to the isothermal crystallization kinetics result, the crystal growth mode of iPP was not affected by the addition of BC and the interfacial compatibility. The spherulite growth rate of the iPP/BC composite increases with increasing crystallization temperature. Especially, the value decreases as the same rule with the complex viscosity and storage modulus of the composite at the same isothermal crystallization temperature. These results suggest that the interface compatibility of iPP/BC composites is greatly improved and the interface compatibility of the M-iPP/BC3 is better than the iPP/CO2. Full article

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9 pages, 22801 KiB

Open AccessArticle

Difference in Macroscopic Morphologies of Amylosic Supramolecular Networks Depending on Guest Polymers in Vine-Twining Polymerization

by Saya Orio, Takuya Shoji, Kazuya Yamamoto and Jun-ichi Kadokawa

Polymers 2018, 10(11), 1277; https://doi.org/10.3390/polym10111277 - 16 Nov 2018

Cited by 8 | Viewed by 3919

Abstract

Amylose, a natural polysaccharide, acts as a host molecule to form supramolecular inclusion complexes in its enzymatically formation process, that is, phosphorylase-catalyzed enzymatic polymerization using the α-d-glucose 1-phosphate monomer and the maltooligosaccharide primer, in the presence of appropriate guest polymers (vine-twining [...] Read more.

Amylose, a natural polysaccharide, acts as a host molecule to form supramolecular inclusion complexes in its enzymatically formation process, that is, phosphorylase-catalyzed enzymatic polymerization using the α-d-glucose 1-phosphate monomer and the maltooligosaccharide primer, in the presence of appropriate guest polymers (vine-twining polymerization). Furthermore, in the vine-twining polymerization using maltooligosaccharide primer-grafted polymers, such as maltoheptaose (G₇)-grafted poly(γ-glutamic acid) (PGA), in the presence of poly(ε-caprolactone) (PCL), the enzymatically elongated amylose graft chains have formed inclusion complexes with PCL among the PGA main-chains to construct supramolecular networks. Either hydrogelation or aggregation as a macroscopic morphology from the products was observed in accordance with PCL/primer feed ratios. In this study, we evaluated macroscopic morphologies from such amylosic supramolecular networks with different guest polymers in the vine-twining polymerization using G₇-grafted PGA in the presence of polytetrahydrofuran (PTHF), PCL, and poly(l-lactide) (PLLA). Consequently, we found that the reaction mixture using PTHF totally turned into a hydrogel form, whereas the products using PCL and PLLA were aggregated in the reaction mixtures. The produced networks were characterized by powder X-ray diffraction and scanning electron microscopic measurements. The difference in the macroscopic morphologies was reasonably explained by stabilities of the complexes depending on the guest polymers. Full article

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18 pages, 3859 KiB

Open AccessArticle

Therapeutic Effect and Metabolic Mechanism of A Selenium-Polysaccharide from Ziyang Green Tea on Chronic Fatigue Syndrome

by Changzhuan Shao, Jing Song, Shanguang Zhao, Hongke Jiang, Baoping Wang and Aiping Chi

Polymers 2018, 10(11), 1269; https://doi.org/10.3390/polym10111269 - 15 Nov 2018

Cited by 18 | Viewed by 4807

Abstract

Ziyang green tea was considered a medicine food homology plant to improve chronic fatigue Ssyndrome (CFS) in China. The aim of this research was to study the therapeutic effect of selenium-polysaccharides (Se-TP) from Ziyang green tea on CFS and explore its metabolic mechanism. [...] Read more.

Ziyang green tea was considered a medicine food homology plant to improve chronic fatigue Ssyndrome (CFS) in China. The aim of this research was to study the therapeutic effect of selenium-polysaccharides (Se-TP) from Ziyang green tea on CFS and explore its metabolic mechanism. A CFS-rats model was established in the present research and Se-TP was administrated to evaluate the therapeutic effect on CFS. Some serum metabolites including blood urea nitrogen (BUN), blood lactate acid (BLA), corticosterone (CORT), and aldosterone (ALD) were checked. Urine metabolites were analyzed via gas chromatography-mass spectrometry (GC-MS). Multivariate statistical analysis was also used to check the data. The results selected biomarkers that were entered into the MetPA database to analyze their corresponding metabolic pathways. The results demonstrated that Se-TP markedly improved the level of BUN and CORT in CFS rats. A total of eight differential metabolites were detected in GC-MS analysis, which were benzoic acid, itaconic acid, glutaric acid, 4-acetamidobutyric acid, creatine, 2-hydroxy-3-isopropylbutanedioic acid, l-dopa, and 21-hydroxypregnenolone. These differential metabolites were entered into the MetPA database to search for the corresponding metabolic pathways and three related metabolic pathways were screened out. The first pathway was steroid hormone biosynthesis. The second was tyrosine metabolism, and the third was arginine-proline metabolism. The 21-hydroxypregnenolone level of rats in the CFS group markedly increased after the Se-TP administration. In conclusion, Se-TP treatments on CFS rats improved their condition. Its metabolic mechanism was closely related to that which regulates the steroid hormone biosynthesis. Full article

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15 pages, 3608 KiB

Open AccessArticle

Starch-Based Flexible Coating for Food Packaging Paper with Exceptional Hydrophobicity and Antimicrobial Activity

by Shuzhen Ni, Hui Zhang, Hongqi Dai and Huining Xiao

Polymers 2018, 10(11), 1260; https://doi.org/10.3390/polym10111260 - 13 Nov 2018

Cited by 54 | Viewed by 10014

Abstract

Herein, we fabricated a starch-based flexible coating for food packaging papers with excellent hydrophobicity and antimicrobial properties. FTIR (Fourier transform infrared) and XRD (X-ray diffraction) spectra revealed the homogeneous dispersion of the ZnO nanoparticles (NPs) in the composite film within 5% ZnO NP [...] Read more.

Herein, we fabricated a starch-based flexible coating for food packaging papers with excellent hydrophobicity and antimicrobial properties. FTIR (Fourier transform infrared) and XRD (X-ray diffraction) spectra revealed the homogeneous dispersion of the ZnO nanoparticles (NPs) in the composite film within 5% ZnO NP dosage. SEM (scanning electron microscope) and AFM (atomic force microscope) micrographs confirmed the increased roughness on the composite film with the increased dosages of ZnO NPs. Hydrophobic characteristics showed that dramatic enhancement was obtained in the values and stabilities of DCAs (dynamic contact angles) in the resultant film and coated paper. TG (thermogravimetry) results demonstrated the increased thermal stabilities of the composite films. Significantly, a decreased water vapor transmission rate was observed in the coated paper. When 20% guanidine-based starch and 2% CMC (carboxy methyl cellulose) was added, a flexible coating with excellent antimicrobial activity towards Escherichia coli can be obtained. Furthermore, the migration of ZnO NPs into the food simulants was well below the overall migration legislative limit. The resultant starch-based flexible composite film and coated paper established an effective approach to develop a green-based material for food packaging applications. Full article

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15 pages, 3325 KiB

Open AccessArticle

Effects of Achyranthes bidentata Polysaccharides on Intestinal Morphology, Immune Response, and Gut Microbiome in Yellow Broiler Chickens Challenged with Escherichia coli K88

by Zhuying Liu, Xiaolong Wang, Shuqi Ou, Muhammed Adebayo Arowolo, De-Xing Hou and Jianhua He

Polymers 2018, 10(11), 1233; https://doi.org/10.3390/polym10111233 - 7 Nov 2018

Cited by 40 | Viewed by 5963

Abstract

The present study was conducted to investigate the effects of dietary Achyranthes bidentata polysaccharide (ABPS) supplementation on performance, immune response, intestinal mucosal morphology, and gut microbiome in yellow-feathered broilers challenged with Escherichia coli K88. A 2 × 2 factorial design was used for [...] Read more.

The present study was conducted to investigate the effects of dietary Achyranthes bidentata polysaccharide (ABPS) supplementation on performance, immune response, intestinal mucosal morphology, and gut microbiome in yellow-feathered broilers challenged with Escherichia coli K88. A 2 × 2 factorial design was used for the trial. Two hundred and forty one-day-old female broilers were randomly assigned to four treatments: (1) negative-control broilers were fed by a basal diet and saline (NG); (2) positive-control broilers were fed by a basal diet and orally challenged with 10⁸ CFU E. coli K88 (CNG); (3) ABP group broilers were fed by a basal diet containing ABPS (500 mg/kg of feed) and saline; (4) CABP group broilers were fed by a basal diet containing ABPS (500 mg/kg of feed) and orally challenged with 10⁸ CFU E. coli K88. Growth performance, serum biochemical indexes, immune responses, intestinal mucosal morphology, and cecal microbial community structure were evaluated. The ABP group had greatest body weight (BW), average daily body weight gain (ADG), and intestinal villus height compared to other treatments (p < 0.05). The CABP group had a higher villus height/crypt depth ratio (V/C) compared with other treatments (p < 0.05). The expression levels of NF-κB were lower in the ABP group. The CNG group had higher Escherichia coli and Enterococcus contents in cecal samples compared to other treatments (p < 0.05). Serum glucose, uric acid, TNF-α, and Secretory Immunoglobulin A (S-IgA) levels were higher in broilers challenged with E. coli (p < 0.001) than that with saline. Broilers challenged with E. coli had reduced taxa richness in the cecal samples. Sequencing of 16S rRNA genes in cecal samples revealed that a lower proportion of Firmicutes and a higher proportion of Proteobacteria were detected in the broilers challenged with E. coli. Compared with the controls, dietary ABPS supplementation increased serum total protein, albumin, and S-IgA levels, but decreased serum glucose, uric acid, and TNF-α levels in broilers (p < 0.05). Diet supplemented with ABPS increased the Firmicutes/Bacteroidetes ratio and the abundance of Ruminococcaceae and Lachnospiraceae, and altered cecal microbiota community structure. These results suggest that ABPS can promote growth performance and improve intestinal morphology and microbiota community structure in broilers challenged with E. coli K88. Full article

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17 pages, 3944 KiB

Open AccessArticle

Application of Industrially Produced Chitosan in the Surface Treatment of Fibre-Based Material: Effect of Drying Method and Number of Coating Layers on Mechanical and Barrier Properties

by Samir Kopacic, Andrea Walzl, Ulrich Hirn, Armin Zankel, Rudolf Kniely, Erich Leitner and Wolfgang Bauer

Polymers 2018, 10(11), 1232; https://doi.org/10.3390/polym10111232 - 7 Nov 2018

Cited by 23 | Viewed by 5199

Abstract

Chitosan is a versatile biopolymer with many interesting functionalities. Its effects on the barrier and mechanical properties of single- or double-coated fibre-based packaging papers in dependence on the applied drying regime were successfully tested. Our investigations revealed chitosan to be a highly robust [...] Read more.

Chitosan is a versatile biopolymer with many interesting functionalities. Its effects on the barrier and mechanical properties of single- or double-coated fibre-based packaging papers in dependence on the applied drying regime were successfully tested. Our investigations revealed chitosan to be a highly robust biopolymer, since the different drying regimes did not alter its contribution to the development of strength and barrier properties of the coated packaging papers. These properties showed a stronger influence of the applied coat weights than of the different drying regimes. The effect of chitosan coatings were quantified by measuring tensile strength (TS), burst strength (BS) and tensile energy absorption (TEA). These revealed that TS, BS and TEA of the coated papers increased significantly. Moreover, the chitosan-coated papers were less permeable against water vapor and air. High grease resistance was observed for double-coated papers, irrespective of the drying regimes. The coated paper surface showed a more hydrophilic character, resulting in lower contact angles and higher water absorption properties. In this study, industrially produced chitosan has been proven to be a renewable, robust biopolymer that can be utilized as an additive to increase strength and the barrier properties of fibre-based materials. Full article

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20 pages, 8230 KiB

Open AccessArticle

Fabrication of Quaternized Chitosan Nanoparticles Using Tripolyphosphate/Genipin Dual Cross-Linkers as a Protein Delivery System

by Kuo-Yu Chen and Si-Ying Zeng

Polymers 2018, 10(11), 1226; https://doi.org/10.3390/polym10111226 - 5 Nov 2018

Cited by 30 | Viewed by 5264

Abstract

Various amounts of 2-((acryloyloxy)ethyl)trimethylammonium chloride were grafted onto chitosan (CS) via redox polymerization method to obtain water-soluble quaternized CS (QCS). The QCS nanoparticles loaded with bovine serum albumin (BSA) were then produced by ionic gelation with tripolyphosphate (TPP) and further covalently cross-linked with [...] Read more.

Various amounts of 2-((acryloyloxy)ethyl)trimethylammonium chloride were grafted onto chitosan (CS) via redox polymerization method to obtain water-soluble quaternized CS (QCS). The QCS nanoparticles loaded with bovine serum albumin (BSA) were then produced by ionic gelation with tripolyphosphate (TPP) and further covalently cross-linked with genipin. The formation of QCS nanoparticles was optimized as a function of monomer grafting yield, QCS/TPP weight ratio, and QCS/genipin weight ratio by Box-Behnken design and response surface methodology. The results showed that QCS nanoparticles prepared with a grafting yield of 50%, QCS/TPP weight ratio of 7.67, and QCS/genipin weight ratio of 60 had a particle size of 193.68 ± 44.92 nm, polydispersity of 0.232, zeta potential of +23.97 mV and BSA encapsulation efficiency of 46.37 ± 2.89%, which were close to the predicted values from mathematical models. In vitro drug release studies at pH 1.2 and pH 7.4 exhibited that the release rate of BSA was significantly decreased and the release period was significantly prolonged after QCS nanoparticles cross-linking with genipin. Therefore, QCS nanoparticles cross-linked with TPP/genipin dual cross-linkers may be a promising protein drug carrier for a prolonged and sustained delivery. Full article

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24 pages, 3681 KiB

Open AccessReview

Strategies for Improving Ocular Drug Bioavailability and Corneal Wound Healing with Chitosan-Based Delivery Systems

by Teodora Irimia, Mihaela Violeta Ghica, Lăcrămioara Popa, Valentina Anuţa, Andreea-Letiţia Arsene and Cristina-Elena Dinu-Pîrvu

Polymers 2018, 10(11), 1221; https://doi.org/10.3390/polym10111221 - 3 Nov 2018

Cited by 93 | Viewed by 7643

Abstract

The main inconvenience of conventional eye drops is the rapid washout of the drugs due to nasolacrimal drainage or ophthalmic barriers. The ocular drug bioavailability can be improved by either prolonging retention time in the cul-de-sac or by increasing the ocular permeability. The [...] Read more.

The main inconvenience of conventional eye drops is the rapid washout of the drugs due to nasolacrimal drainage or ophthalmic barriers. The ocular drug bioavailability can be improved by either prolonging retention time in the cul-de-sac or by increasing the ocular permeability. The focus of this review is to highlight some chitosan-based drug delivery approaches that proved to have good clinical efficacy and high potential for use in ophthalmology. They are exemplified by recent studies exploring in-depth the techniques and mechanisms in order to improve ocular bioavailability of the active substances. Used alone or in combination with other compounds with synergistic action, chitosan enables ocular retention time and corneal permeability. Associated with other stimuli-responsive polymers, it enhances the mechanical strength of the gels. Chitosan and its derivatives increase drug permeability through the cornea by temporarily opening tight junctions between epithelial cells. Different types of chitosan-based colloidal systems have the potential to overcome the ocular barriers without disturbing the vision process. Chitosan also plays a key role in improving corneal wound healing by stimulating the migration of keratinocytes when it is used alone or in combination with other compounds with synergistic action. Full article

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27 pages, 5798 KiB

Open AccessArticle

Injectable and Gellable Chitosan Formulations Filled with Cellulose Nanofibers for Intervertebral Disc Tissue Engineering

by Ingo Doench, Maria E. W. Torres-Ramos, Alexandra Montembault, Paula Nunes de Oliveira, Celia Halimi, Eric Viguier, Laurent Heux, Robin Siadous, Rossana M. S. M. Thiré and Anayancy Osorio-Madrazo

Polymers 2018, 10(11), 1202; https://doi.org/10.3390/polym10111202 - 27 Oct 2018

Cited by 77 | Viewed by 7813

Abstract

The development of non-cellularized injectable suspensions of viscous chitosan (CHI) solutions (1.7–3.3% (w/w)), filled with cellulose nanofibers (CNF) (0.02–0.6% (w/w)) of the type nanofibrillated cellulose, was proposed for viscosupplementation of the intervertebral disc nucleus pulposus [...] Read more.

The development of non-cellularized injectable suspensions of viscous chitosan (CHI) solutions (1.7–3.3% (w/w)), filled with cellulose nanofibers (CNF) (0.02–0.6% (w/w)) of the type nanofibrillated cellulose, was proposed for viscosupplementation of the intervertebral disc nucleus pulposus tissue. The achievement of CNF/CHI formulations which can gel in situ at the disc injection site constitutes a minimally-invasive approach to restore damaged/degenerated discs. We studied physico-chemical aspects of the sol and gel states of the CNF/CHI formulations, including the rheological behavior in relation to injectability (sol state) and fiber mechanical reinforcement (gel state). CNF-CHI interactions could be evidenced by a double flow behavior due to the relaxation of the CHI polymer chains and those interacting with the CNFs. At high shear rates resembling the injection conditions with needles commonly used in surgical treatments, both the reference CHI viscous solutions and those filled with CNFs exhibited similar rheological behavior. The neutralization of the flowing and weakly acidic CNF/CHI suspensions yielded composite hydrogels in which the nanofibers reinforced the CHI matrix. We performed evaluations in relation to the biomedical application, such as the effect of the intradiscal injection of the CNF/CHI formulation in pig and rabbit spine models on disc biomechanics. We showed that the injectable formulations became hydrogels in situ after intradiscal gelation, due to CHI neutralization occurring in contact with the body fluids. No leakage of the injectate through the injection canal was observed and the gelled formulation restored the disc height and loss of mechanical properties, which is commonly related to disc degeneration. Full article

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13 pages, 2782 KiB

Open AccessArticle

Effect of Modified Tapioca Starch on Mechanical, Thermal, and Morphological Properties of PBS Blends for Food Packaging

by Rafiqah S. Ayu, Abdan Khalina, Ahmad Saffian Harmaen, Khairul Zaman, Mohammad Jawaid and Ching Hao Lee

Polymers 2018, 10(11), 1187; https://doi.org/10.3390/polym10111187 - 25 Oct 2018

Cited by 58 | Viewed by 6885

Abstract

In this study, polybutylene succinate (PBS) was blended with five types of modified tapioca starch to investigate the effect of modified tapioca starch in PBS blends for food packaging by identifying its properties. Tensile and flexural properties of blends found deteriorated for insertion [...] Read more.

In this study, polybutylene succinate (PBS) was blended with five types of modified tapioca starch to investigate the effect of modified tapioca starch in PBS blends for food packaging by identifying its properties. Tensile and flexural properties of blends found deteriorated for insertion of starch. This is due to poor interface, higher void contents and hydrolytic degradation of hydrophilic starch. FTIR results show all starch/PBS blends are found with footprints of starch except OH stretching vibration which is absent in B40 blends. Besides, Broad O–H absorption in all specimens show that these are hydrogen bonded molecules and no free O–H bonding was found. SEM testing shows good interfacial bonding between PBS and starch except E40 blends. Therefore, poor results of E40 blends was expected. In TGA, a slightly weight loss found between 80 to 100 °C due to free water removal. Apart from this, insertion of all types of starch reduces thermal stability of blend. However, high crystallinity of starch/PBS blend observed better thermal stability but lower char yield. Starch A and B blends are suggested to be used as food wrap and food container materials while starch D blend is suitable for grocery plastic bags according to observed results. Full article

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16 pages, 4285 KiB

Open AccessArticle

Preparation and Characterization of Potato Starch Film with Various Size of Nano-SiO₂

by Rongfei Zhang, Xiangyou Wang and Meng Cheng

Polymers 2018, 10(10), 1172; https://doi.org/10.3390/polym10101172 - 22 Oct 2018

Cited by 103 | Viewed by 7976

Abstract

The various sizes (15, 30, 80, and 100 nm) of nano-SiO₂/potato starch films were synthesized and characterized. The gas permeability, antibacterial properties, and mechanical properties of the films were evaluated to their potential for application as food packaging materials. Results indicated [...] Read more.

The various sizes (15, 30, 80, and 100 nm) of nano-SiO₂/potato starch films were synthesized and characterized. The gas permeability, antibacterial properties, and mechanical properties of the films were evaluated to their potential for application as food packaging materials. Results indicated that the 100 nm nano-SiO₂ was well dispersed in the starch matrix, which induced an active group on the surface of 100 nm nano-SiO₂ adequately combined with starch macromolecule. The water resistance and mechanical properties of the films were improved with the addition of nano-SiO₂. Notably, resistance to ultraviolet and thermal aging was also enhanced. The nano-SiO₂/potato starch films were more efficient against Escherichia coli (E. coli) than Staphylococcus aureus (S. aureus). Remarkable preservation properties of the films packaging the white mushrooms were obtained, with those of the 100 nm films considered superior. This study can significantly guide the rational choice of the nano-SiO₂ size to meet the packaging requirements of various agricultural products. Full article

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13 pages, 2488 KiB

Open AccessArticle

Effects of Calcium Alginate Submicroparticles on Seed Germination and Seedling Growth of Wheat (Triticum aestivum L.)

by Jinxia He, Ruixin Li, Xue Sun, Wenxia Wang, Jianen Hu, Hongguo Xie and Heng Yin

Polymers 2018, 10(10), 1154; https://doi.org/10.3390/polym10101154 - 16 Oct 2018

Cited by 16 | Viewed by 4328

Abstract

Calcium alginate (CaAlg) submicroparticles have a potential application in agricultural delivery systems. This study investigated the effects of CaAlg submicroparticles on seed germination and seedling growth of wheat. CaAlg submicroparticles with a Z-average diameter of around 250.4 nm and a measured zeta potential [...] Read more.

Calcium alginate (CaAlg) submicroparticles have a potential application in agricultural delivery systems. This study investigated the effects of CaAlg submicroparticles on seed germination and seedling growth of wheat. CaAlg submicroparticles with a Z-average diameter of around 250.4 nm and a measured zeta potential value of about −25.4 mV were prepared and characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM) and energy dispersive X-ray spectrometer (EDS). After this, the effects of the concentration of CaAlg submicroparticles (10–500 μg/mL) on germination percentage, seedling length, the number of adventitious roots, chlorophyll content and soluble protein content were evaluated. The results demonstrated a significant increase in the level of germination percentage (9.0%), seedling index (50.3%), adventitious roots (27.5%), seedling length (17.0%), chlorophyll (8.7%) and soluble protein contents (4.5%) at a concentration of 100 μg/mL. However, an inhibitory effect was observed at a concentration of 500 μg/mL. The SEM examination showed that CaAlg submicroparticles could be successfully adsorbed onto the surface of the wheat seed. Further studies proved that CaAlg submicroparticles at a concentration of 100 μg/mL promoted the expression of indole-3-acetic acid (IAA)-related genes (YUCCA9, AUX1, ARF and UGT) in wheat, which resulted in an increase of 69% and 21% in IAA concentration in wheat roots and shoots, respectively. Full article

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16 pages, 2912 KiB

Open AccessArticle

One-Step Quaternization/Hydroxypropylsulfonation to Improve Paste Stability, Adhesion, and Film Properties of Oxidized Starch

by Wei Li, Zhenzhen Xu, Zongqian Wang and Jian Xing

Polymers 2018, 10(10), 1110; https://doi.org/10.3390/polym10101110 - 8 Oct 2018

Cited by 37 | Viewed by 3427

Abstract

To investigate the influences of quaternization/hydroxypropylsulfonation on viscosity stability, adhesion to fibers and film properties of oxidized tapioca starch (OTS) for ameliorating its end-use ability in applications such as warp-sizing and paper-making, a series of quaternized and hydroxypropylsulfonated OTS (QHOTS) samples were synthesized [...] Read more.

To investigate the influences of quaternization/hydroxypropylsulfonation on viscosity stability, adhesion to fibers and film properties of oxidized tapioca starch (OTS) for ameliorating its end-use ability in applications such as warp-sizing and paper-making, a series of quaternized and hydroxypropylsulfonated OTS (QHOTS) samples were synthesized by simultaneous quaternization and hydroxypropylsulfonation of OTS with N-(3-chloro-2-hydroxypropyl) trimethylammonium chloride (CHPTAC) and 3-chloro-2-hydroxy-1-propanesulfonic acid sodium salt (CHPS-Na). The QHOTS granules were characterized by Fourier transform infra-red spectroscopic and scanning electron microscope techniques. Apparent viscosity and viscosity stability were determined, and adhesion was evaluated by measuring the bonding force of starch to the fibers. Film properties were also estimated in terms of tensile strength, breaking elongation, bending endurance, degree of crystallinity, and moisture regain. It was showed that quaternization/hydroxypropylsulfonation was capable of obviously improving viscosity stability of gelatinized OTS paste, enhancing bonding forces of OTS to cotton and polylactic acid (PLA) fibers, increasing breaking elongation, bending endurance and moisture regain of film and decreasing its tensile strength and degree of crystallinity, thereby obviously stabilizing paste viscosity, improving adhesion to fibers and lessening film brittleness. Increasing the level of quaternization/hydroxypropylsulfonation favored improvement in the stability, enhancement in adhesion and decrease in brittleness. The QHOTS showed potential in the applications of cotton and PLA sizing. Full article

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15 pages, 5146 KiB

Open AccessArticle

Nanoporous PLA/(Chitosan Nanoparticle) Composite Fibrous Membranes with Excellent Air Filtration and Antibacterial Performance

by Hui Li, Zhe Wang, Haiyan Zhang and Zhijuan Pan

Polymers 2018, 10(10), 1085; https://doi.org/10.3390/polym10101085 - 30 Sep 2018

Cited by 80 | Viewed by 7469

Abstract

Particulate matter (PM) pollution, which usually carries viruses and bacteria, has drawn considerable attention as a major threat to public health. In this present study, an environment-friendly antibacterial Poly(lactic acid)(PLA)/chitosan composite air filter was fabricated using the one-step electrospinning technique. The composite PLA/chitosan [...] Read more.

Particulate matter (PM) pollution, which usually carries viruses and bacteria, has drawn considerable attention as a major threat to public health. In this present study, an environment-friendly antibacterial Poly(lactic acid)(PLA)/chitosan composite air filter was fabricated using the one-step electrospinning technique. The composite PLA/chitosan fibres show a highly porous structure, in which chitosan nanoparticles (NPs) were found to be uniformly distributed throughout the entire fibre. The morphologies, through-pore size and distribution, air filtration and anti-microbial properties of these filter media were studied. The results showed that it was not the chitosan content but instead the concentration of the spinning solutions that had the greatest effect on the morphologies of the porous fibres. The relative humidity influenced the nanometre-scale pores on the surface of PLA/chitosan fibres. The PLA/chitosan fibrous membranes with a chitosan to PLA mass ratio of 2.5:8 exhibited a high filtration efficiency of 98.99% and a relatively low pressure drop (147.60 Pa) when the air flow rate was 14 cm/s, while these also had high antibacterial activity of 99.4% and 99.5% against Escherichia coli and Staphylococcus aureus, respectively. It took 33 min for the PM_2.5 concentration to decrease to 0 μg/m³ from 999 μg/m³ using the PLA/chitosan fibrous membranes, which demonstrates obviously effective air purification performance. Full article

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7 pages, 2084 KiB

Open AccessArticle

Cellulose–Chitosan Antibacterial Composite Films Prepared from LiBr Solution

by Jiwook Yang, Gu-Joong Kwon, Kyojung Hwang and Dae-Young Kim

Polymers 2018, 10(10), 1058; https://doi.org/10.3390/polym10101058 - 23 Sep 2018

Cited by 45 | Viewed by 7595

Abstract

Cellulose and chitosan solutions were prepared in 60% LiBr and mixed with a different weight ratio. The washing and drying of the prepared cellulose–chitosan composite films were performed under identical conditions. The color of the liquefied mixtures and films was initially transparent but [...] Read more.

Cellulose and chitosan solutions were prepared in 60% LiBr and mixed with a different weight ratio. The washing and drying of the prepared cellulose–chitosan composite films were performed under identical conditions. The color of the liquefied mixtures and films was initially transparent but changed from colorless to brownish yellow depending on the ratio of chitosan in the solution. The cross section observed in the SEM results indicated that the film developed with a higher ratio of chitosan was more robust and possessed greater antibacterial properties. FT-IR analysis of the films showed that hydrogen bonds between cellulose and chitosan in composite films were successfully achieved and retained excellent mechanical properties. The proper ratio of chitosan in the cellulose solution can increase the tensile strength and improve the elongation of the films; however, the E-modulus property was consistently reduced. The antibacterial activity and mechanical properties of the films were greatly improved as the amount of chitosan in the film increased. Full article

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14 pages, 2857 KiB

Open AccessArticle

Nanocomposite Film Containing Fibrous Cellulose Scaffold and Ag/TiO₂ Nanoparticles and Its Antibacterial Activity

by Yanxiang Li, Jessica Tian, Chuanfang Yang and Benjamin S. Hsiao

Polymers 2018, 10(10), 1052; https://doi.org/10.3390/polym10101052 - 20 Sep 2018

Cited by 28 | Viewed by 7930

Abstract

Cellulose is a natural polymer that is widely used in daily life, but it is susceptible to microorganism growth. In this study, a simple sol–gel technique was utilized to incorporate the cellulose scaffold with Ag/TiO₂ nanoparticles. The morphology and crystal structure of [...] Read more.

Cellulose is a natural polymer that is widely used in daily life, but it is susceptible to microorganism growth. In this study, a simple sol–gel technique was utilized to incorporate the cellulose scaffold with Ag/TiO₂ nanoparticles. The morphology and crystal structure of the as-prepared Ag/TiO₂/cellulose composite film were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. Antibacterial tests involving the use of Escherichia coli (E. coli) were carried out under dark and UV-light conditions to evaluate the efficiency of the Ag/TiO₂/cellulose composite film in comparison with pristine cellulose paper and TiO₂/cellulose composite film. The results indicated that the antibacterial activity of the Ag/TiO₂/cellulose composite film outperformed all other samples, where the Ag content of 0.030 wt% could inhibit more than 99% of E. coli. This study suggests that finely dispersed nanocale Ag/TiO₂ particles in the cellulose scaffold were effective at slowing down bacterial growth, and the mechanisms of this are also discussed. Full article

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17 pages, 13356 KiB

Open AccessArticle

Electrospun Cellulose Nanocrystals/Chitosan/Polyvinyl Alcohol Nanofibrous Films and their Exploration to Metal Ions Adsorption

by Dong Wang, Wanli Cheng, Yiying Yue, Lihui Xuan, Xiaohui Ni and Guangping Han

Polymers 2018, 10(10), 1046; https://doi.org/10.3390/polym10101046 - 20 Sep 2018

Cited by 36 | Viewed by 5677

Abstract

Cellulose nanocrystals/chitosan/polyvinyl alcohol (CNC/CS/PVA) composite nanofibrous films were prepared while using an electrospinning technique and successfully thiol-functionalized. Then, the modified films were used for the sorption-desorption of Cu(II) and Pb(II) ions. Subsequently, the adsorption capacity of the films was investigated by changing the [...] Read more.

Cellulose nanocrystals/chitosan/polyvinyl alcohol (CNC/CS/PVA) composite nanofibrous films were prepared while using an electrospinning technique and successfully thiol-functionalized. Then, the modified films were used for the sorption-desorption of Cu(II) and Pb(II) ions. Subsequently, the adsorption capacity of the films was investigated by changing the CNC loading level, solution pH, and adsorption time. Results showed that the adsorption of metal ions by the films was the best with CNC loading level of 5 wt %, pH of 6, and adsorption time of 4 h. The adsorption behavior of the films was agreed with the Freundlich model. The adsorption equation of metal ions could be described while using a pseudo-second order model. Based on the Langmuir model, the maximum adsorption capacities of Cu(II) and Pb(II) ions were estimated to be 484.06 and 323.49 mg/g, respectively. The Cu(II) and Pb(II) ions adsorption efficiencies of the films after 4 adsorption-desorption cycles were 90.58% and 90.21%, respectively. This study may provide a feasible approach for the application of functional CNC/CS/PVA nanofibrous films in the treatment of water. Full article

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19 pages, 5463 KiB

Open AccessArticle

Removal of Aromatic Chlorinated Pesticides from Aqueous Solution Using β-Cyclodextrin Polymers Decorated with Fe₃O₄ Nanoparticles

by Sebastián Salazar, Daniel Guerra, Nicolás Yutronic and Paul Jara

Polymers 2018, 10(9), 1038; https://doi.org/10.3390/polym10091038 - 19 Sep 2018

Cited by 50 | Viewed by 5219

Abstract

This article describes the sorption properties of cyclodextrin polymers (nanosponges; NS) with the pesticides 4-chlorophenoxyacetic acid (4-CPA) and 2,3,4,6-tetrachlorophenol (TCF), including an evaluation of its efficiency and a comparison with other materials, such as granulated activated carbon (GAC). NS-pesticide complexes were characterized by [...] Read more.

This article describes the sorption properties of cyclodextrin polymers (nanosponges; NS) with the pesticides 4-chlorophenoxyacetic acid (4-CPA) and 2,3,4,6-tetrachlorophenol (TCF), including an evaluation of its efficiency and a comparison with other materials, such as granulated activated carbon (GAC). NS-pesticide complexes were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray powder diffraction (XRPD), proton nuclear magnetic resonance (¹H-NMR), UV–VIS, and thermogravimetric analysis (TGA). This confirms the interactions of the guests with nanosponges and shows that the polymers have favorable sorption capacities for chlorinated aromatic guests. Our studies also show that the inclusion complex is predominantly favored for NS/CPA rather than those formed between TCF and NS due to the size of the adsorbate and steric effects. Sorption studies carried with repeated cycles demonstrate that NS polymers could be an improved technology for pollutant removal from aquatic environments, as they are very efficient and reusable materials. Our experiments and characterization by SEM, EDS, UV–VIS, and magnetization saturation (VSM) also show that NS is an optimal substrate for the deposition of magnetite nanoparticles, thus improving the usefulness and properties of the polymer, as the nanosponges could be retrieved from aqueous solution with a neodymium magnet without losing its efficiency as a pesticide sorbent. Full article

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14 pages, 5064 KiB

Open AccessArticle

Photo-Crosslinked Keratin/Chitosan Membranes as Potential Wound Dressing Materials

by Che-Wei Lin, Yi-Kai Chen, Min Lu, Kuo-Long Lou and Jiashing Yu

Polymers 2018, 10(9), 987; https://doi.org/10.3390/polym10090987 - 4 Sep 2018

Cited by 34 | Viewed by 6915

Abstract

In this study, we combined two kinds of natural polymers, chitosan and keratin, to develop a portable composite membrane via UV irradiation. UV-crosslinking without an additional chemical agent makes the fabrication more ideal by reducing reactants and avoiding residual toxic chemicals. This novel [...] Read more.

In this study, we combined two kinds of natural polymers, chitosan and keratin, to develop a portable composite membrane via UV irradiation. UV-crosslinking without an additional chemical agent makes the fabrication more ideal by reducing reactants and avoiding residual toxic chemicals. This novel composite could perform synergistic functions benefitting from chitosan and keratin; including a strong mechanical strength, biodegradability, biocompatibility, better cell adhesion, and proliferation characteristics. Furthermore, compared with our previous research, this keratin-chitosan composite membrane was improved in that it was made to be portable, enabling it to be versatile and have various applications in vitro and in vivo. Based on these facts, this innovative composite membrane has high potential for serving as an outstanding candidate for wound healing or other biomedical applications. Full article

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13 pages, 3282 KiB

Open AccessArticle

Soft Gelatin Films Modified with Cellulose Acetate Phthalate Pseudolatex Dispersion—Structure and Permeability

by Bartosz Maciejewski, Anna Ström, Anette Larsson and Małgorzata Sznitowska

Polymers 2018, 10(9), 981; https://doi.org/10.3390/polym10090981 - 3 Sep 2018

Cited by 5 | Viewed by 4693

Abstract

Gastroresistant material, based on gelatin and intended to form capsule shells, was characterized. The films were obtained by mixing a gelatin solution with cellulose acetate phthalate (CAP) pseudolatex at an elevated temperature. Microscopic and spectroscopic analyses of the films—intact or subjected to the [...] Read more.

Gastroresistant material, based on gelatin and intended to form capsule shells, was characterized. The films were obtained by mixing a gelatin solution with cellulose acetate phthalate (CAP) pseudolatex at an elevated temperature. Microscopic and spectroscopic analyses of the films—intact or subjected to the acidic treatment—were performed, along with a permeability study of tritium-labeled water. A uniform porous structure formed by CAP within the gelatin gel was observed. The results demonstrated that no interaction of a chemical nature occurred between the components. Additionally, the performed permeability and solubility studies proved that the diffusion of water through the membranes at an acidic pH can be noticeably reduced by adding carrageenan as a secondary gelling/thickening agent. Full article

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12 pages, 3770 KiB

Open AccessArticle

Enhanced Flexibility of Biodegradable Polylactic Acid/Starch Blends Using Epoxidized Palm Oil as Plasticizer

by Raina Jama Awale, Fathilah Binti Ali, Azlin Suhaida Azmi, Noor Illi Mohamad Puad, Hazleen Anuar and Azman Hassan

Polymers 2018, 10(9), 977; https://doi.org/10.3390/polym10090977 - 2 Sep 2018

Cited by 62 | Viewed by 7142

Abstract

The brittleness of polylactic acid (PLA) has always limited its usage, although it has good mechanical strength. In this study, flexibility of PLA/starch (PSt) blend was enhanced using epoxidized palm oil (EPO) as the green plasticizer. The PLA/starch/EPO (PSE) blends were prepared while [...] Read more.

The brittleness of polylactic acid (PLA) has always limited its usage, although it has good mechanical strength. In this study, flexibility of PLA/starch (PSt) blend was enhanced using epoxidized palm oil (EPO) as the green plasticizer. The PLA/starch/EPO (PSE) blends were prepared while using the solution casting method by fixing the content of starch and varying ratio of EPO. The thermal properties, such as glass transition temperature (T_g), melting temperature (T_m), and crystallization temperature (T_cc) were decreased by increasing the amount of EPO into PSt, indicating that EPO increases the chain mobility. Thermogravimetric analysis (TGA) showed that thermal degradation resistance of PSE was higher when compared to PSt. The mechanical testing revealed that EPO at all contents improved the mechanical properties, such as increment of the elongation-at-break and impact strength. Whereas, dynamic mechanical analysis showed that the addition of filler into PLA decreased the storage modulus of PLA. The carbonyl group of the aliphatic ester remained the same in the PSE blends. The morphological study verified the ductility of PSE blends surface when compared to the brittle surface of PSt. As for the soil burial tests, EPO accelerated the degradation of blends. From these results, it can be concluded that EPO improved the flexibility of PLA blends. Full article

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20 pages, 2592 KiB

Open AccessArticle

Insights into Bacterial Cellulose Biosynthesis from Different Carbon Sources and the Associated Biochemical Transformation Pathways in Komagataeibacter sp. W1

by Shan-Shan Wang, Yong-He Han, Jia-Lian Chen, Da-Chun Zhang, Xiao-Xia Shi, Yu-Xuan Ye, Deng-Long Chen and Min Li

Polymers 2018, 10(9), 963; https://doi.org/10.3390/polym10090963 - 31 Aug 2018

Cited by 105 | Viewed by 8084

Abstract

Cellulose is the most abundant and widely used biopolymer on earth and can be produced by both plants and micro-organisms. Among bacterial cellulose (BC)-producing bacteria, the strains in genus Komagataeibacter have attracted wide attention due to their particular ability in furthering BC production. [...] Read more.

Cellulose is the most abundant and widely used biopolymer on earth and can be produced by both plants and micro-organisms. Among bacterial cellulose (BC)-producing bacteria, the strains in genus Komagataeibacter have attracted wide attention due to their particular ability in furthering BC production. Our previous study reported a new strain of genus Komagataeibacter from a vinegar factory. To evaluate its capacity for BC production from different carbon sources, the present study subjected the strain to media spiked with 2% acetate, ethanol, fructose, glucose, lactose, mannitol or sucrose. Then the BC productivity, BC characteristics and biochemical transformation pathways of various carbon sources were fully investigated. After 14 days of incubation, strain W1 produced 0.040–1.529 g L⁻¹ BC, the highest yield being observed in fructose. Unlike BC yields, the morphology and microfibrils of BCs from different carbon sources were similar, with an average diameter of 35–50 nm. X-ray diffraction analysis showed that all membranes produced from various carbon sources had 1–3 typical diffraction peaks, and the highest crystallinity (i.e., 90%) was found for BC produced from mannitol. Similarly, several typical spectra bands obtained by Fourier transform infrared spectroscopy were similar for the BCs produced from different carbon sources, as was the I_α fraction. The genome annotation and Kyoto Encyclopedia of Genes and Genomes analysis revealed that the biochemical transformation pathways associated with the utilization of and BC production from fructose, glucose, glycerol, and mannitol were found in strain W1, but this was not the case for other carbon sources. Our data provides suggestions for further investigations of strain W1 to produce BC by using low molecular weight sugars and gives clues to understand how this strain produces BC based on metabolic pathway analysis. Full article

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14 pages, 4259 KiB

Open AccessArticle

Biodegradable Rice Starch/Carboxymethyl Chitosan Films with Added Propolis Extract for Potential Use as Active Food Packaging

by Rungsiri Suriyatem, Rafael A. Auras, Chitsiri Rachtanapun and Pornchai Rachtanapun

Polymers 2018, 10(9), 954; https://doi.org/10.3390/polym10090954 - 28 Aug 2018

Cited by 74 | Viewed by 6546

Abstract

Active films from rice starch/carboxymethyl chitosan (RS/CMCh) incorporated with propolis extract (ppl) were developed and characterized. The effect of the ppl content (0–10% w/w based on RS/CMCh) on the developed films’ properties were determined by measuring the optical, mechanical, thermal, swelling, barrier, antimicrobial, [...] Read more.

Active films from rice starch/carboxymethyl chitosan (RS/CMCh) incorporated with propolis extract (ppl) were developed and characterized. The effect of the ppl content (0–10% w/w based on RS/CMCh) on the developed films’ properties were determined by measuring the optical, mechanical, thermal, swelling, barrier, antimicrobial, and antioxidant attributes. The thermal stability and biodegradability of the films were also investigated. As the ppl content increased, free radical scavenging and a* and b* color values increased, whereas luminosity (L*) and swellability of the films decreased. The active films with 5–10% ppl possessed antimicrobial ability against Gram-positive bacteria (Staphylococcus aureus and Bacillus cereus). The active film with 10% ppl displayed increased flexibility and thermal stability, without a change in oxygen permeability. The results indicated that incorporation of ppl into RS/CMCh film could enhance the films’ antioxidant and antimicrobial properties. Full article

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21 pages, 2140 KiB

Open AccessArticle

Development and Characterization of Polyamide-Supported Chitosan Nanocomposite Membranes for Hydrophilic Pervaporation

by Ewelina Chrzanowska, Magdalena Gierszewska, Joanna Kujawa, Aneta Raszkowska-Kaczor and Wojciech Kujawski

Polymers 2018, 10(8), 868; https://doi.org/10.3390/polym10080868 - 4 Aug 2018

Cited by 36 | Viewed by 5471

Abstract

An experimental protocol of preparation of homogeneous and nanocomposite chitosan (Ch) based membranes supported on polyamide-6 (PA6) films was developed and described in detail. Montmorillonite (MMT) and Cloisite 30B (C30B) nanoclays were used as nanofillers to improve mechanical properties of chitosan films. The [...] Read more.

An experimental protocol of preparation of homogeneous and nanocomposite chitosan (Ch) based membranes supported on polyamide-6 (PA6) films was developed and described in detail. Montmorillonite (MMT) and Cloisite 30B (C30B) nanoclays were used as nanofillers to improve mechanical properties of chitosan films. The surface, mechanical, and transport properties of PA6 supported Ch, Ch/MMT and Ch/C30B membranes were studied and compared with a pristine, non-supported chitosan membrane. Implementation of advanced analytical techniques e.g., SEM reveal the clays nanoparticles are well dispersed in the chitosan matrix. According to AFM images, composite chitosan/nanoclay membranes possess higher roughness compared with unfilled ones. On the other hand, an incorporation of clay particles insignificantly changed the mechanical and thermal properties of the membranes. It was also found that all membranes are hydrophilic and water is preferentially removed from EtOH/H₂O and iPrOH/H₂O mixtures by pervaporation. Supporting of chitosan and chitosan/nanoclay thin films onto PA6 porous substrate enhanced permeate flux and pervaporation separation index, in comparison to the pristine Ch membrane. Concerning separation factor (β), the highest value equal to 4500 has been found for a chitosan composite membrane containing Cloisite 30B contacting 85/15 wt % iPrOH/H₂O mixture. The mentioned membrane was characterized by the normalized flux of 0.5 μm·kg·m⁻²·h⁻¹. Based on the established data, it was possible to conclude that chitosan membranes are meaningful material in dehydration of azeotropic mixtures. Nevertheless, to boost up the membrane efficiency, the further modification process is required. Full article

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16 pages, 5506 KiB

Open AccessArticle

Enhanced Electrorheological Response of Cellulose: A Double Effect of Modification by Urea-Terminated Silane

by Zhao Liu, Panpan Chen, Xiao Jin, Li-Min Wang, Ying Dan Liu and Hyoung Jin Choi

Polymers 2018, 10(8), 867; https://doi.org/10.3390/polym10080867 - 4 Aug 2018

Cited by 8 | Viewed by 3986

Abstract

As a natural polymer with abundant sources, cellulose was one of the earliest applied electrorheological (ER) materials. However, cellulose-based ER materials have not attracted much attention because of their relatively low ER effect and sensitivity to water. In this study, cellulose rods were [...] Read more.

As a natural polymer with abundant sources, cellulose was one of the earliest applied electrorheological (ER) materials. However, cellulose-based ER materials have not attracted much attention because of their relatively low ER effect and sensitivity to water. In this study, cellulose rods were decorated with a urea-terminated silane, 1-(3-(trimethoxysilyl) propyl) urea, after being swelled in sodium hydroxide solution. The morphologies and structures of the cellulose particles were investigated using scanning electron microscopy, Fourier-transform infrared spectroscopy and X-ray diffraction, confirming the dramatic differences of the treated cellulose particles from the pristine cellulose. Rheological behaviors of the pristine and modified cellulose particles in silicone oil were observed using a rotational rheometer. It was found that the silane-modified cellulose showed higher ER effect and higher dielectric properties than the pristine cellulose particles, which was not only related to the grafted polar molecules but may also be associated with the porous morphologies of the treated cellulose particles. Full article

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16 pages, 1967 KiB

Open AccessArticle

Processing of Superfine Grinding Corn Straw Fiber-Reinforced Starch Film and the Enhancement on Its Mechanical Properties

by Min Wu, Fei Gao, Dong-Min Yin, Qi Luo, Zong-Qiang Fu and Yu-Guang Zhou

Polymers 2018, 10(8), 855; https://doi.org/10.3390/polym10080855 - 2 Aug 2018

Cited by 16 | Viewed by 3928

Abstract

In this study, corn straw (CS) was reduced in size using the superfine grinding process to generate powders with particles of varying sizes (9~16 μm). The lignin, hemicellulose, and cellulose content; particle size distribution; and scanning electron microscopy (SEM) of the CS samples [...] Read more.

In this study, corn straw (CS) was reduced in size using the superfine grinding process to generate powders with particles of varying sizes (9~16 μm). The lignin, hemicellulose, and cellulose content; particle size distribution; and scanning electron microscopy (SEM) of the CS samples were analyzed. Superfine CS, of varying particle sizes, was added to the starch-based films (SF) in various amounts. The resulting corn straw starch-based films (CS/SFs) appeared to have significantly different properties, compared to the original starch-based film (SF, p < 0.05). The power law model and Burger’s model were used to investigate the dynamic mechanical analysis, which indicated that the mechanical properties of CS/SF performed better than that of SF, especially CS/SFs at 0.5–1.5 h ball milling and CS/SFs at a 15% addition amount. The power law model and Burger’s model also presented a strong correlation with the experimental data (>0.90). Full article

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10 pages, 1699 KiB

Open AccessArticle

Structural Properties and Macrophage Activation of Cell Wall Polysaccharides from the Fruiting Bodies of Hericium erinaceus

by Di Wu, Shan Yang, Chuan Tang, Yanfang Liu, Qiaozhen Li, Henan Zhang, Fengjie Cui and Yan Yang

Polymers 2018, 10(8), 850; https://doi.org/10.3390/polym10080850 - 1 Aug 2018

Cited by 5 | Viewed by 10528

Abstract

In this study, water-soluble and alkali-soluble cell wall polysaccharides were obtained from fruiting body extracted residual micropowders of Hericium erinaceus, harvested at seven different growing stages. The structural properties and in vitro immunity activities of cell wall polysaccharides extracted successively by hot [...] Read more.

In this study, water-soluble and alkali-soluble cell wall polysaccharides were obtained from fruiting body extracted residual micropowders of Hericium erinaceus, harvested at seven different growing stages. The structural properties and in vitro immunity activities of cell wall polysaccharides extracted successively by hot water and sodium hydroxide solution were studied, and the results indicated that the yield and content of polysaccharides increased during the reproductive growth stage and decreased with the maturity of the fruiting body. Water-soluble cell wall polysaccharides mainly composed of glucose and galactose at a molar ratio of 3.4–14:1.0, and also contained a small ratio of glucuronic acid. The alkali-soluble cell wall polysaccharides were glucans with lower molecular weight and higher macrophage activation activity in vitro than water-soluble ones. Our findings suggest that the growth stages (H4 and H5) are suitable for harvesting H. erinaceus fruiting bodies with higher cell wall polysaccharide yield and functional benefits. Full article

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16 pages, 6474 KiB

Open AccessArticle

The Effect of Hexanoyl Glycol Chitosan on the Proliferation of Human Mesenchymal Stem Cells

by Young-Hoon Jeong, Hye Min Oh, Man Ryul Lee, C-Yoon Kim, Chanyang Joo, Soon-Jung Park, Yun-Ho Song, Changhee Kang, Hyung-Min Chung, Sun-Woong Kang, Kang Moo Huh and Sung-Hwan Moon

Polymers 2018, 10(8), 839; https://doi.org/10.3390/polym10080839 - 30 Jul 2018

Cited by 9 | Viewed by 6150

Abstract

Adipose-derived mesenchymal stem cells (AD-MSCs) have been studied as desirable cell sources for regenerative medicine and therapeutic application. However, it has still remained a challenge to obtain enough adequate and healthy cells in large quantities. To overcome this limitation, various biomaterials have been [...] Read more.

Adipose-derived mesenchymal stem cells (AD-MSCs) have been studied as desirable cell sources for regenerative medicine and therapeutic application. However, it has still remained a challenge to obtain enough adequate and healthy cells in large quantities. To overcome this limitation, various biomaterials have been used to promote expansion of MSCs in vitro. Recently, hexanoyl glycol chitosan (HGC) was introduced as a new biomaterial for various biomedical applications, in particular 3D cell culture, because of its biodegradability, biocompatibility, and other promising biofunctional properties. In this study, the effect of HGC on the proliferation of AD-MSCs was examined in vitro, and its synergistic effect with basic fibroblast growth factor (bFGF), which has been widely used to promote proliferation of cells, was evaluated. We found that the presence of HGC increased the proliferative capacity of AD-MSCs during long-term culture, even at low concentrations of bFGF. Furthermore, it suppressed the expression of senescence-related genes and improved the mitochondrial functionality. Taken all together, these findings suggest that the HGC demonstrate a potential for sustained growth of AD-MSCs in vitro. Full article

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16 pages, 4061 KiB

Open AccessArticle

Drug Release Properties of Diflunisal from Layer-By-Layer Self-Assembled κ-Carrageenan/Chitosan Nanocapsules: Effect of Deposited Layers

by Sarai Rochín-Wong, Aarón Rosas-Durazo, Paul Zavala-Rivera, Amir Maldonado, María Elisa Martínez-Barbosa, Itziar Vélaz and Judith Tánori

Polymers 2018, 10(7), 760; https://doi.org/10.3390/polym10070760 - 10 Jul 2018

Cited by 38 | Viewed by 5424

Abstract

Engineering of multifunctional drug nanocarriers combining stability and good release properties remains a great challenge. In this work, natural polymers κ-carrageenan (κ-CAR) and chitosan (CS) were deposited onto olive oil nanoemulsion droplets (NE) via layer-by-layer (LbL) self-assembly to study the release mechanisms of [...] Read more.

Engineering of multifunctional drug nanocarriers combining stability and good release properties remains a great challenge. In this work, natural polymers κ-carrageenan (κ-CAR) and chitosan (CS) were deposited onto olive oil nanoemulsion droplets (NE) via layer-by-layer (LbL) self-assembly to study the release mechanisms of the anti-inflammatory diflunisal (DF) as a lipophilic drug model. The nano-systems were characterized by dynamic light scattering (DLS), zeta potential (ζ-potential) measurements, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (XEDS) and Fourier transform infrared spectroscopy (FTIR) to confirm the NE-coating with polymer layers. In addition, kinetic release studies of DF were developed by the dialysis diffusion bag technique. Mathematical models were applied to investigate the release mechanisms. The results showed that stable and suitably sized nanocapsules (~300 nm) were formed. Also, the consecutive adsorption of polyelectrolytes by charge reversal was evidenced. More interestingly, the drug release mechanism varied depending on the number of layers deposited. The nanosized systems containing up to two layers showed anomalous transport and first order kinetics. Formulations with three and four layers exhibited Case II transport releasing diflunisal with zero order kinetics. Hence, our results suggest that these polyelectrolyte nanocapsules have great potential as a multifunctional nanocarrier for drug delivery applications. Full article

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14 pages, 3390 KiB

Open AccessArticle

Oil-Water Separation of Electrospun Cellulose Triacetate Nanofiber Membranes Modified by Electrophoretically Deposited TiO₂/Graphene Oxide

by Saba Naseem, Chang-Mou Wu, Ting-Zhen Xu, Chiu-Chun Lai and Syang-Peng Rwei

Polymers 2018, 10(7), 746; https://doi.org/10.3390/polym10070746 - 5 Jul 2018

Cited by 38 | Viewed by 6629

Abstract

Recycled waste industrial cellulose triacetate (TAC) film, which is one of the key materials in polarizers, was used to produce nanofiber membranes by electrospinning and synergistic assembly with graphene oxide (GO) and titanium dioxide (TiO₂) for oil-water separation. In this study, [...] Read more.

Recycled waste industrial cellulose triacetate (TAC) film, which is one of the key materials in polarizers, was used to produce nanofiber membranes by electrospinning and synergistic assembly with graphene oxide (GO) and titanium dioxide (TiO₂) for oil-water separation. In this study, GO and TiO₂ coated by an electrophoretic deposition method introduced super hydrophilicity onto the recycled TAC (rTAC) membrane, with enhanced water permeability. The results indicate that when the outermost TiO₂ layer of an asymmetric composite fiber membrane is exposed to ultraviolet irradiation; the hydrophilicity of the hydrophilic layer is more effectively promoted. Moreover, this coating could efficiently repel oil, and demonstrated robust self-cleaning performance during the cycle test, with the aid of the photocatalytic properties of TiO₂. The rTAC membrane of networked hydrophobic fibers could also increase the speed of the filtrate flow and the water flux of the oil-water emulsion. The permeate carbon concentration in the water was analyzed using a total organic carbon analyzer. Incorporation of TiO₂/GO onto the rTAC membrane contributed greatly towards enhanced membrane hydrophilicity and antifouling performance. Therefore, the novel TiO₂/GO/rTAC asymmetric composite fiber has promise for applications in oil-water separation. Full article

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16 pages, 5728 KiB

Open AccessArticle

A Novel In Situ Self-Assembling Fabrication Method for Bacterial Cellulose-Electrospun Nanofiber Hybrid Structures

by Muhammad Awais Naeem, Pengfei Lv, Huimin Zhou, Tayyab Naveed and Qufu Wei

Polymers 2018, 10(7), 712; https://doi.org/10.3390/polym10070712 - 28 Jun 2018

Cited by 21 | Viewed by 4736

Abstract

Self-assembling fabrication methodology has recently attracted attention for the production of bio-degradable polymer nanocomposites. In this research work, bacterial cellulose/electrospun nanofiber hybrid mats (BC/CA-ENM) were formed by incorporating cellulose acetate electrospun nanofiber membranes (CA-ENMs) in the fermentation media, followed by in situ self-assembly [...] Read more.

Self-assembling fabrication methodology has recently attracted attention for the production of bio-degradable polymer nanocomposites. In this research work, bacterial cellulose/electrospun nanofiber hybrid mats (BC/CA-ENM) were formed by incorporating cellulose acetate electrospun nanofiber membranes (CA-ENMs) in the fermentation media, followed by in situ self-assembly of bacterial cellulose (BC) nanofibers. ENMs exhibit excessive hydrophobicity, attributed to their high crystallinity and reorientation of hydrophobic groups at the air/solid interfaces. We aimed to improve the hydrophilic and other functional properties of ENMs. As-prepared nanohybrid structures were characterized using SEM and FTIR. SEM results revealed that in situ self-assembling of BC nanofibers onto the electrospun membrane’s surface and penetration into pores gradually increased with extended fermentation periods. The surface hydrophilicity and water absorption capacity of as-prepared hybrid mats was also tested and analyzed. Hybrid mats were observably more hydrophilic than an electrospun membrane and more hydrophobic compared to BC films. In addition, the incorporation of CA electrospun membranes in the culture media as a foundation for BC nanofiber growth resulted in improved tensile strength of the hybrid nanocomposites compared to ENMs. Overall, the results indicated the successful fabrication of nanocomposites through a novel approach, with samples demonstrating improved functional properties. Full article

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17 pages, 3119 KiB

Open AccessArticle

Cellulose-Based Absorbent Production from Bacterial Cellulose and Acrylic Acid: Synthesis and Performance

by Mu-Tan Luo, Hai-Long Li, Chao Huang, Hai-Rong Zhang, Lian Xiong, Xue-Fang Chen and Xin-De Chen

Polymers 2018, 10(7), 702; https://doi.org/10.3390/polym10070702 - 25 Jun 2018

Cited by 36 | Viewed by 5415

Abstract

Cellulose-based superabsorbent was synthesized by bacterial cellulose (BC) grafting acrylic acid (AA) in the presence of N,N′-methylenebisacrylamide (NMBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The influence of different factors on composite synthesis, including the weight ratio [...] Read more.

Cellulose-based superabsorbent was synthesized by bacterial cellulose (BC) grafting acrylic acid (AA) in the presence of N,N′-methylenebisacrylamide (NMBA) as a crosslinker and ammonium persulfate (APS) as an initiator. The influence of different factors on composite synthesis, including the weight ratio of the monomer to BC, initiator content, crosslinker content, AA neutralization degree, reaction temperature, and reaction time on the water absorbency of the composite, were systematically learned. Under the optimized conditions, the maximum water absorbency of the composite was 322 ± 23 g/g distilled water. However, the water absorbency was much less for the different salt solutions and the absorption capacity of the composite decreased as the concentration of the salt solutions increased. The pH value had a significant influence on water absorption performance, and with the increase of temperature, the water retention rate of the composite decreased. Additionally, the structure of this composite was characterized with nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The results of NMR and FT-IR provided evidence that the composite was synthesized by BC and AA, and the microstructure showed that it had good performance for water absorption. In addition, the composite possessed suitable thermal stability, and that it could be used in a few high-temperature environments. Overall, this composite is promising for application in water absorption. Full article

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12 pages, 3438 KiB

Open AccessArticle

A One Pot Method for Preparing an Antibacterial Superabsorbent Hydrogel with a Semi-IPN Structure Based on Tara Gum and Polyquaternium-7

by Jie Shen, Bingjie Li, Xianxu Zhan and Lijuan Wang

Polymers 2018, 10(7), 696; https://doi.org/10.3390/polym10070696 - 22 Jun 2018

Cited by 18 | Viewed by 6931

Abstract

An antibacterial superabsorbent polymer was prepared by graft polymerization of acrylic acid onto tara gum polysaccharide, by adding N,N-dimethyl-N-2-propenyl-2-propen-1-aminium chloride and a polymer with 2-propenamide (polyquaternium-7, PQ7) as an antibacterial agent. The effects of the amount of PQ7 [...] Read more.

An antibacterial superabsorbent polymer was prepared by graft polymerization of acrylic acid onto tara gum polysaccharide, by adding N,N-dimethyl-N-2-propenyl-2-propen-1-aminium chloride and a polymer with 2-propenamide (polyquaternium-7, PQ7) as an antibacterial agent. The effects of the amount of PQ7 in the hydrogel on its swelling ratio were investigated and maximum swelling ratios of 712 g/g and 68 g/g, in distilled water and 0.9 wt % NaCl solution were attained with 0.5 g PQ7 per gram of tara gum. The superabsorbent hydrogel was characterized by using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermal gravimetric analysis. The results showed that poly (acrylic acid) was successfully grafted onto tara gum and a three-dimensional network structure formed with PQ7 chains penetrated in the networks. The antibacterial properties of these superabsorbent hydrogels against Staphylococcus aureus and Escherichia coli improved with increasing PQ7 content. This study demonstrates a method of preparing novel functional superabsorbent hydrogels. Full article

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13 pages, 2482 KiB

Open AccessArticle

Wound Dressings Based on Chitosan-Dialdehyde Cellulose Nanocrystals-Silver Nanoparticles: Mechanical Strength, Antibacterial Activity and Cytotoxicity

by Feng Dong and Shujun Li

Polymers 2018, 10(6), 673; https://doi.org/10.3390/polym10060673 - 16 Jun 2018

Cited by 50 | Viewed by 6533

Abstract

The present work envisages a simple approach to synthesize a new wound dressing based on chitosan-dialdehyde cellulose nanocrystal-silver nanoparticles (CS-DCNC-AgNPs). Silver nanoparticles (AgNPs) were generated in-situ by periodate oxidation of cellulose nanocrystals to generate aldehyde functions, which were used to reduce Ag⁺ [...] Read more.

The present work envisages a simple approach to synthesize a new wound dressing based on chitosan-dialdehyde cellulose nanocrystal-silver nanoparticles (CS-DCNC-AgNPs). Silver nanoparticles (AgNPs) were generated in-situ by periodate oxidation of cellulose nanocrystals to generate aldehyde functions, which were used to reduce Ag⁺ into Ag⁰ in mild alkaline conditions. Subsequently, the dialdehyde cellulose nanocrystal-silver nanoparticles (DCNC-AgNPs) were added to chitosan (CS) to form the wound dressings by solution casting method. The aim was to enhance the antibacterial effect of CS by incorporation of AgNPs and to improve the mechanical strength and hydrophobicity of CS by incorporation of DCNC that cross-linked by hydrogen bonds. The antibacterial activities were evaluated against five gram-negative bacteria, one gram-positive bacteria, and three fungi. The in vitro cytotoxicity assay was performed using the NIH3T3 cell lines by Sulforhodamine B assay. Research outputs signified that CS-DCNC-AgNPs possessed good mechanical strength and hydrophobicity, high antibacterial activity and less cytotoxicity. Our results propose that CS-DCNC-AgNPs can be a promising, safe antibacterial to be incorporated in wound dressings. Full article

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13 pages, 4089 KiB

Open AccessArticle

Preparation and Properties of 3D Printed Alginate–Chitosan Polyion Complex Hydrogels for Tissue Engineering

by Qiongqiong Liu, Qingtao Li, Sheng Xu, Qiujian Zheng and Xiaodong Cao

Polymers 2018, 10(6), 664; https://doi.org/10.3390/polym10060664 - 14 Jun 2018

Cited by 156 | Viewed by 13278

Abstract

Three-dimensional (3D) printing holds great potential for preparing sophisticated scaffolds for tissue engineering. As a result of the shear thinning properties of an alginate solution, it is often used as 3D printing ink. However, it is difficult to prepare scaffolds with complexity structure [...] Read more.

Three-dimensional (3D) printing holds great potential for preparing sophisticated scaffolds for tissue engineering. As a result of the shear thinning properties of an alginate solution, it is often used as 3D printing ink. However, it is difficult to prepare scaffolds with complexity structure and high fidelity, because the alginate solution has a low viscosity and alginate hydrogels prepared with Ca²⁺ crosslinking are mechanically weak. In this work, chitosan powders were dispersed and swelled in an alginate solution, which could effectively improve the viscosity of an alginate solution by 1.5–4 times. With the increase of chitosan content, the shape fidelity of the 3D printed alginate–chitosan polyion complex (AlCh PIC) hydrogels were improved. Scanning electron microscope (SEM) photographs showed that the lateral pore structure of 3D printed hydrogels was becoming more obvious. As a result of the increased reaction ion pairs in comparison to the alginate hydrogels that were prepared with Ca²⁺ crosslinking, AlCh PIC hydrogels were mechanically strong, and the compression stress of hydrogels at a 90% strain could achieve 1.4 MPa without breaking. In addition, human adipose derived stem cells (hASCs) adhered to the 3D printed AlCh PIC hydrogels and proliferated with time, which indicated that the obtained hydrogels were biocompatible and could potentially be used as scaffolds for tissue engineering. Full article

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15 pages, 3647 KiB

Open AccessArticle

Renewable Polysaccharides as Supports for Palladium Phosphine Catalysts

by Oshrat Levy-Ontman, Shira Biton, Boris Shlomov and Adi Wolfson

Polymers 2018, 10(6), 659; https://doi.org/10.3390/polym10060659 - 12 Jun 2018

Cited by 29 | Viewed by 4600

Abstract

The investigation of the use of polysaccharides derived from natural sources to support metal catalysis has been the focus of several studies. Even though these molecules seem to be attractive materials, their full potential for use in support of heterogeneous catalysis still needs [...] Read more.

The investigation of the use of polysaccharides derived from natural sources to support metal catalysis has been the focus of several studies. Even though these molecules seem to be attractive materials, their full potential for use in support of heterogeneous catalysis still needs to be revealed. To that end, we developed a new preparation technique for polysaccharide-based palladium catalysts by immobilizing the palladium phosphine complexes on various renewable polysaccharides. The Suzuki cross-coupling in ethanol, using PdCl₂(TPPTS)₂ supported by various polysaccharides, was determined by gas chromatography and compared to homogeneous free-catalyst support. The PdCl₂(TPPTS)₂, that was immobilized on red algae supports, was successfully used as a heterogeneous catalyst in the Suzuki cross-coupling reaction, yielding high activity, higher than that of the homogeneous complex, without leaching. The FTIR spectrometry of representative heterogeneous polysaccharide-based TPPTS–PdCl₂ catalysts was compared to that of native polysaccharide and polysaccharide-based TPP–PdCl₂ catalysts, indicated on new bands, suggesting that the heterogenization occurs via interactions between the sulfonate group on the TPPTS and the hydroxyl groups on the polysaccharides. EDS and XPS analysis were also performed, confirming that the Pd complex was embedded within the i-carrageenan. A comparison of SEM images of i-carrageenan preparations also shed light on the interaction occurring between the polysaccharides and the TPPTS. Full article

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28 pages, 732 KiB

Open AccessReview

Cellulose Aerogels: Synthesis, Applications, and Prospects

by Lin-Yu Long, Yun-Xuan Weng and Yu-Zhong Wang

Polymers 2018, 10(6), 623; https://doi.org/10.3390/polym10060623 - 6 Jun 2018

Cited by 398 | Viewed by 31804

Abstract

Due to its excellent performance, aerogel is considered to be an especially promising new material. Cellulose is a renewable and biodegradable natural polymer. Aerogel prepared using cellulose has the renewability, biocompatibility, and biodegradability of cellulose, while also having other advantages, such as low [...] Read more.

Due to its excellent performance, aerogel is considered to be an especially promising new material. Cellulose is a renewable and biodegradable natural polymer. Aerogel prepared using cellulose has the renewability, biocompatibility, and biodegradability of cellulose, while also having other advantages, such as low density, high porosity, and a large specific surface area. Thus, it can be applied for many purposes in the areas of adsorption and oil/water separation, thermal insulation, and biomedical applications, as well as many other fields. There are three types of cellulose aerogels: natural cellulose aerogels (nanocellulose aerogels and bacterial cellulose aerogels), regenerated cellulose aerogels, and aerogels made from cellulose derivatives. In this paper, more than 200 articles were reviewed to summarize the properties of these three types of cellulose aerogels, as well as the technologies used in their preparation, such as the sol–gel process and gel drying. In addition, the applications of different types of cellulose aerogels were also introduced. Full article

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13 pages, 3203 KiB

Open AccessArticle

Preparation and Characterization of Regenerated Cellulose Film from a Solution in Lithium Bromide Molten Salt Hydrate

by Xueqin Zhang, Naiyu Xiao, Huihui Wang, Chuanfu Liu and Xuejun Pan

Polymers 2018, 10(6), 614; https://doi.org/10.3390/polym10060614 - 4 Jun 2018

Cited by 66 | Viewed by 7737

Abstract

In this study, the molten salt hydrate of lithium bromide (LiBr) was utilized as a non-derivatizing cellulose dissolution solvent to prepare regenerated cellulose films for kraft pulp. The effects of LiBr concentrations (60, 62, and 65 wt %) and dissolving time (from 5 [...] Read more.

In this study, the molten salt hydrate of lithium bromide (LiBr) was utilized as a non-derivatizing cellulose dissolution solvent to prepare regenerated cellulose films for kraft pulp. The effects of LiBr concentrations (60, 62, and 65 wt %) and dissolving time (from 5 to 40 min with the interval of 5 min) on the structures and the properties of the films were investigated. Fourier transform infrared (FT-IR) and cross-polarization magic-angle spinning carbon-13 nuclear magnetic resonance (CP/MAS ¹³C NMR) characterizations verified the breakage of inter- and intra-cellulose hydrogen bonds during the regeneration, resulting in the disruption of the crystalline structure of cellulose. X-ray diffraction (XRD) data indicated that the regeneration converted the polymorphism of cellulose from I to II as well as decreased its crystallinity. Ultraviolet-visible spectra (UV-Vis) and scanning electron microscopy (SEM) analyses revealed the excellent optical transparency of the films to visible light due to the complete dissolution of cellulose fibers as well as the sufficient breaking of the inter- and intra-cellulose hydrogen bonds. In terms of tensile testing, tuning LiBr concentrations and dissolving time could increase the elongation at break and tensile strength of the films. The maximum elongation at break of 26% and tensile strength of 67 MPa were achieved when the films prepared in 65 wt % LiBr for 10 and 15 min, respectively. These results indicated the great potential of the cellulose films for packaging use. Full article

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19 pages, 12002 KiB

Open AccessArticle

Preparation, Characterization and Wound Healing Effects of New Membranes Based on Chitosan, Hyaluronic Acid and Arginine Derivatives

by Andreea-Teodora Iacob, Maria Drăgan, Nicolae Ghețu, Dragoș Pieptu, Cornelia Vasile, Frédéric Buron, Sylvain Routier, Simona Elena Giusca, Irina-Draga Caruntu and Lenuța Profire

Polymers 2018, 10(6), 607; https://doi.org/10.3390/polym10060607 - 2 Jun 2018

Cited by 39 | Viewed by 6257

Abstract

New membranes based on chitosan and chitosan-hyaluronic acid containing new arginine derivatives with thiazolidine-4-one scaffold have been prepared using the ionic cross-linking method. The presence of the arginine derivatives with thiazolidine-4-one scaffold into the polymer matrix was proved by Fourier-transform infrared spectroscopy (FT-IR). [...] Read more.

New membranes based on chitosan and chitosan-hyaluronic acid containing new arginine derivatives with thiazolidine-4-one scaffold have been prepared using the ionic cross-linking method. The presence of the arginine derivatives with thiazolidine-4-one scaffold into the polymer matrix was proved by Fourier-transform infrared spectroscopy (FT-IR). The scanning electron microscopy (SEM) revealed a micro-porous structure that is an important characteristic for the treatment of burns, favoring the exudate absorption, the rate of colonization, the cell structure, and the angiogenesis process. The developed polymeric membranes also showed good swelling degree, improved hydrophilicity, and biocompatibility in terms of surface free energy components, which supports their application for tissue regeneration. Moreover, the chitosan-arginine derivatives (CS-6h, CS-6i) and chitosan-hyaluronic acid-arginine derivative (CS-HA-6h) membranes showed good healing effects on the burn wound model induced to rats. For these membranes a complete reepithelialization was observed after 15 days of the experiment, which supports a faster healing process. Full article

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16 pages, 7212 KiB

Open AccessArticle

Preparation and Characterization of Superabsorbent Polymers Based on Starch Aldehydes and Carboxymethyl Cellulose

by Jungmin Lee, Soohee Park, Hyun-gyoo Roh, Seungtaek Oh, Sunghoon Kim, Myounguk Kim, Donghyun Kim and Jongshin Park

Polymers 2018, 10(6), 605; https://doi.org/10.3390/polym10060605 - 2 Jun 2018

Cited by 52 | Viewed by 10980

Abstract

Superabsorbent polymers (SAPs) are crosslinked hydrophilic polymers that are capable of absorbing large amounts of water. Commercial SAPs are mostly produced with acrylic acid that cannot be easily biodegraded. Therefore, in this study, polysaccharide-based SAPs using carboxymethyl cellulose as a major component were [...] Read more.

Superabsorbent polymers (SAPs) are crosslinked hydrophilic polymers that are capable of absorbing large amounts of water. Commercial SAPs are mostly produced with acrylic acid that cannot be easily biodegraded. Therefore, in this study, polysaccharide-based SAPs using carboxymethyl cellulose as a major component were prepared. Starch aldehydes and citric acid were selected due to their environment-friendly, non-toxic, and biodegradable properties compared to conventional crosslinking agents. Starch aldehydes were prepared by periodate oxidation, which forms aldehyde groups by taking the places of C–OH groups at C-2 and C-3. Furthermore, starch aldehydes were analyzed through the change in FT-IR spectra, the aldehyde quantitation, and the morphology in FE-SEM images. In the crosslinking of polysaccharide-based SAPs, the acetal bridges from starch aldehydes led to a large amount of water entering the network structure of the SAPs. However, the ester bridges from citric acid interfered with the water penetration. In addition, the swelling behavior of the SAPs was analyzed by the Fickian diffusion model and the Schott’s pseudo second order kinetics model. The relationship between swelling behavior and morphology of the SAPs was analyzed by FE-SEM images. In conclusion, polysaccharide-based SAPs were well prepared and the highest equilibrium swelling ratio was 87.0 g/g. Full article

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11 pages, 2780 KiB

Open AccessArticle

Effect of Xanthan–Chitosan Microencapsulation on the Survival of Lactobacillus acidophilus in Simulated Gastrointestinal Fluid and Dairy Beverage

by Guowei Shu, Yunxia He, Li Chen, Yajuan Song, Jili Cao and He Chen

Polymers 2018, 10(6), 588; https://doi.org/10.3390/polym10060588 - 28 May 2018

Cited by 17 | Viewed by 3895

Abstract

Lactobacillus acidophilus was encapsulated in xanthan–chitosan (XC) and xanthan–chitosan–xanthan (XCX) polyelectrolyte complex (PEC) gels by extrusion method. The obtained capsules were characterized by X-ray diffraction and FTIR spectroscopy. The effects of microencapsulation on the changes in survival and release behavior of the Lactobacillus [...] Read more.

Lactobacillus acidophilus was encapsulated in xanthan–chitosan (XC) and xanthan–chitosan–xanthan (XCX) polyelectrolyte complex (PEC) gels by extrusion method. The obtained capsules were characterized by X-ray diffraction and FTIR spectroscopy. The effects of microencapsulation on the changes in survival and release behavior of the Lactobacillus acidophilus during exposure to simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) were studied. Encapsulated Lactobacillus acidophilus exhibited a significantly higher resistance to SGF and SIF than non-encapsulated samples. In addition, the viability of free and immobilized cells of Lactobacillus acidophilus incorporated into dairy beverages was assessed for 21 days both at room temperature and in refrigerated storage. The results indicated that xanthan–chitosan–xanthan (XCX) and xanthan–chitosan (XC) significantly (p < 0.05) improved the cell survival of Lactobacillus acidophilus in yogurt during 21 days of storage at 4 and 25 °C, when compared to free cells. Full article

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16 pages, 2663 KiB

Open AccessArticle

Novel Bacterial Cellulose/Gelatin Hydrogels as 3D Scaffolds for Tumor Cell Culture

by Jing Wang, Li Zhao, Aixia Zhang, Yuan Huang, Javad Tavakoli and Youhong Tang

Polymers 2018, 10(6), 581; https://doi.org/10.3390/polym10060581 - 24 May 2018

Cited by 52 | Viewed by 7313

Abstract

Three-dimensional (3D) cells in vitro culture are becoming increasingly popular in cancer research because some important signals are lost when cells are cultured in a two-dimensional (2D) substrate. In this work, bacterial cellulose (BC)/gelatin hydrogels were successfully synthesized and were investigated as scaffolds [...] Read more.

Three-dimensional (3D) cells in vitro culture are becoming increasingly popular in cancer research because some important signals are lost when cells are cultured in a two-dimensional (2D) substrate. In this work, bacterial cellulose (BC)/gelatin hydrogels were successfully synthesized and were investigated as scaffolds for cancer cells in vitro culture to simulate tumor microenvironment. Their properties and ability to support normal growth of cancer cells were evaluated. In particular, the human breast cancer cell line (MDA-MD-231) was seeded into BC/gelatin scaffolds to investigate their potential in 3D cell in vitro culture. MTT proliferation assay, scanning electron microscopy, hematoxylin and eosin staining and immunofluorescence were used to determine cell proliferation, morphology, adhesion, infiltration, and receptor expression. The in vitro MDA-MD-231 cell culture results demonstrated that cells cultured on the BC/gelatin scaffolds had significant adhesion, proliferation, ingrowth and differentiation. More importantly, MDA-MD-231 cells cultured in BC/gelatin scaffolds retained triple-negative receptor expression, demonstrating that BC/gelatin scaffolds could be used as ideal in vitro culture scaffolds for tumor cells. Full article

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15 pages, 3718 KiB

Open AccessArticle

The Preparation of Nano-SiO₂/Dialdehyde Cellulose Hybrid Materials as a Novel Cross-Linking Agent for Collagen Solutions

by Cuicui Ding, Yang Zhang, Binhan Yuan, Xiaodong Yang, Ronghui Shi and Min Zhang

Polymers 2018, 10(5), 550; https://doi.org/10.3390/polym10050550 - 21 May 2018

Cited by 7 | Viewed by 4974

Abstract

Nano-SiO₂ was immobilized onto dialdehyde cellulose (DAC) to prepare SiO₂/DAC hybrid materials. Fourier transform infrared spectra (FTIR), thermogravimetric analysis and field emission scanning electron microscopy of SiO₂/DAC indicated that nano-SiO₂ had been successfully hybridized with DAC. X-ray [...] Read more.

Nano-SiO₂ was immobilized onto dialdehyde cellulose (DAC) to prepare SiO₂/DAC hybrid materials. Fourier transform infrared spectra (FTIR), thermogravimetric analysis and field emission scanning electron microscopy of SiO₂/DAC indicated that nano-SiO₂ had been successfully hybridized with DAC. X-ray diffraction suggested that the structure of DAC was influenced by the nano-SiO₂. SiO₂/DAC was then used as the cross-linker of collagen solutions. Gel electrophoresis patterns and FTIR reflected that cross-linking occurred between DAC and collagen, but that collagen retained the native triple-helix, respectively. Differential scanning calorimetry indicated that the thermal stability of collagen could be effectively improved by SiO₂/DAC. Dynamic rheology tests revealed that the flowability of collagens cross-linked by SiO₂/DAC was superior to that of those cross-linked by DAC; meanwhile, collagens cross-linked by SiO₂/DAC possessed a more homogeneous morphology compared to those cross-linked by DAC. The hybridization of SiO₂/DAC as a cross-linker for collagen could effectively prevent the gelation caused by excessive cross-linking, and significantly improve the thermostability of collagen, which could be helpful for collagen being applied in fields including biomaterials, cosmetics, etc. Full article

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15 pages, 4013 KiB

Open AccessArticle

Effect of Chemical Disinfection on Chitosan Coated PMMA and PETG Surfaces—An In Vitro Study

by Katarzyna Walczak, Jessica Thiele, Daniel Geisler, Klaus Boening and Mieszko Wieckiewicz

Polymers 2018, 10(5), 536; https://doi.org/10.3390/polym10050536 - 16 May 2018

Cited by 15 | Viewed by 5880

Abstract

In oral sciences, chitosan application is of interest due to its antimicrobial and hemostatic activity. Chitosan coating of dentures and other intraoral devices could be beneficial for treatment of denture stomatitis or in the management of postoperative bleeding. Disinfection of dentures and prosthodontic [...] Read more.

In oral sciences, chitosan application is of interest due to its antimicrobial and hemostatic activity. Chitosan coating of dentures and other intraoral devices could be beneficial for treatment of denture stomatitis or in the management of postoperative bleeding. Disinfection of dentures and prosthodontic materials is crucial before their use in patients. This study investigated the influence of chemical disinfectants on chitosan-coated surfaces. A total of 100 specimens were made: 50 of PMMA (polymethyl methacrylate), and 50 of PETG (polyethylene terephthalate glycol-modified) material and coated with 2% chitosan acetate solution. In each material, 5 groups (10 specimens each) were established and disinfected with Printosept-ID (L1), MD 520 (L2), Silosept (L3), or Dentavon (L4), or stored in distilled water (L0, control group). After disinfection, all specimens underwent abrasion tests (30,000 cycles in a tooth-brushing simulator). Areas without chitosan coating were measured by digital planimetry both before and after the disinfection/abrasion procedure and a damage-score was calculated. Regarding chitosan coating, the statistical analysis showed a significant influence of the disinfectants tested and significant differences between disinfectants (p < 0.05). Chitosan coating was most stable on PMMA and PETG after disinfection with MD 520 (L2). Otherwise, active oxygen containing disinfectants (L3, L4) led to the greatest alterations in the chitosan coating. Full article

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14 pages, 1705 KiB

Open AccessArticle

Synthesis of Quaternary Ammonium Salts of Chitosan Bearing Halogenated Acetate for Antifungal and Antibacterial Activities

by Jingjing Zhang, Wenqiang Tan, Fang Luan, Xiuli Yin, Fang Dong, Qing Li and Zhanyong Guo

Polymers 2018, 10(5), 530; https://doi.org/10.3390/polym10050530 - 15 May 2018

Cited by 33 | Viewed by 6177

Abstract

In this paper, quaternary ammonium salts of chitosan bearing halogenated acetate, including N,N,N-trimethyl chitosan chloroacetate (TMCSC), N,N,N-trimethyl chitosan dichloroacetate (TMCSDC), N,N,N-trimethyl chitosan trichloroacetate (TMCSTC), and N,N [...] Read more.

In this paper, quaternary ammonium salts of chitosan bearing halogenated acetate, including N,N,N-trimethyl chitosan chloroacetate (TMCSC), N,N,N-trimethyl chitosan dichloroacetate (TMCSDC), N,N,N-trimethyl chitosan trichloroacetate (TMCSTC), and N,N,N-trimethyl chitosan trifluoroacetate (TMCSTF), were prepared via N,N,N-trimethyl chitosan iodide (TMCSI). The obtained chitosan derivatives were characterized by FT-IR, ¹H NMR spectra, ¹³C NMR spectra, and elemental analysis. Their antifungal property against Fusarium oxysporum f. sp. cucumebrium Owen (F. oxysporum f. sp. cucumebrium Owen), Botrytis cinerea (B. cinerea), and Phomopsis asparagi (P. asparagi) were evaluated by hyphal measurement method at concentrations ranging from 0.08 mg/mL to 0.8 mg/mL. Meanwhile, two common bacteria, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), were selected as the model Gram-negative and Gram-positive bacteria to evaluate the antibacterial property of the chitosan derivatives by agar well diffusion method. The results showed that TMCSC, TMCSDC, TMCSTC, and TMCSTF had better antifungal and antibacterial activities than chitosan and TMCSI. In particular, a rule showed that the inhibitory activity decreased in the order: TMCSTF > TMCSTC > TMCSDC > TMCSC > TMCSI > chitosan, which was consistent with the electron-withdrawing property of different halogenated acetate. Apparently, the quaternary ammonium salts of chitosan with stronger electron withdrawing ability possessed relatively greater antifungal and antibacterial activities. This experiment provides a potentially feasible method for the further utilization of chitosan in fields of antifungal and antibacterial biomaterials. Full article

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12 pages, 3538 KiB

Open AccessArticle

Preparation and Evaluation of Coal Fly Ash/Chitosan Composites as Magnetic Supports for Highly Efficient Cellulase Immobilization and Cellulose Bioconversion

by Limin Zang, Xuan Qiao, Lei Hu, Chao Yang, Qifan Liu, Chun Wei, Jianhui Qiu, Haodao Mo, Ge Song, Jun Yang and Chanjuan Liu

Polymers 2018, 10(5), 523; https://doi.org/10.3390/polym10050523 - 14 May 2018

Cited by 19 | Viewed by 4330

Abstract

Two magnetic supports with different morphologies and particle sizes were designed and prepared for cellulase immobilization based on chitosan and industrial by-product magnetic coal fly ash (MCFA). One was prepared by coating chitosan onto spherical MCFA particles to form non-porous MCFA@chitosan gel microcomposites [...] Read more.

Two magnetic supports with different morphologies and particle sizes were designed and prepared for cellulase immobilization based on chitosan and industrial by-product magnetic coal fly ash (MCFA). One was prepared by coating chitosan onto spherical MCFA particles to form non-porous MCFA@chitosan gel microcomposites (Support I) with a size of several micrometers, and the other was prepared using the suspension method to form porous MCFA/chitosan gel beads (Support II) with a size of several hundred micrometers. Cellulase was covalent binding to the support by glutaraldehyde activation method. The morphology, structure and magnetic property of immobilized cellulase were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and a vibrating-sample magnetometer. The cellulase loading on Support I was 85.8 mg/g with a relatlvely high activity recovery of 76.6%, but the immobilized cellulase exhibited low thermal stability. The cellulase loading on Support II was 76.8 mg/g with a relative low activity recovery of 51.9%, but the immobilized cellulase showed high thermal stability. Cellulase immobilized on Support I had a glucose productivity of 219.8 mg glucose/g CMC and remained 69.9% of the original after 10 cycles; whereas the glucose productivity was 246.4 mg glucose/g CMC and kept 75.5% of its initial value after 10 repeated uses for Support II immobilized cellulase. The results indicate that the two supports can be used as cheap and effective supports to immobilize enzymes. Full article

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47 pages, 13076 KiB

Open AccessReview

Recent Advances in Nanocellulose Composites with Polymers: A Guide for Choosing Partners and How to Incorporate Them

by Arindam Chakrabarty and Yoshikuni Teramoto

Polymers 2018, 10(5), 517; https://doi.org/10.3390/polym10050517 - 10 May 2018

Cited by 225 | Viewed by 15347

Abstract

In recent years, the research on nanocellulose composites with polymers has made significant contributions to the development of functional and sustainable materials. This review outlines the chemistry of the interaction between the nanocellulose and the polymer matrix, along with the extent of the [...] Read more.

In recent years, the research on nanocellulose composites with polymers has made significant contributions to the development of functional and sustainable materials. This review outlines the chemistry of the interaction between the nanocellulose and the polymer matrix, along with the extent of the reinforcement in their nanocomposites. In order to fabricate well-defined nanocomposites, the type of nanomaterial and the selection of the polymer matrix are always crucial from the viewpoint of polymer–filler compatibility for the desired reinforcement and specific application. In this review, recent articles on polymer/nanocellulose composites were taken into account to provide a clear understanding on how to use the surface functionalities of nanocellulose and to choose the polymer matrix in order to produce the nanocomposite. Here, we considered cellulose nanocrystal (CNC) and cellulose nanofiber (CNF) as the nanocellulosic materials. A brief discussion on their synthesis and properties was also incorporated. This review, overall, is a guide to help in designing polymer/nanocellulose composites through the utilization of nanocellulose properties and the selection of functional polymers, paving the way to specific polymer–filler interaction. Full article

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14 pages, 2365 KiB

Open AccessArticle

Controlled Levofloxacin Release and Antibacterial Properties of β-Cyclodextrins-Grafted Polypropylene Mesh Devices for Hernia Repair

by Noor Sanbhal, Xiakeer Saitaer, Yan Li, Ying Mao, Ting Zou, Gang Sun and Lu Wang

Polymers 2018, 10(5), 493; https://doi.org/10.3390/polym10050493 - 3 May 2018

Cited by 23 | Viewed by 4527

Abstract

Mesh infection is a major complication of hernia repair. After knitted mesh implantation, bacteria can grow within textile structures causing infection. In this work, polypropylene (PP) mesh devices were two-step grafted with hexamethylene diisocyanate (HDI) and β–cyclodexrins (CD) and then loaded with suitable [...] Read more.

Mesh infection is a major complication of hernia repair. After knitted mesh implantation, bacteria can grow within textile structures causing infection. In this work, polypropylene (PP) mesh devices were two-step grafted with hexamethylene diisocyanate (HDI) and β–cyclodexrins (CD) and then loaded with suitable antimicrobial levofloxacin HCL for hernia mesh-infection prevention. First, oxygen plasma was able to create surface roughness, then HDI was successfully grafted onto PP fiber surfaces. Afterwards, CD was covalently grafted onto the HDI treated PP meshes, and levofloxacin HCL (LVFX) was loaded into the CD cavity of the modified meshes. The modified devices were evaluated for sustained antibiotic properties and drug-release profiles in a phosphate buffer, and sustained drug release was observed between interfaces of meshes and aqueous environment. The antibiotic-loaded PP mesh samples demonstrated sustained antibacterial properties for 7 and 10 days, respectively, against both Gram-negative and Gram-positive bacteria. The CD-captured levofloxacin HCL showed burst release after 6 h but later exhibited sustained release for the next 48 h. Among all samples, the modified mesh LVFX-6 was more stable and showed more sustained drug release and could be employed in future clinical applications. Full article

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11 pages, 2547 KiB

Open AccessArticle

Lipid-Lowering Effect of the Pleurotus eryngii (King Oyster Mushroom) Polysaccharide from Solid-State Fermentation on Both Macrophage-Derived Foam Cells and Zebrafish Models

by Hua Wei, Shang Yue, Shizhu Zhang and Ling Lu

Polymers 2018, 10(5), 492; https://doi.org/10.3390/polym10050492 - 3 May 2018

Cited by 26 | Viewed by 5630

Abstract

Hyperlipidemia is a key risk factor in inducing fatty liver, hypertension, atherosclerosis and cerebrovascular diseases. Previous studies have verified that polysaccharides from fruiting bodies (PEPE) of Pleurotus eryngii (king oyster mushroom) are capable of decreasing the lipid content. In this study, the P. [...] Read more.

Hyperlipidemia is a key risk factor in inducing fatty liver, hypertension, atherosclerosis and cerebrovascular diseases. Previous studies have verified that polysaccharides from fruiting bodies (PEPE) of Pleurotus eryngii (king oyster mushroom) are capable of decreasing the lipid content. In this study, the P. eryngii polysaccharide is obtained by solid-state fermentation (PESF) using lignocellulosic wastes, corn-cobs and wheat bran. The high-performance liquid chromatography (HPLC) assays indicate that PESF has a similar composition to that of PEPE. Meanwhile, PESF has no detectable toxicity and is able to significantly inhibit foam-cell formation in murine macrophage cells (RAW264.7) induced by oxidized low-density lipoprotein. Further verification indicates that PESF has lipid-lowering effects during the lipid absorption phase in a zebrafish hyperlipidemia model. Our findings suggest that the P. eryngii polysaccharide from solid-state fermentation (PESF) can be used as a valuable lipid-lowering food additive or raw materials for producing lipid-lowering drugs. Full article

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18 pages, 4154 KiB

Open AccessArticle

Permeability of Novel Chitosan-g-Poly(Methyl Methacrylate) Amphiphilic Nanoparticles in a Model of Small Intestine In Vitro

by Imrit Noi, Inbar Schlachet, Murali Kumarasamy and Alejandro Sosnik

Polymers 2018, 10(5), 478; https://doi.org/10.3390/polym10050478 - 27 Apr 2018

Cited by 25 | Viewed by 5760

Abstract

Engineering of drug nanocarriers combining fine-tuned mucoadhesive/mucopenetrating properties is currently being investigated to ensure more efficient mucosal drug delivery. Aiming to improve the transmucosal delivery of hydrophobic drugs, we designed a novel nanogel produced by the self-assembly of amphiphilic chitosan graft copolymers ionotropically [...] Read more.

Engineering of drug nanocarriers combining fine-tuned mucoadhesive/mucopenetrating properties is currently being investigated to ensure more efficient mucosal drug delivery. Aiming to improve the transmucosal delivery of hydrophobic drugs, we designed a novel nanogel produced by the self-assembly of amphiphilic chitosan graft copolymers ionotropically crosslinked with sodium tripolyphosphate. In this work, we synthesized, for the first time, chitosan-g-poly(methyl methacrylate) nanoparticles thiolated by the conjugation of N-acetyl cysteine. First, we confirmed that both non-crosslinked and crosslinked nanoparticles in the 0.05–0.1% w/v concentration range display very good cell compatibility in two cell lines that are relevant to oral delivery, Caco-2 cells that mimic the intestinal epithelium and HT29-MTX cells that are a model of mucin-producing goblet cells. Then, we evaluated the effect of crosslinking, nanoparticle concentration, and thiolation on the permeability in vitro utilizing monolayers of (i) Caco-2 and (ii) Caco-2:HT29-MTX cells (9:1 cell number ratio). Results confirmed that the ability of the nanoparticles to cross Caco-2 monolayer was affected by the crosslinking. In addition, thiolated nanoparticles interact more strongly with mucin, resulting in a decrease of the apparent permeability coefficient (P_app) compared to the pristine nanoparticles. Moreover, for all the nanoparticles, higher concentration resulted in lower P_app, suggesting that the transport pathways can undergo saturation. Full article

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13 pages, 1529 KiB

Open AccessArticle

Chitosan Composites Synthesized Using Acetic Acid and Tetraethylorthosilicate Respond Differently to Methylene Blue Adsorption

by Thomas Y. A. Essel, Albert Koomson, Marie-Pearl O. Seniagya, Grace P. Cobbold, Samuel K. Kwofie, Bernard O. Asimeng, Patrick K. Arthur, Gordon Awandare and Elvis K. Tiburu

Polymers 2018, 10(5), 466; https://doi.org/10.3390/polym10050466 - 24 Apr 2018

Cited by 28 | Viewed by 6081

Abstract

The sol-gel and cross-linking processes have been used by researchers to synthesize silica-based nanostructures and optimize their size and morphology by changing either the material or the synthesis conditions. However, the influence of the silica nanostructures on the overall physicochemical and mechanistic properties [...] Read more.

The sol-gel and cross-linking processes have been used by researchers to synthesize silica-based nanostructures and optimize their size and morphology by changing either the material or the synthesis conditions. However, the influence of the silica nanostructures on the overall physicochemical and mechanistic properties of organic biopolymers such as chitosan has received limited attention. The present study used a one-step synthetic method to obtain chitosan composites to monitor the uptake and release of a basic cationic dye (methylene blue) at two different pH values. Firstly, the composites were synthesized and characterized by Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) to ascertain their chemical identity. Adsorption studies were conducted suing methylene blue and these studies revealed that Acetic Acid-Chitosan (AA-CHI), Tetraethylorthosilicate-Chitosan (TEOS-CHI), Acetic Acid-Tetraethylorthosilicate-Chitosan (AA-TEOS-CHI), and Acetic Acid-Chitosan-Tetraethylorthosilicate (AA-CHI-TEOS) had comparatively lower percentage adsorbances in acidic media after 40 h, with AA-CHI adsorbing most of the methylene blue dye. In contrast, these materials recorded higher percentage adsorbances of methylene blue in the basic media. The release profiles of these composites were fitted with an exponential model. The R-squared values obtained indicated that the AA-CHI at pH ~ 2.6 and AA-TEOS-CHI at pH ~ 7.2 of methylene blue had steady and consistent release profiles. The release mechanisms were analyzed using Korsmeyer-Peppas and Hixson-Crowell models. It was deduced that the release profiles of the majority of the synthesized chitosan beads were influenced by the conformational or surface area changes of the methylene blue. This was justified by the higher correlation coefficient or Pearson’s R values (R ≥ 0.5) computed from the Hixson-Crowell model. The results from this study showed that two of the novel materials comprising acetic acid-chitosan and a combination of equimolar ratios of acetic acid-TEOS-chitosan could be useful pH-sensitive probes for various biomedical applications, whereas the other materials involving the two-step synthesis could be found useful in environmental remediation of toxic materials. Full article

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17 pages, 3239 KiB

Open AccessReview

Biomedical Applications of Chitosan and Its Derivative Nanoparticles

by Dongying Zhao, Shuang Yu, Beini Sun, Shuang Gao, Sihan Guo and Kai Zhao

Polymers 2018, 10(4), 462; https://doi.org/10.3390/polym10040462 - 23 Apr 2018

Cited by 429 | Viewed by 21820

Abstract

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely [...] Read more.

Chitosan is a biodegradable natural polymer with many advantages such as nontoxicity, biocompatibility, and biodegradability. It can be applied in many fields, especially in medicine. As a delivery carrier, it has great potential and cannot be compared with other polymers. Chitosan is extremely difficult to solubilize in water, but it can be solubilized in acidic solution. Its insolubility in water is a major limitation for its use in medical applications. Chitosan derivatives can be obtained by chemical modification using such techniques as acylation, alkylation, sulfation, hydroxylation, quaternization, esterification, graft copolymerization, and etherification. Modified chitosan has chemical properties superior to unmodified chitosan. For example, nanoparticles produced from chitosan derivatives can be used to deliver drugs due to their stability and biocompatibility. This review mainly focuses on the properties of chitosan, chitosan derivatives, and the origin of chitosan-based nanoparticles. In addition, applications of chitosan-based nanoparticles in drug delivery, vaccine delivery, antimicrobial applications, and callus and tissue regeneration are also presented. In summary, nanoparticles based on chitosan have great potential for research and development of new nano vaccines and nano drugs in the future. Full article

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16 pages, 4425 KiB

Open AccessArticle

Collagen/Gelatin/Hydroxyethyl Cellulose Composites Containing Microspheres Based on Collagen and Gelatin: Design and Evaluation

by Justyna Kozlowska, Natalia Stachowiak and Alina Sionkowska

Polymers 2018, 10(4), 456; https://doi.org/10.3390/polym10040456 - 19 Apr 2018

Cited by 35 | Viewed by 8801

Abstract

The objective of this study was to develop three-dimensional collagen/gelatin/hydroxyethyl cellulose composites in combination with gelatin or collagen-gelatin loaded microspheres. Microspheres were prepared by an emulsification/crosslinking method. A 1-Ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) mixture were used as a [...] Read more.

The objective of this study was to develop three-dimensional collagen/gelatin/hydroxyethyl cellulose composites in combination with gelatin or collagen-gelatin loaded microspheres. Microspheres were prepared by an emulsification/crosslinking method. A 1-Ethyl-3-(3-dimethyl-aminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) mixture were used as a crosslinking agent for the obtained materials. The structure of the materials was studied using scanning electron microscopy (SEM) and infrared spectroscopy. Moreover, a Calendula officinalis (pot marigold) flower extract release profile of the microsphere-loaded matrices was assessed in vitro. Additionally, porosity, density, stability, swelling and mechanical properties were tested. On the basis of SEM images, the microspheres exhibited a spherical shape and were irregularly dispersed in the polymer matrix. However, it was found that the addition of microparticles to obtained materials did not significantly change their microstructure. We observed a slight decrease in the swelling properties of matrices and an increase in values of Young’s modulus. Significantly, the addition of microspheres to the polymer matrices led to improved loading capacity of materials and release performance of Calendula officinalis flower extract. This makes the collagen/gelatin/hydroxyethyl cellulose composites containing microspheres a promising and suitable vehicle for biomedical, dermatological, or cosmetic applications. Full article

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19 pages, 3389 KiB

Open AccessArticle

Biocompatible and Antibacterial Nitric Oxide-Releasing Pluronic F-127/Chitosan Hydrogel for Topical Applications

by Milena T. Pelegrino, Bruna De Araujo Lima, Mônica H. M. Do Nascimento, Christiane B. Lombello, Marcelo Brocchi and Amedea B. Seabra

Polymers 2018, 10(4), 452; https://doi.org/10.3390/polym10040452 - 18 Apr 2018

Cited by 70 | Viewed by 9595

Abstract

Nitric oxide (NO) is involved in physiological processes, including vasodilatation, wound healing and antibacterial activities. As NO is a free radical, designing drugs to generate therapeutic amounts of NO in controlled spatial and time manners is still a challenge. In this study, the [...] Read more.

Nitric oxide (NO) is involved in physiological processes, including vasodilatation, wound healing and antibacterial activities. As NO is a free radical, designing drugs to generate therapeutic amounts of NO in controlled spatial and time manners is still a challenge. In this study, the NO donor S-nitrosoglutathione (GSNO) was incorporated into the thermoresponsive Pluronic F-127 (PL)-chitosan (CS) hydrogel, with an easy and economically feasible methodology. CS is a polysaccharide with known antimicrobial properties. Scanning electron microscopy, rheology and differential scanning calorimetry techniques were used for hydrogel characterization. The results demonstrated that the hydrogel has a smooth surface, thermoresponsive behavior and good mechanical stability. The kinetics of NO release and GSNO diffusion from GSNO-containing PL/CS hydrogel demonstrated a sustained NO/GSNO release, in concentrations suitable for biomedical applications. The GSNO-PL/CS hydrogel demonstrated a concentration-dependent toxicity to Vero cells, and antimicrobial activity to Pseudomonas aeruginosa (minimum inhibitory concentration and minimum bactericidal concentration values of 0.5 µg·mL⁻¹ of hydrogel, which corresponds to 1 mmol·L⁻¹ of GSNO). Interestingly, the concentration range in which the NO-releasing hydrogel demonstrated an antibacterial effect was not found to be toxic to the Vero mammalian cell. Thus, the GSNO-PL/CS hydrogel is a suitable biomaterial for topical NO delivery applications. Full article

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51 pages, 21605 KiB

Open AccessReview

Chitosan in Non-Viral Gene Delivery: Role of Structure, Characterization Methods, and Insights in Cancer and Rare Diseases Therapies

by Beatriz Santos-Carballal, Elena Fernández Fernández and Francisco M. Goycoolea

Polymers 2018, 10(4), 444; https://doi.org/10.3390/polym10040444 - 15 Apr 2018

Cited by 95 | Viewed by 11667

Abstract

Non-viral gene delivery vectors have lagged far behind viral ones in the current pipeline of clinical trials of gene therapy nanomedicines. Even when non-viral nanovectors pose less safety risks than do viruses, their efficacy is much lower. Since the early studies to deliver [...] Read more.

Non-viral gene delivery vectors have lagged far behind viral ones in the current pipeline of clinical trials of gene therapy nanomedicines. Even when non-viral nanovectors pose less safety risks than do viruses, their efficacy is much lower. Since the early studies to deliver pDNA, chitosan has been regarded as a highly attractive biopolymer to deliver nucleic acids intracellularly and induce a transgenic response resulting in either upregulation of protein expression (for pDNA, mRNA) or its downregulation (for siRNA or microRNA). This is explained as the consequence of a multi-step process involving condensation of nucleic acids, protection against degradation, stabilization in physiological conditions, cellular internalization, release from the endolysosome (“proton sponge” effect), unpacking and enabling the trafficking of pDNA to the nucleus or the siRNA to the RNA interference silencing complex (RISC). Given the multiple steps and complexity involved in the gene transfection process, there is a dearth of understanding of the role of chitosan’s structural features (M_w and degree of acetylation, DA%) on each step that dictates the net transfection efficiency and its kinetics. The use of fully characterized chitosan samples along with the utilization of complementary biophysical and biological techniques is key to bridging this gap of knowledge and identifying the optimal chitosans for delivering a specific gene. Other aspects such as cell type and administration route are also at play. At the same time, the role of chitosan structural features on the morphology, size and surface composition of synthetic virus-like particles has barely been addressed. The ongoing revolution brought about by the recent discovery of CRISPR-Cas9 technology will undoubtedly be a game changer in this field in the short term. In the field of rare diseases, gene therapy is perhaps where the greatest potential lies and we anticipate that chitosans will be key players in the translation of research to the clinic. Full article

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15 pages, 3525 KiB

Open AccessArticle

Comparative Study of Diethylaminoethyl-Chitosan and Methylglycol-Chitosan as Potential Non-Viral Vectors for Gene Therapy

by Sergei V. Raik, Stanislav Andranovitš, Valentina A. Petrova, Yingying Xu, Jenny Ka-Wing Lam, Gordon A. Morris, Alexandra V. Brodskaia, Luca Casettari, Andreii S. Kritchenkov and Yury A. Skorik

Polymers 2018, 10(4), 442; https://doi.org/10.3390/polym10040442 - 14 Apr 2018

Cited by 42 | Viewed by 6812

Abstract

In this paper, we compared the transfection efficiency and cytotoxicity of methylglycol-chitosan (MG-CS) and diethylaminoethyl-chitosan (DEAE-CS_I and DEAE-CS_II with degrees of substitution of 1.2 and 0.57, respectively) to that of Lipofectamine (used as a reference transfection vector). MG-CS contains quaternary amines [...] Read more.

In this paper, we compared the transfection efficiency and cytotoxicity of methylglycol-chitosan (MG-CS) and diethylaminoethyl-chitosan (DEAE-CS_I and DEAE-CS_II with degrees of substitution of 1.2 and 0.57, respectively) to that of Lipofectamine (used as a reference transfection vector). MG-CS contains quaternary amines to improve DNA binding, whereas the DEAE-CS exhibits pH buffering capability that would ostensibly enhance transfection efficiency by promoting endosomal escape. Gel retardation assays showed that both DEAE-CS and MG-CS bound to DNA at a polysaccharide:DNA mass ratio of 2:1. In Calu-3 cells, the DNA transfection activity was significantly better with MG-CS than with DEAE-CS, and the efficiency improved with increasing polysaccharide:DNA ratios. By contrast, the efficiency of DEAE-CS_I and DEAE-CS_II was independent of the polysaccharide:DNA ratio. Conversely, in the transfection-recalcitrant JAWSII cells, both Lipofectamine and MG-CS showed significantly lower DNA transfection activity than in Calu-3 cells, whereas the efficiency of DEAE-CS_I and DEAE-CS_II was similar in both cell lines. The toxicity of DEAE-CS increased with increasing concentrations of the polymer and its degree of substitution, whereas MG-CS demonstrated negligible cytotoxicity, even at the highest concentration studied. Overall, MG-CS proved to be a more efficient and less toxic transfection agent when compared to DEAE-CS. Full article

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10 pages, 20156 KiB

Open AccessArticle

Study on the Use of Microbial Cellulose as a Biocarrier for 1,3-Dihydroxy-2-Propanone and Its Potential Application in Industry

by Lidia Stasiak-Różańska and Justyna Płoska

Polymers 2018, 10(4), 438; https://doi.org/10.3390/polym10040438 - 14 Apr 2018

Cited by 29 | Viewed by 6817

Abstract

Can microbial cellulose (MC) be used as a bio-carrier for 1,3-dihydroxy-2-propanone (DHA)? The aim of this study was to examine the possibility of using MC as a biomaterial for DHA transferring into the stratum corneum and inducing changes in skin color. The MC [...] Read more.

Can microbial cellulose (MC) be used as a bio-carrier for 1,3-dihydroxy-2-propanone (DHA)? The aim of this study was to examine the possibility of using MC as a biomaterial for DHA transferring into the stratum corneum and inducing changes in skin color. The MC patches were obtained from Gluconacetobacter xylinus strain and incubated in solutions with various concentrations of DHA (g·L⁻¹: 20; 50; 80; 110) at 22 °C for 24 h. Afterwards; the patches were applied onto the skin for 15, 30, or 60 min. Skin color changes were assessed visually compared to a control patches without DHA. The intensity of skin color was increasing with the increase of DHA concentration and time of patches application. Application of MC patches with DHA (50 g·L⁻¹) for 30 min ensured the color which was considered the closest to the desired natural tan effect. MC patches containing DHA can be biocarriers enabling DHA transport into the stratum corneum and causing skin color changes. Study results indicate a new possibility for industrial applications of MC; e.g., as a biocarrier in masking the symptoms of vitiligo or production of self-tanning agents in the form of masks. Full article

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15 pages, 56235 KiB

Open AccessArticle

The Application of Small-Angle Light Scattering for Rheo-Optical Characterization of Chitosan Colloidal Solutions

by Piotr Owczarz, Patryk Ziółkowski and Marek Dziubiński

Polymers 2018, 10(4), 431; https://doi.org/10.3390/polym10040431 - 13 Apr 2018

Cited by 12 | Viewed by 6228

Abstract

In the recent studies on chitosan hydrogels, it was found that understanding both rheological and structural properties plays an important role in their application. Therefore, a combination of two independent techniques was applied to investigate micro- and macroscopic properties of chitosan colloidal system. [...] Read more.

In the recent studies on chitosan hydrogels, it was found that understanding both rheological and structural properties plays an important role in their application. Therefore, a combination of two independent techniques was applied to investigate micro- and macroscopic properties of chitosan colloidal system. Studies on viscous properties, as well as the sol-gel phase transition process, were performed using rheological methods coupled with the small angle light scattering (SALS) technique. Based on the anisotropy of scattering patterns obtained during rotational shear tests, it was found that the chitosan solution reveals two different behaviors delimited by the critical value of the shear rate. Below a critical value, chitosan clusters are deformed without breaking up aggregates, whereas after exceeding a critical value, chitosan clusters apart from deformation also breakup into smaller aggregates. The values of the radius of gyration determined by applying the Debye function allow one to state that with an increase of chitosan concentration, molecule size decreases. An analysis of the light scattering data from the temperature ramp test showed that with an increase of temperature, the level of polymer coil swelling increases. Simultaneously, the supply of thermal energy leads to a neutralization of the charge of chitosan chains. As a consequence, the formation of intermolecular links occurs and a gel structure is formed. Full article

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12 pages, 1632 KiB

Open AccessArticle

Effects of Different Temperatures on the Chemical Structure and Antitumor Activities of Polysaccharides from Cordyceps militaris

by Eliyas Nurmamat, Hongxing Xiao, Yan Zhang and Ziwei Jiao

Polymers 2018, 10(4), 430; https://doi.org/10.3390/polym10040430 - 12 Apr 2018

Cited by 42 | Viewed by 5687

Abstract

The effects of different extraction temperatures (4 and 80 °C) on the physicochemical properties and antitumor activity of water soluble polysaccharides (CMPs-4 and CMPs-80) from Cordyceps militaris (C. militaris) were evaluated in this study. The results of gas chromatography (GC) and high-performance gel [...] Read more.

The effects of different extraction temperatures (4 and 80 °C) on the physicochemical properties and antitumor activity of water soluble polysaccharides (CMPs-4 and CMPs-80) from Cordyceps militaris (C. militaris) were evaluated in this study. The results of gas chromatography (GC) and high-performance gel permeation chromatography (HPGPC) showed that a higher extraction temperature could degrade the polysaccharides with 188 kDa, mainly composed of glucose, and increase the dissolution rate of polysaccharides about 308 kDa, mainly consisting of rhamnose and galactose. In addition, the CMPs displayed the same sugar ring and category of glycosidic linkage based on Fourier-transform infrared spectroscopy (FTIR) analysis, however, their invisible structural difference occurred in the specific rotation and conformational characteristics according to the results of specific optical rotation measurement and Congo red test. In vitro antitumor experiments indicated that CMPs-4 possessed stronger inhibitory effects on human esophagus cancer Eca-109 cells by inducing cell apoptosis more than CMPs-80 did. These findings demonstrated that the polysaccharides extracted with cold water (4 °C) could be applied as a novel alternative chemotherapeutic agent or dietary supplement with its underlying antitumor property. Full article

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26 pages, 53578 KiB

Open AccessReview

Aliphatic Polyester Nanofibers Functionalized with Cyclodextrins and Cyclodextrin-Guest Inclusion Complexes

by Ganesh Narayanan, Jialong Shen, Ramiz Boy, Bhupender S. Gupta and Alan E. Tonelli

Polymers 2018, 10(4), 428; https://doi.org/10.3390/polym10040428 - 11 Apr 2018

Cited by 30 | Viewed by 5585

Abstract

The fabrication of nanofibers by electrospinning has gained popularity in the past two decades; however, only in this decade, have polymeric nanofibers been functionalized using cyclodextrins (CDs) or their inclusion complexes (ICs). By combining electrospinning of polymers with free CDs, nanofibers can be [...] Read more.

The fabrication of nanofibers by electrospinning has gained popularity in the past two decades; however, only in this decade, have polymeric nanofibers been functionalized using cyclodextrins (CDs) or their inclusion complexes (ICs). By combining electrospinning of polymers with free CDs, nanofibers can be fabricated that are capable of capturing small molecules, such as wound odors or environmental toxins in water and air. Likewise, combining polymers with cyclodextrin-inclusion complexes (CD-ICs), has shown promise in enhancing or controlling the delivery of small molecule guests, by minor tweaking in the technique utilized in fabricating these nanofibers, for example, by forming core–shell or multilayered structures and conventional electrospinning, for controlled and rapid delivery, respectively. In addition to small molecule delivery, the thermomechanical properties of the polymers can be significantly improved, as our group has shown recently, by adding non-stoichiometric inclusion complexes to the polymeric nanofibers. We recently reported and thoroughly characterized the fabrication of polypseudorotaxane (PpR) nanofibers without a polymeric carrier. These PpR nanofibers show unusual rheological and thermomechanical properties, even when the coverage of those polymer chains is relatively sparse (~3%). A key advantage of these PpR nanofibers is the presence of relatively stable hydroxyl groups on the outer surface of the nanofibers, which can subsequently be taken advantage of for bioconjugation, making them suitable for biomedical applications. Although the number of studies in this area is limited, initial results suggest significant potential for bone tissue engineering, and with additional bioconjugation in other areas of tissue engineering. In addition, the behaviors and uses of aliphatic polyester nanofibers functionalized with CDs and CD-ICs are briefly described and summarized. Based on these observations, we attempt to draw conclusions for each of these combinations, and the relationships that exist between their presence and the functional behaviors of their nanofibers. Full article

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15 pages, 15278 KiB

Open AccessArticle

Preliminary Structural Characteristics of Polysaccharides from Pomelo Peels and Their Antitumor Mechanism on S180 Tumor-Bearing Mice

by Juan Yu, Haiyu Ji and Anjun Liu

Polymers 2018, 10(4), 419; https://doi.org/10.3390/polym10040419 - 9 Apr 2018

Cited by 26 | Viewed by 6644

Abstract

In this study, the polysaccharides (PPs) from pomelo peels were investigated for their structural characteristics and antitumor mechanism on sarcoma S180-bearing mice. Components, FT-IR, and GC analysis showed that PPs, mainly composed of glucose, were typical acid polysaccharides with α-d-pyranoid glucose [...] Read more.

In this study, the polysaccharides (PPs) from pomelo peels were investigated for their structural characteristics and antitumor mechanism on sarcoma S180-bearing mice. Components, FT-IR, and GC analysis showed that PPs, mainly composed of glucose, were typical acid polysaccharides with α-d-pyranoid glucose containing 74.52% carbohydrate and 16.33% uronic acid. The in vivo antitumor tests revealed that PPs could effectively suppress the transplanted S180 tumors growth, as well as protect the immune organs, improve proliferation ability of splenic lymphocytes and killing activity of NK cells in tumor-bearing mice. Furthermore, the levels of serum cytokines (IL-2, IFN-γ and TNF-α) and the proportion of CD4⁺ T cells in peripheral blood of mice bearing S180 tumors were also significantly increased after treatment with PPs. Meanwhile, the transplanted S180 tumor cells exhibited obvious apoptotic phenotype after PPs treatment by arresting the cell cycle in S phase, down-regulating the Bcl-2 expressions and up-regulating the Bax levels. These data showed that PPs were mainly composed of glucose with α-d-pyranoid ring and could induce apoptosis of solid tumor cells by enhancing the antitumor immunity of tumor-bearing mice, which would provide a theoretical basis for the practical application in food and medical industries. Full article

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18 pages, 10012 KiB

Open AccessArticle

How Glycerol and Water Contents Affect the Structural and Functional Properties of Starch-Based Edible Films

by Ewelina Basiak, Andrzej Lenart and Frédéric Debeaufort

Polymers 2018, 10(4), 412; https://doi.org/10.3390/polym10040412 - 8 Apr 2018

Cited by 251 | Viewed by 21036

Abstract

As starch is an inexpensive, filmogenic, easily processable and a widely available material, it is a material that can be utilized in the creation of biodegradable films and containers, presenting as a viable alternative to polymers derived from petrol. Moreover, starch could also [...] Read more.

As starch is an inexpensive, filmogenic, easily processable and a widely available material, it is a material that can be utilized in the creation of biodegradable films and containers, presenting as a viable alternative to polymers derived from petrol. Moreover, starch could also be used to create edible coatings for fresh foods in order to extend shelf life. As such, wheat starch films with two glycerol contents were formulated to mimic the effects of compounds currently used to coat fruit. Their structural and functional properties were characterized. This study found that the transfer properties of starch films containing 33% of plasticizer was less effective than film comprised of 50% glycerol. Water diffusivity, oxygen permeability, and water vapor permeability at two different humidity gradients, surface tension, works of surface adhesion and cohesion, and moisture sorption were tested. Glycerol content does not play a significant role on the color or mechanical properties. This work shows that glycerol can strongly affect the functional properties of starch-based coatings and films. Full article

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16 pages, 3891 KiB

Open AccessReview

Development of Mucoadhesive Chitosan Derivatives for Use as Submucosal Injections

by Hidemi Hattori and Masayuki Ishihara

Polymers 2018, 10(4), 410; https://doi.org/10.3390/polym10040410 - 6 Apr 2018

Cited by 4 | Viewed by 5415

Abstract

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been used for surgical treatment of early gastric cancer. These endoscopic techniques require proper submucosal injections beneath the tumor to provide a sufficiently high submucosal fluid cushion (SFC) to facilitate clean dissection and [...] Read more.

Endoscopic mucosal resection (EMR) and endoscopic submucosal dissection (ESD) have been used for surgical treatment of early gastric cancer. These endoscopic techniques require proper submucosal injections beneath the tumor to provide a sufficiently high submucosal fluid cushion (SFC) to facilitate clean dissection and resection of the tumor. Until now, the submucosal injection materials developed for endoscopic techniques such as EMR and ESD of tumors have been composed of macromolecules, proteins, or polysaccharides. We have been investigating the use of chitosan, a product that is obtained by the alkaline deacetylation of chitin, the second-most abundant natural polysaccharide. Specifically, we have been studying a photocrosslinked chitosan hydrogel (PCH) and solubilized chitosan derivatives for use as novel submucosal injections for endoscopic techniques. Notably, chitosan derivatives with lactose moieties linked to the amino groups of its glucosamine units can specifically interact with acidic mucopolysaccharides and mucins in submucosa without the need for the incorporation of harmful photoreactive groups nor potentially mutagenic ultraviolet irradiation. Full article

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13 pages, 2445 KiB

Open AccessArticle

Antioxidant Activity and Antifungal Activity of Chitosan Derivatives with Propane Sulfonate Groups

by Fang Luan, Lijie Wei, Jingjing Zhang, Yingqi Mi, Fang Dong, Qing Li and Zhanyong Guo

Polymers 2018, 10(4), 395; https://doi.org/10.3390/polym10040395 - 3 Apr 2018

Cited by 34 | Viewed by 5165

Abstract

We successfully synthesized the water-soluble chitosan derivatives propane sulfonated chitosan (PSCS) and dipropane sulfonated chitosan (DPSCS) in this paper. These derivatives were characterized by FTIR, ¹H NMR, and ¹³C NMR. Moreover, the antioxidant activity of the chitosan derivatives was evaluated by [...] Read more.

We successfully synthesized the water-soluble chitosan derivatives propane sulfonated chitosan (PSCS) and dipropane sulfonated chitosan (DPSCS) in this paper. These derivatives were characterized by FTIR, ¹H NMR, and ¹³C NMR. Moreover, the antioxidant activity of the chitosan derivatives was evaluated by free radical scavenging ability (against DPPH-radical, hydroxyl-radical, and superoxide-radical) and ferric reducing power. Meanwhile, inhibitory effects against two fungi were also tested. Our results suggested antioxidant abilities and antifungal properties were in order of DPSCS > PSCS > CS, which were consistent with the number of propane sulfonated groups. The scavenging activity of DPSCS against superoxide-radical and DPPH-radical were 94.1% and 100% at 1.6 mg/mL, respectively. The inhibitory indices of DPSCS against P. asparagi and F. oxysporum were up to 82.2% and 94% at 1.0 mg/mL, respectively. Obviously, the number of propane sulfonated groups of chitosan derivatives not only contributes to antioxidant activity, but also to antifungal activity. Therefore, DPSCS with more propane sulfonated groups endowed with antioxidant and antifungal activity that can be used as a candidate material in the food and pharmaceutical industries. Full article

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17 pages, 3371 KiB

Open AccessArticle

Reversible pH-Sensitive Chitosan-Based Hydrogels. Influence of Dispersion Composition on Rheological Properties and Sustained Drug Delivery

by Nieves Iglesias, Elsa Galbis, Concepción Valencia, M.-Violante De-Paz and Juan A. Galbis

Polymers 2018, 10(4), 392; https://doi.org/10.3390/polym10040392 - 1 Apr 2018

Cited by 28 | Viewed by 6929

Abstract

The present work deals with the synthesis of micro-structured biomaterials based on chitosan (CTS) for their applications as biocompatible carriers of drugs and bioactive compounds. Twelve dispersions were prepared by means of functional cross-linking with tricarballylic acid (TCA); they were characterized by Fourier [...] Read more.

The present work deals with the synthesis of micro-structured biomaterials based on chitosan (CTS) for their applications as biocompatible carriers of drugs and bioactive compounds. Twelve dispersions were prepared by means of functional cross-linking with tricarballylic acid (TCA); they were characterized by Fourier transform infrared spectroscopy (FT-IR), modulated temperature differential scanning calorimetry (MTDSC) and scanning electron microscopy (SEM), and their rheological properties were studied. To the best of the authors’ knowledge, no study has been carried out on the influence of CTS concentration, degree of cross-linking and drug loading on chitosan hydrogels for drug delivery systems (DDS) and is investigated herein for the first time. The influence of dispersion composition (polymer concentration and degree of cross-linking) revealed to exert a marked impact on its rheological properties, going from liquid-like to viscoelastic gels. The release profiles of a model drug, diclofenac sodium (DCNa), as well as their relationships with polymer concentration, drug loading and degree of cross-linking were evaluated. Similar to the findings on rheological properties, a wide range of release profiles was encountered. These formulations were found to display a well-controlled drug release strongly dependent on the formulation composition. Cumulative drug release under physiological conditions for 96 h ranged from 8% to 67%. For comparative purpose, Voltaren emulgel^® from Novartis Pharmaceuticals was also investigated and the latter was the formulation with the highest cumulative drug release (85%). Some formulations showed similar spreadability values to the commercial hydrogel. The comparative study of three batches confirmed the reproducibility of the method, leading to systems particularly suitable for their use as drug carriers. Full article

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14 pages, 300 KiB

Open AccessReview

Application of Chitin/Chitosan and Their Derivatives in the Papermaking Industry

by Zhaoping Song, Guodong Li, Feixiang Guan and Wenxia Liu

Polymers 2018, 10(4), 389; https://doi.org/10.3390/polym10040389 - 1 Apr 2018

Cited by 87 | Viewed by 11636

Abstract

Chitin/chitosan and their derivatives have become of great interest as functional materials in many fields within the papermaking industry. They have been employed in papermaking wet-end, paper surface coating, papermaking wastewater treatment, and other sections of the papermaking industry due to their structure [...] Read more.

Chitin/chitosan and their derivatives have become of great interest as functional materials in many fields within the papermaking industry. They have been employed in papermaking wet-end, paper surface coating, papermaking wastewater treatment, and other sections of the papermaking industry due to their structure and chemical properties. The purpose of this paper is to briefly discuss the application of chitin/chitosan and their derivatives in the papermaking industry. The development of their application in the papermaking area will be reviewed and summarized. Full article

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9 pages, 1119 KiB

Open AccessArticle

Recyclable Heterogeneous Chitosan Supported Copper Catalyst for Silyl Conjugate Addition to α,β-Unsaturated Acceptors in Water

by Lei Zhu, Bojie Li, Shan Wang, Wei Wang, Liansheng Wang, Liang Ding and Caiqin Qin

Polymers 2018, 10(4), 385; https://doi.org/10.3390/polym10040385 - 1 Apr 2018

Cited by 14 | Viewed by 4250

Abstract

The first example of an environmentally-benign chitosan supported copper catalyzed conjugate silylation of α,β-unsaturated acceptors was accomplished in water under mild conditions. This protocol provides an efficient pathway to achieve an important class of β-silyl carbonyl compounds and the desired products were obtained [...] Read more.

The first example of an environmentally-benign chitosan supported copper catalyzed conjugate silylation of α,β-unsaturated acceptors was accomplished in water under mild conditions. This protocol provides an efficient pathway to achieve an important class of β-silyl carbonyl compounds and the desired products were obtained in good to excellent yields. Gram-scale synthesis and easy transformation of obtained β-silyl products were also been demonstrated. Remarkably, this chitosan supported copper catalyst can be easily recycled and reused six times without any significant decrease of catalytic activity. The advantages of this newly developed method include operational simplicity, good functional group tolerance, scale-up ability, ready availability, and easy recyclability of catalyst. Full article

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11 pages, 2801 KiB

Open AccessArticle

Fluorescent Labeling of Polysaccharides from Masson Pine Pollen and Its Effect on RAW264.7 Macrophages

by Mengmeng Sun, Fangchen Su, Jinxin Yang, Zheng Gao and Yue Geng

Polymers 2018, 10(4), 372; https://doi.org/10.3390/polym10040372 - 26 Mar 2018

Cited by 19 | Viewed by 8007

Abstract

In order to explore the immediate effect of polysaccharides and macrophages, polysaccharides from masson pine pollen (PPM60) were labeled with fluorescein isothiocyanate (FITC) by using a chemical-derived method, and the reactant was named PPM60-Tyr-FITC. Direct interaction of PPM60-Tyr-FITC and RAW264.7 macrophages could be [...] Read more.

In order to explore the immediate effect of polysaccharides and macrophages, polysaccharides from masson pine pollen (PPM60) were labeled with fluorescein isothiocyanate (FITC) by using a chemical-derived method, and the reactant was named PPM60-Tyr-FITC. Direct interaction of PPM60-Tyr-FITC and RAW264.7 macrophages could be detected by flow cytometer (FCM), and this interaction could be inhibited by Pitstop 2 (clathrin inhibitor) and TAK-242 (Toll-like receptor 4 inhibitor). The results of confocal laser scanning microscopy (CLSM) also revealed that there was a co-localization phenomenon between PPM60-Tyr-FITC and RAW264.7 macrophage receptors, and it could be suppressed by Pitstop 2 and TAK-242. It was confirmed that PPM60 enters into RAW264.7 macrophages mainly through endocytosis, rather than the phagocytosis, and TLR4 played a mediating role. Full article

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18 pages, 18321 KiB

Open AccessArticle

Sorption of Hg(II) and Pb(II) Ions on Chitosan-Iron(III) from Aqueous Solutions: Single and Binary Systems

by Byron Lapo, Hary Demey, Jessenia Zapata, Cristhian Romero and Ana María Sastre

Polymers 2018, 10(4), 367; https://doi.org/10.3390/polym10040367 - 25 Mar 2018

Cited by 34 | Viewed by 5906

Abstract

The present work describes the study of mercury Hg(II) and lead Pb(II) removal in single and binary component systems into easily prepared chitosan-iron(III) bio-composite beads. Scanning electron microscopy and energy-dispersive X-ray (SEM-EDX) analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and point [...] Read more.

The present work describes the study of mercury Hg(II) and lead Pb(II) removal in single and binary component systems into easily prepared chitosan-iron(III) bio-composite beads. Scanning electron microscopy and energy-dispersive X-ray (SEM-EDX) analysis, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and point of zero charge (pH_pzc) analysis were carried out. The experimental set covered pH study, single and competitive equilibrium, kinetics, chloride and sulfate effects as well as sorption–desorption cycles. In single systems, the Langmuir nonlinear model fitted the experimental data better than the Freundlich and Sips equations. The sorbent material has more affinity to Hg(II) rather than Pb(II) ions, the maximum sorption capacities were 1.8 mmol·g⁻¹ and 0.56 mmol·g⁻¹ for Hg(II) and Pb(II), respectively. The binary systems data were adjusted with competitive Langmuir isotherm model. The presence of sulfate ions in the multicomponent system [Hg(II)-Pb(II)] had a lesser impact on the sorption efficiency than did chloride ions, however, the presence of chloride ions improves the selectivity towards Hg(II) ions. The bio-based material showed good recovery performance of metal ions along three sorption–desorption cycles. Full article

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13 pages, 12351 KiB

Open AccessArticle

Thermal, Structural, and Rheological Characterization of Waxy Starch as a Cryogel for Its Application in Food Processing

by Jonathan Coria-Hernández, Abraham Méndez-Albores, Rosalía Meléndez-Pérez, Marta Elvia Rosas-Mendoza and José Luis Arjona-Román

Polymers 2018, 10(4), 359; https://doi.org/10.3390/polym10040359 - 23 Mar 2018

Cited by 12 | Viewed by 4408

Abstract

Starch is the major component of cereal, pulses, and root crops. Starch consists of two kinds of glucose polymers, amylose and amylopectin. Waxy starch—with 99–100% amylopectin—has distinctive properties, which define its functionality in many food applications. In this research, a novel material was [...] Read more.

Starch is the major component of cereal, pulses, and root crops. Starch consists of two kinds of glucose polymers, amylose and amylopectin. Waxy starch—with 99–100% amylopectin—has distinctive properties, which define its functionality in many food applications. In this research, a novel material was prepared through the cryogelification of waxy starch (WS) using four cycles of freezing and thawing in indirect contact with liquid nitrogen at −150 °C. Polyvinyl alcohol (PVA) was used as a reference. The cryogels were characterized using several validation methodologies: modulated differential scanning calorimetry (MDSC), scanning electron microscopy (SEM), rheology, and Fourier transform infrared (FTIR) spectroscopy with diffuse reflectance (DR). Based on the number of freeze–thaw cycles, significant changes were found (P < 0.05) showing important structural modifications as well as reorganization of the polymeric matrix. Two cryogelification cycles of the WS were enough to obtain the best structural and functional characteristics, similar to those of PVA, which has already been tested as a cryogel. From these results, it is concluded that WS has potential as a cryogel for application in food processing. Full article

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29 pages, 5407 KiB

Open AccessFeature PaperReview

Chitin Deacetylases: Structures, Specificities, and Biotech Applications

by Laia Grifoll-Romero, Sergi Pascual, Hugo Aragunde, Xevi Biarnés and Antoni Planas

Polymers 2018, 10(4), 352; https://doi.org/10.3390/polym10040352 - 22 Mar 2018

Cited by 108 | Viewed by 10731

Abstract

Depolymerization and de-N-acetylation of chitin by chitinases and deacetylases generates a series of derivatives including chitosans and chitooligosaccharides (COS), which are involved in molecular recognition events such as modulation of cell signaling and morphogenesis, immune responses, and host-pathogen interactions. Chitosans and [...] Read more.

Depolymerization and de-N-acetylation of chitin by chitinases and deacetylases generates a series of derivatives including chitosans and chitooligosaccharides (COS), which are involved in molecular recognition events such as modulation of cell signaling and morphogenesis, immune responses, and host-pathogen interactions. Chitosans and COS are also attractive scaffolds for the development of bionanomaterials for drug/gene delivery and tissue engineering applications. Most of the biological activities associated with COS seem to be largely dependent not only on the degree of polymerization but also on the acetylation pattern, which defines the charge density and distribution of GlcNAc and GlcNH₂ moieties in chitosans and COS. Chitin de-N-acetylases (CDAs) catalyze the hydrolysis of the acetamido group in GlcNAc residues of chitin, chitosan, and COS. The deacetylation patterns are diverse, some CDAs being specific for single positions, others showing multiple attack, processivity or random actions. This review summarizes the current knowledge on substrate specificity of bacterial and fungal CDAs, focusing on the structural and molecular aspects of their modes of action. Understanding the structural determinants of specificity will not only contribute to unravelling structure-function relationships, but also to use and engineer CDAs as biocatalysts for the production of tailor-made chitosans and COS for a growing number of applications. Full article

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33 pages, 4306 KiB

Open AccessReview

Chitosan Derivatives: Introducing New Functionalities with a Controlled Molecular Architecture for Innovative Materials

by Waldo M. Argüelles-Monal, Jaime Lizardi-Mendoza, Daniel Fernández-Quiroz, Maricarmen T. Recillas-Mota and Marcelino Montiel-Herrera

Polymers 2018, 10(3), 342; https://doi.org/10.3390/polym10030342 - 20 Mar 2018

Cited by 137 | Viewed by 13503

Abstract

The functionalization of polymeric substances is of great interest for the development of innovative materials for advanced applications. For many decades, the functionalization of chitosan has been a convenient way to improve its properties with the aim of preparing new materials with specialized [...] Read more.

The functionalization of polymeric substances is of great interest for the development of innovative materials for advanced applications. For many decades, the functionalization of chitosan has been a convenient way to improve its properties with the aim of preparing new materials with specialized characteristics. In the present review, we summarize the latest methods for the modification and derivatization of chitin and chitosan under experimental conditions, which allow a control over the macromolecular architecture. This is because an understanding of the interdependence between chemical structure and properties is an important condition for proposing innovative materials. New advances in methods and strategies of functionalization such as the click chemistry approach, grafting onto copolymerization, coupling with cyclodextrins, and reactions in ionic liquids are discussed. Full article

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14 pages, 13361 KiB

Open AccessArticle

Lignocellulose-Chitosan-Multiwalled Carbon Nanotube Composites with Improved Mechanical Strength, Dimensional Stability and Fire Retardancy

by Zhe Wang, Yutao Yan, Xiaoping Shen, Temeng Qian, Junjie Wang, Qingfeng Sun and Chunde Jin

Polymers 2018, 10(3), 341; https://doi.org/10.3390/polym10030341 - 20 Mar 2018

Cited by 11 | Viewed by 4618

Abstract

A novel composite composed of lignocellulose (LC), glutaraldehyde crosslinked chitosan (GC) and multiwalled carbon nanotube (MWCNT) was fabricated by the hot-pressing process. The effect of the additional GC and MWCNT on the mechanical strength, dimensional stability and fire retardancy of lignocellulose composites was [...] Read more.

A novel composite composed of lignocellulose (LC), glutaraldehyde crosslinked chitosan (GC) and multiwalled carbon nanotube (MWCNT) was fabricated by the hot-pressing process. The effect of the additional GC and MWCNT on the mechanical strength, dimensional stability and fire retardancy of lignocellulose composites was investigated. The results showed that LC/GC/MWCNT composite exhibited the maximum modulus of rupture (MOR) of 35.3 MPa, modulus of elasticity (MOE) of 2789.1 MPa and internal bonding (IB) strength of 1.2 MPa. Meanwhile, the LC/GC/MWCNT composite displayed improved dimensional stability with a thickness swelling (TS) value of 22.4%. Besides, the LC/GC/MWCNT composite exhibited improved fire retardancy with a limiting oxygen index of 29.0%. The peak heat release rate, the total heat release, the total smoke production and the maximum smoke production ratio of LC/GC/MWCNT composite decreased by 15.9%, 10.7%, 45.5% and 20.7% compared with those of LC composite, respectively. Therefore, the LC/GC/MWCNT composite may be a promising candidate for green wood based composites. Full article

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14 pages, 5854 KiB

Open AccessArticle

⁶⁰Co γ-ray Irradiation Crosslinking of Chitosan/Graphene Oxide Composite Film: Swelling, Thermal Stability, Mechanical, and Antibacterial Properties

by Dawei Zhang, Shuai Yang, Yuanqing Chen, Siyu Liu, Hongtao Zhao and Jiyou Gu

Polymers 2018, 10(3), 294; https://doi.org/10.3390/polym10030294 - 9 Mar 2018

Cited by 46 | Viewed by 5505

Abstract

In this paper, chitosan (CS)/graphene oxide (GO) composite films were prepared, and the effect of γ-ray irradiation on the properties of composite films was investigated. The irradiation crosslinking reaction occurred in composite films with the existence of acetic acid, and the properties changed [...] Read more.

In this paper, chitosan (CS)/graphene oxide (GO) composite films were prepared, and the effect of γ-ray irradiation on the properties of composite films was investigated. The irradiation crosslinking reaction occurred in composite films with the existence of acetic acid, and the properties changed upon the various irradiation dose. The swelling degree of the composite film with 0 wt % GO decreased with the increasing of the irradiation dose, but the swelling degree of which with GO increased instead. The thermal stability increased with the increasing of the irradiation dose, but the effect of the irradiation on the thermal stability weakened as the increasing of the content of GO, due to the enhanced irradiation resistance performance. The tensile strength increased firstly and decreased subsequently with the increasing of the irradiation dose and the content of GO. Composite films showed the enhanced antibacterial activity against Bacillus subtilis, compared to Escherichia coli and Staphylococcus aureus. The antibacterial activity weakened with the increasing of the content of GO. The antibacterial activity was relatively stronger when the irradiation dose was 20 KGy. In addition, the structural, crystal, and morphological properties of composite films were characterized by FT-IR, XRD, and SEM. It is worth noting that the GO was pre-functionalized via KH560 for the better compatibility with CS matrix. Full article

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18 pages, 4042 KiB

Open AccessArticle

Extraction Optimization, Purification, Antioxidant Activity, and Preliminary Structural Characterization of Crude Polysaccharide from an Arctic Chlorella sp.

by Hong Song, Meilin He, Chuankun Gu, Dong Wei, Yuqi Liang, Junmei Yan and Changhai Wang

Polymers 2018, 10(3), 292; https://doi.org/10.3390/polym10030292 - 9 Mar 2018

Cited by 71 | Viewed by 8722

Abstract

The arctic strain of Chlorella sp. (Chlorella-Arc) exists in the coldest and driest arctic ecosystems, and it is a new resource of active polysaccharides. The extraction of crude polysaccharide from Chlorella-Arc was optimized using the response surface methodology. A crude [...] Read more.

The arctic strain of Chlorella sp. (Chlorella-Arc) exists in the coldest and driest arctic ecosystems, and it is a new resource of active polysaccharides. The extraction of crude polysaccharide from Chlorella-Arc was optimized using the response surface methodology. A crude polysaccharide yield of approximately 9.62 ± 0.11% dry weight was obtained under these optimized conditions. Three fractions (P-I, P-II, and P-III) were present after purification by 2-diethylaminoethanol Sepharose Fast Flow and Sephadex G-100 chromatography. The P-IIa fraction demonstrated significant antioxidant activities. Moreover, P-IIa was an α- and β-type heteropolysaccharide with a pyran group and contained variable amounts of rhamnose, arabinose, glucose, and galactose based on fourier-transform infrared spectroscopy, high-performance liquid chromatography, and ¹H and ¹³C nuclear magnetic resonance imaging. Production of high amounts of polysaccharide may allow further exploration of the microalgae Chlorella-Arc as a natural antioxidant. Full article

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26 pages, 22538 KiB

Open AccessFeature PaperArticle

Bioactive Sr(II)/Chitosan/Poly(ε-caprolactone) Scaffolds for Craniofacial Tissue Regeneration. In Vitro and In Vivo Behavior

by Itzia Rodríguez-Méndez, Mar Fernández-Gutiérrez, Amairany Rodríguez-Navarrete, Raúl Rosales-Ibáñez, Lorena Benito-Garzón, Blanca Vázquez-Lasa and Julio San Román

Polymers 2018, 10(3), 279; https://doi.org/10.3390/polym10030279 - 7 Mar 2018

Cited by 13 | Viewed by 5179

Abstract

In craniofacial tissue regeneration, the current gold standard treatment is autologous bone grafting, however, it presents some disadvantages. Although new alternatives have emerged there is still an urgent demand of biodegradable scaffolds to act as extracellular matrix in the regeneration process. A potentially [...] Read more.

In craniofacial tissue regeneration, the current gold standard treatment is autologous bone grafting, however, it presents some disadvantages. Although new alternatives have emerged there is still an urgent demand of biodegradable scaffolds to act as extracellular matrix in the regeneration process. A potentially useful element in bone regeneration is strontium. It is known to promote stimulation of osteoblasts while inhibiting osteoclasts resorption, leading to neoformed bone. The present paper reports the preparation and characterization of strontium (Sr) containing hybrid scaffolds formed by a matrix of ionically cross-linked chitosan and microparticles of poly(ε-caprolactone) (PCL). These scaffolds of relatively facile fabrication were seeded with osteoblast-like cells (MG-63) and human bone marrow mesenchymal stem cells (hBMSCs) for application in craniofacial tissue regeneration. Membrane scaffolds were prepared using chitosan:PCL ratios of 1:2 and 1:1 and 5 wt % Sr salts. Characterization was performed addressing physico-chemical properties, swelling behavior, in vitro biological performance and in vivo biocompatibility. Overall, the composition, microstructure and swelling degree (≈245%) of scaffolds combine with the adequate dimensional stability, lack of toxicity, osteogenic activity in MG-63 cells and hBMSCs, along with the in vivo biocompatibility in rats allow considering this system as a promising biomaterial for the treatment of craniofacial tissue regeneration. Full article

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11 pages, 2243 KiB

Open AccessArticle

Effect of Cationic Surface Modification on the Rheological Behavior and Microstructure of Nanocrystalline Cellulose

by Yanjun Tang, Xiaoyu Wang, Biaobiao Huang, Zhanbin Wang and Nan Zhang

Polymers 2018, 10(3), 278; https://doi.org/10.3390/polym10030278 - 7 Mar 2018

Cited by 21 | Viewed by 5134

Abstract

In the present work, the microstructure and rheological behavior of nanocrystalline cellulose (NCC) and cationically modified NCC (CNCC) were comparatively studied. The resultant CNCC generally showed improved dispersion and higher thermal stability in comparison to the un-modified NCC. The rheological behavior demonstrated that [...] Read more.

In the present work, the microstructure and rheological behavior of nanocrystalline cellulose (NCC) and cationically modified NCC (CNCC) were comparatively studied. The resultant CNCC generally showed improved dispersion and higher thermal stability in comparison to the un-modified NCC. The rheological behavior demonstrated that the viscosity of the NCC suspension substantially decreased with the increasing shear rate (0.01–100 s⁻¹), showing the typical characteristics of a pseudoplastic fluid. In contrast, the CNCC suspensions displayed a typical three-region behavior, regardless of changes in pH, temperature, and concentration. Moreover, the CNCC suspensions exhibited higher shear stress and viscosity at a given shear rate (0.01–100 s⁻¹) than the NCC suspension. Meanwhile, the dynamic viscoelasticity measurements revealed that the CNCC suspensions possessed a higher elastic (G′) and loss modulus (G″) than NCC suspensions over the whole frequency range (0.1–500 rad·s⁻¹), providing evidence that the surface cationization of NCC makes it prone to behave as a gel-like structure. Full article

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15 pages, 4858 KiB

Open AccessArticle

Nature-Inspired Green Procedure for Improving Performance of Protein-Based Nanocomposites via Introduction of Nanofibrillated Cellulose-Stablized Graphene/Carbon Nanotubes Hybrid

by Shicun Jin, Kuang Li and Jianzhang Li

Polymers 2018, 10(3), 270; https://doi.org/10.3390/polym10030270 - 6 Mar 2018

Cited by 27 | Viewed by 7841

Abstract

Soy protein isolate (SPI) provides a potential alternative biopolymer source to fossil fuels, but improving the mechanical properties and water resistance of SPI composites remains a huge challenge. Inspired by the synergistic effect of natural nacre, we developed a novel approach to fabricate [...] Read more.

Soy protein isolate (SPI) provides a potential alternative biopolymer source to fossil fuels, but improving the mechanical properties and water resistance of SPI composites remains a huge challenge. Inspired by the synergistic effect of natural nacre, we developed a novel approach to fabricate high-performance SPI nanocomposite films based on 2D graphene (G) nanosheets and 1D carbon nanotubes (CNTs) and nanofibrillated cellulose (NFC) using a casting method. The introduction of web-like NFC promoted the uniform dispersion of graphene/CNTs in the biopolymer matrix, as well as a high extent of cross-linkage combination between the fillers and SPI matrix. The laminated and cross-linked structures of the different nanocomposite films were observed by field-emission scanning electron microscope (FE-SEM) images. Due to the synergistic interactions of π–π stacking and hydrogen bonding between the nanofillers and SPI chains, the tensile strength of SPI/G/CNT/NFC film significantly increased by 78.9% and the water vapor permeability decreased by 31.76% in comparison to neat SPI film. In addition, the ultraviolet-visible (UV-vis) light barrier performance, thermal stability, and hydrophobicity of the films were significantly improved as well. This bioinspired synergistic reinforcing strategy opens a new path for constructing high-performance nanocomposites. Full article

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10 pages, 3388 KiB

Open AccessReview

The Use of Polymer Chitosan in Intravesical Treatment of Urinary Bladder Cancer and Infections

by Andreja Erman and Peter Veranič

Polymers 2018, 10(3), 265; https://doi.org/10.3390/polym10030265 - 5 Mar 2018

Cited by 13 | Viewed by 6117

Abstract

The most frequent diseases of the urinary bladder are bacterial infections and bladder cancers. For both diseases, very high recurrence rates are characteristic: 50–80% for bladder cancer and more than 50% for bladder infections, causing loss of millions of dollars per year for [...] Read more.

The most frequent diseases of the urinary bladder are bacterial infections and bladder cancers. For both diseases, very high recurrence rates are characteristic: 50–80% for bladder cancer and more than 50% for bladder infections, causing loss of millions of dollars per year for medical treatment and sick leave. Despite years of searching for better treatment, the prevalence of bladder infections and bladder cancer remains unchanged and is even increasing in recent years. Very encouraging results in treatment of both diseases recently culminated from studies combining biopolymer chitosan with immunotherapy, and chitosan with antibiotics for treatment of bladder cancer and cystitis, respectably. In both pathways of research, the discoveries involving chitosan reached a successful long-lasting cure. The property of chitosan that boosted the effectivity of illness-specific drugs is its ability to enhance the accessibility of these drugs to the very sources of both pathologies that individual treatments without chitosan failed to achieve. Chitosan can thus be recognised as a very promising co-player in treatment of bladder cancer and bacterial cystitis. Full article

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17 pages, 9953 KiB

Open AccessArticle

Influence of Chitosan Ascorbate Chirality on the Gelation Kinetics and Properties of Silicon-Chitosan-Containing Glycerohydrogels

by Natalia O. Gegel, Yulia Yu. Zhuravleva, Anna B. Shipovskaya, Olga N. Malinkina and Irina V. Zudina

Polymers 2018, 10(3), 259; https://doi.org/10.3390/polym10030259 - 2 Mar 2018

Cited by 25 | Viewed by 5122

Abstract

The influence of the chirality of chitosan ascorbate on the gelation kinetics and the properties of hybrid silicon-chitosan-containing glycerohydrogels were studied with a deep estimation of the stereospecificity of chitosan polysalts with l- and d-ascorbic acid diastereomers and their biological effects. [...] Read more.

The influence of the chirality of chitosan ascorbate on the gelation kinetics and the properties of hybrid silicon-chitosan-containing glycerohydrogels were studied with a deep estimation of the stereospecificity of chitosan polysalts with l- and d-ascorbic acid diastereomers and their biological effects. It has been established that l- and d-diastereomerically enriched chitosan ascorbates are characterized by a positive Cotton effect and differ in the wavelength of the maximum of the dichroic band (250 and 240 nm), as well as in the values of its specific ellipticity (21.8 × 10⁵ and 39.2 × 10⁵ deg·mL·dm⁻¹·g⁻¹), the sign of specific optical rotation (+ and −), the type of dispersion curves (anomalous and smooth), as well as the condensed phase morphology (anisodiametric particles with optical anisotropy and confocal domains of spherical shape, respectively). In the biomimetic sol-gel synthesis of silicon-chitosan-containing glycerohydrogels using silicon tetraglycerolate as a precursor, it was found that chitosan d-ascorbate retarded gelation. Thin congruent plates obtained from the corresponding glycerohydrogels based on chitosan d-ascorbate have higher mechanical strength and elasticity under uniaxial stretching and lower values of Young’s modulus. It has been shown that the systems based on chitosan d-ascorbate show the greatest antibacterial activity against Staphylococcus aureus 209P and Escherichia coli 113-13 and significantly promote the viability of normal human dermal fibroblasts. The results of our assessment of the biological properties of chitosan polysalts are unexpected, since ascorbic acid exhibits biological activity as its l-isomer only. Full article

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19 pages, 4233 KiB

Open AccessArticle

Biomaterials Based on Electrospun Chitosan. Relation between Processing Conditions and Mechanical Properties

by Christian Enrique Garcia Garcia, Félix Armando Soltero Martínez, Frédéric Bossard and Marguerite Rinaudo

Polymers 2018, 10(3), 257; https://doi.org/10.3390/polym10030257 - 1 Mar 2018

Cited by 31 | Viewed by 4915

Abstract

In this paper, it is shown that pure chitosan nanofibers and films were prepared with success in 0.5 M acetic acid as solvent using poly (ethylene oxide) (PEO) at different yields, allowing electrospinning of the blends. After processing, a neutralization step of chitosan [...] Read more.

In this paper, it is shown that pure chitosan nanofibers and films were prepared with success in 0.5 M acetic acid as solvent using poly (ethylene oxide) (PEO) at different yields, allowing electrospinning of the blends. After processing, a neutralization step of chitosan followed by water washing is performed, preserving the initial morphology of chitosan materials. The influence of the yield in PEO in the blend on the degree of swelling and hydrophilicity of films and nanofibers is demonstrated. Then, the mechanical behavior of blended nanofibers and films used as reference are determined for small stress applied in the linear domain by DMA and by uniaxial traction up to rupture. The dried and wet states are covered for the first time. It is shown that the mechanical properties are increased when electrospinning is performed in the presence of PEO up to a 70/30 chitosan/PEO weight ratio even after PEO extraction. This result can be explained by a better dispersion of the chitosan in the presence of PEO. Full article

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14 pages, 1688 KiB

Open AccessArticle

Exopolysaccharide Gellan Gum and Derived Oligo-Gellan Enhance Growth and Antimicrobial Activity in Eucomis Plants

by Piotr Salachna, Małgorzata Mizielińska and Marcin Soból

Polymers 2018, 10(3), 242; https://doi.org/10.3390/polym10030242 - 27 Feb 2018

Cited by 41 | Viewed by 6345

Abstract

One of the visible trends in the cultivation of plants, particularly of medicinal ones, is the increasing interest of researchers in polysaccharides and their derivatives that show biostimulatory properties and are also safe to use. In the current study, we evaluated the effects [...] Read more.

One of the visible trends in the cultivation of plants, particularly of medicinal ones, is the increasing interest of researchers in polysaccharides and their derivatives that show biostimulatory properties and are also safe to use. In the current study, we evaluated the effects of gellan gum and its depolymerized form oligo-gellan, on growth and antimicrobial activity of two ornamental species Eucomis bicolor and Eucomis comosa used in natural medicine. The biopolymers were applied in the form of bulb coating prepared by using polyelectrolyte complexes. In both species investigated, gellan gum and oligo-gellan enhanced the fresh weight of leaves and bulbs, the performance of the photosynthetic apparatus, and the leaf content of basic macronutrients. In comparison with the control, the plants treated with oligo-gellan accumulated more biomass, were first to flower, and had the highest leaf content of potassium. The extracts from the bulbs treated with gellan gum and oligo-gellan showed higher effectiveness in reducing the count of Bacillus atrophaeus, Escherichia coli, and Staphylococcus aureus than those from the bulbs not treated with the polysaccharides. The research described here largely expands our current knowledge on the effects of gellan gum derivatives and has a huge practical potential in agriculture production. Full article

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18 pages, 3262 KiB

Open AccessFeature PaperArticle

Biosynthetic Pathway and Genes of Chitin/Chitosan-Like Bioflocculant in the Genus Citrobacter

by Masahiro Takeo, Kazuyuki Kimura, Shanmugam Mayilraj, Takuya Inoue, Shohei Tada, Kouki Miyamoto, Masami Kashiwa, Keishi Ikemoto, Priyanka Baranwal, Daiichiro Kato and Seiji Negoro

Polymers 2018, 10(3), 237; https://doi.org/10.3390/polym10030237 - 27 Feb 2018

Cited by 12 | Viewed by 6027

Abstract

Chitin/chitosan, one of the most abundant polysaccharides in nature, is industrially produced as a powder or flake form from the exoskeletons of crustaceans such as crabs and shrimps. Intriguingly, many bacterial strains in the genus Citrobacter secrete a soluble chitin/chitosan-like polysaccharide into the [...] Read more.

Chitin/chitosan, one of the most abundant polysaccharides in nature, is industrially produced as a powder or flake form from the exoskeletons of crustaceans such as crabs and shrimps. Intriguingly, many bacterial strains in the genus Citrobacter secrete a soluble chitin/chitosan-like polysaccharide into the culture medium during growth in acetate. Because this polysaccharide shows strong flocculation activity for suspended solids in water, it can be used as a bioflocculant (BF). The BF synthetic pathway of C. freundii IFO 13545 is expected from known bacterial metabolic pathways to be as follows: acetate is metabolized in the TCA cycle and the glyoxylate shunt via acetyl-CoA. Next, fructose 6-phosphate is generated from the intermediates of the TCA cycle through gluconeogenesis and enters into the hexosamine synthetic pathway to form UDP-N-acetylglucosamine, which is used as a direct precursor to extend the BF polysaccharide chain. We conducted the draft genome sequencing of IFO 13545 and identified all of the candidate genes corresponding to the enzymes in this pathway in the 5420-kb genome sequence. Disruption of the genes encoding acetyl-CoA synthetase and isocitrate lyase by homologous recombination resulted in little or no growth on acetate, indicating that the cell growth depends on acetate assimilation via the glyoxylate shunt. Disruption of the gene encoding glucosamine 6-phosphate synthase, a key enzyme for the hexosamine synthetic pathway, caused a significant decrease in flocculation activity, demonstrating that this pathway is primarily used for the BF biosynthesis. A gene cluster necessary for the polymerization and secretion of BF, named bfpABCD, was also identified for the first time. In addition, quantitative RT-PCR analysis of several key genes in the expected pathway was conducted to know their expression in acetate assimilation and BF biosynthesis. Based on the data obtained in this study, an overview of the BF synthetic pathway is discussed. Full article

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0 pages, 6747 KiB

Open AccessArticle

RETRACTED: Preparation of Amidoxime-Functionalized β-Cyclodextrin-Graft-(Maleic Anhydride-co-Acrylonitrule) Copolymer and Evaluation of the Adsorption and Regeneration Properties of Uranium

by Liu Yang, Lei Bi, Zhiwei Lei, Yu Miao, Bolin Li, Tonghuan Liu and Wangsuo Wu

Polymers 2018, 10(3), 236; https://doi.org/10.3390/polym10030236 - 27 Feb 2018

Cited by 17 | Viewed by 6266 | Retraction

Abstract

The β-cyclodextrin-graft-(maleic anhydride-co-acrylonitrule) copolymer (β-CD-g-(MAH-co-AN)) synthesized through radical polymerization reactions of β-cyclodextrin (β-CD) with maleic anhydride (MAH) and acrylonitrule (AN) in the special monomer proportion, chemically modify with amidoxime groups to obtained the new adsorbent, which was terms as [...] Read more.

The β-cyclodextrin-graft-(maleic anhydride-co-acrylonitrule) copolymer (β-CD-g-(MAH-co-AN)) synthesized through radical polymerization reactions of β-cyclodextrin (β-CD) with maleic anhydride (MAH) and acrylonitrule (AN) in the special monomer proportion, chemically modify with amidoxime groups to obtained the new adsorbent, which was terms as amidoxime-functionalized β-cyclodextrin-graft-(maleic anhydride-co-acrylonitrule) copolymer (β-CD-g-(MAH-co-AO)). Based on the characteristic results of Fourier transform infrared spectra (FTIR), scanning electron microscopy (SEM), X-ray Diffraction (XRD), and thermalgravity analysis (TGA) techniques, the grafted nitrile groups were successfully converted to amidoxime groups by reaction with hydroxylamine. In this report, the influence of different factors such as pH value and ionic strength, solid-liquid ratio, contact time, initial U(VI) concentration, and temperature on adsorption was investigated by a batch adsorption experiment. The adsorption process fitting results show that the adsorption followed the Langmuir isotherm model and the maximum adsorption capacity was 0.747 g/g at pH 4.0. In addition, the regeneration performance was investigated by varying the concentration of eluent, temperature, and contact time. Under the desorption condition of 0.10 M HNO₃, the adsorbents can be reused 12 times in the case that the adsorption capacity was not significantly reduced. The functionalized copolymer exhibits high selectivity under circumstance of other co-existing ions is present in the solution. Full article

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32 pages, 3043 KiB

Open AccessReview

Chitosan Based Self-Assembled Nanoparticles in Drug Delivery

by Javier Pérez Quiñones, Hazel Peniche and Carlos Peniche

Polymers 2018, 10(3), 235; https://doi.org/10.3390/polym10030235 - 26 Feb 2018

Cited by 248 | Viewed by 21888

Abstract

Chitosan is a cationic polysaccharide that is usually obtained by alkaline deacetylation of chitin poly(N-acetylglucosamine). It is biocompatible, biodegradable, mucoadhesive, and non-toxic. These excellent biological properties make chitosan a good candidate for a platform in developing drug delivery systems having improved [...] Read more.

Chitosan is a cationic polysaccharide that is usually obtained by alkaline deacetylation of chitin poly(N-acetylglucosamine). It is biocompatible, biodegradable, mucoadhesive, and non-toxic. These excellent biological properties make chitosan a good candidate for a platform in developing drug delivery systems having improved biodistribution, increased specificity and sensitivity, and reduced pharmacological toxicity. In particular, chitosan nanoparticles are found to be appropriate for non-invasive routes of drug administration: oral, nasal, pulmonary and ocular routes. These applications are facilitated by the absorption-enhancing effect of chitosan. Many procedures for obtaining chitosan nanoparticles have been proposed. Particularly, the introduction of hydrophobic moieties into chitosan molecules by grafting to generate a hydrophobic-hydrophilic balance promoting self-assembly is a current and appealing approach. The grafting agent can be a hydrophobic moiety forming micelles that can entrap lipophilic drugs or it can be the drug itself. Another suitable way to generate self-assembled chitosan nanoparticles is through the formation of polyelectrolyte complexes with polyanions. This paper reviews the main approaches for preparing chitosan nanoparticles by self-assembly through both procedures, and illustrates the state of the art of their application in drug delivery. Full article

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17 pages, 7812 KiB

Open AccessArticle

Biocompatible Chitosan Oligosaccharide Modified Gold Nanorods as Highly Effective Photothermal Agents for Ablation of Breast Cancer Cells

by Panchanathan Manivasagan, Subramaniyan Bharathiraja, Madhappan Santha Moorthy, Sudip Mondal, Thanh Phuoc Nguyen, Hyehyun Kim, Thi Tuong Vy Phan, Kang Dae Lee and Junghwan Oh

Polymers 2018, 10(3), 232; https://doi.org/10.3390/polym10030232 - 26 Feb 2018

Cited by 43 | Viewed by 5486

Abstract

Photothermal therapy (PTT) using biocompatible nanomaterials have recently attracted much attention as a novel candidate technique for cancer therapy. In this work we report the performance of newly synthesized multidentate chitosan oligosaccharide modified gold nanorods (AuNRs-LA-COS) as novel agents for PTT of cancer [...] Read more.

Photothermal therapy (PTT) using biocompatible nanomaterials have recently attracted much attention as a novel candidate technique for cancer therapy. In this work we report the performance of newly synthesized multidentate chitosan oligosaccharide modified gold nanorods (AuNRs-LA-COS) as novel agents for PTT of cancer cells due to their excellent biocompatibility, photothermal stability, and high absorption in the near-infrared (NIR) region. The AuNRs-LA-COS exhibit a strong NIR absorption peak at 838 nm with a mean length of 26 ± 3.1 nm and diameter of 6.8 ± 1.7 nm, respectively. The temperature of AuNRs-LA-COS rapidly reached 52.6 °C for 5 min of NIR laser irradiation at 2 W/cm². The AuNRs-LA-COS had very low cytotoxicity and exhibited high efficiency for the ablation of breast cancer cells in vitro. The tumor-bearing mice were completely ablated without tumor recurrence after photothermal treatment with AuNRs-LA-COS (25 µg/mL) under laser irradiation. In summary, this study demonstrated that AuNRs-LA-COS with laser irradiation as novel agents pave an alternative way for breast cancer therapy and hold great promise for clinical trials in the near future. Full article

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8 pages, 3864 KiB

Open AccessCommunication

Nanosphere Lithography of Chitin and Chitosan with Colloidal and Self-Masking Patterning

by Rakkiyappan Chandran, Kyle Nowlin and Dennis R. LaJeunesse

Polymers 2018, 10(2), 218; https://doi.org/10.3390/polym10020218 - 23 Feb 2018

Cited by 9 | Viewed by 10291

Abstract

Complex surface topographies control, define, and determine the properties of insect cuticles. In some cases, these nanostructured materials are a direct extension of chitin-based cuticles. The cellular mechanisms that generate these elaborate chitin-based structures are unknown, and involve complicated cellular and biochemical “bottom-up” [...] Read more.

Complex surface topographies control, define, and determine the properties of insect cuticles. In some cases, these nanostructured materials are a direct extension of chitin-based cuticles. The cellular mechanisms that generate these elaborate chitin-based structures are unknown, and involve complicated cellular and biochemical “bottom-up” processes. We demonstrated that a synthetic “top-down” fabrication technique—nanosphere lithography—generates surfaces of chitin or chitosan that mimic the arrangement of nanostructures found on the surface of certain insect wings and eyes. Chitin and chitosan are flexible and biocompatible abundant natural polymers, and are a sustainable resource. The fabrication of nanostructured chitin and chitosan materials enables the development of new biopolymer materials. Finally, we demonstrated that another property of chitin and chitosan—the ability to self-assemble nanosilver particles—enables a novel and powerful new tool for the nanosphere lithographic method: the ability to generate a self-masking thin film. The scalability of the nanosphere lithographic technique is a major limitation; however, the silver nanoparticle self-masking enables a one-step thin-film cast or masking process, which can be used to generate nanostructured surfaces over a wide range of surfaces and areas. Full article

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25 pages, 995 KiB

Open AccessReview

Cosmetics and Cosmeceutical Applications of Chitin, Chitosan and Their Derivatives

by Inmaculada Aranaz, Niuris Acosta, Concepción Civera, Begoña Elorza, Javier Mingo, Carolina Castro, María De los Llanos Gandía and Angeles Heras Caballero

Polymers 2018, 10(2), 213; https://doi.org/10.3390/polym10020213 - 22 Feb 2018

Cited by 293 | Viewed by 20824

Abstract

Marine resources are well recognized for their biologically active substances with great potential applications in the cosmeceutical industry. Among the different compounds with a marine origin, chitin and its deacetylated derivative—chitosan—are of great interest to the cosmeceutical industry due to their unique biological [...] Read more.

Marine resources are well recognized for their biologically active substances with great potential applications in the cosmeceutical industry. Among the different compounds with a marine origin, chitin and its deacetylated derivative—chitosan—are of great interest to the cosmeceutical industry due to their unique biological and technological properties. In this review, we explore the different functional roles of chitosan as a skin care and hair care ingredient, as an oral hygiene agent and as a carrier for active compounds, among others. The importance of the physico-chemical properties of the polymer in its use in cosmetics are particularly highlighted. Moreover, we analyse the market perspectives of this polymer and the presence in the market of chitosan-based products. Full article

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14 pages, 3381 KiB

Open AccessArticle

α-Cyclodextrin and α-Cyclodextrin Polymers as Oxygen Nanocarriers to Limit Hypoxia/Reoxygenation Injury: Implications from an In Vitro Model

by Saveria Femminò, Claudia Penna, Federica Bessone, Fabrizio Caldera, Nilesh Dhakar, Daniele Cau, Pasquale Pagliaro, Roberta Cavalli and Francesco Trotta

Polymers 2018, 10(2), 211; https://doi.org/10.3390/polym10020211 - 22 Feb 2018

Cited by 35 | Viewed by 5107

Abstract

The incidence of heart failure (HF) is increasing worldwide and myocardial infarction (MI), which follows ischemia and reperfusion (I/R), is often at the basis of HF development. Nanocarriers are interesting particles for their potential application in cardiovascular disease. Impaired drug delivery in ischemic [...] Read more.

The incidence of heart failure (HF) is increasing worldwide and myocardial infarction (MI), which follows ischemia and reperfusion (I/R), is often at the basis of HF development. Nanocarriers are interesting particles for their potential application in cardiovascular disease. Impaired drug delivery in ischemic disease is challenging. Cyclodextrin nanosponges (NS) can be considered innovative tools for improving oxygen delivery in a controlled manner. This study has developed new α-cyclodextrin-based formulations as oxygen nanocarriers such as native α-cyclodextrin (α-CD), branched α-cyclodextrin polymer (α-CD POLY), and α-cyclodextrin nanosponges (α-CD NS). The three different α-CD-based formulations were tested at 0.2, 2, and 20 µg/mL to ascertain their capability to reduce cell mortality during hypoxia and reoxygenation (H/R) in vitro protocols. H9c2, a cardiomyoblast cell line, was exposed to normoxia (20% oxygen) or hypoxia (5% CO₂ and 95% N₂). The different formulations, applied before hypoxia, induced a significant reduction in cell mortality (in a range of 15% to 30%) when compared to samples devoid of oxygen. Moreover, their application at the beginning of reoxygenation induced a considerable reduction in cell death (12% to 20%). α-CD NS showed a marked efficacy in controlled oxygenation, which suggests an interesting potential for future medical application of polymer systems for MI treatment. Full article

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21 pages, 3040 KiB

Open AccessArticle

Neodymium Recovery by Chitosan/Iron(III) Hydroxide [ChiFer(III)] Sorbent Material: Batch and Column Systems

by Hary Demey, Byron Lapo, Montserrat Ruiz, Agustin Fortuny, Muriel Marchand and Ana M. Sastre

Polymers 2018, 10(2), 204; https://doi.org/10.3390/polym10020204 - 19 Feb 2018

Cited by 34 | Viewed by 6229

Abstract

A low cost composite material was synthesized for neodymium recovery from dilute aqueous solutions. The in-situ production of the composite containing chitosan and iron(III) hydroxide (ChiFer(III)) was improved and the results were compared with raw chitosan particles. The sorbent was characterized using Fourier [...] Read more.

A low cost composite material was synthesized for neodymium recovery from dilute aqueous solutions. The in-situ production of the composite containing chitosan and iron(III) hydroxide (ChiFer(III)) was improved and the results were compared with raw chitosan particles. The sorbent was characterized using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy-energy dispersive X-ray analyses (SEM-EDX). The equilibrium studies were performed using firstly a batch system, and secondly a continuous system. The sorption isotherms were fitted with the Langmuir, Freundlich, and Sips models; experimental data was better described with the Langmuir equation and the maximum sorption capacity was 13.8 mg g-1 at pH 4. The introduction of iron into the biopolymer matrix increases by four times the sorption uptake of the chitosan; the individual sorption capacity of iron (into the composite) was calculated as 30.9 mg Nd/g Fe. The experimental results of the columns were fitted adequately using the Thomas model. As an approach to Nd-Fe-B permanent magnets effluents, a synthetic dilute effluent was simulated at pH 4, in order to evaluate the selectivity of the sorbent material; the overshooting of boron in the column system confirmed the higher selectivity toward neodymium ions. The elution step was carried out using MilliQ-water with the pH set to 3.5 (dilute HCl solution). Full article

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14 pages, 1511 KiB

Open AccessArticle

Mucoadhesive Cyclodextrin-Modified Thiolated Poly(aspartic acid) as a Potential Ophthalmic Drug Delivery System

by Mária Budai-Szűcs, Eszter L. Kiss, Barnabás Áron Szilágyi, András Szilágyi, Benjámin Gyarmati, Szilvia Berkó, Anita Kovács, Gabriella Horvát, Zoltán Aigner, Judit Soós and Erzsébet Csányi

Polymers 2018, 10(2), 199; https://doi.org/10.3390/polym10020199 - 16 Feb 2018

Cited by 28 | Viewed by 5551

Abstract

Thiolated poly(aspartic acid) is known as a good mucoadhesive polymer in aqueous ophthalmic formulations. In this paper, cyclodextrin-modified thiolated poly(aspartic acid) was synthesized for the incorporation of prednisolone, a lipophilic ophthalmic drug, in an aqueous in situ gellable mucoadhesive solution. This polymer combines [...] Read more.

Thiolated poly(aspartic acid) is known as a good mucoadhesive polymer in aqueous ophthalmic formulations. In this paper, cyclodextrin-modified thiolated poly(aspartic acid) was synthesized for the incorporation of prednisolone, a lipophilic ophthalmic drug, in an aqueous in situ gellable mucoadhesive solution. This polymer combines the advantages of cyclodextrins and thiolated polymers. The formation of the cyclodextrin-drug complex in the gels was analyzed by X-ray powder diffraction. The ocular applicability of the polymer was characterized by means of physicochemical, rheological and drug diffusion tests. It was established that the chemical bonding of the cyclodextrin molecule did not affect the complexation of prednisolone, while the polymer solution preserved its in situ gellable and good mucoadhesive characteristics. The chemical immobilization of cyclodextrin modified the diffusion profile of prednisolone and prolonged drug release was observed. The combination of free and immobilized cyclodextrins provided the best release profile because the free complex can diffuse rapidly, while the bonded complex ensures a prolonged action. Full article

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10 pages, 230 KiB

Open AccessReview

Recent Advances of Chitosan Applications in Plants

by Massimo Malerba and Raffaella Cerana

Polymers 2018, 10(2), 118; https://doi.org/10.3390/polym10020118 - 26 Jan 2018

Cited by 170 | Viewed by 10845

Abstract

In recent years, the search for biological methods to avoid the application of chemical products in agriculture has led to investigating the use of biopolymers-based materials. Among the tested biomaterials, the best results were obtained from those based on the biopolymer chitosan (CHT). [...] Read more.

In recent years, the search for biological methods to avoid the application of chemical products in agriculture has led to investigating the use of biopolymers-based materials. Among the tested biomaterials, the best results were obtained from those based on the biopolymer chitosan (CHT). CHT, available in large quantities from the deacetylation of chitin, has multiple advantages: it is safe, inexpensive and can be easily associated with other compounds to achieve better performance. In this review, we have summarized the latest researches of the application of CHT on plant productivity, plant protection against the attack of pathogens and extension of the commercial life of detached fruits. Full article

23 pages, 3017 KiB

Open AccessArticle

Structural, Mechanical, and Transport Properties of Electron Beam-Irradiated Chitosan Membranes at Different Doses

by Alia Baroudi, Carmen García-Payo and Mohamed Khayet

Polymers 2018, 10(2), 117; https://doi.org/10.3390/polym10020117 - 26 Jan 2018

Cited by 28 | Viewed by 4304

Abstract

Chitosan powder irradiated by electron beam at different doses, up to 250 kGy, was used to prepare membranes for drug release applications. The irradiation effect on the molecular weight of powder chitosan, the characteristics of the prepared membranes, and their transport of sulfamerazine [...] Read more.

Chitosan powder irradiated by electron beam at different doses, up to 250 kGy, was used to prepare membranes for drug release applications. The irradiation effect on the molecular weight of powder chitosan, the characteristics of the prepared membranes, and their transport of sulfamerazine sodium salt (SULF) were investigated. The effect of the addition of glutaraldehyde (GLA) as a crosslinking agent in the chitosan solution used for the preparation of the membranes was also studied. A decrease in the chitosan molecular weight with the increase in the irradiation dose was observed, while the membranes prepared with the irradiated chitosan at higher dose exhibited lower swelling. However, an opposite behavior was detected when the membranes were prepared with GLA-crosslinked chitosan. A GLA crosslinking agent reduced the crystallinity of the chitosan membranes and the swelling, whereas the water contact angle and SULF transport increased with the increase in the irradiation dose. Full article

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12 pages, 4483 KiB

Open AccessArticle

Enhanced Solubilization of Fluoranthene by Hydroxypropyl β-Cyclodextrin Oligomer for Bioremediation

by Kyeong Hui Park, Jae Min Choi, Eunae Cho and Seunho Jung

Polymers 2018, 10(2), 111; https://doi.org/10.3390/polym10020111 - 24 Jan 2018

Cited by 10 | Viewed by 5730

Abstract

Fluoranthene (FT) is a polycyclic aromatic hydrocarbon (PAH), consisting of naphthalene and benzene rings connected by a five-member ring. It is widespread in the environment. The hydrophobicity of FT limits its availability for biological uptake and degradation. In this study, hydroxypropyl β-cyclodextrin oligomers [...] Read more.

Fluoranthene (FT) is a polycyclic aromatic hydrocarbon (PAH), consisting of naphthalene and benzene rings connected by a five-member ring. It is widespread in the environment. The hydrophobicity of FT limits its availability for biological uptake and degradation. In this study, hydroxypropyl β-cyclodextrin oligomers (HP-β-CD-ol) were synthesized with epichlorohydrin (EP), while the solubility enhancement of FT by HP-β-CD-ol was investigated in water. The synthesized HP-β-CD-ol was characterized by MALDI-TOF mass spectrometry (MS), ¹H NMR, and ¹³C NMR spectroscopy. The solubility of FT increased 178-fold due to the complex formation with HP-β-CD oligomers. The inclusion complexes of FT/HP-β-CD-ol were analyzed using Fourier-Transform Infrared (FT-IR), Differential Scanning Calorimetry (DSC), Scanning Electron Microscope (SEM), and Nuclear Overhauser Effect Spectroscopy Nuclear magnetic resonance (NOESY NMR) spectroscopy. On the basis of these results, HP-β-CD-ol is recommended as a potential solubilizer for the development of PAH removal systems. Full article

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12 pages, 3370 KiB

Open AccessArticle

Thermo-Responsive Starch-g-(PAM-co-PNIPAM): Controlled Synthesis and Effect of Molecular Components on Solution Rheology

by Yifei Fan, Nadia Boulif and Francesco Picchioni

Polymers 2018, 10(1), 92; https://doi.org/10.3390/polym10010092 - 19 Jan 2018

Cited by 28 | Viewed by 8318

Abstract

A series of highly branched random copolymers of acrylamide (AM) and N-isopropylacrylamide (NIPAM) have been prepared from a waxy potato starch-based macroinitiator by aqueous Cu⁰-mediated living radical polymerization (Cu⁰-mediated LRP). The NIPAM intake in the copolymer was varied [...] Read more.

A series of highly branched random copolymers of acrylamide (AM) and N-isopropylacrylamide (NIPAM) have been prepared from a waxy potato starch-based macroinitiator by aqueous Cu⁰-mediated living radical polymerization (Cu⁰-mediated LRP). The NIPAM intake in the copolymer was varied between 0% and 50 mol % to evaluate the influence of chain composition on the aqueous rheological properties as well as their low critical solution temperature (LCST). The viscosity of the copolymer was found to increase with the NIPAM intake and an LCST can be observed when the NIPAM content is high enough (e.g., 50 mol %). In addition, thermo-thickening behavior was observed at a low shear rate (γ ≤ 10 s⁻¹) and higher NIPAM content was found to shift the onset of thermo-thickening behavior to a lower temperature. However, the absolute increase in viscosity values is reduced with the NIPAM intake. Besides this, an interesting significant thermo-thickening behavior was also observed on highly branched starch-g-polyacrylamide at high temperatures (>80 °C), which has not been previously reported. Rheology tests also revealed a good salt-resistant property in copolymers with low NIPAM content (e.g., <25 mol %). Considering the viscosity profile in saline as compared to that in pure water, this NIPAM intake seems to represent an optimum balance of viscosity and salt-resistance performance. Full article

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14 pages, 4105 KiB

Open AccessArticle

Rheo-Kinetic Study of Sol-Gel Phase Transition of Chitosan Colloidal Systems

by Piotr Owczarz, Patryk Ziółkowski, Zofia Modrzejewska, Sławomir Kuberski and Marek Dziubiński

Polymers 2018, 10(1), 47; https://doi.org/10.3390/polym10010047 - 5 Jan 2018

Cited by 21 | Viewed by 5623

Abstract

Chitosan colloidal systems, created by dispersing in aqueous solutions of hydrochloric acid, with and without the addition of disodium β-glycerophosphate (β-NaGP), were prepared for the investigation of forming mechanisms of chitosan hydrogels. Three types of chitosan were used in varying molecular weights. The [...] Read more.

Chitosan colloidal systems, created by dispersing in aqueous solutions of hydrochloric acid, with and without the addition of disodium β-glycerophosphate (β-NaGP), were prepared for the investigation of forming mechanisms of chitosan hydrogels. Three types of chitosan were used in varying molecular weights. The impacts of the charge and shape of the macromolecules on the phase transition process were assessed. The chitosan system without the addition of β-NaGP was characterized by stiff and entangled molecules, in contrast to the chitosan system with the addition of β-NaGP, wherein the molecules adopt a more flexible and disentangled form. Differences in molecules shapes were confirmed using the Zeta potential and thixotropy experiments. The chitosan system without β-NaGP revealed a rapid nature of phase transition—consistent with diffusion-limited aggregation (DLA). The chitosan system with β-NaGP revealed a two-step nature of phase transition, wherein the first step was consistent with reaction-limited aggregation (RLA), while the second step complied with diffusion-limited aggregation (DLA). Full article

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2367 KiB

Open AccessArticle

A Facial Strategy for Catalyst and Reducing Agent Synchronous Separation for AGET ATRP Using Thiol-Grafted Cellulose Paper as Reducing Agent

by Xiaowu Jiang, Jie Han, Lunan Cao, Yan Bao, Jian Shi, Jing Zhang, Lingli Ni and Jing Chen

Polymers 2018, 10(1), 26; https://doi.org/10.3390/polym10010026 - 25 Dec 2017

Cited by 7 | Viewed by 5353

Abstract

Atom Transfer Radical Polymerization (ATRP) has been a powerful tool to synthesize well-defined functional polymers, which are widely used in biology, drug/gene delivery and antibacterial materials, etc. However, the potential toxic residues in polymer reduced its service life and limited its applications. In [...] Read more.

Atom Transfer Radical Polymerization (ATRP) has been a powerful tool to synthesize well-defined functional polymers, which are widely used in biology, drug/gene delivery and antibacterial materials, etc. However, the potential toxic residues in polymer reduced its service life and limited its applications. In order to overcome the problem, in this work, a novel polymerization system of activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP) for synchronous separation of the metal catalyst and byproduct of reducing agent was developed, using thiol-grafted cellulose paper (Cell-SH) as a solid reducing agent. The polymerization kinetics were investigated in detail, and the “living” features of the novel polymerization system were confirmed by chain-end analysis and chain extension experiment for the resultant polymethyl methacrylate (PMMA). It is noted that the copper residual in obtained PMMA was less than 20 ppm, just by filtering the sheet-like byproduct of the reducing agent. Full article

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3624 KiB

Open AccessArticle

Chitosan–Zinc(II) Complexes as a Bio-Sorbent for the Adsorptive Abatement of Phosphate: Mechanism of Complexation and Assessment of Adsorption Performance

by Maryam Roza Yazdani, Elina Virolainen, Kevin Conley and Riku Vahala

Polymers 2018, 10(1), 25; https://doi.org/10.3390/polym10010025 - 25 Dec 2017

Cited by 54 | Viewed by 8389

Abstract

This study examines zinc(II)–chitosan complexes as a bio-sorbent for phosphate removal from aqueous solutions. The bio-sorbent is prepared and is characterized via Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Point of Zero Charge (pH_PZC)–drift method. The adsorption capacity [...] Read more.

This study examines zinc(II)–chitosan complexes as a bio-sorbent for phosphate removal from aqueous solutions. The bio-sorbent is prepared and is characterized via Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Point of Zero Charge (pH_PZC)–drift method. The adsorption capacity of zinc(II)–chitosan bio-sorbent is compared with those of chitosan and ZnO–chitosan and nano-ZnO–chitosan composites. The effect of operational parameters including pH, temperature, and competing ions are explored via adsorption batch mode. A rapid phosphate uptake is observed within the first three hours of contact time. Phosphate removal by zinc(II)–chitosan is favored when the surface charge of bio-sorbent is positive/or neutral e.g., within the pH range inferior or around its pH_PZC, 7. Phosphate abatement is enhanced with decreasing temperature. The study of background ions indicates a minor effect of chloride, whereas nitrate and sulfate show competing effect with phosphate for the adsorptive sites. The adsorption kinetics is best described with the pseudo-second-order model. Sips (R² > 0.96) and Freundlich (R² ≥ 0.95) models suit the adsorption isotherm. The phosphate reaction with zinc(II)–chitosan is exothermic, favorable and spontaneous. The complexation of zinc(II) and chitosan along with the corresponding mechanisms of phosphate removal are presented. This study indicates the introduction of zinc(II) ions into chitosan improves its performance towards phosphate uptake from 1.45 to 6.55 mg/g and provides fundamental information for developing bio-based materials for water remediation. Full article

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3135 KiB

Open AccessArticle

Preparation of Antibacterial Cellulose Paper Using Layer-by-Layer Assembly for Cooked Beef Preservation at Ambient Temperature

by Hui Li, Rongqi Cui, Lincai Peng, Shengbao Cai, Pan Li and Tianqing Lan

Polymers 2018, 10(1), 15; https://doi.org/10.3390/polym10010015 - 23 Dec 2017

Cited by 19 | Viewed by 5671

Abstract

Positively-charged ε-poly(l-lysine) (ε-PL) and negatively-charged carboxymethyl cellulose (CMC) were alternately deposited on a cellulose paper surface by the layer-by-layer (LBL) assembly technique. The formation of ε-PL/CMC multilayers was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), and zeta [...] Read more.

Positively-charged ε-poly(l-lysine) (ε-PL) and negatively-charged carboxymethyl cellulose (CMC) were alternately deposited on a cellulose paper surface by the layer-by-layer (LBL) assembly technique. The formation of ε-PL/CMC multilayers was confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectra (FTIR), and zeta potential measurement. The morphologies of the multilayer-modified cellulose paper were observed by scanning electron microscopy (SEM). The ε-PL/CMC multilayers effectively improved not only the antibacterial activity of cellulose paper against both Escherichia coli and Staphylococcus aureus, but also the cellulose paper tensile strength property. Cellulose paper modified with a (ε-PL/CMC)_4.5 multilayer exhibited the strongest antibacterial activity, selected for preserving cooked beef for nine days at ambient temperature, could extend the shelf-life of beef for about three days compared with common commercial PE films. The prepared antibacterial paper did not show any evidence of the cytotoxic effect since it could not increase the cytoplasmic lactate dehydrogenase release from L-929 fibroblast cells in contact with the antibacterial paper, suggesting the possibility of utilization in food packaging field. Full article

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Open AccessArticle

Combination of Magnetic Lignocellulosic Particles, High-Density Polyethylene, and Carbon Black for the Construction of Composites with Tunable Functionalities

by Jingfa Zhang, Haowei Wang, Haigang Wang, Dan Xing, Zhijun Zhang and Qingwen Wang

Polymers 2018, 10(1), 9; https://doi.org/10.3390/polym10010009 - 22 Dec 2017

Cited by 10 | Viewed by 4361

Abstract

Biocomposites with unique functionalities for tailored applications are promising products for a sustainable future. In this work, a process concept of forming functional composites by combining of high-density polyethylene, carbon black, and magnetic lignocellulosic particles (wood flour) was demonstrated. The impacts of process [...] Read more.

Biocomposites with unique functionalities for tailored applications are promising products for a sustainable future. In this work, a process concept of forming functional composites by combining of high-density polyethylene, carbon black, and magnetic lignocellulosic particles (wood flour) was demonstrated. The impacts of process parameters on morphologies, crystalline phase, and magnetic intensity of wood flour were identified. Magnetic, antistatic and mechanical properties of biocomposites were also evaluated. Lignocellulosic particles were encapsulated with magnetic nanoparticles, and the resulting composites exhibited tunable magnetic and antistatic properties. A noticeable feature is that magnetic nanoparticles were uniformly distributed in the matrices as a result of anchorage to lignocellulosic particles. Magnetic lignocellulosic particles and polymer resin had good compatibility. The resulting composites provided another opportunity for shielding materials, which could reduce the radiation in the living environment. These findings could provide a tunable strategy of the tailored use of lignocellulose-based composites in functional applications. Full article

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Open AccessArticle

A pH-Sensing Film from Tamarind Seed Polysaccharide with Litmus Lichen Extract as an Indicator

by Tieqiang Liang and Lijuan Wang

Polymers 2018, 10(1), 13; https://doi.org/10.3390/polym10010013 - 22 Dec 2017

Cited by 46 | Viewed by 7579

Abstract

A new pH-sensing film was developed by using tamarind seed polysaccharide (TSP) and natural dye extracted from litmus lichen (LLE). The addition of LLE from 0 to 2.5% decreased the tensile strength and elongation at break from 30.20 to 29.97 MPa and 69.73% [...] Read more.

A new pH-sensing film was developed by using tamarind seed polysaccharide (TSP) and natural dye extracted from litmus lichen (LLE). The addition of LLE from 0 to 2.5% decreased the tensile strength and elongation at break from 30.20 to 29.97 MPa and 69.73% to 60.13%, respectively, but increased the water vapor permeability from 0.399 × 10⁻⁹ to 0.434 × 10⁻⁹ g·s⁻¹·m⁻¹·Pa⁻¹. The UV–Vis spectra of the litmus lichen extract (LLE) in the pH range of 4–10 showed that the color clearly changed from orange to blue. The characterization results showed that TSP interacted with LLE through hydrogen bonds. The color of the film varied from orange (pH 4.0) to blue-violet (pH 10.0). The full cream milk spoilage test indicated that the film is suitable for application in full cream milk spoilage detection. The developed pH-sensing film could be used as a promising diagnostic tool for the detection of food spoilage. Full article

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Open AccessArticle

Microencapsulation of Lactobacillus Acidophilus by Xanthan-Chitosan and Its Stability in Yoghurt

by Guowei Shu, Yunxia He, Li Chen, Yajuan Song, Jiangpeng Meng and He Chen

Polymers 2017, 9(12), 733; https://doi.org/10.3390/polym9120733 - 20 Dec 2017

Cited by 18 | Viewed by 6467

Abstract

Microencapsulations of Lactobacillus acidophilus in xanthan-chitosan (XC) and xanthan-chitosan-xanthan (XCX) polyelectrolyte complex (PEC) gels were prepared in this study. The process of encapsulation was optimized with the aid of response surface methodology (RSM). The optimum condition was chitosan of 0.68%, xanthan of 0.76%, [...] Read more.

Microencapsulations of Lactobacillus acidophilus in xanthan-chitosan (XC) and xanthan-chitosan-xanthan (XCX) polyelectrolyte complex (PEC) gels were prepared in this study. The process of encapsulation was optimized with the aid of response surface methodology (RSM). The optimum condition was chitosan of 0.68%, xanthan of 0.76%, xanthan-L. acidophilus mixture (XLM)/chitosan of 1:2.56 corresponding to a high viable count (1.31 ± 0.14) × 10¹⁰ CFU·g⁻¹, and encapsulation yield 86 ± 0.99%, respectively. Additionally, the application of a new encapsulation system (XC and XCX) in yoghurt achieved great success in bacterial survival during the storage of 21 d at 4 °C and 25 °C, respectively. Specially, pH and acidity in yogurt were significantly influenced by the new encapsulation system in comparison to free suspension during 21 d storage. Our study provided a potential encapsulation system for probiotic application in dairy product which paving a new way for functional food development. Full article

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Open AccessArticle

Characterization of Wood-Plastic Composites Made with Different Lignocellulosic Materials that Vary in Their Morphology, Chemical Composition and Thermal Stability

by Ke-Chang Hung, Heng Yeh, Teng-Chun Yang, Tung-Lin Wu, Jin-Wei Xu and Jyh-Horng Wu

Polymers 2017, 9(12), 726; https://doi.org/10.3390/polym9120726 - 17 Dec 2017

Cited by 26 | Viewed by 7140

Abstract

In this study, four kinds of lignocellulosic fibers (LFs), namely, those from Chinese fir (Cunninghamia lanceolata), Taiwan red pine (Pinus taiwanensis), India-charcoal trema (Trema orientalis) and makino bamboo (Phyllostachys makinoi), were selected as reinforcements and incorporated into high-density polyethylene (HDPE) to manufacture wood-plastic [...] Read more.

In this study, four kinds of lignocellulosic fibers (LFs), namely, those from Chinese fir (Cunninghamia lanceolata), Taiwan red pine (Pinus taiwanensis), India-charcoal trema (Trema orientalis) and makino bamboo (Phyllostachys makinoi), were selected as reinforcements and incorporated into high-density polyethylene (HDPE) to manufacture wood-plastic composites (WPCs) by a flat platen pressing process. In addition to comparing the differences in the physico-mechanical properties of these composites, their chemical compositions were evaluated and their thermal decomposition kinetics were analyzed to investigate the effects of the lignocellulosic species on the properties of the WPCs. The results showed that the WPC made with Chinese fir displayed a typical M-shaped vertical density profile due to the high aspect ratio of its LFs, while a flat vertical density profile was observed for the WPCs made with other LFs. Thus, the WPC made with Chinese fir exhibited higher flexural properties and lower internal bond strength (IB) than other WPCs. In addition, the Taiwan red pine contained the lowest holocellulose content and the highest extractives and α-cellulose contents, which gave the resulting WPC lower water absorption and flexural properties. On the other hand, consistent with the flexural properties, the results of thermal decomposition kinetic analysis showed that the activation energy of the LFs at 10% of the conversion rate increased in the order of Taiwan red pine (146–161 kJ/mol), makino bamboo (158–175 kJ/mol), India-charcoal trema (185–194 kJ/mol) and Chinese fir (194–202 kJ/mol). These results indicate that the morphology, chemical composition and thermal stability of the LFs can have a substantial impact on the physico-mechanical properties of the resulting WPCs. Full article

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Open AccessArticle

Aerogels from Chitosan Solutions in Ionic Liquids

by Gonzalo Santos-López, Waldo Argüelles-Monal, Elizabeth Carvajal-Millan, Yolanda L. López-Franco, Maricarmen T. Recillas-Mota and Jaime Lizardi-Mendoza

Polymers 2017, 9(12), 722; https://doi.org/10.3390/polym9120722 - 16 Dec 2017

Cited by 29 | Viewed by 6390

Abstract

Chitosan aerogels conjugates the characteristics of nanostructured porous materials, i.e., extended specific surface area and nano scale porosity, with the remarkable functional properties of chitosan. Aerogels were obtained from solutions of chitosan in ionic liquids (ILs), 1-butyl-3-methylimidazolium acetate (BMIMAc), and 1-ethyl-3-methyl-imidazolium acetate (EMIMAc), [...] Read more.

Chitosan aerogels conjugates the characteristics of nanostructured porous materials, i.e., extended specific surface area and nano scale porosity, with the remarkable functional properties of chitosan. Aerogels were obtained from solutions of chitosan in ionic liquids (ILs), 1-butyl-3-methylimidazolium acetate (BMIMAc), and 1-ethyl-3-methyl-imidazolium acetate (EMIMAc), in order to observe the effect of the solvent in the structural characteristics of this type of materials. The process of elaboration of aerogels comprised the formation of physical gels through anti-solvent vapor diffusion, liquid phase exchange, and supercritical CO₂ drying. The aerogels maintained the chemical identity of chitosan according to Fourier transform infrared spectrophotometer (FT-IR) spectroscopy, indicating the presence of their characteristic functional groups. The internal structure of the obtained aerogels appears as porous aggregated networks in microscopy images. The obtained materials have specific surface areas over 350 m²/g and can be considered mesoporous. According to swelling experiments, the chitosan aerogels could absorb between three and six times their weight of water. However, the swelling and diffusion coefficient decreased at higher temperatures. The structural characteristics of chitosan aerogels that are obtained from ionic liquids are distinctive and could be related to solvation dynamic at the initial state. Full article

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Open AccessReview

Exploiting Microbial Polysaccharides for Biosorption of Trace Elements in Aqueous Environments—Scope for Expansion via Nanomaterial Intervention

by Manikandan Muthu, Hui-Fen Wu, Judy Gopal, Iyyakkannu Sivanesan and Sechul Chun

Polymers 2017, 9(12), 721; https://doi.org/10.3390/polym9120721 - 16 Dec 2017

Cited by 31 | Viewed by 7090

Abstract

With pollution sounding high alarms all around us, there is an immediate necessity for remediation. In most cases, the remediation measures require further remediation—the anti-pollutants themselves cause pollution. In this correspondence, the search deepens towards natural biogenic components that can be used for [...] Read more.

With pollution sounding high alarms all around us, there is an immediate necessity for remediation. In most cases, the remediation measures require further remediation—the anti-pollutants themselves cause pollution. In this correspondence, the search deepens towards natural biogenic components that can be used for bioremediation. Polysaccharide and biosorption have been themes in discussion for quite some time, where a slow decline in the enthusiasm in this area has been observed. This review revisits the importance of using polysaccharide based materials for biosorption. The need for polysaccharide-based nanocomposites, which hold better promise for greater deliverables, is emphasized as a means of rejuvenating the future perspectives in this area of application. Full article

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Open AccessArticle

Hydroxypropyltrimethyl Ammonium Chloride Chitosan Functionalized-PLGA Electrospun Fibrous Membranes as Antibacterial Wound Dressing: In Vitro and In Vivo Evaluation

by Shengbing Yang, Xiuguo Han, Yuhang Jia, Hongbo Zhang and Tingting Tang

Polymers 2017, 9(12), 697; https://doi.org/10.3390/polym9120697 - 11 Dec 2017

Cited by 39 | Viewed by 8874

Abstract

A novel poly(lactic-co-glycolic acid) (PLGA)-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) composite nanofiber wound dressing was prepared through electrospinning and the entrapment-graft technique as an antibacterial dressing for cutaneous wound healing. HACC with 30% degrees of substitution (DS) was immobilized onto the surface [...] Read more.

A novel poly(lactic-co-glycolic acid) (PLGA)-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) composite nanofiber wound dressing was prepared through electrospinning and the entrapment-graft technique as an antibacterial dressing for cutaneous wound healing. HACC with 30% degrees of substitution (DS) was immobilized onto the surface of PLGA membranes via the reaction between carboxyl groups in PLGA after alkali treatment and the reactive groups (–NH₂) in HACC molecules. The naked PLGA and chitosan graft PLGA (PLGA-CS) membranes served as controls. The surface immobilization was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and energy dispersive X-ray spectrometry (EDX). The morphology studies showed that the membranes remain uniform after the immobilization process. The effects of the surface modification by HACC and CS on the biological properties of the membranes were also investigated. Compared with PLGA and PLGA-CS, PLGA-HACC exhibited more effective antibacterial activity towards both Gram-positive (S. aureus) and Gram-negative (P. aeruginosa) bacteria. The newly developed fibrous membranes were evaluated in vitro for their cytotoxicity using human dermal fibroblasts (HDFs) and human keratinocytes (HaCaTs) and in vivo using a wound healing mice model. It was revealed that PLGA-HACC fibrous membranes exhibited favorable cytocompatibility and significantly stimulated adhesion, spreading and proliferation of HDFs and HaCaTs. PLGA-HACC exhibited excellent wound healing efficacy, which was confirmed using a full thickness excision wound model in S. aureus-infected mice. The experimental results in this work suggest that PLGA-HACC is a strong candidate for use as a therapeutic biomaterial in the treatment of infected wounds. Full article

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Open AccessArticle

Effects of Acid and Salt Solutions on the Pasting, Rheology and Texture of Lotus Root Starch–Konjac Glucomannan Mixture

by Fusheng Zhang, Min Liu, Fang Mo, Meixia Zhang and Jiong Zheng

Polymers 2017, 9(12), 695; https://doi.org/10.3390/polym9120695 - 10 Dec 2017

Cited by 24 | Viewed by 7253

Abstract

To explore the functional properties of mixed biopolymer systems affected by acid and salts. The effects of acid and salt solutions (i.e., NaCl, KCl and CaCl₂) on the pasting, rheology, texture and microstructure of lotus root starch–konjac glucomannan (LRS/KGM) mixtures were [...] Read more.

To explore the functional properties of mixed biopolymer systems affected by acid and salts. The effects of acid and salt solutions (i.e., NaCl, KCl and CaCl₂) on the pasting, rheology, texture and microstructure of lotus root starch–konjac glucomannan (LRS/KGM) mixtures were assessed. Acid (citric acid buffer) treatment worsened the pasting (except for breakdown viscosity), rheological (except for fluid index), and textural properties, thereby inhibiting retrogradation, weakening pseudoplasticity and thickening, and reducing mixture viscoelasticity. Furthermore, it led to destructive ruptures and large pores in the internal microstructure. Salt treatment worsened the pasting properties (except for setback viscosity), thus inhibiting retrogradation and weakening pseudoplasticity, but enhanced the rheological properties, improving thickening and fluctuating viscoelasticity of the mixture. Moreover, salt addition decreased the hardness while increasing mixture cohesiveness, and modified the elasticity, adhesiveness and internal microstructure in a salt type- and concentration-dependent manner. A salt solution concentration of 0.5 mol/L NaCl, 0.1 mol/L KCl, and 0.5 mol/L CaCl₂ led to the mixture with the best texture and gel network. Full article

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Open AccessReview

Preparation, Characterization and Application of Polysaccharide-Based Metallic Nanoparticles: A Review

by Cong Wang, Xudong Gao, Zhongqin Chen, Yue Chen and Haixia Chen

Polymers 2017, 9(12), 689; https://doi.org/10.3390/polym9120689 - 8 Dec 2017

Cited by 135 | Viewed by 12479

Abstract

Polysaccharides are natural biopolymers that have been recognized to be the most promising hosts for the synthesis of metallic nanoparticles (MNPs) because of their outstanding biocompatible and biodegradable properties. Polysaccharides are diverse in size and molecular chains, making them suitable for the reduction [...] Read more.

Polysaccharides are natural biopolymers that have been recognized to be the most promising hosts for the synthesis of metallic nanoparticles (MNPs) because of their outstanding biocompatible and biodegradable properties. Polysaccharides are diverse in size and molecular chains, making them suitable for the reduction and stabilization of MNPs. Considerable research has been directed toward investigating polysaccharide-based metallic nanoparticles (PMNPs) through host–guest strategy. In this review, approaches of preparation, including top-down and bottom-up approaches, are presented and compared. Different characterization techniques such as scanning electron microscopy, transmission electron microscopy, dynamic light scattering, UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction and small-angle X-ray scattering are discussed in detail. Besides, the applications of PMNPs in the field of wound healing, targeted delivery, biosensing, catalysis and agents with antimicrobial, antiviral and anticancer capabilities are specifically highlighted. The controversial toxicological effects of PMNPs are also discussed. This review can provide significant insights into the utilization of polysaccharides as the hosts to synthesize MPNs and facilitate their further development in synthesis approaches, characterization techniques as well as potential applications. Full article

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Open AccessArticle

Biocompatibility Assessment of Conducting PANI/Chitosan Nanofibers for Wound Healing Applications

by Panagiota Moutsatsou, Karen Coopman and Stella Georgiadou

Polymers 2017, 9(12), 687; https://doi.org/10.3390/polym9120687 - 8 Dec 2017

Cited by 61 | Viewed by 7138

Abstract

As electroactive polymers have recently presented potential in applications in the tissue engineering and biomedical field, this study is aiming at the fabrication of composite nanofibrous membranes containing conducting polyaniline and at the evaluation of their biocompatibility. For that purpose, conducting polyaniline–chitosan (PANI/CS) [...] Read more.

As electroactive polymers have recently presented potential in applications in the tissue engineering and biomedical field, this study is aiming at the fabrication of composite nanofibrous membranes containing conducting polyaniline and at the evaluation of their biocompatibility. For that purpose, conducting polyaniline–chitosan (PANI/CS) defect free nanofibres of different ratios (1:3; 3:5 and 1:1) were produced with the electrospinning method. They were characterized as for their morphology, hydrophilicity and electrical conductivity. The membranes were then evaluated for their cellular biocompatibility in terms of cell attachment, morphology and cell proliferation. The effect of the PANI content on the membrane properties is discussed. Increase in PANI content resulted in membranes with higher hydrophobicity and higher electrical conductivity. It was found that none of the membranes showed any toxic effects on osteoblasts and fibroblasts, and that they all supported cell attachment and growth, even to a greater extent than tissue culture plastic. The membrane with the PANI/CS ratio 1:3 supports better cell attachment and proliferation for both cell lines due to a synergistic effect of hydrophilicity retention due to the high chitosan content and the conductivity that PANI introduced to the membrane. Full article

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Open AccessArticle

Drag Reduction Using Polysaccharides in a Taylor–Couette Flow

by Pallavi Bhambri, Ravin Narain and Brian Fleck

Polymers 2017, 9(12), 683; https://doi.org/10.3390/polym9120683 - 7 Dec 2017

Cited by 7 | Viewed by 4849

Abstract

Three different polysaccharides, aloe vera, Tamarind powder and pineapple fibers, are utilized as drag reducing agents in a turbulent flow. Using a Taylor–Couette setup, consisting of a rotating inner cylinder, for measuring the drag reduction, a range of Reynolds numbers from 4 × [...] Read more.

Three different polysaccharides, aloe vera, Tamarind powder and pineapple fibers, are utilized as drag reducing agents in a turbulent flow. Using a Taylor–Couette setup, consisting of a rotating inner cylinder, for measuring the drag reduction, a range of Reynolds numbers from 4 × 10⁴ to 3 × 10⁵ has been explored in this study. The results are in good agreement with previous studies on polysaccharides conducted in a pipe/channel flow and a maximum drag reduction of 35% has been observed. Further, novel additives such as cellulose nanocrystals (CNC), surfactants and CNC grafted with surfactants are also examined in this study for drag reduction. CNC due to its rigid rod structure reduced the drag by 30%. Surfactant, due to its unique micelle formation showed maximum drag reduction of 80% at low Re. Further, surfactant was grafted on CNC and was examined for drag reduction. However, drag reduction property of surfactant was observed to be significantly reduced after grafting on CNC. The effect of Reynolds number on drag reduction is studied for all the additives investigated in this study. Full article

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Open AccessCommunication

Confinement Effects on Polymer Dynamics: Thermo-Responsive Behaviours of Hydroxypropyl Cellulose Polymers in Phospholipid-Coated Droplets (Water-in-Oil Emulsion)

by Kazunari Yoshida, Keitaro Horii, Azusa Saito, Akito Takashima and Izumi Nishio

Polymers 2017, 9(12), 680; https://doi.org/10.3390/polym9120680 - 6 Dec 2017

Cited by 8 | Viewed by 4983

Abstract

In order to construct the artificial cells and to understand the physicochemical properties of living cells, it is important to clarify the cell-sized confinement effect on the behaviours of bio-inspired polymers. We report the dynamic behaviours of aqueous hydroxypropyl cellulose (HPC) solution coated [...] Read more.

In order to construct the artificial cells and to understand the physicochemical properties of living cells, it is important to clarify the cell-sized confinement effect on the behaviours of bio-inspired polymers. We report the dynamic behaviours of aqueous hydroxypropyl cellulose (HPC) solution coated with phospholipids in oil (water-in-oil droplets, W/O droplets), accompanied by an increase in the temperature. We directly observed the beginning of phase separation of HPC solution using a fluorescence microscope and confirmed the dependence of such phenomena on droplet size. The results indicate that the start time of phase separation is decreased with an increase in droplet size. The experimental results suggest that the confinement situation accelerates the phase separation of aqueous HPC solutions. Full article

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Open AccessReview

Hydrogels for Cartilage Regeneration, from Polysaccharides to Hybrids

by Daniela Anahí Sánchez-Téllez, Lucía Téllez-Jurado and Luís María Rodríguez-Lorenzo

Polymers 2017, 9(12), 671; https://doi.org/10.3390/polym9120671 - 4 Dec 2017

Cited by 67 | Viewed by 11941

Abstract

The aims of this paper are: (1) to review the current state of the art in the field of cartilage substitution and regeneration; (2) to examine the patented biomaterials being used in preclinical and clinical stages; (3) to explore the potential of polymeric [...] Read more.

The aims of this paper are: (1) to review the current state of the art in the field of cartilage substitution and regeneration; (2) to examine the patented biomaterials being used in preclinical and clinical stages; (3) to explore the potential of polymeric hydrogels for these applications and the reasons that hinder their clinical success. The studies about hydrogels used as potential biomaterials selected for this review are divided into the two major trends in tissue engineering: (1) the use of cell-free biomaterials; and (2) the use of cell seeded biomaterials. Preparation techniques and resulting hydrogel properties are also reviewed. More recent proposals, based on the combination of different polymers and the hybridization process to improve the properties of these materials, are also reviewed. The combination of elements such as scaffolds (cellular solids), matrices (hydrogel-based), growth factors and mechanical stimuli is needed to optimize properties of the required materials in order to facilitate tissue formation, cartilage regeneration and final clinical application. Polymer combinations and hybrids are the most promising materials for this application. Hybrid scaffolds may maximize cell growth and local tissue integration by forming cartilage-like tissue with biomimetic features. Full article

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Open AccessArticle

Effect of Cross-Linking on the Performances of Starch-Based Biopolymer as Gel Electrolyte for Dye-Sensitized Solar Cell Applications

by Pavithra Nagaraj, Asija Sasidharan, Velayutham David and Anandan Sambandam

Polymers 2017, 9(12), 667; https://doi.org/10.3390/polym9120667 - 1 Dec 2017

Cited by 40 | Viewed by 9158

Abstract

Dye-sensitized solar cells (DSSCs) have become a validated and economically credible competitor to the traditional solid-state junction photovoltaic devices. DSSCs based on biopolymer gel electrolyte systems offer the perspective of competitive conversion efficiencies with a very low-cost fabrication. In this paper, a new [...] Read more.

Dye-sensitized solar cells (DSSCs) have become a validated and economically credible competitor to the traditional solid-state junction photovoltaic devices. DSSCs based on biopolymer gel electrolyte systems offer the perspective of competitive conversion efficiencies with a very low-cost fabrication. In this paper, a new starch-based biopolymer gel electrolyte system is prepared by mixing lithium iodide and iodine with bare and citric acid cross-linked potato starches with glycerol as the plasticizing agent. The effect of the preparation methods on the starch cross-linking degree as well as the photoconversion efficiency of the resulting DSSC cells is carefully analyzed. Fourier transform spectroscopy, X-ray diffraction, and scanning electron microscopy were used to characterize the morphology and conformational changes of starch in the electrolytes. The conductivity of the biopolymer electrolytes was determined by electrochemical impedance spectroscopy. DSSC based on the starch-gel polymer electrolytes were characterized by photovoltaic measurements and electrochemical impedance spectroscopy. Results clearly show that the cross-linking increases the recombination resistance and open circuit voltage (V_OC) of the DSSC, and thereby the photoconversion efficiency of the cell. In particular, electrolytes containing 1.4 g bare and cross-linked starches showed ionic conductivities of σ = 1.61, 0.59, 0.38, and 0.35 S cm⁻¹, and the corresponding DSSCs showed efficiencies of 1.2, 1.4, 0.93, and 1.11%, respectively. Full article

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Open AccessArticle

Microwave Assisted Preparation of Antimicrobial Chitosan with Guanidine Oligomers and Its Application in Hygiene Paper Products

by Junrong Li, Ying Ye, Huining Xiao, Beihai He and Liying Qian

Polymers 2017, 9(12), 633; https://doi.org/10.3390/polym9120633 - 24 Nov 2017

Cited by 10 | Viewed by 4721

Abstract

Guanidinylated chitosan (GCS) was prepared by grafting guanidine oligomers onto chitosan under microwave irradiation. The structure of GCS characterized by FT-IR and ¹H NMR verified the covalent bonding between the guanidine oligomers and chitosan; the effects of molar ratio, reaction temperature, and [...] Read more.

Guanidinylated chitosan (GCS) was prepared by grafting guanidine oligomers onto chitosan under microwave irradiation. The structure of GCS characterized by FT-IR and ¹H NMR verified the covalent bonding between the guanidine oligomers and chitosan; the effects of molar ratio, reaction temperature, and time were investigated and the degree of substitution of GCS reached a maximum of 25.5% under optimized conditions in this work. The resulting GCS showed significantly enhanced antimicrobial activities. The results obtained from the dynamic UV absorption of Escherichia coli (E. coli) and atomic force microscopy (AFM) revealed that the deactivation of E. coli by GCS was due to the destructing of the cell membrane and the prompt release of cytoplasm from the bacterial cells. The adsorption of GCS onto cellulose fibers and the antimicrobial efficiency of the hygiene papers with GCS were also investigated. Microwave irradiation as a green assisted method was applied to promote this reaction. This facile approach allowed chitosan to be guanidinylated without tedious preparation procedures and thus broadened its application as a biocompatible antimicrobial agent. Full article

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Open AccessArticle

Extraction and Characterization of Cellulose Nanocrystals from Tea Leaf Waste Fibers

by Nur Hayati Abdul Rahman, Buong Woei Chieng, Nor Azowa Ibrahim and Norizah Abdul Rahman

Polymers 2017, 9(11), 588; https://doi.org/10.3390/polym9110588 - 7 Nov 2017

Cited by 104 | Viewed by 12060

Abstract

The aim was to explore the utilization of tea leaf waste fibers (TLWF) as a source for the production of cellulose nanocrystals (CNC). TLWF was first treated with alkaline, followed by bleaching before being hydrolyzed with concentrated sulfuric acid. The materials attained after [...] Read more.

The aim was to explore the utilization of tea leaf waste fibers (TLWF) as a source for the production of cellulose nanocrystals (CNC). TLWF was first treated with alkaline, followed by bleaching before being hydrolyzed with concentrated sulfuric acid. The materials attained after each step of chemical treatments were characterized and their chemical compositions were studied. The structure analysis was examined by Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). From FTIR analysis, two peaks at 1716 and 1207 cm⁻¹—which represent C=O stretchingand C–O stretching, respectively—disappeared in the spectra after the alkaline and bleaching treatments indicated that hemicellulose and lignin were almost entirely discarded from the fiber. The surface morphology of TLWF before and after chemical treatments was investigated by scanning electron microscopy (SEM) while the dimension of CNC was determined by transmission electron microscopy (TEM). The extraction of CNC increased the surface roughness and the crystallinity index of fiber from 41.5% to 83.1%. Morphological characterization from TEM revealed the appearance of needle-like shaped CNCs with average diameter of 7.97 nm. The promising results from all the analyses justify TLWF as a principal source of natural materials which can produce CNC. Full article

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Open AccessCommunication

Reducing Water Sensitivity of Chitosan Biocomposite Films Using Gliadin Particles Made by In Situ Method

by Dajian Huang, Zonghong Ma, Zhuo Zhang and Qiling Quan

Polymers 2017, 9(11), 583; https://doi.org/10.3390/polym9110583 - 6 Nov 2017

Cited by 10 | Viewed by 4399

Abstract

In order to sustain rapid expansion in the field of biocomposites, it is necessary to develop novel fillers that are biodegradable, and easy to disperse and obtain. In this work, gliadin particles (GPs) fabricated through an in situ method have been reported as [...] Read more.

In order to sustain rapid expansion in the field of biocomposites, it is necessary to develop novel fillers that are biodegradable, and easy to disperse and obtain. In this work, gliadin particles (GPs) fabricated through an in situ method have been reported as fillers for creating chitosan (CS)-based biocomposite films. In general, the particles tend to agglomerate in the polymer matrix at high loading (approximately >10%) in the biopolymer/particles composites prepared by the traditional solution-blending method. However, the micrographs of biocomposites confirmed that the GPs are well dispersed in the CS matrix in all CS/GPs composites even at a high loading of 30% in this study. It was found that the GPs could improve the mechanical properties of the biocomposites. In addition, the results of moisture uptake and solubility in water of biocomposites showed that water resistance of biocomposites was enhanced by the introduction of GPs. These results suggested that GPs fabricated through an in situ method could be a good candidate for use in biopolymer-based composites. Full article

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Open AccessArticle

Effect of Cellulose Nanocrystals and Bacterial Cellulose on Disintegrability in Composting Conditions of Plasticized PHB Nanocomposites

by Irene Teresita Seoane, Liliana Beatriz Manfredi, Viviana Paola Cyras, Luigi Torre, Elena Fortunati and Debora Puglia

Polymers 2017, 9(11), 561; https://doi.org/10.3390/polym9110561 - 28 Oct 2017

Cited by 43 | Viewed by 6564

Abstract

Poly(hydroxybutyrate) (PHB)-based films, reinforced with bacterial cellulose (BC) or cellulose nanocrystals (CNC) and plasticized using a molecular (tributyrin) or a polymeric plasticizer (poly(adipate diethylene)), were produced by solvent casting. Their morphological, thermal, wettability, and chemical properties were investigated. Furthermore, the effect of adding [...] Read more.

Poly(hydroxybutyrate) (PHB)-based films, reinforced with bacterial cellulose (BC) or cellulose nanocrystals (CNC) and plasticized using a molecular (tributyrin) or a polymeric plasticizer (poly(adipate diethylene)), were produced by solvent casting. Their morphological, thermal, wettability, and chemical properties were investigated. Furthermore, the effect of adding both plasticizers (20 wt % respect to the PHB content) and biobased selected nanofillers added at different contents (2 and 4 wt %) on disintegrability in composting conditions was studied. Results of contact angle measurements and calorimetric analysis validated the observed behavior during composting experiments, indicating how CNC aggregation, due to the hydrophilic nature of the filler, slows down the degradation rate but accelerates it in case of increasing content. In contrast, nanocomposites with BC presented an evolution in composting similar to neat PHB, possibly due to the lower hydrophilic character of this material. The addition of the two plasticizers contributed to a better dispersion of the nanoparticles by increasing the interaction between the cellulosic reinforcements and the matrix, whereas the increased crystallinity of the incubated samples in a second stage in composting provoked a reduction in the disintegration rate. Full article

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Open AccessArticle

Reducing the Amount of Catalyst in TEMPO-Oxidized Cellulose Nanofibers: Effect on Properties and Cost

by Albert Serra, Israel González, Helena Oliver-Ortega, Quim Tarrès, Marc Delgado-Aguilar and Pere Mutjé

Polymers 2017, 9(11), 557; https://doi.org/10.3390/polym9110557 - 26 Oct 2017

Cited by 88 | Viewed by 7924

Abstract

Cellulose nanofibers (CNF) are interesting biopolymers that find numerous applications in different scientific and technological fields. However, manufacturing costs are still one of the main drawbacks for the industrial production of highly fibrillated, transparent CNF suspensions. In the present study, cellulose nanofibers were [...] Read more.

Cellulose nanofibers (CNF) are interesting biopolymers that find numerous applications in different scientific and technological fields. However, manufacturing costs are still one of the main drawbacks for the industrial production of highly fibrillated, transparent CNF suspensions. In the present study, cellulose nanofibers were produced from bleached eucalyptus pulp via TEMPO-mediated oxidation with varying amounts of NaClO and passed through a high-pressure homogenizer. The CNFs were chemically and physically characterized; cellulose nanopapers were also produced to study tensile properties. Production costs were also calculated. Results indicated that CNF properties are strongly dependent on the carboxyl content. Manufacturing costs showed that chemicals, in particular TEMPO catalyst, represent a large part of the final cost of CNFs. In order to solve this problem, a set of samples were prepared where the amount of TEMPO was gradually reduced. Characterization of samples prepared in this way showed that not only were the costs reduced, but also that the final properties of the CNFs were not significantly affected when the amount of TEMPO was reduced to half. Full article

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Open AccessArticle

Preparation and Evaluation of Green Composites from Microcrystalline Cellulose and a Soybean-Oil Derivative

by Wendi Liu, Ming-en Fei, Yang Ban, Anming Jia and Renhui Qiu

Polymers 2017, 9(10), 541; https://doi.org/10.3390/polym9100541 - 23 Oct 2017

Cited by 49 | Viewed by 7005

Abstract

The present work aimed at developing fully green composites from renewable materials, i.e., acrylated epoxidized soybean oil (AESO) and microcrystalline cellulose (MCC) by a solution casting method. The reinforcing effect of MCC on AESO resins was optimized by adjusting MCC loading from 20 [...] Read more.

The present work aimed at developing fully green composites from renewable materials, i.e., acrylated epoxidized soybean oil (AESO) and microcrystalline cellulose (MCC) by a solution casting method. The reinforcing effect of MCC on AESO resins was optimized by adjusting MCC loading from 20 to 40 wt % in terms of physical, mechanical, and thermal properties as well as water absorption of the resulting MCC/AESO composites. The interaction between MCC and AESO was characterized by Fourier transform infrared (FTIR) analysis, which revealed possible hydrogen bonds between the –OH groups of MCC along with the polar components of AESO including C=O, –OH, and epoxy groups. This was further evidenced by a benign interfacial adhesion between MCC and AESO resins as revealed by scanning electron microscope (SEM) analysis. The incorporation of MCC into AESO resins significantly increased the density, hardness, flexural strength, and flexural modulus of the MCC/AESO composites, indicative of a significant reinforcing effect of MCC on AESO resins. The composite with 30 wt % MCC obtained the highest physical and mechanical properties due to the good dispersion and interfacial interaction between MCC and AESO matrix; the density, hardness, flexural strength, and flexural modulus of the composite were 15.7%, 25.0%, 57.2%, and 129.7% higher than those of pure AESO resin, respectively. However, the water resistance at room temperature and 100 °C of the composites were dramatically decreased due to the inherent hydrophilicity of MCC. Full article

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Open AccessArticle

A Concise Synthesis of Three Branches Derived from Polysaccharide RN1 and Anti-Pancreatic Cancer Activity Study

by Deqin Cai, Yanli Yao, Yubo Tang, Zheng Wang, Wei Shi, Wei Huang and Kan Ding

Polymers 2017, 9(10), 536; https://doi.org/10.3390/polym9100536 - 21 Oct 2017

Cited by 5 | Viewed by 5327

Abstract

RN1, a polysaccharide from flowers of Panax pseudo-ginsieng Wall. Var. notoginseng (Burkill) Hoo & Tseng, is a potential multi-targeting drug candidate for pancreatic cancer treatment. However, the active targeting domain of RN1 is still unknown. Herein, three RN1 derived branches were synthesized via [...] Read more.

RN1, a polysaccharide from flowers of Panax pseudo-ginsieng Wall. Var. notoginseng (Burkill) Hoo & Tseng, is a potential multi-targeting drug candidate for pancreatic cancer treatment. However, the active targeting domain of RN1 is still unknown. Herein, three RN1 derived branches were synthesized via [3+2] or [2+2] strategies, efficiently. Two pentasaccharides, 18 and 27, showed similar inhibition effect on pancreatic cancer BxPC-3 cells to that of RN1 at same concentration. Interestingly, tetrasaccharide 21 potently inhibited gemcitabineresistant cell line Panc-1 at high concentration. These suggest that the branches of RN1 might be the active targeting domain and tetrasaccharide 21 might be a potential leading compound for pancreatic cancer with gemcitabine resistance. Full article

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Open AccessCommunication

Evaluation of Chitosan and Cellulosic Polymers as Binding Adsorbent Materials to Prevent Aflatoxin B1, Fumonisin B1, Ochratoxin, Trichothecene, Deoxynivalenol, and Zearalenone Mycotoxicoses Through an In Vitro Gastrointestinal Model for Poultry

by Bruno Solís-Cruz, Daniel Hernández-Patlán, Eric Beyssac, Juan D. Latorre, Xochitl Hernandez-Velasco, Ruben Merino-Guzman, Guillermo Tellez and Raquel López-Arellano

Polymers 2017, 9(10), 529; https://doi.org/10.3390/polym9100529 - 19 Oct 2017

Cited by 45 | Viewed by 8429

Abstract

Mycotoxins are secondary toxic metabolites that are produced by fungi representing threats to human and animal health. The objective of this study was to evaluate the adsorption capacity of Chitosan (CHI), and three cellulosic polymers (HPMC, CMC, and MCC), on six mycotoxins (AFB [...] Read more.

Mycotoxins are secondary toxic metabolites that are produced by fungi representing threats to human and animal health. The objective of this study was to evaluate the adsorption capacity of Chitosan (CHI), and three cellulosic polymers (HPMC, CMC, and MCC), on six mycotoxins (AFB₁; FUB₁; OTA; T-2; DON; and, ZEA) using an in vitro digestive model for poultry. The adsorbent capacity of the materials in the supernatant of each compartment was evaluated by a non-competitive chemiluminescent assay. Control groups with no adsorbent material had an adsorption value of 0.00% against all six mycotoxins that were evaluated. All four materials tested showed significant (p < 0.05) binding activity against all of the mycotoxins when compared with the control non-treated group. However HPMC, CMC, and MCC showed better adsorbent capacity when compared with CHI. Full article

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Open AccessArticle

Facile Cellulose Dissolution and Characterization in the Newly Synthesized 1,3-Diallyl-2-ethylimidazolium Acetate Ionic Liquid

by Hui Zhang, Yaoguang Xu, Yuqi Li, Zexiang Lu, Shilin Cao, Mizi Fan, Liulian Huang and Lihui Chen

Polymers 2017, 9(10), 526; https://doi.org/10.3390/polym9100526 - 18 Oct 2017

Cited by 35 | Viewed by 8038

Abstract

A facile cellulose solvent 1,3-diallyl-2-ethylimidazolium acetate ([AAeim][OAc]) with high electrical conductivity has been designed and synthesized for the first time, via a quaternization reaction and ion exchange method. The dissolution characteristics of cellulose in this solvent were studied in detail. Meanwhile, the co-solvent [...] Read more.

A facile cellulose solvent 1,3-diallyl-2-ethylimidazolium acetate ([AAeim][OAc]) with high electrical conductivity has been designed and synthesized for the first time, via a quaternization reaction and ion exchange method. The dissolution characteristics of cellulose in this solvent were studied in detail. Meanwhile, the co-solvent system was designed by adding an aprotic polar solvent dimethyl sulfoxide (DMSO) in [AAeim][OAc]. The effects of temperature and the mass ratio of DMSO to [AAeim][OAc] on the solubility of cellulose were studied. Furthermore, the effects of regeneration on the molecular structure and thermal stability of cellulose were determined by Fourier transform infrared spectroscopy (FT-IR), thermal gravity analysis (TGA) and X-ray diffraction (XRD). The findings revealed that the synthesized ionic liquid (IL) has a relatively low viscosity, high conductivity and a good dissolving capacity for bamboo dissolving pulp cellulose (Degree of Polymerization: DP = 650). The macromolecular chain of the cellulose is less damaged during the dissolution and regeneration process. Due to the increased number of “free” anions [OAc]⁻and cations [AAeim]⁺, the addition of DMSO can significantly increase the solubility of the cellulose up to 12 wt % at the mass ratio of 3:1, indicating that the synthesized IL has a potential application in the electrospinning field. Full article

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Open AccessArticle

Evaluation of Thermal and Thermomechanical Behaviour of Bio-Based Polyamide 11 Based Composites Reinforced with Lignocellulosic Fibres

by Helena Oliver-Ortega, José Alberto Méndez, Pere Mutjé, Quim Tarrés, Francesc Xavier Espinach and Mònica Ardanuy

Polymers 2017, 9(10), 522; https://doi.org/10.3390/polym9100522 - 18 Oct 2017

Cited by 32 | Viewed by 7375

Abstract

In this work, polyamide 11 (PA11) and stone ground wood fibres (SGW) were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of [...] Read more.

In this work, polyamide 11 (PA11) and stone ground wood fibres (SGW) were used, as an alternative to non-bio-based polymer matrices and reinforcements, to obtain short fibre reinforced composites. The impact of the reinforcement on the thermal degradation, thermal transitions and microstructure of PA11-based composites were studied. Natural fibres have lower degradation temperatures than PA11, thus, composites showed lower onset degradation temperatures than PA11, as well. The thermal transition and the semi-crystalline structure of the composites were similar to PA11. On the other hand, when SGW was submitted to an annealing treatment, the composites prepared with these fibres increased its crystallinity, with increasing fibre contents, compared to PA11. The differences between the glass transition temperatures of annealed and untreated composites decreased with the fibre contents. Thus, the fibres had a higher impact in the composites mechanical behaviour than on the mobility of the amorphous phase. The crystalline structure of PA11 and PA11-SGW composites, after annealing, was transformed to α’ more stable phase, without any negative impact on the properties of the fibres. Full article

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Open AccessArticle

Fabrication of Al₂O₃ Nano-Structure Functional Film on a Cellulose Insulation Polymer Surface and Its Space Charge Suppression Effect

by Jian Hao, Yanqing Li, Ruijin Liao, Guoyong Liu, Qiang Liao and Chao Tang

Polymers 2017, 9(10), 502; https://doi.org/10.3390/polym9100502 - 12 Oct 2017

Cited by 36 | Viewed by 6551

Abstract

Cellulose insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in [...] Read more.

Cellulose insulation polymer (paper/pressboard) has been widely used in high voltage direct current (HVDC) transformers. One of the most challenging issues in the insulation material used for HVDC equipment is the space charge accumulation. Effective ways to suppress the space charge injection/accumulation in insulation material is currently a popular research topic. In this study, an aluminium oxide functional film was deposited on a cellulose insulation pressboard surface using reactive radio frequency (RF) magnetron sputtering. The sputtered thin film was characterized by the scanning electron microscopy/energy dispersive spectrometer (SEM/EDS), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The influence of the deposited functional film on the dielectric properties and the space charge injection/accumulation behaviour was investigated. A preliminary exploration of the space charge suppression effect is discussed. SEM/EDS, XPS, and XRD results show that the nano-structured Al₂O₃ film with amorphous phase was successfully fabricated onto the fibre surface. The cellulose insulation pressboard surface sputtered by Al₂O₃ film has lower permittivity, conductivity, and dissipation factor values in the lower frequency (<10³ Hz) region. The oil-impregnated sputtered pressboard presents an apparent space-charge suppression effect. Compared with the pressboard sputtered with Al₂O₃ film for 90 min, the pressboard sputtered with Al₂O₃ film for 60 min had a better space charge suppression effect. Ultra-small Al₂O₃ particles (<10 nm) grew on the surface of the larger nanoparticles. The nano-structured Al₂O₃ film sputtered on the fibre surface could act as a functional barrier layer for suppression of the charge injection and accumulation. This study offers a new perspective in favour of the application of insulation pressboard with a nano-structured function surface against space charge injection/accumulation in HVDC equipment. Full article

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Open AccessArticle

Isolation and Characterization of Cellulose from Different Fruit and Vegetable Pomaces

by Monika Szymańska-Chargot, Monika Chylińska, Karolina Gdula, Arkadiusz Kozioł and Artur Zdunek

Polymers 2017, 9(10), 495; https://doi.org/10.3390/polym9100495 - 9 Oct 2017

Cited by 223 | Viewed by 18293

Abstract

A new fractionation process was developed to achieve valorization of fruit and vegetable pomaces. The importance of the residues from fruits and vegetables is still growing; therefore; the study presents the novel route of a fractioning process for the conversion of agro-industrial biomasses, [...] Read more.

A new fractionation process was developed to achieve valorization of fruit and vegetable pomaces. The importance of the residues from fruits and vegetables is still growing; therefore; the study presents the novel route of a fractioning process for the conversion of agro-industrial biomasses, such as pomaces, into useful feedstocks with potential application in the fields of fuels, chemicals, and polymers. Hence, the biorefinery process is expected to convert them into various by-products offering a great diversity of low-cost materials. The final product of the process is the cellulose of the biofuel importance. The study presents the novel route of the fractioning process for the conversion of agro-industrial biomasses, such as pomaces, into useful feedstocks with a potential application in the fields of fuels, chemicals, and polymers. Therefore the aim of this paper was to present the novel route of the pomaces fraction and the characterization of residuals. Pomaces from apple, cucumber, carrot, and tomato were treated sequentially with water, acidic solution, alkali solution, and oxidative reagent in order to obtain fractions reach in sugars, pectic polysaccharides, hemicellulose, cellulose, and lignin. Pomaces were characterized by dry matter content, neutral detergent solubles, hemicellulose, cellulose, and lignin. Obtained fractions were characterized by the content of pectins expressed as galacturonic acid equivalent and hemicelluloses expressed as a xyloglucan equivalent. The last fraction and residue was cellulose characterized by crystallinity degree by X-ray diffractometer (XRD), microfibril diameter by atomic force microscope (AFM), and overall morphology by scanning electron microscope (SEM). The hemicelluloses content was similar in all pomaces. Moreover, all the materials were characterized by the high pectins level in extracts evaluated as galacturonic acid content. The lignins content compared with other plant biomasses was on a very low level. The cellulose fraction was the highest in cucumber pomace. The cellulose fraction was characterized by crystallinity degree, microfibril diameter, and overall morphology. Isolated cellulose had a very fine structure with relatively high crystalline index but small crystallites. Full article

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Open AccessArticle

Imidazole, a New Tunable Reagent for Producing Nanocellulose, Part I: Xylan-Coated CNCs and CNFs

by Jia Mao, Hatem Abushammala, Hubert Hettegger, Thomas Rosenau and Marie-Pierre Laborie

Polymers 2017, 9(10), 473; https://doi.org/10.3390/polym9100473 - 27 Sep 2017

Cited by 20 | Viewed by 5796

Abstract

Imidazole is reported to be an effective reactant for the production of nanocellulose from hardwood pulp. The morphologies and surface properties of the nanocellulose can be simply tailored according to the water content in the imidazole system: with pure imidazole, cellulose nanofibrils (CNFs) [...] Read more.

Imidazole is reported to be an effective reactant for the production of nanocellulose from hardwood pulp. The morphologies and surface properties of the nanocellulose can be simply tailored according to the water content in the imidazole system: with pure imidazole, cellulose nanofibrils (CNFs) in a yield of 10 wt % can be produced. With 25 wt % of water in imidazole, cellulose nanocrystals (CNCs) are obtained in 20 wt % yield. Both nanocelluloses exhibit crystallinity indices in the order of 70%. Interestingly, they retain the original xylan from the pulp with ca. 9–10 wt % of residual xylan content. Full article

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Open AccessArticle

Physico-Chemical Properties of Soybean Meal-Based Adhesives Reinforced by Ethylene Glycol Diglycidyl Ether and Modified Nanocrystalline Cellulose

by Xiaona Li, Mingsong Chen, Jizhi Zhang, Qiang Gao, Shifeng Zhang and Jianzhang Li

Polymers 2017, 9(9), 463; https://doi.org/10.3390/polym9090463 - 20 Sep 2017

Cited by 28 | Viewed by 9643

Abstract

An eco-friendly soybean meal-based adhesive (SM adhesive) was developed by incorporating ethylene glycol diglycidyl ether (EGDE) and nanocrystalline cellulose (NCC). In order to introduce epoxy groups, NCC was modified by KH560 (denoted as MNCC). The functional groups, thermal stability, and cross section of [...] Read more.

An eco-friendly soybean meal-based adhesive (SM adhesive) was developed by incorporating ethylene glycol diglycidyl ether (EGDE) and nanocrystalline cellulose (NCC). In order to introduce epoxy groups, NCC was modified by KH560 (denoted as MNCC). The functional groups, thermal stability, and cross section of the resultant adhesive were characterized. Three-ply plywood was fabricated to measure the dry and wet shear strength of the adhesive. The experimental results showed that the epoxy groups on MNCC reacted with the carboxyl group of SM protein molecules, forming a crosslinking network and a ductile adhesive layer. As a result, compared with the SM adhesive modified by EGDE, the thermal stability of the adhesive with MNCC was improved and the wet shear strength was increased to 1.08 MPa. Full article

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Open AccessArticle

Bioconversion of Waste Fiber Sludge to Bacterial Nanocellulose and Use for Reinforcement of CTMP Paper Sheets

by Genqiang Chen, Guochao Wu, Björn Alriksson, Wei Wang, Feng F. Hong and Leif J. Jönsson

Polymers 2017, 9(9), 458; https://doi.org/10.3390/polym9090458 - 18 Sep 2017

Cited by 31 | Viewed by 8523

Abstract

Utilization of bacterial nanocellulose (BNC) for large-scale applications is restricted by low productivity in static cultures and by the high cost of the medium. Fiber sludge, a waste stream from pulp and paper mills, was enzymatically hydrolyzed to sugar, which was used for [...] Read more.

Utilization of bacterial nanocellulose (BNC) for large-scale applications is restricted by low productivity in static cultures and by the high cost of the medium. Fiber sludge, a waste stream from pulp and paper mills, was enzymatically hydrolyzed to sugar, which was used for the production of BNC by the submerged cultivation of Komagataeibacter xylinus. Compared with a synthetic glucose-based medium, the productivity of purified BNC from the fiber sludge hydrolysate using shake-flasks was enhanced from 0.11 to 0.17 g/(L × d), although the average viscometric degree of polymerization (DP_v) decreased from 6760 to 6050. The cultivation conditions used in stirred-tank reactors (STRs), including the stirring speed, the airflow, and the pH, were also investigated. Using STRs, the BNC productivity in fiber-sludge medium was increased to 0.32 g/(L × d) and the DP_v was increased to 6650. BNC produced from the fiber sludge hydrolysate was used as an additive in papermaking based on the chemithermomechanical pulp (CTMP) of birch. The introduction of BNC resulted in a significant enhancement of the mechanical strength of the paper sheets. With 10% (w/w) BNC in the CTMP/BNC mixture, the tear resistance was enhanced by 140%. SEM images showed that the BNC cross-linked and covered the surface of the CTMP fibers, resulting in enhanced mechanical strength. Full article

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Open AccessCommunication

Multilayered Films Produced by Layer-by-Layer Assembly of Chitosan and Alginate as a Potential Platform for the Formation of Human Adipose-Derived Stem Cell aggregates

by Javad Hatami, Sandra G. Silva, Mariana B. Oliveira, Rui R. Costa, Rui L. Reis and João F. Mano

Polymers 2017, 9(9), 440; https://doi.org/10.3390/polym9090440 - 13 Sep 2017

Cited by 20 | Viewed by 6553

Abstract

The construction of multilayered films with tunable properties could offer new routes to produce biomaterials as a platform for 3D cell cultivation. In this study, multilayered films produced with five bilayers of chitosan and alginate (CHT/ALG) were built using water-soluble modified mesyl and [...] Read more.

The construction of multilayered films with tunable properties could offer new routes to produce biomaterials as a platform for 3D cell cultivation. In this study, multilayered films produced with five bilayers of chitosan and alginate (CHT/ALG) were built using water-soluble modified mesyl and tosyl–CHT via layer-by-layer (LbL) self-assembly. NMR results demonstrated the presences of mesyl (2.83 ppm) and tosyl groups (2.39, 7.37 and 7.70 ppm) in the chemical structure of modified chitosans. The buildup of multilayered films was monitored by quartz-crystal-microbalance (QCM-D) and film thickness was estimated using the Voigt-based viscoelastic model. QCM-D results demonstrated that CHT/ALG films constructed using mesyl or tosyl modifications (mCHT/ALG) were significantly thinner in comparison to the CHT/ALG films constructed with unmodified chitosan (p < 0.05). Adhesion analysis demonstrated that human adipose stem cells (hASCs) did not adhere to the mCHT/ALG multilayered films and formed aggregates with sizes between ca. 100–200 µm. In vitro studies on cell metabolic activity and live/dead staining suggested that mCHT/ALG multilayered films are nontoxic toward hACSs. Multilayered films produced via LbL assembly of ALG and off-the-shelf, water-soluble modified chitosans could be used as a scaffold for the 3D aggregates formation of hASCs in vitro. Full article

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Open AccessArticle

Simple Green Route to Performance Improvement of Fully Bio-Based Linseed Oil Coating Using Nanofibrillated Cellulose

by Stefan Veigel, Eva-Marieke Lems, Gerhard Grüll, Christian Hansmann, Thomas Rosenau, Tanja Zimmermann and Wolfgang Gindl-Altmutter

Polymers 2017, 9(9), 425; https://doi.org/10.3390/polym9090425 - 7 Sep 2017

Cited by 17 | Viewed by 6098

Abstract

Due to their bio-based character, oil-based coatings become more and more prevalent in wood surface finishing. These coatings impart appealing optical and haptic properties to the wood surface, but lack sufficient protection against water and mechanical influences. The present study reports a simple [...] Read more.

Due to their bio-based character, oil-based coatings become more and more prevalent in wood surface finishing. These coatings impart appealing optical and haptic properties to the wood surface, but lack sufficient protection against water and mechanical influences. The present study reports a simple green route to improve the performance of linseed oil coating by the addition of nanofibrillated cellulose (NFC). In order to achieve surface chemical compatibility with linseed oil, NFC was chemically modified with acetic anhydride and (2-dodecen-1-yl)succinic anhydride, respectively, using propylene carbonate as a solvent. NFC/linseed oil formulations were prepared and applied to wood substrates. The wear resistance of oil-coated wood surfaces was assessed by a newly developed test combining abrasive loading with subsequent contact angle measurement. As revealed by infrared and nuclear magnetic resonance (NMR) spectroscopy, as well as X-ray diffraction (XRD), NFC has been successfully modified without significantly affecting the structure of cellulose. In abrasion tests, all NFC-modified oil coatings performed better than the original oil. Interestingly, NFC only suspended in propylene carbonate, i.e., without chemical modification, had the strongest improvement effect on the coating’s wear resistance. This was primarily attributed to the loose network structure of this NFC variant which effectively prevents the oil from penetration into the wood surface, thus forming a protective NFC/oil composite layer on the wood surface. Full article

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Open AccessArticle

The Influence of Cellulose Nanocrystals on the Hydration and Flexural Strength of Portland Cement Pastes

by Tengfei Fu, Francisco Montes, Prannoy Suraneni, Jeffrey Youngblood and Jason Weiss

Polymers 2017, 9(9), 424; https://doi.org/10.3390/polym9090424 - 7 Sep 2017

Cited by 74 | Viewed by 7531

Abstract

Recent research has shown that cellulose nanocrystals (CNCs) can be used at low dosage levels (approximately 0.2% by volume of cement) to increase the extent of hydration and to improve the flexural strength of cement pastes. However, the previous work was based on [...] Read more.

Recent research has shown that cellulose nanocrystals (CNCs) can be used at low dosage levels (approximately 0.2% by volume of cement) to increase the extent of hydration and to improve the flexural strength of cement pastes. However, the previous work was based on using a CNC made from a single source material and processing technique and was performed using only Type V cement. This work examines the influence of various raw material sources and processing techniques used to make the CNCs. In total, nine different CNCs were investigated with pastes made using Type I/II and Type V cements. Isothermal calorimetry (IC), thermogravimetric analysis (TGA) and ball-on-three-ball (B3B) flexural strength testing were used to quantify the performance of CNC-cement composites. IC and TGA results showed that CNCs increased the degree of hydration in all systems. IC results showed that the increase in total heat release was greater in the Type V than in the Type I/II cement paste systems. B3B flexural testing indicated an increase in flexural strength of up to 20% with both Type I/II and Type V systems. These results also showed that the performance of CNC-cement composites can be affected by the source and manufacturing process used to make the CNC. Full article

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Open AccessArticle

Cellulose Acetate Phthalate and Antiretroviral Nanoparticle Fabrications for HIV Pre-Exposure Prophylaxis

by Subhra Mandal, Karl Khandalavala, Rachel Pham, Patrick Bruck, Marisa Varghese, Andrew Kochvar, Ashley Monaco, Pavan Kumar Prathipati, Christopher Destache and Annemarie Shibata

Polymers 2017, 9(9), 423; https://doi.org/10.3390/polym9090423 - 7 Sep 2017

Cited by 19 | Viewed by 7146

Abstract

To adequately reduce new HIV infections, development of highly effective pre-exposure prophylaxis (PrEP) against HIV infection in women is necessary. Cellulose acetate phthalate (CAP) is a pH sensitive polymer with HIV-1 entry inhibitory properties. Dolutegravir (DTG) is an integrase strand transfer inhibitor with [...] Read more.

To adequately reduce new HIV infections, development of highly effective pre-exposure prophylaxis (PrEP) against HIV infection in women is necessary. Cellulose acetate phthalate (CAP) is a pH sensitive polymer with HIV-1 entry inhibitory properties. Dolutegravir (DTG) is an integrase strand transfer inhibitor with potent antiretroviral activity. DTG delivered in combination with CAP may significantly improve current PrEP against HIV. In the present study, the development of DTG-loaded CAP nanoparticles incorporated in thermosensitive (TMS) gel at vaginal pH 4.2 and seminal fluid pH 7.4 is presented as proof-of-concept for improved PrEP. Water–oil–in–water homogenization was used to fabricate DTG-loaded CAP nanoparticles (DTG–CAP–NPs). Size, polydispersity, and morphological analyses illustrate that DTG–CAP–NPs were smooth and spherical, ≤200 nm in size, and monodispersed with a polydispersity index PDI ≤ 0.2. The drug encapsulation (EE%) and release profile of DTG–CAP–NPs was determined by HPLC analysis. The EE% of DTG in DTG–CAP–NPs was evaluated to be ~70%. The thermal sensitivity of the TMS gel was optimized and the pH dependency was evaluated by rheological analysis. DTG release studies in TMS gel revealed that DTG–CAP–NPs were stable in TMS gel at pH 4.2 while DTG–CAP–NPs in TMS gel at pH 7.4 rapidly release DTG (≥80% release within 1 h). Cytotoxicity studies using vaginal cell lines revealed that DTG–CAP–NPs were relatively non-cytotoxic at concentration <1 µg/mL. Confocal microscopic studies illustrate that ≥98% cells retained DTG–CAP–NPs intracellularly over seven days. Antiretroviral drug loaded nanocellulose fabrications in TMS gel delivered intravaginally may enhance both microbicidal and antiretroviral drug efficacy and may present a novel option for female PrEP against HIV. Full article

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Open AccessArticle

TEMPO-Oxidized Cellulose with High Degree of Oxidation

by Zuwu Tang, Wenyan Li, Xinxing Lin, He Xiao, Qingxian Miao, Liulian Huang, Lihui Chen and Hui Wu

Polymers 2017, 9(9), 421; https://doi.org/10.3390/polym9090421 - 6 Sep 2017

Cited by 142 | Viewed by 18054

Abstract

In this paper, water-soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose with a high degree of oxidation was prepared by a two-step process using bamboo dissolving pulp. The first step was to destroy the cellulose crystal I by NaOH/urea solution to obtain cellulose powder with decreased crystallinity. [...] Read more.

In this paper, water-soluble 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose with a high degree of oxidation was prepared by a two-step process using bamboo dissolving pulp. The first step was to destroy the cellulose crystal I by NaOH/urea solution to obtain cellulose powder with decreased crystallinity. The second step was to oxidize the cellulose powder by TEMPO oxidation. The TEMPO-oxidized cellulose was analyzed by Fourier transform infrared spectroscopy (FTIR), conductimetry, X-ray diffraction (XRD), fiber analyzer, and transmission electron microscopy (TEM). FTIR showed that the hydroxymethyl groups in cellulose chains were converted into carboxyl groups. The degree of oxidation measured by conductimetry titration was as high as 91.0%. The TEMPO-oxidized cellulose was soluble in water for valuable polyelectrolytes and intermediates. Full article

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Open AccessArticle

Effect of Urea and Borate Plasticizers on Rheological Response of Corn Starch

by Khalid A. Ibrahim, Muhammad Y. Naz, Shaharin A. Sulaiman, Abdul Ghaffar, Yasir Jamil and Nasser M. Abdel-Salam

Polymers 2017, 9(9), 361; https://doi.org/10.3390/polym9090361 - 6 Sep 2017

Cited by 4 | Viewed by 8309

Abstract

Although starch based materials have an array of fascinating industrial applications, the native starches do not show good mechanical strength, thermal stability, and rheological properties for their use in the mainstream processing industry. For example, the use of starches for producing controlled release [...] Read more.

Although starch based materials have an array of fascinating industrial applications, the native starches do not show good mechanical strength, thermal stability, and rheological properties for their use in the mainstream processing industry. For example, the use of starches for producing controlled release fertilizers is a new research endeavor with detailed knowledge still to come. The thermal processing of native starches with water as a plasticizer results in poor physical and pasting properties of the final product. Therefore in this study, corn starch was thermally processed with urea and borate in a water medium. The pure starch (PS), starch-urea (SU), starch-borate (SB), and starch-urea-borate (SUB) samples were prepared and characterized for their rheological traits. The PS sample exhibited a peak viscosity of 299 cP after 17 min of thermal processing. Further heating of the suspension caused a decrease in viscosity of 38 points due to thermal cracking of the starch granules. A similar trend was depicted in the viscosity measurements of SU, SB, and SUB adhesives. However, the viscosity of these samples remained slightly higher than that for PS. Also, the reduction in viscosity after the peak value was not as notable as for PS. The modified starch behaved like a gel and its storage modulus was significantly higher than the loss modulus. The lower magnitudes of storage and loss moduli revealed that the modified starch was in the form of a weak gel and not a solid. The PS is more fluid in nature with dominating loss modulus at lower angular frequencies. Full article

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Open AccessArticle

The Effect of Moisture on Cellulose Nanocrystals Intended as a High Gas Barrier Coating on Flexible Packaging Materials

by Ghislain Fotie, Riccardo Rampazzo, Marco Aldo Ortenzi, Stefano Checchia, Dimitrios Fessas and Luciano Piergiovanni

Polymers 2017, 9(9), 415; https://doi.org/10.3390/polym9090415 - 5 Sep 2017

Cited by 37 | Viewed by 8066

Abstract

Cellulose nanocrystals (CNCs) exhibit outstanding gas barrier properties, which supports their use as a biobased and biodegradable barrier coating on flexible food packaging materials. As highly hydrophilic biopolymers, however, CNCs have a strong sensitivity to water that can be detrimental to applications with [...] Read more.

Cellulose nanocrystals (CNCs) exhibit outstanding gas barrier properties, which supports their use as a biobased and biodegradable barrier coating on flexible food packaging materials. As highly hydrophilic biopolymers, however, CNCs have a strong sensitivity to water that can be detrimental to applications with fresh foods and in moist conditions due to the loss of barrier properties. In this work, the oxygen and water vapor permeability of polyethylene terephthalate (PET) films coated with CNCs obtained from cotton linters were measured at varying levels of relative humidity, both in adsorption and desorption, and from these data, the diffusion and solubility coefficients were estimated. Therefore, the characterization of CNCs was aimed at understanding the fundamentals of the water-CNCs interaction and proposing counteractions. The CNCs’ moisture absorption and desorption isotherms at 25 °C were collected in the range of relative humidity 0–97% using different techniques and analyzed through GAB (Guggenheim-Anderson-de Boer) and Oswin models. The effects of moisture on the water status, following the freezable water index, and on the crystal structure of CNCs were investigated by Differential Scanning Calorimetry and by X-ray Powder Diffraction, respectively. These findings point to the opportunity of coupling CNCs with hydrophobic layers in order to boost their capabilities as barrier packaging materials. Full article

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Open AccessArticle

Triethyl Citrate (TEC) as a Dispersing Aid in Polylactic Acid/Chitin Nanocomposites Prepared via Liquid-Assisted Extrusion

by Natalia Herrera, Anshu Anjali Singh, Asier M. Salaberria, Jalel Labidi, Aji P. Mathew and Kristiina Oksman

Polymers 2017, 9(9), 406; https://doi.org/10.3390/polym9090406 - 31 Aug 2017

Cited by 41 | Viewed by 9797

Abstract

The production of fully bio-based and biodegradable nanocomposites has gained attention during recent years due to environmental reasons; however, the production of these nanocomposites on the large-scale is challenging. Polylactic acid/chitin nanocrystal (PLA/ChNC) nanocomposites with triethyl citrate (TEC) at varied concentrations (2.5, 5.0, [...] Read more.

The production of fully bio-based and biodegradable nanocomposites has gained attention during recent years due to environmental reasons; however, the production of these nanocomposites on the large-scale is challenging. Polylactic acid/chitin nanocrystal (PLA/ChNC) nanocomposites with triethyl citrate (TEC) at varied concentrations (2.5, 5.0, and 7.5 wt %) were prepared using liquid-assisted extrusion. The goal was to find the minimum amount of the TEC plasticizer needed to enhance the ChNC dispersion. The microscopy study showed that the dispersion and distribution of the ChNC into PLA improved with the increasing TEC content. Hence, the nanocomposite with the highest plasticizer content (7.5 wt %) showed the highest optical transparency and improved thermal and mechanical properties compared with its counterpart without the ChNC. Gel permeation chromatography confirmed that the water and ethanol used during the extrusion did not degrade PLA. Further, Fourier transform infrared spectroscopy showed improved interaction between PLA and ChNC through hydrogen bonding when TEC was added. All results confirmed that the plasticizer plays an important role as a dispersing aid in the processing of PLA/ChNC nanocomposites. Full article

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Open AccessArticle

CO₂-Responsive Graft Modified Chitosan for Heavy Metal (Nickel) Recovery

by Evan A. W. Madill, Omar Garcia-Valdez, Pascale Champagne and Michael F. Cunningham

Polymers 2017, 9(9), 394; https://doi.org/10.3390/polym9090394 - 26 Aug 2017

Cited by 29 | Viewed by 7002

Abstract

Chitosan was chemically functionalized with poly(diethylaminoethyl methacrylate) (PDEAEMA) using a grafting to approach to produce a CO₂-responsive material for adsorbing metals from wastewater streams. A need for improved economical and greener approaches to recover heavy metals from wastewater streams exists due [...] Read more.

Chitosan was chemically functionalized with poly(diethylaminoethyl methacrylate) (PDEAEMA) using a grafting to approach to produce a CO₂-responsive material for adsorbing metals from wastewater streams. A need for improved economical and greener approaches to recover heavy metals from wastewater streams exists due to increasing resource scarcity. Chitosan is currently used as an adsorbent for heavy metals but suffers from some properties that can be disadvantageous to its effectiveness; it is difficult to effectively disperse in water (which limits available surface area) and to regenerate. We set out to improve its effectiveness by grafting CO₂-responsive tertiary amine containing polymers onto the chitosan backbone, with the goals of preparing and assessing a new type of adsorbent based on a novel concept; using carbon dioxide switchable polymers to enhance the performance of chitosan. PDEAEMA chains prepared by nitroxide-mediated polymerization were grafted onto chitosan functionalized with glycidyl methacrylate. In carbonated water, the grafted chitosan displayed improved dispersibility and exhibited a Ni(II) adsorption capacity higher than several other chemically functionalized chitosan variants reported in the literature with the regenerated material having a higher capacity than all physical and chemical derivatives reported in the literature. The results of this study validate the continued development of this material for applications in heavy metal removal and recovery from wastewater streams. Full article

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Open AccessArticle

Dry-Spun Neat Cellulose Nanofibril Filaments: Influence of Drying Temperature and Nanofibril Structure on Filament Properties

by Shokoofeh Ghasemi, Mehdi Tajvidi, Douglas W. Bousfield, Douglas J. Gardner and William M. Gramlich

Polymers 2017, 9(9), 392; https://doi.org/10.3390/polym9090392 - 25 Aug 2017

Cited by 40 | Viewed by 6787

Abstract

Cellulose nanofibrils (CNF) were spun into filaments directly from suspension without the aid of solvents. The influence of starting material properties and drying temperature on the properties of filaments produced from three different CNF suspensions was studied. Refiner-produced CNF was ground using a [...] Read more.

Cellulose nanofibrils (CNF) were spun into filaments directly from suspension without the aid of solvents. The influence of starting material properties and drying temperature on the properties of filaments produced from three different CNF suspensions was studied. Refiner-produced CNF was ground using a microgrinder at grinding times of 50 and 100 minutes. Filament spinning was performed using a syringe pump-heat gun setting at three drying temperatures of 210 °C, 320 °C and 430 °C. The structure of starting CNF materials was first evaluated using a combination of optical and atomic force microscopy (AFM) techniques. Surface free energy analysis and attenuated total reflectance—Fourier transform infrared spectroscopy (ATR–FTIR) were used to study changes in hydrophobicity due to grinding. Morphology of the filaments was studied using SEM micrographs. The influence of different drying temperatures and grinding times on mechanical properties of the CNF filaments were further investigated through tensile tests and results were compared using statistical analysis .It was observed that drying temperature did not significantly influence the tensile properties of the filaments while cellulose nanofiber suspension type (grinding time) had a significant influence and improved mechanical properties. FTIR results confirmed an increase in crystallinity index and decrease in hydroxyl group availability due to grinding. Full article

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Open AccessArticle

Use of Bacterial Cellulose and Crosslinked Cellulose Nanofibers Membranes for Removal of Oil from Oil-in-Water Emulsions

by Enas Hassan, Mohammad Hassan, Ragab Abou-zeid, Linn Berglund and Kristiina Oksman

Polymers 2017, 9(9), 388; https://doi.org/10.3390/polym9090388 - 23 Aug 2017

Cited by 48 | Viewed by 8831

Abstract

Abstract: Never-dried bacterial cellulose (BC) and crosslinked cellulose nanofibers (CNF) were used for the removal of oil from stabilized and non-stabilized oil-in-water emulsions with droplet sizes less than 1 µm. The CNF membranes were exchanged with isopropyl alcohol before drying. The microscopic [...] Read more.

Abstract: Never-dried bacterial cellulose (BC) and crosslinked cellulose nanofibers (CNF) were used for the removal of oil from stabilized and non-stabilized oil-in-water emulsions with droplet sizes less than 1 µm. The CNF membranes were exchanged with isopropyl alcohol before drying. The microscopic structure of the prepared membranes was evaluated using scanning electron microscopy (SEM); the water flux and the rejection of oil were evaluated using a dead-end filtration cell. BC harvested after different incubation time periods (2 to 10 days) did not show a change in the width of the nanofibers, but only the thickness of the membranes was increased. Pure water flux was not affected as a result of increasing thicknesses of BC membranes harvested after 4–10 days while BC harvested after two days had significantly higher water flux than the others. BC showed a higher flux and efficiency in removing oil from oil emulsions than CNF membranes. Removal of oil by the different membranes from the non-stabilized oil emulsion was more efficient than from the stabilized one. Full article

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Open AccessArticle

Human Mesenchymal Stem Cells Differentiation Regulated by Hydroxyapatite Content within Chitosan-Based Scaffolds under Perfusion Conditions

by Anamarija Rogina, Maja Antunović, Lidija Pribolšan, Katarina Caput Mihalić, Andreja Vukasović, Alan Ivković, Inga Marijanović, Gloria Gallego Ferrer, Marica Ivanković and Hrvoje Ivanković

Polymers 2017, 9(9), 387; https://doi.org/10.3390/polym9090387 - 23 Aug 2017

Cited by 25 | Viewed by 7354

Abstract

The extensive need for hard tissue substituent greatly motivates development of suitable allogeneic grafts for therapeutic recreation. Different calcium phosphate phases have been accepted as scaffold’s components with positive influence on osteoinduction and differentiation of human mesenchymal stem cells, in terms of their [...] Read more.

The extensive need for hard tissue substituent greatly motivates development of suitable allogeneic grafts for therapeutic recreation. Different calcium phosphate phases have been accepted as scaffold’s components with positive influence on osteoinduction and differentiation of human mesenchymal stem cells, in terms of their higher fraction within the graft. Nevertheless, the creation of unlimited nutrients diffusion through newly formed grafts is of great importance. The media flow accomplished by perfusion forces can provide physicochemical, and also, biomechanical stimuli for three-dimensional bone-construct growth. In the present study, the influence of a different scaffold’s composition on the human mesenchymal stem cells (hMSCs) differentiation performed in a U-CUP bioreactor under perfusion conditioning was investigated. The histological and immunohistochemical analysis of cultured bony tissues, and the evaluation of osteogenic genes’ expression indicate that the lower fraction of in situ formed hydroxyapatite in the range of 10–30% within chitosan scaffold could be preferable for bone-construct development. Full article

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Open AccessCommunication

Chitin-Based Anisotropic Nanostructures of Butterfly Wings for Regulating Cells Orientation

by Abdelrahman Elbaz, Jie Lu, Bingbing Gao, Fuyin Zheng, Zhongde Mu, Yuanjin Zhao and Zhongze Gu

Polymers 2017, 9(9), 386; https://doi.org/10.3390/polym9090386 - 23 Aug 2017

Cited by 19 | Viewed by 11028 | Correction

Abstract

In recent years, multiple types of substrates have been applied for regulating cell orientation. Among them, surface topography patterns with grooves or ridges have been widely utilizing for cell culturing. However, this construction is still complicated, low cost-effective and exhibits some technological limitations [...] Read more.

In recent years, multiple types of substrates have been applied for regulating cell orientation. Among them, surface topography patterns with grooves or ridges have been widely utilizing for cell culturing. However, this construction is still complicated, low cost-effective and exhibits some technological limitations with either “top-down” or “bottom-up” approaches. Here, a simple and green method was developed by utilizing butterfly wings (Morpho menelaus, Papilio ulysses telegonus and Ornithoptera croesus lydius) with natural anisotropic nanostructures to generate cell alignment. A two-step chemical treatment was proposed to achieve more hydrophilic butterfly wings preceding cell culturing. Furthermore, calcein acetoxymethyl ester (Calcein-AM) staining and Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay results demonstrated the appropriate viability of NIH-3T3 fibroblast cells on those butterfly wings. Moreover, the cells displayed a high degree of alignment in each specimen of these wings. We anticipate that those originating from natural butterfly wings will pose important applications for tissue engineering. Full article

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Open AccessArticle

Mechanical Properties of Composite Hydrogels of Alginate and Cellulose Nanofibrils

by Olav Aarstad, Ellinor Bævre Heggset, Ina Sander Pedersen, Sindre Hove Bjørnøy, Kristin Syverud and Berit Løkensgard Strand

Polymers 2017, 9(8), 378; https://doi.org/10.3390/polym9080378 - 19 Aug 2017

Cited by 86 | Viewed by 8917

Abstract

Alginate and cellulose nanofibrils (CNF) are attractive materials for tissue engineering and regenerative medicine. CNF gels are generally weaker and more brittle than alginate gels, while alginate gels are elastic and have high rupture strength. Alginate properties depend on their guluronan and mannuronan [...] Read more.

Alginate and cellulose nanofibrils (CNF) are attractive materials for tissue engineering and regenerative medicine. CNF gels are generally weaker and more brittle than alginate gels, while alginate gels are elastic and have high rupture strength. Alginate properties depend on their guluronan and mannuronan content and their sequence pattern and molecular weight. Likewise, CNF exists in various qualities with properties depending on, e.g., morphology and charge density. In this study combinations of three types of alginate with different composition and two types of CNF with different charge and degree of fibrillation have been studied. Assessments of the composite gels revealed that attractive properties like high rupture strength, high compressibility, high gel rigidity at small deformations (Young’s modulus), and low syneresis was obtained compared to the pure gels. The effects varied with relative amounts of CNF and alginate, alginate type, and CNF quality. The largest effects were obtained by combining oxidized CNF with the alginates. Hence, by combining the two biopolymers in composite gels, it is possible to tune the rupture strength, Young’s modulus, syneresis, as well as stability in physiological saline solution, which are all important properties for the use as scaffolds in tissue engineering. Full article

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Open AccessArticle

Bacterial Nanocellulose from Side-Streams of Kombucha Beverages Production: Preparation and Physical-Chemical Properties

by Stefan-Ovidiu Dima, Denis-Mihaela Panaitescu, Csongor Orban, Marius Ghiurea, Sanda-Maria Doncea, Radu Claudiu Fierascu, Cristina Lavinia Nistor, Elvira Alexandrescu, Cristian-Andi Nicolae, Bogdan Trică, Angela Moraru and Florin Oancea

Polymers 2017, 9(8), 374; https://doi.org/10.3390/polym9080374 - 18 Aug 2017

Cited by 111 | Viewed by 17118

Abstract

We focused on preparing cellulose nanofibrils by purification, separation, and mechanical treatment of Kombucha membranes (KM) resulted as secondary product from beverage production by fermentation of tea broth with symbiotic culture of bacteria and yeast (SCOBY). We purified KM using two alkaline solutions, [...] Read more.

We focused on preparing cellulose nanofibrils by purification, separation, and mechanical treatment of Kombucha membranes (KM) resulted as secondary product from beverage production by fermentation of tea broth with symbiotic culture of bacteria and yeast (SCOBY). We purified KM using two alkaline solutions, 1 and 4 M NaOH, which afterwards were subjected to various mechanical treatments. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) were employed to evaluate the purification degree, the size and aspect of cellulose fibrils after each treatment step, the physical-chemical properties of intermediary and final product, and for comparison with micro-crystalline cellulose from wooden sources. We determined that 1 M NaOH solution leads to approx. 85% purification, while a higher concentration assures almost 97% impurities removal. XRD analysis evidenced an increase in crystallinity from 37% to 87% after purification, the characteristic diffractograms of Iα and Iβ cellulose allomorphs, and a further decrease in crystallinity to 46% after microfluidization, fact correlated with a drastically decrease in fibrils’ size. FTIR analysis evidenced the appearance of new chain ends by specific transmission bands at 2941 and 2843cm⁻¹. Full article

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Open AccessArticle

Surface Modification of Poly(lactic acid) Fabrics with Plasma Pretreatment and Chitosan/Siloxane Polyesters Coating for Color Strength Improvement

by Chee-Chan Wang, Li-Huei Lin, Chi-Wu Chen and Yu-Chun Lo

Polymers 2017, 9(8), 371; https://doi.org/10.3390/polym9080371 - 18 Aug 2017

Cited by 20 | Viewed by 5919

Abstract

As people in the 21st century become increasingly environmentally aware, environmentally friendly products have come into focus. As such, environmentally friendly textiles and eco-textiles have become an international trend in research and development. Poly(lactic acid) fiber, which is biodegradable, holds much promise, but [...] Read more.

As people in the 21st century become increasingly environmentally aware, environmentally friendly products have come into focus. As such, environmentally friendly textiles and eco-textiles have become an international trend in research and development. Poly(lactic acid) fiber, which is biodegradable, holds much promise, but it is difficult to deep dye. This study used chitosan, succine anhydride, siloxane, and polyethylene glycol to produce a series of chitosan/siloxane polyesters that have a hydrophilic component (chitosan) and a hydrophobic component (siloxane), and this chitosan/siloxane polyester can be coated on poly(lactic acid) fiber, which we had subjected to Argon plasma treatment to increase their antimicrobial properties and to increase the fibers dyeing efficiency. The study shows that, after the surface plasma treatment, longer PEG chain lengths resulted in higher K/S values. This result suggests that the surface plasma pretreatment and chitosan/siloxane polyesters coating showed that lower ∆E values result in more leveling dyeing of poly(lactic acid) fiber. Full article

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Open AccessArticle

Pulp Fines—Characterization, Sheet Formation, and Comparison to Microfibrillated Cellulose

by Wolfgang Johann Fischer, Melanie Mayr, Stefan Spirk, David Reishofer, Lukas Andreas Jagiello, Romana Schmiedt, Jerome Colson, Armin Zankel and Wolfgang Bauer

Polymers 2017, 9(8), 366; https://doi.org/10.3390/polym9080366 - 17 Aug 2017

Cited by 56 | Viewed by 8171

Abstract

In the pulp and paper industry different types of pulp or fiber fines are generated during the pulping (primary fines, mechanical fines), and/or the refining process (secondary fines). Besides fibers, these cellulosic microparticles are a further component of the paper network. Fines, which [...] Read more.

In the pulp and paper industry different types of pulp or fiber fines are generated during the pulping (primary fines, mechanical fines), and/or the refining process (secondary fines). Besides fibers, these cellulosic microparticles are a further component of the paper network. Fines, which are defined as the fraction of pulp that is able to pass through a mesh screen or a perforated plate having a hole diameter of 76 μm, are known to influence the properties of the final paper product. To better understand the effect and properties of this material, fines have to be separated from the pulp and investigated as an independent material. In the present study, fines are isolated from the pulp fraction by means of a laboratory pressure screen. To allow for further processing, the solids content of the produced fines suspension was increased using dissolved air flotation. Morphological properties of different types of fines and other cellulosic microparticles, such as microfibrillated celluloses (MFC) are determined and compared to each other. Furthermore, handsheets are prepared from these materials and properties, such as apparent density, contact angle, modulus of elasticity, and strain are measured giving similar results for the analyzed types of fines in comparison to the tested MFC grades. The analysis of the properties of fiber fines contributes on the one hand to a better understanding of how these materials influences the final paper products, and on the other hand, helps in identifying other potential applications of this material. Full article

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Open AccessArticle

Development of Synergistic Antimicrobial Coating of p-Aramid Fibers Using Ag Nanoparticles and Glycidyltrimethylammonium Chloride (GTAC) without the Aid of a Cross-Linking Agent

by Chankyu Kang, Dajeong Ahn, Changhyun Roh, Sam Soo Kim and Jaewoong Lee

Polymers 2017, 9(8), 357; https://doi.org/10.3390/polym9080357 - 11 Aug 2017

Cited by 11 | Viewed by 5537

Abstract

Functional p-aramid fibers that can express antimicrobial activity were produced by simple processing of silver nanoparticles (AgNPs), which are well known as antimicrobial agents, by using glycidyltrimethylammonium chloride (GTAC), a quaternary ammonium salt. P-aramid fibers were treated with GTAC by the pad-dry-cure process [...] Read more.

Functional p-aramid fibers that can express antimicrobial activity were produced by simple processing of silver nanoparticles (AgNPs), which are well known as antimicrobial agents, by using glycidyltrimethylammonium chloride (GTAC), a quaternary ammonium salt. P-aramid fibers were treated with GTAC by the pad-dry-cure process and put into an Ag colloid solution for reactions at 40 °C for 90 min to prepare GTAC/AgNPs-treated p-aramid fibers. Through these processes, GTAC was used as a substitute for existing cross-linking agents. The changes in the degree of attachment of AgNPs to the surface of p-aramid fibers were determined using a scanning electron microscope according to parameters such as GTAC concentration, Ag colloid concentration, and reaction temperature. Through this study, the following results were obtained: (i) The tensile strength of AgNPs/GTAC-treated p-aramid fibers was found to be about 80% of that of untreated p-aramid fibers; (ii) Thermogravimetric analysis showed that the thermal stability of p-aramid fibers did not change much after GTAC/AgNPs treatment and (iii) Antimicrobial activity analysis showed that AgNPs/GTAC-treated p-aramid fibers exhibited superior antibacterial properties compared to untreated p-aramid fibers, which may or may not be the effect of GTAC or AgNPs, or both. Full article

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Open AccessArticle

Isolation and Characterization of Cellulose Nanocrystals from Oil Palm Mesocarp Fiber

by Buong Woei Chieng, Syn Huey Lee, Nor Azowa Ibrahim, Yoon Yee Then and Yuet Ying Loo

Polymers 2017, 9(8), 355; https://doi.org/10.3390/polym9080355 - 11 Aug 2017

Cited by 191 | Viewed by 11203

Abstract

The aim was to explore the utilization of oil palm mesocarp fiber (OPMF) as a source for the production of cellulose nanocrystals (CNC). OPMF was first treated with alkali and then bleached before the production of CNC by acid hydrolysis (H₂SO [...] Read more.

The aim was to explore the utilization of oil palm mesocarp fiber (OPMF) as a source for the production of cellulose nanocrystals (CNC). OPMF was first treated with alkali and then bleached before the production of CNC by acid hydrolysis (H₂SO₄). The produced materials were characterized using Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), a scanning electron microscope (SEM) and a transmission electron microscope (TEM). It was proven that acid hydrolysis can increase the crystallinity of bleached OPMF and reduce the dimension of cellulose to nano scale. Changes in the peaks of the FTIR spectrum at 2852 (C-H stretching), 1732 (C=O stretching) and 1234 cm⁻¹ (C-O stretching) indicated that the alkali treatment completely removed hemicelluloses and lignin from the fiber surface. This can be seen from the thermogram obtained from the TGA characterization. Morphological characterization clearly showed the formation of rod-shaped CNCs. The promising results prove that OPMF is a valuable source for the production of CNC. Full article

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Open AccessArticle

Characterization of Type-II Acetylated Cellulose Nanocrystals with Various Degree of Substitution and Its Compatibility in PLA Films

by Feng Dong, Meiling Yan, Chunde Jin and Shujun Li

Polymers 2017, 9(8), 346; https://doi.org/10.3390/polym9080346 - 6 Aug 2017

Cited by 42 | Viewed by 8095

Abstract

In order to decrease the self-agglomeration and improve the hydrophobic properties of type-II acetylated cellulose nanocrystals (ACNC II), various degree of substitution (DS) values of ACNCs were successfully prepared by a single-step method from microcrystalline cellulose with anhydrous phosphoric acid as the solvent, [...] Read more.

In order to decrease the self-agglomeration and improve the hydrophobic properties of type-II acetylated cellulose nanocrystals (ACNC II), various degree of substitution (DS) values of ACNCs were successfully prepared by a single-step method from microcrystalline cellulose with anhydrous phosphoric acid as the solvent, and acetic anhydride as the acetylation reagent, under different reaction temperatures (20–40 °C). To thoroughly investigate the DS values of ACNC II, analyses were performed using Fourier transform infrared spectroscopy (FT-IR), ¹³C cross polarization-magic angle spinning (CP-MAS) nuclear magnetic resonance (NMR), and X-ray photoelectron spectroscopy (XPS). At a reaction temperature of 40°C, the highest DS value was successfully obtained. XRD proved that the crystal structure of ACNC II with various DS values was maintained after acetylation. TEM showed the threadlike shape for ACNC II with various DS values. The ACNC II with various DS values was introduced into a polylactic acid (PLA) matrix to produce PLA/ACNC composite films, which showed improved rheological and thermal properties. This improvement was primarily attributed to good dispersion of the ACNC II, and the interfacial compatibility between ACNC II and the PLA matrix. This study aims to analyze the compatibility of ACNC II with various DS values in the PLA matrix by microstructure, crystallization, and rheological and thermal tests. Full article

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Open AccessArticle

Membranes Based on Cellulose Nanofibers and Activated Carbon for Removal of Escherichia coli Bacteria from Water

by Mohammad Hassan, Ragab Abou-Zeid, Enas Hassan, Linn Berglund, Yvonne Aitomäki and Kristiina Oksman

Polymers 2017, 9(8), 335; https://doi.org/10.3390/polym9080335 - 3 Aug 2017

Cited by 69 | Viewed by 12600

Abstract

Cellulosic nanomaterials are potential candidates in different areas, especially in water treatment. In the current work, palm fruit stalks cellulose nanofibers (CNF), TEMPO-oxidized CNF (OCNF), and activated carbon (AC) were used to make thin film membranes for removal of E. coli bacteria from [...] Read more.

Cellulosic nanomaterials are potential candidates in different areas, especially in water treatment. In the current work, palm fruit stalks cellulose nanofibers (CNF), TEMPO-oxidized CNF (OCNF), and activated carbon (AC) were used to make thin film membranes for removal of E. coli bacteria from water. Two types of layered membranes were produced: a single layer setup of crosslinked CNF and a two-layer setup of AC/OCNF (bottom) and crosslinked CNF (up) on hardened filter paper. The prepared membranes were evaluated regarding their microstructure and layers thickness using scanning electron microscopy (SEM). Water flux and rejection of E. coli bacteria was tested using dead end stirred cells at 1 MPa pressure. Thickness of the cosslinked CNF layer in both types of membranes was about 0.75 micron. The results showed that exchanging water by isopropyl alcohol before drying increased porosity of membranes, and thus resulted in increasing pure water flux and flux of bacteria suspension. The two-layer AC/OCNF/CNF membrane had much higher water flux than the single layer CNF due to higher porosity seen on the surface of the former. Both types of membranes showed high capability of removing E. coli bacteria (rejection ~96–99%) with slightly higher efficiency for the AC/OCNF/CNF membrane than CNF membrane. AC/OCNF/CNF membrane also showed resistance against growth of E. coli and S. aureus bacteria on the upper CNF surface while the single layer CNF membrane did not show resistance against growth of the aforementioned bacteria. Full article

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Open AccessArticle

Nanopaper Properties and Adhesive Performance of Microfibrillated Cellulose from Different (Ligno-)Cellulosic Raw Materials

by Stefan Pinkl, Stefan Veigel, Jérôme Colson and Wolfgang Gindl-Altmutter

Polymers 2017, 9(8), 326; https://doi.org/10.3390/polym9080326 - 31 Jul 2017

Cited by 13 | Viewed by 6313

Abstract

The self-adhesive potential of nanocellulose from aqueous cellulosic suspensions is of interest with regard to a potential replacement of synthetic adhesives. In order to evaluate the performance of microfibrillated cellulose from different (ligno-)cellulosic raw materials for this purpose, softwood and hardwood powder were [...] Read more.

The self-adhesive potential of nanocellulose from aqueous cellulosic suspensions is of interest with regard to a potential replacement of synthetic adhesives. In order to evaluate the performance of microfibrillated cellulose from different (ligno-)cellulosic raw materials for this purpose, softwood and hardwood powder were fibrillated and compared to sugar beet pulp as a representative non-wood cellulose resource, and conventional microfibrillated cellulose produced from bleached pulp. An alkali pre-treatment of woody and sugar beet raw materials enhanced the degree of fibrillation achieved, same as TEMPO-mediated oxidation of microfibrillated cellulose. Nanopapers produced from fibrillated material showed highly variable density and mechanical performance, demonstrating that properties may be tuned by the choice of raw material. While nanopaper strength was highest for TEMPO-oxidated microfibrillated cellulose, fibrillated untreated sugar beet pulp showed the best adhesive performance. Different microscopic methods (AFM, SEM, light microscopy) examined the interface between wood and fibrillated material, showing particular distinctions to commercial adhesives. It is proposed that fibrillated material suspensions, which achieve bond strength up to 60% of commercial urea-formaldehyde adhesive, may provide a viable solution to bio-based adhesives in certain applications where wet-strength is not an issue. Full article

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Open AccessArticle

Improvement in Functional Properties of Soy Protein Isolate-Based Film by Cellulose Nanocrystal–Graphene Artificial Nacre Nanocomposite

by Kuang Li, Shicun Jin, Yufei Han, Jianzhang Li and Hui Chen

Polymers 2017, 9(8), 321; https://doi.org/10.3390/polym9080321 - 30 Jul 2017

Cited by 34 | Viewed by 7935

Abstract

A facile, inexpensive, and green approach for the production of stable graphene dispersion was proposed in this study. We fabricated soy protein isolate (SPI)-based nanocomposite films with the combination of 2D negative charged graphene and 1D positive charged polyethyleneimine (PEI)-modified cellulose nanocrystals (CNC) [...] Read more.

A facile, inexpensive, and green approach for the production of stable graphene dispersion was proposed in this study. We fabricated soy protein isolate (SPI)-based nanocomposite films with the combination of 2D negative charged graphene and 1D positive charged polyethyleneimine (PEI)-modified cellulose nanocrystals (CNC) via a layer-by-layer assembly method. The morphologies and surface charges of graphene sheets and CNC segments were characterized by atomic force microscopy and Zeta potential measurements. The hydrogen bonds and multiple interface interactions between the filler and SPI matrix were analyzed by Attenuated Total Reflectance–Fourier Transform Infrared spectra and X-ray diffraction patterns. Scanning electron microscopy demonstrated the cross-linked and laminated structures in the fracture surface of the films. In comparison with the unmodified SPI film, the tensile strength and surface contact angles of the SPI/graphene/PEI-CNC film were significantly improved, by 99.73% and 37.13% respectively. The UV–visible light barrier ability, water resistance, and thermal stability were also obviously enhanced. With these improved functional properties, this novel bio-nanocomposite film showed considerable potential for application for food packaging materials. Full article

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Open AccessArticle

Two-Photon-Induced Microstereolithography of Chitosan-g-Oligolactides as a Function of Their Stereochemical Composition

by Tatiana S. Demina, Kseniia N. Bardakova, Nikita V. Minaev, Eugenia A. Svidchenko, Alexander V. Istomin, Galina P. Goncharuk, Leonid V. Vladimirov, Andrey V. Grachev, Alexander N. Zelenetskii, Peter S. Timashev and Tatiana A. Akopova

Polymers 2017, 9(7), 302; https://doi.org/10.3390/polym9070302 - 24 Jul 2017

Cited by 29 | Viewed by 6254

Abstract

Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for [...] Read more.

Chitosan-g-oligolactide copolymers with relatively long oligolactide grafted chains of various stereochemical compositions have been synthetized via a solvent-free mechanochemical technique and tailored to fabricate three-dimensional hydrogels using two-photon induced microstereolithography. An effect of the characteristics of chitosan and oligolactide used for the synthesis on the grafting yield and copolymer’s behavior were evaluated using fractional analysis, FTIR-spectroscopy, dynamic light scattering, and UV-spectrophotometry. The lowest copolymer yield was found for the system based on chitosan with higher molecular weight, while the samples consisting of low-molecular weight chitosan showed higher grafting degrees, which were comparable in both the cases of l,l- or l,d-oligolactide grafting. The copolymer processability in the course of two-photon stereolithography was evaluated as a function of the copolymer’s characteristics and stereolithography conditions. The structure and mechanical properties of the model film samples and fabricated 3D hydrogels were studied using optical and scanning electron microscopy, as well as by using tensile and nanoindenter devices. The application of copolymer with oligo(l,d-lactide) side chains led to higher processability during two-photon stereolithography in terms of the response to the laser beam, reproduction of the digital model, and the mechanical properties of the fabricated hydrogels. Full article

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Open AccessArticle

Effect of Plasticizer Type on Tensile Property and In Vitro Indomethacin Release of Thin Films Based on Low-Methoxyl Pectin

by Pensak Jantrawut, Tanpong Chaiwarit, Kittisak Jantanasakulwong, Claire Hélène Brachais and Odile Chambin

Polymers 2017, 9(7), 289; https://doi.org/10.3390/polym9070289 - 20 Jul 2017

Cited by 97 | Viewed by 8796

Abstract

This study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w) [...] Read more.

This study developed the interests of low-methoxyl pectin (LMP) together with plasticizers for the preparation of elastic thin films. The effect of different plasticizer types (glycerol: Gly; sorbitol: Sor; propylene glycol: PG; and polyethylene glycol 300: PEG 300) and concentrations (20–40% w/w) on mechanical and thermal properties of LMP films as well as on in vitro release of indomethacin were evaluated. Without any plasticizer, a brittle LMP film with low tensile strength and % elongation at break was obtained. Addition of plasticizers from 20% to 40% caused reduction in the tensile strength and Young’s modulus values, whereas percent elongation was increased. Forty percent Gly-plasticized and PG-plasticized films were selected to deliver indomethacin in comparison with non-plasticized film. No significant difference in indomethacin release profiles was displayed between the films. The analysis of indomethacin release model indicated that more than one drug release mechanism from the film formulation was involved and possibly the combination of both diffusion and erosion. Even though indomethacin incorporated in non-plasticized film showed similar release profile, Gly or PG should be added to enhanced film flexibility and decrease film brittleness. Full article

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Open AccessArticle

Effect of Nanofibrillated Cellulose Content on the Temperature and Near Infrared Responses of Polyvinyl Butyral Nanofibers-Containing Bilayer Hydrogel System

by Qian Zhao, Luping Ning, Yunhong Liang, Zhihui Zhang and Luquan Ren

Polymers 2017, 9(7), 270; https://doi.org/10.3390/polym9070270 - 6 Jul 2017

Cited by 9 | Viewed by 5837

Abstract

A novel kind of nanofibrillated cellulose (NFC) reinforced polyvinyl butyral (PVB) nanofibers-containing bilayer hydrogel system was successfully fabricated via the combination of a one-step, in-situ, free radical polymerization and electrospinning. The hydrogel owned high mechanical strength, thermoresponsive, and near infrared bending/unbending properties. The [...] Read more.

A novel kind of nanofibrillated cellulose (NFC) reinforced polyvinyl butyral (PVB) nanofibers-containing bilayer hydrogel system was successfully fabricated via the combination of a one-step, in-situ, free radical polymerization and electrospinning. The hydrogel owned high mechanical strength, thermoresponsive, and near infrared bending/unbending properties. The cross-linking density of hydrogels enhanced along with the increase of NFC content. The addition of NFC and PVB nanofibers presented tiny influence on the variation of chemical bond and volume phase transition temperature. The combination between NFC and PVB nanofibers enhanced the mechanical strength and decreased the strain value, which built the base for high bonding strength of two layers and efficient thermoresponsive and near infrared responses. With the increase of NFC content, the bending degree became smaller. The bilayer hydrogel dimensions affected the deformation degree. Bilayer hydrogels with different NFC content own different deformation abilities, which can be designed as different parts of soft actuators and provide superior performance to satisfy various practical application demands. Full article

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Open AccessArticle

Chestnut Honey Impregnated Carboxymethyl Cellulose Hydrogel for Diabetic Ulcer Healing

by Jong-Seok Park, Sung-Jun An, Sung-In Jeong, Hui-Jeong Gwon, Youn-Mook Lim and Young-Chang Nho

Polymers 2017, 9(7), 248; https://doi.org/10.3390/polym9070248 - 27 Jun 2017

Cited by 38 | Viewed by 8982

Abstract

Honey-based wound dressings have attracted a lot of attention from modern scientists owing to their anti-inflammatory and antibacterial effects without antibiotic resistance. Such dressings also promote moist wound healing, and have been considered natural, abundant, and cheap materials for folk marketing. This study [...] Read more.

Honey-based wound dressings have attracted a lot of attention from modern scientists owing to their anti-inflammatory and antibacterial effects without antibiotic resistance. Such dressings also promote moist wound healing, and have been considered natural, abundant, and cheap materials for folk marketing. This study investigated the various behaviors and characteristics of chestnut honey-impregnated carboxymethyl cellulose sodium hydrogel paste (CH–CMC) as a therapeutic dressing, such as its moist retention, antibacterial activity for inhibiting the growth of Staphylococcus aureus and Escherichia coli, and the rate of wound healing in db/db mice. The results provide good evidence, suggesting that CH–CMC has potential as a competitive candidate for diabetic ulcer wound healing. Full article

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Open AccessArticle

Preparation and Characterization of Chitosan/Soy Protein Isolate Nanocomposite Film Reinforced by Cu Nanoclusters

by Kuang Li, Shicun Jin, Xiaorong Liu, Hui Chen, Jing He and Jianzhang Li

Polymers 2017, 9(7), 247; https://doi.org/10.3390/polym9070247 - 25 Jun 2017

Cited by 61 | Viewed by 7189

Abstract

Soy protein isolate (SPI) based films have received considerable attention for use in packaging materials. However, SPI-based films exhibit relatively poor mechanical properties and water resistance ability. To tackle these challenges, chitosan (CS) and endogenous Cu nanoclusters (NCs) capped with protein were proposed [...] Read more.

Soy protein isolate (SPI) based films have received considerable attention for use in packaging materials. However, SPI-based films exhibit relatively poor mechanical properties and water resistance ability. To tackle these challenges, chitosan (CS) and endogenous Cu nanoclusters (NCs) capped with protein were proposed and designed to modify SPI-based films. Attenuated total reflectance-Fourier transform infrared spectroscopy and X-ray diffraction patterns of composite films demonstrated that interactions, such as hydrogen bonds in the film forming process, promoted the cross-linking of composite films. The surface microstructure of CS/SPI films modified with Cu NCs was more uniform and transmission electron microscopy (TEM) showed that uniform and discrete clusters were formed. Compared with untreated SPI films, the tensile strength and elongation at break of composite films were simultaneously improved by 118.78% and 74.93%, respectively. Moreover, these composite films also exhibited higher water contact angle and degradation temperature than that of pure SPI film. The water vapor permeation of the modified film also decreased. These improved properties of functional bio-polymers show great potential as food packaging materials. Full article

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Open AccessArticle

Reinforcement of Gelatin-Based Nanofilled Polymer Biocomposite by Crystalline Cellulose from Cotton for Advanced Wound Dressing Applications

by Shukanta Bhowmik, Jahid M. M. Islam, Tonmoy Debnath, Muhammed Yusuf Miah, Shovon Bhattacharjee and Mubarak A. Khan

Polymers 2017, 9(6), 222; https://doi.org/10.3390/polym9060222 - 13 Jun 2017

Cited by 42 | Viewed by 11100

Abstract

This study is designed to extract crystalline cellulose from cotton and reinforcing gelatin film for biomedical applications, especially as a wound dressing material for its exceptional biocompatibility and bio-activity. Moreover, gelatin helps in wound healing and crystalline cellulose as additive can improve its [...] Read more.

This study is designed to extract crystalline cellulose from cotton and reinforcing gelatin film for biomedical applications, especially as a wound dressing material for its exceptional biocompatibility and bio-activity. Moreover, gelatin helps in wound healing and crystalline cellulose as additive can improve its properties. Crystalline cellulose was prepared through hydrolysis and the effects of crystalline cellulose loading on the morphology, mechanical properties, and water sensitivity of the nanocomposite were investigated by means of scanning electron microscopy, tensile strength testing, and water absorption testing. Developed biocomposite film showed homogeneous dispersion of crystalline cellulose within the gelatin matrix and strong interfacial adherence between the matrix and reinforcement. Samples were tested for biocompatibility and in vitro cytotoxicity and found to have excellent biocompatibility without having any cytotoxicity. In vivo wound healing study in an animal model showed 40% increased healing than the model dressed by conventional dressing. Full article

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Preparation and Characterization of Quaternized Chitosan Coated Alginate Microspheres for Blue Dextran Delivery

by Kuo-Yu Chen and Si-Ying Zeng

Polymers 2017, 9(6), 210; https://doi.org/10.3390/polym9060210 - 7 Jun 2017

Cited by 18 | Viewed by 5920

Abstract

In this study, 2-[(Acryloyloxy)ethyl]trimethylammonium chloride was graft polymerized onto chitosan (CS) to form quaternary ammonium CS (QAC) by using ammonium persulfate as a redox initiator. Alginate (ALG) microspheres loaded with a water-soluble macromolecular model drug, blue dextran (BD), were obtained by corporation of [...] Read more.

In this study, 2-[(Acryloyloxy)ethyl]trimethylammonium chloride was graft polymerized onto chitosan (CS) to form quaternary ammonium CS (QAC) by using ammonium persulfate as a redox initiator. Alginate (ALG) microspheres loaded with a water-soluble macromolecular model drug, blue dextran (BD), were obtained by corporation of coaxial gas-flow method and ionic gelation process. CS and QAC were then coated on the surfaces of ALG microspheres to generate core/shell structured CS/ALG and QAC/ALG microspheres, respectively. The experiment result showed that QAC/ALG microspheres had a smaller particle size due to the stronger electrostatic interactions between QAC and ALG molecules. In vitro drug release studies at pH 7.4 and pH 9.0 exhibited that the release rate of BD was significantly decreased after ALG microspheres coating with CS and QAC. Moreover, ALG microspheres coated with QAC showed a prolonged release profile for BD at pH 9.0. Therefore, QAC/ALG microspheres may be a promising hydrophilic macromolecular drug carrier for a prolonged and sustained delivery. Full article

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Open AccessArticle

Synthesis of Polymer Nanocomposites Based on [Methyl Cellulose]_(1−x):(CuS)_x (0.02 M ≤ x ≤ 0.08 M) with Desired Optical Band Gaps

by Shujahadeen B. Aziz, Mariwan A. Rasheed and Hameed M. Ahmed

Polymers 2017, 9(6), 194; https://doi.org/10.3390/polym9060194 - 30 May 2017

Cited by 94 | Viewed by 8916

Abstract

In this paper, the sample preparation of polymer nanocomposites based on methyl cellulose (MC) with small optical bandgaps has been discussed. Copper monosulfide (CuS) nanoparticles have been synthesized from the sodium sulphide (Na₂S) and copper chloride (CuCl₂) salts. Distinguishable [...] Read more.

In this paper, the sample preparation of polymer nanocomposites based on methyl cellulose (MC) with small optical bandgaps has been discussed. Copper monosulfide (CuS) nanoparticles have been synthesized from the sodium sulphide (Na₂S) and copper chloride (CuCl₂) salts. Distinguishable localized surface resonance plasmon (LSRP) absorption peaks for CuS nanoparticles within the 680–1090 nm scanned wavelength range were observed for the samples. An absorption edge (E_d) was found to be widely shifted to a lower photon energy region. A linear relationship between the refractive index of the samples and the CuS fraction was utilized to describe the distribution of the particle. The optical bandgap of MC was reduced from 6.2 to 2.3 eV upon the incorporation of 0.08 M of CuS nanoparticles. The optical dielectric loss, as an alternative method, was used successfully to estimate the optical bandgap. Moreover, the electronic transition type was identified by using Tauc’s extrapolation method. The plots of the optical dielectric constant and energy bandgap as a function of the CuS concentration were utilized to examine the validity of the Penn model. For the nanocomposite samples, the Urbach energy was found to be increased, which can be evidence for a large possible number of bands-to-tail and tail-to-tail transitions. However, from the X-ray diffraction (XRD) analysis, it was also found that the synthesized CuS nanoparticles disrupted the crystallinity phase of the MC polymer. Finally, fourier transform infrared (FTIR) spectroscopy for the samples was also performed. Significant decreases of transmittance intensity as well as band shifting in the FTIR spectra were observed for the doped samples. Full article

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Open AccessArticle

Effect of High Salt Concentration (HSC) on Structural, Morphological, and Electrical Characteristics of Chitosan Based Solid Polymer Electrolytes

by Shujahadeen B. Aziz, Omed Gh. Abdullah, Mariwan A. Rasheed and Hameed M. Ahmed

Polymers 2017, 9(6), 187; https://doi.org/10.3390/polym9060187 - 24 May 2017

Cited by 144 | Viewed by 11199

Abstract

Chitosan (CS) films doped with sodium triflate (NaTf) were prepared by the solution cast technique. The structural and morphological behaviors of the samples were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD patterns were deconvoluted to estimate the [...] Read more.

Chitosan (CS) films doped with sodium triflate (NaTf) were prepared by the solution cast technique. The structural and morphological behaviors of the samples were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD patterns were deconvoluted to estimate the degree of crystallinity of the samples. The SEM micrograph showed the crystalline structure of the sample contained 50 wt % of NaTf salt. The disappearance of broad peaks of chitosan at 2θ ≈ 21° and 2θ ≈ 32° confirmed the occurrence of ion association at 50 wt % of NaTf salt. In impedance plots, a low frequency spike region and a high frequency semicircle, were distinguishable for low salt concentrations. The highest ambient temperature direct current (DC) electrical conductivity obtained for CS:NaTf was found to be 2.41 × 10⁻⁴ S/cm for the sample containing 40 wt % of NaTf salt. The role of lattice energy of salts on DC ionic conductivity was also discussed. The temperature dependence of DC conductivity was found to follow the well-known Arrhenius relationship. From the alternating current (AC) conductivity spectra, three distinct regions were recognized for the samples with NaTf salt concentration ranging from 10 wt % to 30 wt %. The plateau region of AC spectra was used to estimate the DC conductivity. Full article

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Open AccessArticle

Electrospun Polycaprolactone/Aloe Vera_Chitosan Nanofibrous Asymmetric Membranes Aimed for Wound Healing Applications

by Sónia P. Miguel, Maximiano P. Ribeiro, Paula Coutinho and Ilídio J. Correia

Polymers 2017, 9(5), 183; https://doi.org/10.3390/polym9050183 - 21 May 2017

Cited by 166 | Viewed by 10911

Abstract

Today, none of the wound dressings available on the market is fully capable of reproducing all the features of native skin. Herein, an asymmetric electrospun membrane was produced to mimic both layers of skin. It comprises a top dense layer (manufactured with polycaprolactone) [...] Read more.

Today, none of the wound dressings available on the market is fully capable of reproducing all the features of native skin. Herein, an asymmetric electrospun membrane was produced to mimic both layers of skin. It comprises a top dense layer (manufactured with polycaprolactone) that was designed to provide mechanical support to the wound and a bottom porous layer (composed of chitosan and Aloe Vera) aimed to improve the bactericidal activity of the membrane and ultimately the healing process. The results obtained revealed that the produced asymmetric membranes displayed a porosity, wettability, as well as mechanical properties similar to those presented by the native skin. Fibroblast cells were able to adhere, spread, and proliferate on the surface of the membranes and the intrinsic structure of the two layers of the membrane is capable of avoiding the invasion of microorganisms while conferring bioactive properties. Such data reveals the potential of these asymmetric membranes, in the near future, to be applied as wound dressings. Full article

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Open AccessArticle

Osteochondral Regeneration Induced by TGF-β Loaded Photo Cross-Linked Hyaluronic Acid Hydrogel Infiltrated in Fused Deposition-Manufactured Composite Scaffold of Hydroxyapatite and Poly (Ethylene Glycol)-Block-Poly(ε-Caprolactone)

by Yi-Ho Hsieh, Ming-Fa Hsieh, Chih-Hsiang Fang, Cho-Pei Jiang, Bojain Lin and Hung-Maan Lee

Polymers 2017, 9(5), 182; https://doi.org/10.3390/polym9050182 - 20 May 2017

Cited by 23 | Viewed by 8105

Abstract

The aim of this study was to report the fabrication of porous scaffolds with pre-designed internal pores using a fused deposition modeling (FDM) method. Polycaprolactone (PCL) is a suitable material for the FDM method due to the fact it can be melted and [...] Read more.

The aim of this study was to report the fabrication of porous scaffolds with pre-designed internal pores using a fused deposition modeling (FDM) method. Polycaprolactone (PCL) is a suitable material for the FDM method due to the fact it can be melted and has adequate flexural modulus and strength to be formed into a filament. In our study, the filaments of methoxy poly(ethylene glycol)-block-poly(ε-caprolactone) having terminal groups of carboxylic acid were deposited layer by layer. Raw materials having a weight ratio of hydroxyapatite (HAp) to polymer of 1:2 was used for FDM. To promote cell adhesion, amino groups of the Arg-Gly-Asp(RGD) peptide were condensed with the carboxylic groups on the surface of the fabricated scaffold. Then the scaffold was infiltrated with hydrogel of glycidyl methacrylate hyaluronic acid loading with 10 ng/mL of TGF-β1 and photo cross-linked on the top of the scaffolds. Serious tests of mechanical and biological properties were performed in vitro. HAp was found to significantly increase the compressive strength of the porous scaffolds. Among three orientations of the filaments, the lay down pattern 0°/90° scaffolds exhibited the highest compressive strength. Fluorescent staining of the cytoskeleton found that the osteoblast-like cells and stem cells well spread on RGD-modified PEG-PCL film indicating a favorable surface for the proliferation of cells. An in vivo test was performed on rabbit knee. The histological sections indicated that the bone and cartilage defects produced in the knees were fully healed 12 weeks after the implantation of the TGF-β1 loaded hydrogel and scaffolds, and regenerated cartilage was hyaline cartilage as indicated by alcian blue and periodic acid-schiff double staining. Full article

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Open AccessArticle

In Situ Self-Assembled Nanocomposites from Bacterial Cellulose Reinforced with Eletrospun Poly(lactic acid)/Lipids Nanofibers

by Chunhui Xiang and Nuria C. Acevedo

Polymers 2017, 9(5), 179; https://doi.org/10.3390/polym9050179 - 19 May 2017

Cited by 20 | Viewed by 6993

Abstract

The goal of this study is to explore a new strategy to improve the mechanical and hydrophobic properties of bacterial cellulose (BC) mats. The present work is the first to report the preparation of in situ self-assembled BC nanocomposites using electrospun hydrophobic poly(lactic [...] Read more.

The goal of this study is to explore a new strategy to improve the mechanical and hydrophobic properties of bacterial cellulose (BC) mats. The present work is the first to report the preparation of in situ self-assembled BC nanocomposites using electrospun hydrophobic poly(lactic acid) (PLA) or PLA/lipids (PLA/Lip) nanofiber mats as foundation for BC nanofiber growth. Adding electrospun PLA mats to the BC culture media led to a two-fold increase in toughness with a 52% increase in elongation of the nanocomposites with regard to BC. The incorporation of electrospun PLA and PLA/Lip nanofiber mats lowered the moisture regain and water vapor transmission of BC nanocomposites relative to pure BC mats. The interfacial bonding between the individual components of a nanocomposite is a key factor for the improvement of composite strength, stiffness, and barrier properties; thus additional strategies to improve interaction between hydrophilic BC and hydrophobic PLA fibers need to be explored. Full article

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pH Dependence of Chitosan Enzymolysis

by Bi Foua Claude Alain Gohi, Hong-Yan Zeng, A Dan Pan, Jing Han and Jian Yuan

Polymers 2017, 9(5), 174; https://doi.org/10.3390/polym9050174 - 13 May 2017

Cited by 16 | Viewed by 6501

Abstract

As a means of making chitosan more useful in biotechnological applications, it was hydrolyzed using pepsin, chitosanase and α-amylase. The enzymolysis behavior of these enzymes was further systematically studied for its effectiveness in the production of low-molecular-weight chitosans (LMWCs) and other derivatives. The [...] Read more.

As a means of making chitosan more useful in biotechnological applications, it was hydrolyzed using pepsin, chitosanase and α-amylase. The enzymolysis behavior of these enzymes was further systematically studied for its effectiveness in the production of low-molecular-weight chitosans (LMWCs) and other derivatives. The study showed that these enzymes depend on ion hydronium (H3O+), thus on pH with a pH dependence fitting R2 value of 0.99. In y = 1.484[H^+] + 0.114, the equation of pH dependence, when [H^+] increases by one, y (k_0/k_m) increases by 1.484. From the temperature dependence study, the activation energy (Ea) and pre-exponential factor (A) were almost identical for two of the enzymes, but a considerable difference was observed in comparison with the third enzyme. Chitosanase and pepsin had nearly identical Ea, but α-amylase was significantly lower. This serves as evidence that the hydrolysis reaction of α-amylase relies on low-barrier hydrogen bonds (LBHBs), which explains its low Ea in actual conditions. The confirmation of this phenomenon was further derived from a similarly considerable difference in the order magnitudes of A between α-amylase and the other two enzymes, which was more than five. Variation of the rate constants of the enzymatic hydrolysis of chitosan with temperature follows the Arrhenius equation. Full article

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A High-Performance Soy Protein Isolate-Based Nanocomposite Film Modified with Microcrystalline Cellulose and Cu and Zn Nanoclusters

by Kuang Li, Shicun Jin, Hui Chen, Jing He and Jianzhang Li

Polymers 2017, 9(5), 167; https://doi.org/10.3390/polym9050167 - 6 May 2017

Cited by 45 | Viewed by 7702

Abstract

Soy protein isolate (SPI)-based materials are abundant, biocompatible, renewable, and biodegradable. In order to improve the tensile strength (TS) of SPI films, we prepared a novel composite film modified with microcrystalline cellulose (MCC) and metal nanoclusters (NCs) in this study. The effects of [...] Read more.

Soy protein isolate (SPI)-based materials are abundant, biocompatible, renewable, and biodegradable. In order to improve the tensile strength (TS) of SPI films, we prepared a novel composite film modified with microcrystalline cellulose (MCC) and metal nanoclusters (NCs) in this study. The effects of the modification of MCC on the properties of SPI-Cu NCs and SPI-Zn NCs films were investigated. Attenuated total reflectance-Fourier transformed infrared spectroscopy analyses and X-ray diffraction patterns characterized the strong interactions and reduction of the crystalline structure of the composite films. Scanning electron microscopy (SEM) showed the enhanced cross-linked and entangled structure of modified films. Compared with an untreated SPI film, the tensile strength of the SPI-MCC-Cu and SPI-MCC-Zn films increased from 2.91 to 13.95 and 6.52 MPa, respectively. Moreover, the results also indicated their favorable water resistance with a higher water contact angle. Meanwhile, the composite films exhibited increased initial degradation temperatures, demonstrating their higher thermostability. The results suggested that MCC could effectively improve the performance of SPI-NCs films, which would provide a novel preparation method for environmentally friendly SPI-based films in the applications of packaging materials. Full article

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Open AccessArticle

Novel Polyvinyl Alcohol/Starch Electrospun Fibers as a Strategy to Disperse Cellulose Nanocrystals into Poly(lactic acid)

by Carol López de Dicastillo, Karina Roa, Luan Garrido, Alejandro Pereira and Maria Jose Galotto

Polymers 2017, 9(4), 117; https://doi.org/10.3390/polym9040117 - 7 Apr 2017

Cited by 21 | Viewed by 6433

Abstract

In this work, electrospun fibers of polyvinyl alcohol (PV) and starch (ST) were obtained to improve dispersion of cellulose nanocrystals (CNC) within a poly(lactic acid) (PLA) matrix with the aim of enhancing mechanical and barrier properties. The development and characterization of electrospun fibers [...] Read more.

In this work, electrospun fibers of polyvinyl alcohol (PV) and starch (ST) were obtained to improve dispersion of cellulose nanocrystals (CNC) within a poly(lactic acid) (PLA) matrix with the aim of enhancing mechanical and barrier properties. The development and characterization of electrospun fibers with and without CNC, followed by their incorporation in PLA at three concentrations (0.5%, 1% and 3% with respect to CNC) were investigated. Morphological, structural, thermal, mechanical and barrier properties of these nanocomposites were studied. The purpose of this study was not only to compare the properties of PLA nanocomposites with CNC embedded into electrospun fibers and nanocomposites with freeze-dried CNC, but also to study the effect of electrospinning process and the incorporation of CNC on the PV and starch properties. SEM micrographs confirmed the homogenous dispersion of fibers through PLA matrix. X-ray analysis revealed that the electrospinning process decreased the crystallinity of PV and starch. The presence of CNC enhanced the thermal stability of electrospun fibers. Electrospun fibers showed an interesting nucleating effect since crystallinity of PLA was strongly increased. Nanocomposites with electrospun fibers containing CNC presented slightly higher flexibility and ductility without decreasing barrier properties. Full article

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Preparation, Characterization and Mechanical Properties of Bio-Based Polyurethane Adhesives from Isocyanate-Functionalized Cellulose Acetate and Castor Oil for Bonding Wood

by Adrián Tenorio-Alfonso, María Carmen Sánchez and José M. Franco

Polymers 2017, 9(4), 132; https://doi.org/10.3390/polym9040132 - 5 Apr 2017

Cited by 65 | Viewed by 11224

Abstract

Nowadays, different types of natural carbohydrates such as sugars, starch, cellulose and their derivatives are widely used as renewable raw materials. Vegetable oils are also considered as promising raw materials to be used in the synthesis of high quality products in different applications, [...] Read more.

Nowadays, different types of natural carbohydrates such as sugars, starch, cellulose and their derivatives are widely used as renewable raw materials. Vegetable oils are also considered as promising raw materials to be used in the synthesis of high quality products in different applications, including in the adhesive field. According to this, several bio-based formulations with adhesion properties were synthesized first by inducing the functionalization of cellulose acetate with 1,6-hexamethylene diisocyanate and then mixing the resulting biopolymer with a variable amount of castor oil, from 20% to 70% (wt). These bio-based adhesives were mechanically characterized by means of small-amplitude oscillatory torsion measurements, at different temperatures, and standardized tests to evaluate tension loading (ASTM-D906) and peel strength (ASTM-D903). In addition, thermal properties and stability of the synthesized bio-polyurethane formulations were also analyzed through differential scanning calorimetry and thermal gravimetric analysis. As a result, the performance of these bio-polyurethane products as wood adhesives were compared and analyzed. Bio-polyurethane formulations exhibited a simple thermo-rheological behavior below a critical temperature of around 80–100 °C depending on the castor oil/cellulose acetate weight ratio. Formulation with medium castor oil/biopolymer weight ratio (50:50 % wt) showed the most suitable mechanical properties and adhesion performance for bonding wood. Full article

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Open AccessArticle

Toxicity, Biocompatibility, pH-Responsiveness and Methotrexate Release from PVA/Hyaluronic Acid Cryogels for Psoriasis Therapy

by Cătălina Natalia Cheaburu Yilmaz, Daniela Pamfil, Cornelia Vasile, Nela Bibire, Raoul-Vasile Lupuşoru, Carmen-Lăcrămioara Zamfir and Cătălina Elena Lupușoru

Polymers 2017, 9(4), 123; https://doi.org/10.3390/polym9040123 - 27 Mar 2017

Cited by 34 | Viewed by 9105

Abstract

Poly(vinyl alcohol)/hyaluronic acid cryogels loaded with methotrexate were studied. The physical–chemical characterization of cryogels was performed by FT-IR spectroscopy, scanning electron microscopy, differential scanning calorimetry and dynamic mechanical thermal analysis. Acute toxicity and haematological parameters were determined by “in vivo” tests. The biocompatibility [...] Read more.

Poly(vinyl alcohol)/hyaluronic acid cryogels loaded with methotrexate were studied. The physical–chemical characterization of cryogels was performed by FT-IR spectroscopy, scanning electron microscopy, differential scanning calorimetry and dynamic mechanical thermal analysis. Acute toxicity and haematological parameters were determined by “in vivo” tests. The biocompatibility tests proved that the obtained cryogels showed significantly decreased toxicity and are biocompatible. The pH-responsiveness of the swelling behaviour and of the methotrexate release from the poly(vinyl alcohol)/hyaluronic acid (PVA/HA) cryogels were studied in a pH interval of 2–7.4. A significant change in properties was found at pH 5.5 specific for treatment of affected skin in psoriasis disease. Full article

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Open AccessArticle

Thermo-Responsive Poly(N-Isopropylacrylamide)-Cellulose Nanocrystals Hybrid Hydrogels for Wound Dressing

by Katarzyna Zubik, Pratyawadee Singhsa, Yinan Wang, Hathaikarn Manuspiya and Ravin Narain

Polymers 2017, 9(4), 119; https://doi.org/10.3390/polym9040119 - 24 Mar 2017

Cited by 133 | Viewed by 12833

Abstract

Thermo-responsive hydrogels containing poly(N-isopropylacrylamide) (PNIPAAm), reinforced both with covalent and non-covalent interactions with cellulose nanocrystals (CNC), were synthesized via free-radical polymerization in the absence of any additional cross-linkers. The properties of PNIPAAm-CNC hybrid hydrogels were dependent on the amounts of incorporated [...] Read more.

Thermo-responsive hydrogels containing poly(N-isopropylacrylamide) (PNIPAAm), reinforced both with covalent and non-covalent interactions with cellulose nanocrystals (CNC), were synthesized via free-radical polymerization in the absence of any additional cross-linkers. The properties of PNIPAAm-CNC hybrid hydrogels were dependent on the amounts of incorporated CNC. The thermal stability of the hydrogels decreased with increasing CNC content. The rheological measurement indicated that the elastic and viscous moduli of hydrogels increased with the higher amounts of CNC addition, representing stronger mechanical properties of the hydrogels. Moreover, the hydrogel injection also supported the hypothesis that CNC reinforced the hydrogels; the increased CNC content exhibited higher structural integrity upon injection. The PNIPAAm-CNC hybrid hydrogels exhibited clear thermo-responsive behavior; the volume phase transition temperature (VPTT) was in the range of 36 to 39 °C, which is close to normal human body temperature. For wound dressing purposes, metronidazole, an antibiotic and antiprotozoal often used for skin infections, was used as a target drug to study drug-loading and the release properties of the hydrogels. The hydrogels showed a good drug-loading capacity at room temperature and a burst drug release, which was followed by slow and sustained release at 37 °C. These results suggested that newly developed drugs containing injectable hydrogels are promising materials for wound dressing. Full article

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Open AccessArticle

Preparation and Characterization of Antibacterial Cellulose/Chitosan Nanofiltration Membranes

by Rengui Weng, Lihui Chen, Shan Lin, Hui Zhang, Hui Wu, Kai Liu, Shilin Cao and Liulian Huang

Polymers 2017, 9(4), 116; https://doi.org/10.3390/polym9040116 - 23 Mar 2017

Cited by 65 | Viewed by 7023

Abstract

Abstract: Presently, most nanofiltration membranes are prepared with non-biodegradable petrochemical materials. This process is harmful to the ecosystem and consumes a large amount of non-renewable energy. In this study, biodegradable and biocompatible antibacterial cellulose/chitosan nanofiltration membranes (BC/CS-NFMs) were fabricated and characterized for [...] Read more.

Abstract: Presently, most nanofiltration membranes are prepared with non-biodegradable petrochemical materials. This process is harmful to the ecosystem and consumes a large amount of non-renewable energy. In this study, biodegradable and biocompatible antibacterial cellulose/chitosan nanofiltration membranes (BC/CS-NFMs) were fabricated and characterized for their mechanical strength, antimicrobial activity, salt and dye filtration performance, and polyethylene glycol (PEG) retention using Thermal gravimetric analysis (TGA), Field emission scanning electron microscopy(FE-SEM), Fourier transform infrared spectroscopy(FT-IR), and X-ray diffraction (XRD). The BC/CS-NFMs were obtained by the hydrolysis and carboxymethylation of dense cellulose/chitosan membranes (BC/CSMs). The tensile strength of the BC/CS-NFMs decreased as the chitosan content increased. In addition, the thermal stability and antibacterial ability of the BC/CS-NFMs improved. The pore size is less than 1 nm, and a spongy, layered structure is observed in the cross-sectional FE-SEM images. FT-IR analysis shows that a part of the hydroxyl in cellulose transforms to carboxymethyl during the hydrolysis and carboxymethylation of the BC/CSMs. No obvious changes can be observed in the cellulose and chitosan after the blend membrane formation from the XRD measurements. Based on the experimental results on the permeation and rejection of BC/CS-NFMs, different proportions of cellulose and chitosan nanofiltration membranes almost did not affect the water flux and rejection rate. The BC/CS-NFMs showed better water flux and a higher rejection rate in aqueous dye-salt solutions. Full article

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Open AccessArticle

Preparation and Application of Starch/Polyvinyl Alcohol/Citric Acid Ternary Blend Antimicrobial Functional Food Packaging Films

by Zhijun Wu, Jingjing Wu, Tingting Peng, Yutong Li, Derong Lin, Baoshan Xing, Chunxiao Li, Yuqiu Yang, Li Yang, Lihua Zhang, Rongchao Ma, Weixiong Wu, Xiaorong Lv, Jianwu Dai and Guoquan Han

Polymers 2017, 9(3), 102; https://doi.org/10.3390/polym9030102 - 14 Mar 2017

Cited by 122 | Viewed by 13558

Abstract

Ternary blend films were prepared with different ratios of starch/polyvinyl alcohol (PVA)/citric acid. The films were characterized by field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis, as well as Fourier transform infrared (FTIR) analysis. The influence of different ratios of starch/polyvinyl alcohol (PVA)/citric [...] Read more.

Ternary blend films were prepared with different ratios of starch/polyvinyl alcohol (PVA)/citric acid. The films were characterized by field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis, as well as Fourier transform infrared (FTIR) analysis. The influence of different ratios of starch/polyvinyl alcohol (PVA)/citric acid and different drying times on the performance properties, transparency, tensile strength (TS), water vapor permeability (WVP), water solubility (WS), color difference (ΔE), and antimicrobial activity of the ternary blends films were investigated. The starch/polyvinyl alcohol/citric acid (S/P/C^1:1:0, S/P/C^3:1:0.08, and S/P/C^3:3:0.08) films were all highly transparent. The S/P/C^3:3:0.08 had a 54.31 times water-holding capacity of its own weight and its mechanical tensile strength was 46.45 MPa. In addition, its surface had good uniformity and compactness. The S/P/C^3:1:0.08 and S/P/C^3:3:0.08 showed strong antimicrobial activity to Listeria monocytogenes and Escherichia coli, which were the food-borne pathogenic bacteria used. The freshness test results of fresh figs showed that all of the blends prevented the formation of condensed water on the surface of the film, and the S/P/C^3:1:0.08 and S/P/C^3:3:0.08 prevented the deterioration of figs during storage. The films can be used as an active food packaging system due to their strong antibacterial effect. Full article

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Open AccessArticle

Synthesis and Characterization of Methyl Cellulose/Keratin Hydrolysate Composite Membranes

by Bernd M. Liebeck, Natalia Hidalgo, Georg Roth, Crisan Popescu and Alexander Böker

Polymers 2017, 9(3), 91; https://doi.org/10.3390/polym9030091 - 4 Mar 2017

Cited by 39 | Viewed by 9062

Abstract

It is known that aqueous keratin hydrolysate solutions can be produced from feathers using superheated water as solvent. This method is optimized in this study by varying the time and temperature of the heat treatment in order to obtain a high solute content [...] Read more.

It is known that aqueous keratin hydrolysate solutions can be produced from feathers using superheated water as solvent. This method is optimized in this study by varying the time and temperature of the heat treatment in order to obtain a high solute content in the solution. With the dissolved polypeptides, films are produced using methyl cellulose as supporting material. Thereby, novel composite membranes are produced from bio-waste. It is expected that these materials exhibit both protein and polysaccharide properties. The influence of the embedded keratin hydrolysates on the methyl cellulose structure is investigated using Fourier transform infrared spectroscopy (FTIR) and wide angle X-ray diffraction (WAXD). Adsorption peaks of both components are present in the spectra of the membranes, while the X-ray analysis shows that the polypeptides are incorporated into the semi-crystalline methyl cellulose structure. This behavior significantly influences the mechanical properties of the composite films as is shown by tensile tests. Since further processing steps, e.g., crosslinking, may involve a heat treatment, thermogravimetric analysis (TGA) is applied to obtain information on the thermal stability of the composite materials. Full article

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Open AccessArticle

Sustainable and Low Viscous 1-Allyl-3-methylimidazolium Acetate + PEG Solvent for Cellulose Processing

by Airong Xu and Quan Li

Polymers 2017, 9(2), 54; https://doi.org/10.3390/polym9020054 - 16 Feb 2017

Cited by 9 | Viewed by 5510

Abstract

Developing sustainable, low viscous and efficient solvents are always advantageous to the processing/fabricating of cellulose materials in practical applications. To this end, in this work novel solvents were developed; ([Amim][CH₃COO]/PEG) by dissolving polyethylene glycol 200 (PEG-200) in 1-allyl-3-methylimidazolium acetate ([Amim][CH₃ [...] Read more.

Developing sustainable, low viscous and efficient solvents are always advantageous to the processing/fabricating of cellulose materials in practical applications. To this end, in this work novel solvents were developed; ([Amim][CH₃COO]/PEG) by dissolving polyethylene glycol 200 (PEG-200) in 1-allyl-3-methylimidazolium acetate ([Amim][CH₃COO]). The solubilities of cellulose in [Amim][CH₃COO]/PEG solvents were determined as a function of temperature, and the possible dissolution mechanism of cellulose in [Amim][CH₃COO]/PEG solvent was investigated. The novel solvent exhibits outstanding advantages for good dissolution capacity of cellulose, such as low viscosity, negligible vapor pressure, and recycling capability. The [CH₃COO]⁻ anion and the [Amim]⁺ cation of [Amim][CH₃COO] in [Amim][CH₃COO]/PEG-10 are the driving force for cellulose dissolution verified by the ¹³C NMR spectra. In addition, the regenerated cellulose films from [Amim][CH₃COO]/PEG solvent were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and thermogravimetric analysis (TGA) to estimate their morphologies and structures. Full article

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Open AccessArticle

Enhancement of Curcumin Bioavailability Using Nanocellulose Reinforced Chitosan Hydrogel

by Thennakoon M. Sampath Udeni Gunathilake, Yern Chee Ching and Cheng Hock Chuah

Polymers 2017, 9(2), 64; https://doi.org/10.3390/polym9020064 - 15 Feb 2017

Cited by 117 | Viewed by 13416

Abstract

A unique biodegradable, superporous, swellable and pH sensitive nanocellulose reinforced chitosan hydrogel with dynamic mechanical properties was prepared for oral administration of curcumin. Curcumin, a less water-soluble drug was used due to the fact that the fast swellable, superporous hydrogel could release a [...] Read more.

A unique biodegradable, superporous, swellable and pH sensitive nanocellulose reinforced chitosan hydrogel with dynamic mechanical properties was prepared for oral administration of curcumin. Curcumin, a less water-soluble drug was used due to the fact that the fast swellable, superporous hydrogel could release a water-insoluble drug to a great extent. CO₂ gas foaming was used to fabricate hydrogel as it eradicates using organic solvents. Field emission scanning electron microscope images revealed that the pore size significantly increased with the formation of widely interconnected porous structure in gas foamed hydrogels. The maximum compression of pure chitosan hydrogel was 25.9 ± 1 kPa and it increased to 38.4 ± 1 kPa with the introduction of 0.5% cellulose nanocrystals. In vitro degradation of hydrogels was found dependent on the swelling ratio and the amount of CNC of the hydrogel. All the hydrogels showed maximum swelling ratios greater than 300%. The 0.5% CNC-chitosan hydrogel showed the highest swelling ratio of 438% ± 11%. FTIR spectrum indicated that there is no interaction between drug and ingredients present in hydrogels. The drug release occurred in non-Fickian (anomalous) manner in simulated gastric medium. The drug release profiles of hydrogels are consistent with the data obtained from the swelling studies. After gas foaming of the hydrogel, the drug loading efficiency increased from 41% ± 2.4% to 50% ± 2.0% and release increased from 0.74 to 1.06 mg/L. The drug release data showed good fitting to Ritger-Peppas model. Moreover, the results revealed that the drug maintained its chemical activity after in vitro release. According to the results of this study, CNC reinforced chitosan hydrogel can be suggested to improve the bioavailability of curcumin for the absorption from stomach and upper intestinal tract. Full article

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Open AccessReview

Chitosan Combined with ZnO, TiO₂ and Ag Nanoparticles for Antimicrobial Wound Healing Applications: A Mini Review of the Research Trends

by Vu Khac Hoang Bui, Duckshin Park and Young-Chul Lee

Polymers 2017, 9(1), 21; https://doi.org/10.3390/polym9010021 - 9 Jan 2017

Cited by 196 | Viewed by 18636

Abstract

Chitosan is a natural polymer that has been widely utilized for many purposes in the food, textile, agriculture, water treatment, cosmetic and pharmaceutical industries. Based on its characteristics, including biodegradability, non-toxicity and antimicrobial properties, it has been employed effectively in wound healing applications. [...] Read more.

Chitosan is a natural polymer that has been widely utilized for many purposes in the food, textile, agriculture, water treatment, cosmetic and pharmaceutical industries. Based on its characteristics, including biodegradability, non-toxicity and antimicrobial properties, it has been employed effectively in wound healing applications. Importantly, however, it is necessary to improve chitosan’s capacities by combination with zinc oxide (ZnO), titanium dioxide (TiO₂) and silver (Ag) nanoparticles (NPs). In this review of many of the latest research papers, we take a closer look at the antibacterial effectiveness of chitosan combined with ZnO, TiO₂ and Ag NPs and also evaluate the specific wound healing application potentials. Full article

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Open AccessArticle

Thixotropic Supramolecular Pectin-Poly(Ethylene Glycol) Methacrylate (PEGMA) Hydrogels

by Siew Yin Chan, Wee Sim Choo, David James Young and Xian Jun Loh

Polymers 2016, 8(11), 404; https://doi.org/10.3390/polym8110404 - 18 Nov 2016

Cited by 29 | Viewed by 10348

Abstract

Pectin is an anionic, water-soluble polymer predominantly consisting of covalently 1,4-linked α-d-galacturonic acid units. This naturally occurring, renewable and biodegradable polymer is underutilized in polymer science due to its insolubility in organic solvents, which renders conventional polymerization methods impractical. To circumvent [...] Read more.

Pectin is an anionic, water-soluble polymer predominantly consisting of covalently 1,4-linked α-d-galacturonic acid units. This naturally occurring, renewable and biodegradable polymer is underutilized in polymer science due to its insolubility in organic solvents, which renders conventional polymerization methods impractical. To circumvent this problem, cerium-initiated radical polymerization was utilized to graft methoxy-poly(ethylene glycol) methacrylate (mPEGMA) onto pectin in water. The copolymers were characterized by ¹H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA), and used in the formation of supramolecular hydrogels through the addition of α-cyclodextrin (α-CD) to induce crosslinking. These hydrogels possessed thixotropic properties; shear-thinning to liquid upon agitation but settling into gels at rest. In contrast to most of the other hydrogels produced through the use of poly(ethylene glycol) (PEG)-grafted polymers, the pectin-PEGMA/α-CD hydrogels were unaffected by temperature changes. Full article

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Open AccessArticle

Fluorescence Imaging in Genipin Crosslinked Chitosan–Poly(vinyl pyrrolidone) Hydrogels

by Simon Matcham and Katarina Novakovic

Polymers 2016, 8(11), 385; https://doi.org/10.3390/polym8110385 - 28 Oct 2016

Cited by 20 | Viewed by 6780

Abstract

Recent research has identified genipin as a promising natural crosslinking agent for biocompatible hydrogels as genipin is significantly less cytotoxic than current synthetic crosslinking agents, such as glutaraldehyde. Conveniently, fluorophores can be produced when genipin crosslinks. In this study, fluorescence intensity measurements of [...] Read more.

Recent research has identified genipin as a promising natural crosslinking agent for biocompatible hydrogels as genipin is significantly less cytotoxic than current synthetic crosslinking agents, such as glutaraldehyde. Conveniently, fluorophores can be produced when genipin crosslinks. In this study, fluorescence intensity measurements of genipin crosslinked chitosan-poly(vinyl pyrrolidone) hydrogels have been explored as a dynamic, in situ method for tracing sol-gel transition. These pH-responsive smart materials have a future in medical applications, in particular in tissue engineering and drug delivery, where methods to follow the process in situ and in real-time are crucial for future advancement. Samples were prepared using deionised water, pH 4, and pH 10 solutions, and studied at 24 and 37 °C over a 24 h period. Both temperature and pH have been found to affect sol-gel transition in the hydrogels studied. The transition from acidic (pH 4) to basic (pH 10) solution resulted in reduced fluorescence intensity suggesting that, under more basic conditions, genipin molecules self-polymerise, reducing the number of molecules available for reaction with the amino groups of chitosan. Three-dimensional representations of the fluorescence present in a hydrogel sample have also been produced from the data, enabling the visualisation of variation in fluorescence with time at the surface of the hydrogel. Full article

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Open AccessArticle

Preparation of a Novel Chitosan Based Biopolymer Dye and Application in Wood Dyeing

by Xiaoqian Wang, Ruilin Tang, Yang Zhang, Zhiming Yu and Chusheng Qi

Polymers 2016, 8(9), 338; https://doi.org/10.3390/polym8090338 - 10 Sep 2016

Cited by 71 | Viewed by 10242

Abstract

A novel chitosan-based biopolymer dye possessing antibacterial properties was synthesized by reaction of O-carboxymethyl chitosan and Acid Red GR. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), degree of substitution (DS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), X-ray [...] Read more.

A novel chitosan-based biopolymer dye possessing antibacterial properties was synthesized by reaction of O-carboxymethyl chitosan and Acid Red GR. The synthesized materials were characterized by Fourier transform infrared spectroscopy (FTIR), degree of substitution (DS), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TG), X-ray diffraction (XRD), water solubility test, antibacterial property test, and dyeing performance, including dye uptake, color difference, and fastness. Results showed that the synthesized dye was combined by –NH₃⁺ of O-carboxymethyl chitosan and the sulfonic group of Acid Red GR. According to the comprehensive analysis of XRD and water solubility, the introduction of the carboxymethyl group and acid dye molecule changed the structure of the chitosan from compact to loose, which improved the synthesized dye’s water solubility. However, the thermal stability of the synthesized dye was decreased. The antibacterial property of the poplar wood dyed with the synthesized dye was enhanced and its antibacterial rate, specifically against Staphylococcus aureus and Escherichia coli, also increased to a rate of more than 99%. However, the dye uptake of the synthesized dye was lower than that of the original dye. Despite this, though, the dyeing effect of the synthesized dye demonstrated better water-fastness, and light-fastness than the original dye. Therefore, the novel chitosan-based biopolymer dye can be a promising product for wood dyeing. Full article

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Open AccessArticle

Characteristic of Gelatine, Carrageenan and Sodium Alginate Hydrosols Treated by Direct Electric Current

by Żaneta Król, Magdalena Malik, Krzysztof Marycz and Andrzej Jarmoluk

Polymers 2016, 8(8), 275; https://doi.org/10.3390/polym8080275 - 30 Jul 2016

Cited by 43 | Viewed by 7019

Abstract

The aim of the study was to investigate the effect of using direct electric current (DC) of 400 mA for five minutes on the physiochemical properties of gelatine (2%, 4%, and 8%), carrageenan (1.5%, 2%, and 2.5%) and sodium alginate (0.75%, 1%, and [...] Read more.

The aim of the study was to investigate the effect of using direct electric current (DC) of 400 mA for five minutes on the physiochemical properties of gelatine (2%, 4%, and 8%), carrageenan (1.5%, 2%, and 2.5%) and sodium alginate (0.75%, 1%, and 1.25%) hydrosols with different sodium chloride concentration. The pH, oxidation-reduction potential (ORP), electrical conductivity (EC), available chlorine concentration (ACC) and rheological parameters were measured. Moreover, Fourier transform infrared spectroscopy (FT-IR) and Scanning Electron Microscopy (SEM) analysis were carried out. The results have shown that pH, ORP, EC and ACC values are changed upon applying DC and the magnitude of change depends on the concentration of the polymer and the addition of sodium chloride. After seven days of storage, the ACC of the samples exposed to DC decreased by 88%–96%. The FT-IR spectra demonstrated that the structure of gelatine, carrageenan and sodium alginate are not significantly affected by DC. Furthermore, the use of DC did not affect the flow and gelation temperature of the hydrosols. These results suggest that the use of DC did not cause undesirable changes in hydrosols layer and these innovative materials can be used, e.g., for food preservation. Full article

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Open AccessArticle

Oxidized Xanthan Gum and Chitosan as Natural Adhesives for Cork

by Diana Paiva, Carolina Gonçalves, Isabel Vale, Margarida M. S. M. Bastos and Fernão D. Magalhães

Polymers 2016, 8(7), 259; https://doi.org/10.3390/polym8070259 - 14 Jul 2016

Cited by 48 | Viewed by 12292

Abstract

Natural cork stopper manufacturing produces a significant amount of cork waste, which is granulated and combined with synthetic glues for use in a wide range of applications. There is a high demand for using biosourced polymers in these composite materials. In this study, [...] Read more.

Natural cork stopper manufacturing produces a significant amount of cork waste, which is granulated and combined with synthetic glues for use in a wide range of applications. There is a high demand for using biosourced polymers in these composite materials. In this study, xanthan gum (XG) and chitosan (CS) were investigated as possible natural binders for cork. Xanthan gum was oxidized at two different aldehyde contents as a strategy to improve its water resistance. This modification was studied in detail by ¹H and ¹³C nuclear magnetic resonance (NMR), and the degree of oxidation was determined by the hydroxylamine hydrochloride titration method. The performance of the adhesives was studied by tensile tests and total soluble matter (TSM) determinations. Xanthan gum showed no water resistance, contrary to oxidized xanthan gum and chitosan. It is hypothesized that the good performance of oxidized xanthan gum is due to the reaction of aldehyde groups—formed in the oxidation process—with hydroxyl groups on the cork surface during the high temperature drying. Combining oxidized xanthan gum with chitosan did not yield significant improvements. Full article

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Open AccessArticle

Correction of MHS Viscosimetric Constants upon Numerical Simulation of Temperature Induced Degradation Kinetic of Chitosan Solutions

by Vincenzo Maria De Benedictis, Giulia Soloperto and Christian Demitri

Polymers 2016, 8(6), 210; https://doi.org/10.3390/polym8060210 - 31 May 2016

Cited by 7 | Viewed by 6875

Abstract

The Mark–Houwink–Sakurada (MHS) equation allows for estimation of rheological properties, if the molecular weight is known along with good understanding of the polymer conformation. The intrinsic viscosity of a polymer solution is related to the polymer molecular weight according to the MHS equation, [...] Read more.

The Mark–Houwink–Sakurada (MHS) equation allows for estimation of rheological properties, if the molecular weight is known along with good understanding of the polymer conformation. The intrinsic viscosity of a polymer solution is related to the polymer molecular weight according to the MHS equation, where the value of the constants is related to the specific solvent and its concentration. However, MHS constants do not account for other characteristics of the polymeric solutions, i.e., Deacetilation Degree (DD) when the solute is chitosan. In this paper, the degradation of chitosan in different acidic environments by thermal treatment is addressed. In particular, two different solutions are investigated (used as solvent acetic or hydrochloric acid) with different concentrations used for the preparation of chitosan solutions. The samples were treated at different temperatures (4, 30, and 80 °C) and time points (3, 6 and 24 h). Rheological, Gel Permeation Chromatography (GPC), Fourier Transform Infrared Spectroscopy (FT-IR), Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analyses (TGA) were performed in order to assess the degradation rate of the polymer backbones. Measured values of molecular weight have been integrated in the simulation of the batch degradation of chitosan solutions for evaluating MHS coefficients to be compared with their corresponding experimental values. Evaluating the relationship between the different parameters used in the preparation of chitosan solutions (e.g., temperature, time, acid type and concentration), and their contribution to the degradation of chitosan backbone, it is important to have a mathematical frame that could account for phenomena involved in polymer degradation that go beyond the solvent-solute combination. Therefore, the goal of the present work is to propose an integration of MHS coefficients for chitosan solutions that contemplate a deacetylation degree for chitosan systems or a more general substitution degree for polymers in which viscosity depends not only on molecular weight and solvent combinations. Full article

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Open AccessArticle

Repair Effect of Seaweed Polysaccharides with Different Contents of Sulfate Group and Molecular Weights on Damaged HK-2 Cells

by Poonam Bhadja, Cai-Yan Tan, Jian-Ming Ouyang and Kai Yu

Polymers 2016, 8(5), 188; https://doi.org/10.3390/polym8050188 - 19 May 2016

Cited by 66 | Viewed by 8088

Abstract

The structure–activity relationships and repair mechanism of six low-molecular-weight seaweed polysaccharides (SPSs) on oxalate-induced damaged human kidney proximal tubular epithelial cells (HK-2) were investigated. These SPSs included Laminaria japonica polysaccharide, degraded Porphyra yezoensis polysaccharide, degraded Gracilaria lemaneiformis polysaccharide, degraded Sargassum fusiforme polysaccharide, Eucheuma [...] Read more.

The structure–activity relationships and repair mechanism of six low-molecular-weight seaweed polysaccharides (SPSs) on oxalate-induced damaged human kidney proximal tubular epithelial cells (HK-2) were investigated. These SPSs included Laminaria japonica polysaccharide, degraded Porphyra yezoensis polysaccharide, degraded Gracilaria lemaneiformis polysaccharide, degraded Sargassum fusiforme polysaccharide, Eucheuma gelatinae polysaccharide, and degraded Undaria pinnatifida polysaccharide. These SPSs have a narrow difference of molecular weight (from 1968 to 4020 Da) after degradation by controlling H₂O₂ concentration. The sulfate group (–SO₃H) content of the six SPSs was 21.7%, 17.9%, 13.3%, 8.2%, 7.0%, and 5.5%, respectively, and the –COOH contents varied between 1.0% to 1.7%. After degradation, no significant difference was observed in the contents of characteristic –SO₃H and –COOH groups of polysaccharides. The repair effect of polysaccharides was determined using cell-viability test by CCK-8 assay and cell-morphology test by hematoxylin-eosin staining. The results revealed that these SPSs within 0.1–100 μg/mL did not express cytotoxicity in HK-2 cells, and each polysaccharide had a repair effect on oxalate-induced damaged HK-2 cells. Simultaneously, the content of polysaccharide –SO₃H was positively correlated with repair ability. Furthermore, the low-molecular-weight degraded polysaccharides showed better repair activity on damaged HK-2 cells than their undegraded counterpart. Our results can provide reference for inhibiting the formation of kidney stones and for developing original anti-stone polysaccharide drugs. Full article

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Open AccessReview

Supramolecular Nanostructures Based on Cyclodextrin and Poly(ethylene oxide): Syntheses, Structural Characterizations and Applications for Drug Delivery

by Yue Zheng and Ian W. Wyman

Polymers 2016, 8(5), 198; https://doi.org/10.3390/polym8050198 - 17 May 2016

Cited by 29 | Viewed by 8983

Abstract

Cyclodextrins (CDs) have been extensively studied as drug delivery carriers through host–guest interactions. CD-based poly(pseudo)rotaxanes, which are composed of one or more CD rings threading on the polymer chain with or without bulky groups (or stoppers), have attracted great interest in the development [...] Read more.

Cyclodextrins (CDs) have been extensively studied as drug delivery carriers through host–guest interactions. CD-based poly(pseudo)rotaxanes, which are composed of one or more CD rings threading on the polymer chain with or without bulky groups (or stoppers), have attracted great interest in the development of supramolecular biomaterials. Poly(ethylene oxide) (PEO) is a water-soluble, biocompatible polymer. Depending on the molecular weight, PEO can be used as a plasticizer or as a toughening agent. Moreover, the hydrogels of PEO are also extensively studied because of their outstanding characteristics in biological drug delivery systems. These biomaterials based on CD and PEO for controlled drug delivery have received increasing attention in recent years. In this review, we summarize the recent progress in supramolecular architectures, focusing on poly(pseudo)rotaxanes, vesicles and supramolecular hydrogels based on CDs and PEO for drug delivery. Particular focus will be devoted to the structures and properties of supramolecular copolymers based on these materials as well as their use for the design and synthesis of supramolecular hydrogels. Moreover, the various applications of drug delivery techniques such as drug absorption, controlled release and drug targeting based CD/PEO supramolecular complexes, are also discussed. Full article

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Open AccessArticle

Study on Alginate–Chitosan Complex Formed with Different Polymers Ratio

by Dominika Kulig, Anna Zimoch-Korzycka, Andrzej Jarmoluk and Krzysztof Marycz

Polymers 2016, 8(5), 167; https://doi.org/10.3390/polym8050167 - 4 May 2016

Cited by 185 | Viewed by 12161

Abstract

Biomaterials based on polyelectrolyte complexation are an innovative concept of coatings and packaging production to be applied in a wide range of food products. The aim of this study was to obtain and characterize a sodium alginate–chitosan complex material with variable degree of [...] Read more.

Biomaterials based on polyelectrolyte complexation are an innovative concept of coatings and packaging production to be applied in a wide range of food products. The aim of this study was to obtain and characterize a sodium alginate–chitosan complex material with variable degree of polyion interactions by complexation of oppositely charged polysaccharides. In order to characterize polyelectrolyte complexes, theromogravimetric analysis (TGA), dynamic mechanical thermal analysis (DMTA), nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), matrix-assisted laser desorption/ionization technique with time of flight analyzer (MALDI-TOF), and scanning electron microscopy (SEM) were performed. TGA analysis showed that thermal decomposition temperature depends on the polymer ratio (R) and thermal resistance of samples was improved by increasing chitosan dosage. Accordingly to DMTA results, polyelectrolyte complexation led to obtain more flexible and resistant to mechanical deformation materials. Comparative analysis of the FTIR spectra of single polyelectrolytes, chitosan and alginate, and their mixtures indicated the formation of the polyelectrolyte complex without addition of reinforcing substances. MALDI-TOF analysis confirms the creation of polyelectrolyte aggregates (~197 Da) in samples with R ≥ 0.8; and their chemical stability and safety were proven by NMR analysis. The higher R the greater the number of polyanion–polycation aggregates seen in SEM as film morphology roughness. Full article

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Open AccessArticle

²H Solid-State NMR Analysis of the Dynamics and Organization of Water in Hydrated Chitosan

by Fenfen Wang, Rongchun Zhang, Tiehong Chen and Pingchuan Sun

Polymers 2016, 8(4), 149; https://doi.org/10.3390/polym8040149 - 19 Apr 2016

Cited by 12 | Viewed by 6855

Abstract

Understanding water–biopolymer interactions, which strongly affect the function and properties of biopolymer-based tissue engineering and drug delivery materials, remains a challenge. Chitosan, which is an important biopolymer for the construction of artificial tissue grafts and for drug delivery, has attracted extensive attention in [...] Read more.

Understanding water–biopolymer interactions, which strongly affect the function and properties of biopolymer-based tissue engineering and drug delivery materials, remains a challenge. Chitosan, which is an important biopolymer for the construction of artificial tissue grafts and for drug delivery, has attracted extensive attention in recent decades, where neutralization with an alkali solution can substantially enhance the final properties of chitosan films cast from an acidic solution. In this work, to elucidate the effect of water on the properties of chitosan films, we investigated the dynamics and different states of water in non-neutralized (CTS-A) and neutralized (CTS-N) hydrated chitosan by mobility selective variable-temperature (VT) ²H solid-state NMR spectroscopy. Four distinct types of water exist in all of the samples with regards to dynamic behavior. First, non-freezable, rigid and strongly bound water was found in the crystalline domain at low temperatures. The second component consists of weakly bound water, which is highly mobile and exhibits isotropic motion, even below 260 K. Another type of water undergoes well-defined 180° flips around their bisector axis. Moreover, free water is also present in the films. For the CTS-A sample in particular, another special water species were bounded to acetic acid molecules via strong hydrogen bonding. In the case of CTS-N, the onset of motions of the weakly bound water molecules at 260 K was revealed by ²H-NMR spectroscopy. This water is not crystalline, even below 260 K, which is also the major contribution to the flexibility of chitosan chains and thus toughness of materials. By contrast, such motion was not observed in CTS-A. On the basis of the ²H solid-state NMR results, it is concluded that the unique toughness of CTS-N mainly originates from the weakly bound water as well as the interactions between water and the chitosan chains. Full article

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Open AccessArticle

Preparation of Esterified Bacterial Cellulose for Improved Mechanical Properties and the Microstructure of Isotactic Polypropylene/Bacterial Cellulose Composites

by Bo Wang, Dan Yang, Hai-rong Zhang, Chao Huang, Lian Xiong, Jun Luo and Xin-de Chen

Polymers 2016, 8(4), 129; https://doi.org/10.3390/polym8040129 - 12 Apr 2016

Cited by 27 | Viewed by 6856

Abstract

Bacterial cellulose (BC) has great potential to be used as a new filler to reinforce isotactic polypropylene (iPP) due to its high crystallinity, biodegradability, and efficient mechanical properties. In this study, esterification was used to modify BC, which improved the surface compatibility of [...] Read more.

Bacterial cellulose (BC) has great potential to be used as a new filler to reinforce isotactic polypropylene (iPP) due to its high crystallinity, biodegradability, and efficient mechanical properties. In this study, esterification was used to modify BC, which improved the surface compatibility of the iPP and BC. The results indicated that the cellulose octoate (CO) changed the surface properties from hydrophilic to lipophilic. Compared to the pure iPP, the tensile strength, charpy notched impact strength, and tensile modulus of the iPP/BC composites increased by 9.9%, 7.77%, and 15.64%, respectively. However, the addition of CO reinforced the iPP/CO composites. The tensile strength, charpy notched impact strength, and tensile modulus of the iPP/CO composites increased by 14.23%, 14.08%, and 17.82% compared to the pure iPP. However, the elongation at break of both the composites is decreased. The SEM photographs and particle size distribution of the composites showed improvements when the change of polarity of the BC surface, interface compatibility, and dispersion of iPP improved. Full article

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Open AccessArticle

New Concept of Polymethyl Methacrylate (PMMA) and Polyethylene Terephthalate (PET) Surface Coating by Chitosan

by Mieszko Wieckiewicz, Eric Wolf, Gert Richter, Heike Meissner and Klaus Boening

Polymers 2016, 8(4), 132; https://doi.org/10.3390/polym8040132 - 7 Apr 2016

Cited by 15 | Viewed by 9065

Abstract

Chitosan is known for its hemostatic and antimicrobial properties and might be useful for temporary coating of removable dentures or intraoral splints to control bleeding after oral surgery or as a supportive treatment in denture stomatitis. This study investigated a new method to [...] Read more.

Chitosan is known for its hemostatic and antimicrobial properties and might be useful for temporary coating of removable dentures or intraoral splints to control bleeding after oral surgery or as a supportive treatment in denture stomatitis. This study investigated a new method to adhere chitosan to polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET). There were 70 cylindrical specimens made from PMMA and 70 from PET (13 mm diameter, 6 mm thickness). The materials with ten specimens each were sandblasted at 2.8 or 4.0 bar with aluminum oxide 110 μm or/and aluminum oxide coated with silica. After sandblasting, all specimens were coated with a 2% or 4% acetic chitosan solution with a thickness of 1 mm. Then the specimens were dried for 120 min at 45 °C. The precipitated chitosan was neutralized with 1 mol NaOH. After neutralization, all specimens underwent abrasion tests using the tooth-brushing simulator with soft brushes (load 2N, 2 cycles/s, 32 °C, 3000 and 30,000 cycles). After each run, the specimen surfaces were analyzed for areas of remaining chitosan by digital planimetry under a light microscope. The best chitosan adhesion was found after sandblasting with aluminum oxide coated with silica (U-Test, p < 0.05) in both the PMMA and the PET groups. Hence, with relatively simple technology, a reliable bond of chitosan to PMMA and PET could be achieved. Full article

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Open AccessArticle

Preparation of Highly Dispersed Reduced Graphene Oxide Modified with Carboxymethyl Chitosan for Highly Sensitive Detection of Trace Cu(II) in Water

by Sheng Chen, Rui Ding, Xiuling Ma, Liqun Xue, Xiuzhu Lin, Xiaoping Fan and Zhimin Luo

Polymers 2016, 8(4), 78; https://doi.org/10.3390/polym8040078 - 1 Apr 2016

Cited by 16 | Viewed by 6391

Abstract

In this article, reduced graphene oxide (RGO)/carboxymethyl chitosan (CMC) composites (RGO/CMC) were synthesized by a hydrothermal method through in-situ reduction and modification of graphene oxide (GO) in the presence of CMC. An electrochemical sensor for the determination of Cu(II) by differential pulse anodic [...] Read more.

In this article, reduced graphene oxide (RGO)/carboxymethyl chitosan (CMC) composites (RGO/CMC) were synthesized by a hydrothermal method through in-situ reduction and modification of graphene oxide (GO) in the presence of CMC. An electrochemical sensor for the determination of Cu(II) by differential pulse anodic stripping voltammetry (DPASV) was constructed by an electrode modified with RGO/CMC. The fabricated electrochemical sensor shows a linear range of 0.02–1.2 μmol·L⁻¹, a detection limit of 3.25 nmol·L⁻¹ (S/N = 3) and a sensitivity of 130.75 μA·μmol·L⁻¹·cm⁻², indicating the sensor has an excellent detection performance for Cu(II). Full article

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Open AccessArticle

Crosslinked and Dyed Chitosan Fiber Presenting Enhanced Acid Resistance and Bioactivities

by Xiao-Qiong Li and Ren-Cheng Tang

Polymers 2016, 8(4), 119; https://doi.org/10.3390/polym8040119 - 1 Apr 2016

Cited by 21 | Viewed by 6033

Abstract

The application of biodegradable chitosan fiber for healthy and hygienic textiles is limited due to its poor acid resistance in wet processing and poor antioxidant activity. In order to prepare chitosan fiber with good acid resistance and high antioxidant activity, chitosan fiber was [...] Read more.

The application of biodegradable chitosan fiber for healthy and hygienic textiles is limited due to its poor acid resistance in wet processing and poor antioxidant activity. In order to prepare chitosan fiber with good acid resistance and high antioxidant activity, chitosan fiber was first crosslinked by a water-soluble aziridine crosslinker, and then dyed with natural lac dye consisting of polyphenolic anthraquinone compounds. The main application conditions and crosslinking mechanism of the aziridine crosslinker, the adsorption mechanism and building-up property of lac dye on the crosslinked fiber, and the effects of crosslinking and dyeing on the antioxidant and antibacterial activities of chitosan fiber were studied. The crosslinked fiber exhibited greatly reduced weight loss in acidic solution, and possessed excellent acid resistance. Lac dye displayed a very high adsorption capability on the crosslinked fiber and a high utilization rate under weakly acidic medium. The Langmuir–Nernst isotherm was the best model to describe the adsorption behavior of lac dye, and Langmuir adsorption had great contribution to total adsorption. Lac dyeing imparted good antioxidant activity to chitosan fiber. Crosslinking and dyeing had no impact on the good inherent antibacterial activity of chitosan fiber. Full article

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Open AccessArticle

Thermosensitive Behavior and Antibacterial Activity of Cotton Fabric Modified with a Chitosan-poly(N-isopropylacrylamide) Interpenetrating Polymer Network Hydrogel

by Boxiang Wang, Xiaolin Wu, Jia Li, Xu Hao, Jie Lin, Dehong Cheng and Yanhua Lu

Polymers 2016, 8(4), 110; https://doi.org/10.3390/polym8040110 - 28 Mar 2016

Cited by 51 | Viewed by 12198

Abstract

To increase the themosensitive behavior and antibacterial activity of cotton fabric, a series of poly (N-isopropylacrylamide)/chitosan (PNIPAAm/Cs) hydrogels was synthesized by interpenetrating polymer network (IPN) technology using a redox initiator. The IPN PNIPAAm/Cs hydrogel was characterized by Fourier transform infrared spectroscopy [...] Read more.

To increase the themosensitive behavior and antibacterial activity of cotton fabric, a series of poly (N-isopropylacrylamide)/chitosan (PNIPAAm/Cs) hydrogels was synthesized by interpenetrating polymer network (IPN) technology using a redox initiator. The IPN PNIPAAm/Cs hydrogel was characterized by Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results indicated that the IPN PNIPAAm/Cs hydrogel has a lower critical solution temperature (LCST) at 33 °C. The IPN hydrogel was then used to modify cotton fabric using glutaric dialdehyde (GA) as a crosslinking agent following a double-dip-double-nip process. The results demonstrated that the modified cotton fabric showed obvious thermosensitive behavior and antibacterial activity. The contact angle of the modified cotton fabric has a sharp rise around 33 °C, and the modified cotton fabric showed an obvious thermosensitive behavior. The bacterial reduction of modified cotton fabric against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were more than 99%. This study presents a valuable route towards smart textiles and their applications in functional clothing. Full article

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Open AccessFeature PaperArticle

PEG-Chitosan Hydrogel with Tunable Stiffness for Study of Drug Response of Breast Cancer Cells

by Fei-Chien Chang, Ching-Ting Tsao, Anqi Lin, Mengying Zhang, Sheeny Lan Levengood and Miqin Zhang

Polymers 2016, 8(4), 112; https://doi.org/10.3390/polym8040112 - 26 Mar 2016

Cited by 44 | Viewed by 11863

Abstract

Mechanical properties of the extracellular matrix have a profound effect on the behavior of anchorage-dependent cells. However, the mechanisms that define the effects of matrix stiffness on cell behavior remains unclear. Therefore, the development and fabrication of synthetic matrices with well-defined stiffness is [...] Read more.

Mechanical properties of the extracellular matrix have a profound effect on the behavior of anchorage-dependent cells. However, the mechanisms that define the effects of matrix stiffness on cell behavior remains unclear. Therefore, the development and fabrication of synthetic matrices with well-defined stiffness is invaluable for studying the interactions of cells with their biophysical microenvironment in vitro. We demonstrate a methoxypolyethylene glycol (mPEG)-modified chitosan hydrogel network where hydrogel stiffness can be easily modulated under physiological conditions by adjusting the degree of mPEG grafting onto chitosan (PEGylation). We show that the storage modulus of the hydrogel increases as PEGylation decreases and the gels exhibit instant self-recovery after deformation. Breast cancer cells cultured on the stiffest hydrogels adopt a more malignant phenotype with increased resistance to doxorubicin as compared with cells cultured on tissue culture polystyrene or Matrigel. This work demonstrates the utility of mPEG-modified chitosan hydrogel, with tunable mechanical properties, as an improved replacement of conventional culture system for in vitro characterization of breast cancer cell phenotype and evaluation of cancer therapies. Full article

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Open AccessArticle

Functionalized Cellulose Networks for Efficient Oil Removal from Oil–Water Emulsions

by Uttam C. Paul, Despina Fragouli, Ilker S. Bayer and Athanassia Athanassiou

Polymers 2016, 8(2), 52; https://doi.org/10.3390/polym8020052 - 17 Feb 2016

Cited by 50 | Viewed by 8406

Abstract

The separation of oil from water in emulsions is a great environmental challenge, since oily wastewater is industrially produced. Here, we demonstrate a highly efficient method to separate oil from water in non-stabilized emulsions, using functionalized cellulose fiber networks. This is achieved by [...] Read more.

The separation of oil from water in emulsions is a great environmental challenge, since oily wastewater is industrially produced. Here, we demonstrate a highly efficient method to separate oil from water in non-stabilized emulsions, using functionalized cellulose fiber networks. This is achieved by the modification of the wetting properties of the fibers, transforming them from oil- and water-absorbing to water-absorbing and oil-proof. In particular, two diverse layers of polymeric coatings, paraffin wax and poly(dimethylsiloxane)-b-poly(ethylene oxide) (PDMS-b-PEO) diblock copolymer, are applied on the surface of each individual fiber by a two-step dip adsorption process. The resulting cellulose networks exhibit superhydrophilicity and underwater superoleophobicity and they are mechanically reinforced. Therefore, the described treatment makes cellulose fiber networks excellent candidates for the filtration and subsequent removal of oil from oil-in-water non-stabilized emulsions with oil separation efficiency up to 99%. The good selectivity, reproducibility, and cost effectiveness of the preparation process leads to the production of low cost filters that can be used in oil–water separation applications. Full article

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Open AccessArticle

Artificial Neural Network and Response Surface Methodology Modeling in Ionic Conductivity Predictions of Phthaloylchitosan-Based Gel Polymer Electrolyte

by Ahmad Danial Azzahari, Siti Nor Farhana Yusuf, Vidhya Selvanathan and Rosiyah Yahya

Polymers 2016, 8(2), 22; https://doi.org/10.3390/polym8020022 - 29 Jan 2016

Cited by 19 | Viewed by 6345

Abstract

A gel polymer electrolyte system based on phthaloylchitosan was prepared. The effects of process variables, such as lithium iodide, caesium iodide, and 1-butyl-3-methylimidazolium iodide were investigated using a distance-based ternary mixture experimental design. A comparative approach was made between response surface methodology (RSM) [...] Read more.

A gel polymer electrolyte system based on phthaloylchitosan was prepared. The effects of process variables, such as lithium iodide, caesium iodide, and 1-butyl-3-methylimidazolium iodide were investigated using a distance-based ternary mixture experimental design. A comparative approach was made between response surface methodology (RSM) and artificial neural network (ANN) to predict the ionic conductivity. The predictive capabilities of the two methodologies were compared in terms of coefficient of determination R² based on the validation data set. It was shown that the developed ANN model had better predictive outcome as compared to the RSM model. Full article

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Open AccessReview

Seaweed Polysaccharide-Based Nanoparticles: Preparation and Applications for Drug Delivery

by Jayachandran Venkatesan, Sukumaran Anil, Se-Kwon Kim and Min Suk Shim

Polymers 2016, 8(2), 30; https://doi.org/10.3390/polym8020030 - 26 Jan 2016

Cited by 148 | Viewed by 18727

Abstract

In recent years, there have been major advances and increasing amounts of research on the utilization of natural polymeric materials as drug delivery vehicles due to their biocompatibility and biodegradability. Seaweed polysaccharides are abundant resources and have been extensively studied for several biological, [...] Read more.

In recent years, there have been major advances and increasing amounts of research on the utilization of natural polymeric materials as drug delivery vehicles due to their biocompatibility and biodegradability. Seaweed polysaccharides are abundant resources and have been extensively studied for several biological, biomedical, and functional food applications. The exploration of seaweed polysaccharides for drug delivery applications is still in its infancy. Alginate, carrageenan, fucoidan, ulvan, and laminarin are polysaccharides commonly isolated from seaweed. These natural polymers can be converted into nanoparticles (NPs) by different types of methods, such as ionic gelation, emulsion, and polyelectrolyte complexing. Ionic gelation and polyelectrolyte complexing are commonly employed by adding cationic molecules to these anionic polymers to produce NPs of a desired shape, size, and charge. In the present review, we have discussed the preparation of seaweed polysaccharide-based NPs using different types of methods as well as their usage as carriers for the delivery of various therapeutic molecules (e.g., proteins, peptides, anti-cancer drugs, and antibiotics). Seaweed polysaccharide-based NPs exhibit suitable particle size, high drug encapsulation, and sustained drug release with high biocompatibility, thereby demonstrating their high potential for safe and efficient drug delivery. Full article

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Open AccessArticle

Study of Enzymatically Treated Alginate/Chitosan Hydrosols in Sponges Formation Process

by Anna Zimoch-Korzycka, Dominika Kulig, Andrzej Jarmoluk, Krzysztof Marycz and Weronika Matuszczak

Polymers 2016, 8(1), 8; https://doi.org/10.3390/polym8010008 - 5 Jan 2016

Cited by 108 | Viewed by 6347

Abstract

The aim of the study was to produce 3D sponges based on enzymatically modified lysozyme selected polysaccharides and assess their physicochemical properties. The alginate/chitosan sponges were formed from polymers hydrosols in different proportions at a final concentration of 1% polysaccharides. Hydrosols were modified [...] Read more.

The aim of the study was to produce 3D sponges based on enzymatically modified lysozyme selected polysaccharides and assess their physicochemical properties. The alginate/chitosan sponges were formed from polymers hydrosols in different proportions at a final concentration of 1% polysaccharides. Hydrosols were modified by lysozyme addition of 1000 U. Hydrosols without or with enzyme were analyzed for their reducing sugar content, rheological properties and ability to scavenge free radicals. Sponges formed from hydrosols were tested for solubility and compressive properties. Only chitosan was hydrolyzed by lysozyme. The morphology of sponges was investigated by scanning electron microscopy (SEM). It was proven that the antioxidant properties of hydrosols are dependent on the concentration of chitosan. It was also shown that the addition of lysozyme negatively affected the free radical scavenging ability of single hydrosols of alginate and chitosan, and their mixtures. The Ostwald de Waele as well as Herschel–Bulkley models of rheological properties fitted the experimental data well (R² is between 0.947 and 1.000). Increase in textural features values of sponges was observed. Sponges with pure alginate and pure chitosan were almost completely soluble. The enzyme addition significantly changed the characteristics of the cross-section structure of sponges, and made the surface smoother. Full article

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2015

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Open AccessArticle

Synthesis and Biological Evaluation of New Imine- and Amino-Chitosan Derivatives

by Huda E. Abdelwahab, Seham Y. Hassan, Galila A. Yacout, Mohamed A. Mostafa and Mohamed M. El Sadek

Polymers 2015, 7(12), 2690-2700; https://doi.org/10.3390/polym7121532 - 21 Dec 2015

Cited by 39 | Viewed by 6458

Abstract

N-substituted chitosan derivatives were synthesized through condensation with a number of selected aryl and heteroaryl aldehydes. The synthesis of the amino-derivatives has been carried out by reductive amination with sodium borohydride as reducing agent. Their structures were characterized by (FT-IR, ¹HNMR, [...] Read more.

N-substituted chitosan derivatives were synthesized through condensation with a number of selected aryl and heteroaryl aldehydes. The synthesis of the amino-derivatives has been carried out by reductive amination with sodium borohydride as reducing agent. Their structures were characterized by (FT-IR, ¹HNMR, and XRD). The antimicrobial activity of Chitosan Schiff’s base (CSB) derivatives were investigated against four types of bacteria and two crop-threatening pathogenic fungi, and the results indicated that the antibacterial and antifungal activities of the investigated derivatives are very promising. Additionally, different concentrations of the triazolo-Schiff’s base derivative 3c were used for cytotoxicity screening against Human Breast Adenocarcinoma Cells (MCF-7), Human Colon Carcinoma Cells (HCT-116), and Human Hepatocellular Liver Carcinoma Cells (HepG-2), and the obtained data revealed that the examined compounds have an excellent cell growth inhibitory effects on the cell lines as compared to standard. Full article

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Open AccessArticle

Preparation and Characterization of EG-Chitosan Nanocomposites via Direct Exfoliation: A Green Methodology

by Christian Demitri, Anna Moscatello, Antonella Giuri, Maria Grazia Raucci and Carola Esposito Corcione

Polymers 2015, 7(12), 2584-2594; https://doi.org/10.3390/polym7121535 - 9 Dec 2015

Cited by 13 | Viewed by 5929

Abstract

In this study, free-standing expanded graphite chitosan (EG-chitosan) nanocomposite films have been prepared using a novel green and simple preparation method, starting from a commercial expandable graphite (GIC). The in situ exfoliation of GIC by a solvent-free sonication method was monitored as a [...] Read more.

In this study, free-standing expanded graphite chitosan (EG-chitosan) nanocomposite films have been prepared using a novel green and simple preparation method, starting from a commercial expandable graphite (GIC). The in situ exfoliation of GIC by a solvent-free sonication method was monitored as a function of the process parameters using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and UV-visible transmittance (UV-VIS) analyses. The optimal process parameters were selected in order to obtain an efficient dispersion of EG in chitosan solutions. The effective EG amount after the in situ exfoliation was also determined by thermogravimetric analyses. Full article

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Open AccessArticle

The Effect of β-Glycerophosphate Crosslinking on Chitosan Cytotoxicity and Properties of Hydrogels for Vaginal Application

by Emilia Szymaǹska, Katarzyna Sosnowska, Wojciech Miltyk, Małgorzata Rusak, Anna Basa and Katarzyna Winnicka

Polymers 2015, 7(11), 2223-2244; https://doi.org/10.3390/polym7111510 - 4 Nov 2015

Cited by 34 | Viewed by 10302

Abstract

Mucoadhesive gelling systems based on chitosan and chitosan/β-glycerophosphate (β-GP) were developed in order to increase clotrimazole residence time in the vaginal cavity. Ex vivo mucoadhesiveness using porcine vaginal mucosa followed with mechanical, viscoelastic, and swelling properties of prepared hydrogels were evaluated. Drug-free, sterile, [...] Read more.

Mucoadhesive gelling systems based on chitosan and chitosan/β-glycerophosphate (β-GP) were developed in order to increase clotrimazole residence time in the vaginal cavity. Ex vivo mucoadhesiveness using porcine vaginal mucosa followed with mechanical, viscoelastic, and swelling properties of prepared hydrogels were evaluated. Drug-free, sterile, unmodified, and β-GP crosslinked chitosan were investigated for the in vitro cytotoxicity in CRL 2616 human vaginal mucosa cells using MTT assay, fluorescent microscopy, and flow cytometry analysis. Chitosan/β-GP hydrogels exhibited pseudoplastic and thixotropic properties. Ionic interaction between β-GP and chitosan improved mechanical properties of hydrogels in terms of hardness, cohesiveness, and compressibility. The hydrogels’ ability to interact with porcine vaginal mucosa (measured as force of detachment and work of adhesion) was comparable to those obtained with reference mucoadhesive gel Replens™. Surprisingly, greater mucoadhesive properties were noticed for chitosan/β-GP hydrogels. The cytotoxic effect of unmodified and β-GP crosslinked chitosan was hardly affected by chitosan molecular weight, exhibited mainly through inducing apoptosis, and was found to be significantly lower in the presence of chitosan/β-GP. Furthermore, the higher amount of β-GP was used to crosslink chitosan, the lower cytotoxic effect was observed. Full article

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Open AccessArticle

Microwave-Absorbing Properties of Rice Starch

by Daming Fan, Huijie Shen, Luelue Huang, Yishu Gao, Huizhang Lian, Jianxin Zhao, Hao Zhang and Wei Chen

Polymers 2015, 7(9), 1895-1904; https://doi.org/10.3390/polym7091487 - 22 Sep 2015

Cited by 14 | Viewed by 6087

Abstract

In the food industry, research into the characteristics of microwave-heated materials has focused on dielectric properties. However, the lack of studies on microwave-absorbing properties has hindered the application of microwave technology. The aim of the present study was to investigate the microwave-absorbing properties [...] Read more.

In the food industry, research into the characteristics of microwave-heated materials has focused on dielectric properties. However, the lack of studies on microwave-absorbing properties has hindered the application of microwave technology. The aim of the present study was to investigate the microwave-absorbing properties of rice starch. It should be noted that this was the first time that the improved arch method was used to measure the microwave reflection loss (RL) of the starch dispersion. The results showed that the microwave absorption of the liquid system corresponded to the classical quarter-wavelength resonator model. When the concentration of the native starch was increased from 1% to 30%, the RL decreased from −5.1 dB to −1.2 dB at 2.45 GHz. Therefore, the absorption rate of microwave, γ_ab, decreased from 69.1% to 24.1%. At 1.7 to 2.6 GHz, the interference effect of pregelatinization rice starch in an aqueous system on the microwave absorption properties became weak compared to native starch. Full article

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Open AccessArticle

Preparation and Evaluation of Vancomycin-Loaded N-trimethyl Chitosan Nanoparticles

by Jiaojiao Xu, Beihua Xu, Dan Shou, Xiaojing Xia and Ying Hu

Polymers 2015, 7(9), 1850-1870; https://doi.org/10.3390/polym7091488 - 22 Sep 2015

Cited by 91 | Viewed by 12135

Abstract

Chronic intracellular infections caused by drug-resistant pathogens pose a challenge to the treatment of chronic osteomyelitis. Such treatment requires an intracellular delivery system for the sustained release of antibiotics such as vancomycin (VCM), which is an antibiotic of last resort used against many [...] Read more.

Chronic intracellular infections caused by drug-resistant pathogens pose a challenge to the treatment of chronic osteomyelitis. Such treatment requires an intracellular delivery system for the sustained release of antibiotics such as vancomycin (VCM), which is an antibiotic of last resort used against many clinically resistant bacteria. In this work, we report VCM-loaded N-trimethyl chitosan (TMC) nanoparticles and their potential application for drug delivery. The results showed that the prepared nanoparticles were predominantly spherical in shape with an average particle diameter of 220 nm, a positive zeta potential, and a loading efficiency of 73.65% ± 1.83%. Furthermore, their drug release profile followed the Higuchi model for sustained release, with non-Fickian diffusion. Over a 24-h period, 6.51% ± 0.58% of the drug within the optimized nanoparticles was released. In vitro cytology showed that osteoblasts (OBs) exhibited higher alkaline phosphatase activity (ALP) after exposure to TMC nanoparticle material. Furthermore, TMC nanoparticles increased the uptake of water-soluble quantum dots (QDs) by OBs, and both nanoparticles and VCM/TMC mixtures improved OB proliferative activity. We also investigated the minimum inhibitory concentration (MIC, 60 μg/mL), half maximal inhibitory concentration (IC50, 48.47 μg/mL), diameter of inhibition zone (DIZ, 1.050 cm), and turbidimetric (TB) assay of nanoparticles. All data demonstrated that VCM/TMC nanoparticles had excellent antibacterial activity against the Gram-positive bacterium Staphylococcus aureus. These findings suggest that VCM-loaded TMC nanoparticles have good potential for the sustained delivery of antibiotics to bone infections. Full article

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Open AccessArticle

Preparation and Properties of Cellulose Laurate (CL)/Starch Nanocrystals Acetate (SNA) Bio-nanocomposites

by Feng-Yuan Huang, Xiao-Jie Wu, Yan Yu and Yan-Hua Lu

Polymers 2015, 7(7), 1331-1345; https://doi.org/10.3390/polym7071331 - 14 Jul 2015

Cited by 13 | Viewed by 10548

Abstract

In the present paper, a series of totally novel bio-nanocomposite films from cellulose laurate (CL) and starch nanocrystals acetate (SNA) were fabricated, and the properties of nanocomposite films were investigated in detail. SNA was obtained by modifying starch nanocrystals (SNs) produced by sulfuric [...] Read more.

In the present paper, a series of totally novel bio-nanocomposite films from cellulose laurate (CL) and starch nanocrystals acetate (SNA) were fabricated, and the properties of nanocomposite films were investigated in detail. SNA was obtained by modifying starch nanocrystals (SNs) produced by sulfuric acid hydrolysis of corn starch with acetic anhydride. The favorable dispersity of SNA in chloroform made it ready to convert into nanocomposite films with CL via casting/evaporation method. The transmittance, thermal behavior, mechanical properties, barrier properties and hydrophobicity of CL/SNA nanocomposite films were investigated with UV-vis spectrophotometer, simultaneous thermal analyzer (STA), universal tensile tester/dynamic thermomechanical analysis (DMA), water vapor permeation meter/oxygen permeability tester, and contact angle tester, respectively. The transmittance of nanocomposite films decreased with the increase of SNA content. Thermogravimetric analysis (TGA) results showed that the introduction of SNA into CL matrix did not severely decrease the thermal behavior of CL/SNA nanocomposites. Moreover, non-linear and linear mechanical analysis reflected the enhancement of SNA. At lower contents of SNA (<5.0 wt%), the values of Young’s modulus, tensile strength and the elongation at break of nanocomposite films were comparable with those of neat CL. However, with the increase of SNA, the Young’s modulus and tensile strength were improved significantly and were accompanied by the decreased elongation at break. The water vapor permeability (WVP) and oxygen permeability (P_O₂) of CL/SNA nanocomposite films were significantly improved by the addition of SNA. Full article

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Open AccessArticle

Effect of Plasticizer Type and Concentration on Tensile, Thermal and Barrier Properties of Biodegradable Films Based on Sugar Palm (Arenga pinnata) Starch

by Muhammed L. Sanyang, Salit M. Sapuan, Mohammad Jawaid, Mohamad R. Ishak and Japar Sahari

Polymers 2015, 7(6), 1106-1124; https://doi.org/10.3390/polym7061106 - 18 Jun 2015

Cited by 380 | Viewed by 21765

Abstract

The use of starch based films as a potential alternative choice to petroleum derived plastics is imperative for environmental waste management. This study presents a new biopolymer (sugar palm starch) for the preparation of biodegradable packaging films using a solution casting technique. The [...] Read more.

The use of starch based films as a potential alternative choice to petroleum derived plastics is imperative for environmental waste management. This study presents a new biopolymer (sugar palm starch) for the preparation of biodegradable packaging films using a solution casting technique. The effect of different plasticizer types (glycerol (G), sorbitol (S) and glycerol-sorbitol (GS) combination) with varying concentrations (0, 15, 30 and 45, w/w%) on the tensile, thermal and barrier properties of sugar palm starch (SPS) films was evaluated. Regardless of plasticizer types, the tensile strength of plasticized SPS films decreased, whereas their elongation at break (E%) increased as the plasticizer concentrations were raised. However, the E% for G and GS-plasticized films significantly decreased at a higher plasticizer concentration (45% w/w) due to the anti-plasticization effect of plasticizers. Change in plasticizer concentration showed an insignificant effect on the thermal properties of S-plasticized films. The glass transition temperature of SPS films slightly decreased as the plasticizer concentration increased from 15% to 45%. The plasticized films exhibited increased water vapor permeability values from 4.855 × 10⁻¹⁰ to 8.70 × 10⁻¹⁰ g·m⁻¹·s⁻¹·Pa⁻¹, irrespective of plasticizer types. Overall, the current study manifested that plasticized sugar palm starch can be regarded as a promising biopolymer for biodegradable films. Full article

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Open AccessReview

Methylcellulose, a Cellulose Derivative with Original Physical Properties and Extended Applications

by Pauline L. Nasatto, Frédéric Pignon, Joana L. M. Silveira, Maria Eugênia R. Duarte, Miguel D. Noseda and Marguerite Rinaudo

Polymers 2015, 7(5), 777-803; https://doi.org/10.3390/polym7050777 - 24 Apr 2015

Cited by 369 | Viewed by 34956

Abstract

This review covers the preparation, characterization, properties, and applications of methylcelluloses (MC). In particular, the influence of different chemical modifications of cellulose (under both heterogeneous and homogeneous conditions) is discussed in relation to the physical properties (solubility, gelation) of the methylcelluloses. The molecular [...] Read more.

This review covers the preparation, characterization, properties, and applications of methylcelluloses (MC). In particular, the influence of different chemical modifications of cellulose (under both heterogeneous and homogeneous conditions) is discussed in relation to the physical properties (solubility, gelation) of the methylcelluloses. The molecular weight (MW) obtained from the viscosity is presented together with the nuclear magnetic resonance (NMR) analysis required for the determination of the degree of methylation. The influence of the molecular weight on the main physical properties of methylcellulose in aqueous solution is analyzed. The interfacial properties are examined together with thermogelation. The surface tension and adsorption at interfaces are described: surface tension in aqueous solution is independent of molecular weight but the adsorption at the solid interface depends on the MW, the higher the MW the thicker the polymeric layer adsorbed. The two-step mechanism of gelation is confirmed and it is shown that the elastic moduli of high temperature gels are not dependent on the molecular weight but only on polymer concentration. Finally, the main applications of MC are listed showing the broad range of applications of these water soluble cellulose derivatives. Full article

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Open AccessArticle

Keratin/Polyvinyl Alcohol Blend Films Cross-Linked by Dialdehyde Starch and Their Potential Application for Drug Release

by Yao Dou, Buning Zhang, Ming He, Guoqiang Yin, Yingde Cui and Irina N. Savina

Polymers 2015, 7(3), 580-591; https://doi.org/10.3390/polym7030580 - 23 Mar 2015

Cited by 75 | Viewed by 11209

Abstract

Feather keratin (FK) extracted from feathers represents a valuable source of biodegradable and biocompatible polymer. The aim of this study was the development and characterization of blended films based on FK and polyvinyl alcohol (PVA) cross-linked by dialdehyde starch (DAS) for a potential [...] Read more.

Feather keratin (FK) extracted from feathers represents a valuable source of biodegradable and biocompatible polymer. The aim of this study was the development and characterization of blended films based on FK and polyvinyl alcohol (PVA) cross-linked by dialdehyde starch (DAS) for a potential drug release application. The compatibility of FK/PVA was improved when cross-linked by DAS: the relative crystallinity of the PVA/FK film slightly decreased, and the enthalpy value for the melting peak decreased by about 50% for the cross-linked films. The total soluble mass of all blend films in water was below 35% at 37 °C, indicating a good stability of the films in water. The results of the Rhodamine B dye (as a model drug) release tests showed that the release rates decreased with increasing DAS content. DAS-induced cross-linking improves several important properties of the FK/PVA films, such as the compactness, the compatibility, and the stability in water. These improvements offer the potential to expand the application of FK films in the biomaterial field. Full article

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Open AccessReview

Chitosan: Gels and Interfacial Properties

by Julie Nilsen-Nygaard, Sabina P. Strand, Kjell M. Vårum, Kurt I. Draget and Catherine T. Nordgård

Polymers 2015, 7(3), 552-579; https://doi.org/10.3390/polym7030552 - 13 Mar 2015

Cited by 254 | Viewed by 25168

Abstract

Chitosan is a unique biopolymer in the respect that it is abundant, cationic, low-toxic, non-immunogenic and biodegradable. The relative occurrence of the two monomeric building units (N-acetyl-glucosamine and d-glucosamine) is crucial to whether chitosan is predominantly an ampholyte or predominantly a [...] Read more.

Chitosan is a unique biopolymer in the respect that it is abundant, cationic, low-toxic, non-immunogenic and biodegradable. The relative occurrence of the two monomeric building units (N-acetyl-glucosamine and d-glucosamine) is crucial to whether chitosan is predominantly an ampholyte or predominantly a polyelectrolyte at acidic pH-values. The chemical composition is not only crucial to its surface activity properties, but also to whether and why chitosan can undergo a sol–gel transition. This review gives an overview of chitosan hydrogels and their biomedical applications, e.g., in tissue engineering and drug delivery, as well as the chitosan’s surface activity and its role in emulsion formation, stabilization and destabilization. Previously unpublished original data where chitosan acts as an emulsifier and flocculant are presented and discussed, showing that highly-acetylated chitosans can act both as an emulsifier and as a flocculant. Full article

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Open AccessArticle

Study on the Effect of Silanization and Improvement in the Tensile Behavior of Graphene-Chitosan-Composite

by Dae Sung Kim, Vivek Dhand, Kyong Yop Rhee and Soo-Jin Park

Polymers 2015, 7(3), 527-551; https://doi.org/10.3390/polym7030527 - 13 Mar 2015

Cited by 74 | Viewed by 14693

Abstract

In the present study, silane-functionalized graphene (f-graphene)-reinforced chitosan nanocomposite films exhibiting enhanced mechanical properties have been prepared by the solution casting method. These nanocomposite films were characterized by X-ray diffraction, Raman spectroscopy and thermogravimetric analysis. In order to investigate the effect of silane [...] Read more.

In the present study, silane-functionalized graphene (f-graphene)-reinforced chitosan nanocomposite films exhibiting enhanced mechanical properties have been prepared by the solution casting method. These nanocomposite films were characterized by X-ray diffraction, Raman spectroscopy and thermogravimetric analysis. In order to investigate the effect of silane functionalization, tensile tests were performed on original, oxidized and silane-functionalized graphene-reinforced chitosan nanocomposite films. Tensile results show that silane functionalization groups offer a substantial increase in the interfacial adhesion between filler and host matrix. This result is also confirmed by the surface morphology of the fracture surface in scanning electron microscope analysis. Qualitative analysis using Raman and Fourier transform infrared spectroscopy revealed the existence of Si–O–Si and Si–O–C bonds in the silanized composite. Thermal analysis of the samples shows that the material is stable up till 250 °C and maintains its thermal stability all throughout the process until it starts degrading after 510 °C. Atomic force microscopy reveals that the material is well exfoliated after the oxidation of graphene and also displays the existence of 3–6 layers of exfoliated graphene sheets. X-ray photoelectron spectroscopy studies also reveal the existence of silicon in the single state and quantify the sample to be approximately around 4% (±0.5%) of the total atomic weight. Full article

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Open AccessArticle

Characterization and Properties of Hydrogels Made from Neutral Soluble Chitosans

by Henry M. Franzén, Kurt Ingar Draget, Joakim Langebäck and Julie Nilsen-Nygaard

Polymers 2015, 7(3), 373-389; https://doi.org/10.3390/polym7030373 - 18 Feb 2015

Cited by 24 | Viewed by 6911

Abstract

The current paper focuses on the preparation and some characteristics of viscoelastic hydrogels, ViscoGels™, made from chitosans having a random acylation pattern. Three different chitosan batches with a high fraction of acetylation were selected based on their M_w, and the impact [...] Read more.

The current paper focuses on the preparation and some characteristics of viscoelastic hydrogels, ViscoGels™, made from chitosans having a random acylation pattern. Three different chitosan batches with a high fraction of acetylation were selected based on their M_w, and the impact of degree of cross-linking on these chitosan samples has been studied with respect to the properties of the final hydrogels. Rheological long term (12 month) stability and gelling kinetics data are presented together with results from swelling studies at different pH. Finally, an example illustrating these gels potential as drug delivery vehicles is presented and discussed. Full article

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5240 KiB

Open AccessReview

Active Peptide-Conjugated Chitosan Matrices as an Artificial Basement Membrane

by Kentaro Hozumi, Jun Kumai, Yuji Yamada and Motoyoshi Nomizu

Polymers 2015, 7(2), 281-297; https://doi.org/10.3390/polym7020281 - 11 Feb 2015

Cited by 6 | Viewed by 8603

Abstract

The basement membrane, a thin extracellular matrix, plays a critical role in tissue development and repair. Laminins are the major component of basement membrane and have diverse biological activities. We have identified various cell-adhesive peptides from laminins and their specific cell surface receptors. [...] Read more.

The basement membrane, a thin extracellular matrix, plays a critical role in tissue development and repair. Laminins are the major component of basement membrane and have diverse biological activities. We have identified various cell-adhesive peptides from laminins and their specific cell surface receptors. Polysaccharides, including chitosan, have been used as scaffolds, which regulate cellular functions for tissue engineering. We have developed laminin-derived active peptide-chitosan matrices as functional scaffolds. The biological activity of the peptides was enhanced when the peptides were conjugated to a chitosan matrix, suggesting that the peptide-chitosan matrix approach has an advantage for an active biomaterial. Further, the laminin peptide-chitosan matrices have the potential to mimic the basement membrane and are useful for tissue engineering as an artificial basement membrane. Full article

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Open AccessReview

Poriferan Chitin as a Versatile Template for Extreme Biomimetics

by Marcin Wysokowski, Iaroslav Petrenko, Allison L. Stelling, Dawid Stawski, Teofil Jesionowski and Hermann Ehrlich

Polymers 2015, 7(2), 235-265; https://doi.org/10.3390/polym7020235 - 9 Feb 2015

Cited by 182 | Viewed by 16549

Abstract

In this mini-review, we shall first cover a short history of the discovery of chitin isolated from sponges; as well as its evolutionarily ancient roots. Next, we will delve into the unique structural, mechanical, and thermal properties of this naturally occurring polymer to [...] Read more.

In this mini-review, we shall first cover a short history of the discovery of chitin isolated from sponges; as well as its evolutionarily ancient roots. Next, we will delve into the unique structural, mechanical, and thermal properties of this naturally occurring polymer to illuminate how its physicochemical properties may find uses in diverse areas of the material sciences. We show how the unique properties and morphology of sponge chitin renders it quite useful for the new route of “Extreme Biomimetics”; where high temperatures and pressures allow a range of interesting bioinorganic composite materials to be made. These new biomaterials have electrical, chemical, and material properties that have applications in water filtration, medicine, catalysis, and biosensing. Full article

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Open AccessArticle

Direct Determination of Chitosan–Mucin Interactions Using a Single-Molecule Strategy: Comparison to Alginate–Mucin Interactions

by Kristin E. Haugstad, Armend G. Håti, Catherine T. Nordgård, Patricia S. Adl, Gjertrud Maurstad, Marit Sletmoen, Kurt I. Draget, Rita S. Dias and Bjørn T. Stokke

Polymers 2015, 7(2), 161-185; https://doi.org/10.3390/polym7020161 - 29 Jan 2015

Cited by 34 | Viewed by 9871

Abstract

Aqueous chitosan possesses attractive interaction capacities with various molecular groups that can be involved in hydrogen bonds and electrostatic and hydrophobic interactions. In the present paper, we report on the direct determination of chitosan–mucin molecular pair interactions at various solvent conditions as compared [...] Read more.

Aqueous chitosan possesses attractive interaction capacities with various molecular groups that can be involved in hydrogen bonds and electrostatic and hydrophobic interactions. In the present paper, we report on the direct determination of chitosan–mucin molecular pair interactions at various solvent conditions as compared to alginate–mucin interactions. Two chitosans of high molecular weight with different degrees of acetylation—thus possessing different solubility profiles in aqueous solution as a function of pH and two alginates with different fractions of α-guluronic acid were employed. The interaction properties were determined through a direct unbinding assay at the single-molecular pair level using an atomic force microscope. When probed against immobilized mucin, both chitosans and alginates revealed unbinding profiles characteristic of localized interactions along the polymers. The interaction capacities and estimated parameters of the energy landscapes of the pairwise chitosan–mucin and alginate–mucin interactions are discussed in view of possible contributions from various fundamental forces. Signatures arising both from an electrostatic mechanism and hydrophobic interaction are identified in the chitosan–mucin interaction properties. The molecular nature of the observed chitosan–mucin and alginate–mucin interactions indicates that force spectroscopy provides fundamental insights that can be useful in understanding the surface binding properties of other potentially mucoadhesive polymers. Full article

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2014

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Open AccessReview

Chitosan to Connect Biology to Electronics: Fabricating the Bio-Device Interface and Communicating Across This Interface

by Eunkyoung Kim, Yuan Xiong, Yi Cheng, Hsuan-Chen Wu, Yi Liu, Brian H. Morrow, Hadar Ben-Yoav, Reza Ghodssi, Gary W. Rubloff, Jana Shen, William E. Bentley, Xiaowen Shi and Gregory F. Payne

Polymers 2015, 7(1), 1-46; https://doi.org/10.3390/polym7010001 - 24 Dec 2014

Cited by 88 | Viewed by 16826

Abstract

Individually, advances in microelectronics and biology transformed the way we live our lives. However, there remain few examples in which biology and electronics have been interfaced to create synergistic capabilities. We believe there are two major challenges to the integration of biological components [...] Read more.

Individually, advances in microelectronics and biology transformed the way we live our lives. However, there remain few examples in which biology and electronics have been interfaced to create synergistic capabilities. We believe there are two major challenges to the integration of biological components into microelectronic systems: (i) assembly of the biological components at an electrode address, and (ii) communication between the assembled biological components and the underlying electrode. Chitosan possesses a unique combination of properties to meet these challenges and serve as an effective bio-device interface material. For assembly, chitosan’s pH-responsive film-forming properties allow it to “recognize” electrode-imposed signals and respond by self-assembling as a stable hydrogel film through a cathodic electrodeposition mechanism. A separate anodic electrodeposition mechanism was recently reported and this also allows chitosan hydrogel films to be assembled at an electrode address. Protein-based biofunctionality can be conferred to electrodeposited films through a variety of physical, chemical and biological methods. For communication, we are investigating redox-active catechol-modified chitosan films as an interface to bridge redox-based communication between biology and an electrode. Despite significant progress over the last decade, many questions still remain which warrants even deeper study of chitosan’s structure, properties, and functions. Full article

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Open AccessArticle

Fabrication of Chitin/Poly(butylene succinate)/Chondroitin Sulfate Nanoparticles Ternary Composite Hydrogel Scaffold for Skin Tissue Engineering

by S. Deepthi, C. V. Sidhy Viha, Chaochai Thitirat, Tetsuya Furuike, Hiroshi Tamura and Rangasamy Jayakumar

Polymers 2014, 6(12), 2974-2984; https://doi.org/10.3390/polym6122974 - 16 Dec 2014

Cited by 31 | Viewed by 11559

Abstract

Skin loss is one of the oldest and still not totally resolved problems in the medical field. Since spontaneous healing of the dermal defects would not occur, the regeneration of full thickness of skin requires skin substitutes. Tissue engineering constructs would provide a [...] Read more.

Skin loss is one of the oldest and still not totally resolved problems in the medical field. Since spontaneous healing of the dermal defects would not occur, the regeneration of full thickness of skin requires skin substitutes. Tissue engineering constructs would provide a three dimensional matrix for the reconstruction of skin tissue and the repair of damage. The aim of the present work is to develop a chitin based scaffold, by blending it with poly(butylene succinate) (PBS), an aliphatic, biodegradable and biocompatible synthetic polymer with excellent mechanical properties. The presence of chondroitin sulfate nanoparticles (CSnp) in the scaffold would favor cell adhesion. A chitin/PBS/CSnp composite hydrogel scaffold was developed and characterized by SEM (Scanning Electron Microscope), FTIR (Fourier Transform Infrared Spectroscopy), and swelling ratio of scaffolds were analyzed. The scaffolds were evaluated for the suitability for skin tissue engineering application by cytotoxicity, cell attachment, and cell proliferation studies using human dermal fibroblasts (HDF). The cytotoxicity and cell proliferation studies using HDF confirm the suitability of the scaffold for skin regeneration. In short, these results show promising applicability of the developed chitin/PBS/CSnps ternary composite hydrogel scaffolds for skin tissue regeneration. Full article

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2014 KiB

Open AccessArticle

Interfacial Properties of Methylcelluloses: The Influence of Molar Mass

by Pauline L. Nasatto, Frédéric Pignon, Joana L. M. Silveira, Maria Eugênia R. Duarte, Miguel D. Noseda and Marguerite Rinaudo

Polymers 2014, 6(12), 2961-2973; https://doi.org/10.3390/polym6122961 - 12 Dec 2014

Cited by 22 | Viewed by 6800

Abstract

The interfacial interactions of four methylcelluloses having the same average degree of substitution and distribution of methyl groups, but different molar masses, are studied at ambient temperature and at very low polymer concentrations. Firstly, the surface tension σ at the water/air interface is [...] Read more.

The interfacial interactions of four methylcelluloses having the same average degree of substitution and distribution of methyl groups, but different molar masses, are studied at ambient temperature and at very low polymer concentrations. Firstly, the surface tension σ at the water/air interface is determined for the progressive addition of methylcellulose up to 100 mg/L; σ starts to decrease over 1 mg/L up to the critical aggregation concentration (CAC) at 10 mg/L. The curves describing the influence of polymer concentration on σ are independent of the molar mass at equilibrium. Secondly, the adsorption of methylcellulose on silica particles is estimated from ζ-potential measurements. The data are interpreted in terms of an increase of the adsorbed layer thickness at the interface when the molar mass of methylcellulose increases. It is concluded that methylcellulose is adsorbed, forming trains and loops at the interface based on the equilibrium between surface free energy and solvent quality. Full article

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Open AccessArticle

Exploration of a Chemo-Mechanical Technique for the Isolation of Nanofibrillated Cellulosic Fiber from Oil Palm Empty Fruit Bunch as a Reinforcing Agent in Composites Materials

by Ireana Yusra A. Fatah, H. P. S. Abdul Khalil, Md. Sohrab Hossain, Astimar A. Aziz, Yalda Davoudpour, Rudi Dungani and Amir Bhat

Polymers 2014, 6(10), 2611-2624; https://doi.org/10.3390/polym6102611 - 21 Oct 2014

Cited by 146 | Viewed by 14846

Abstract

The aim of the present study was to determine the influence of sulphuric acid hydrolysis and high-pressure homogenization as an effective chemo-mechanical process for the isolation of quality nanofibrillated cellulose (NFC). The cellulosic fiber was isolated from oil palm empty fruit bunch (OPEFB) [...] Read more.

The aim of the present study was to determine the influence of sulphuric acid hydrolysis and high-pressure homogenization as an effective chemo-mechanical process for the isolation of quality nanofibrillated cellulose (NFC). The cellulosic fiber was isolated from oil palm empty fruit bunch (OPEFB) using acid hydrolysis methods and, subsequently, homogenized using a high-pressure homogenizer to produce NFC. The structural analysis and the crystallinity of the raw fiber and extracted cellulose were carried out by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). The morphology and thermal stability were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetric (TGA) analyses, respectively. The FTIR results showed that lignin and hemicellulose were removed effectively from the extracted cellulose nanofibrils. XRD analysis revealed that the percentage of crystallinity was increased from raw EFB to microfibrillated cellulose (MFC), but the decrease for NFC might due to a break down the hydrogen bond. The size of the NFC was determined within the 5 to 10 nm. The TGA analysis showed that the isolated NFC had high thermal stability. The finding of present study reveals that combination of sulphuric acid hydrolysis and high-pressure homogenization could be an effective chemo-mechanical process to isolate cellulose nanofibers from cellulosic plant fiber for reinforced composite materials. Full article

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Open AccessArticle

Barrier Properties of Polylactic Acid in Cellulose Based Packages Using Montmorillonite as Filler

by Daniela Sánchez Aldana, Eduardo Duarte Villa, Miguel De Dios Hernández, Guillermo González Sánchez, Quintín Rascón Cruz, Sergio Flores Gallardo, Hilda Piñon Castillo and Lourdes Ballinas Casarrubias

Polymers 2014, 6(9), 2386-2403; https://doi.org/10.3390/polym6092386 - 19 Sep 2014

Cited by 54 | Viewed by 10874

Abstract

Polylactic acid (PLA) and montmorillonite (CB) as filler were studied as coatings for cellulose based packages. Amorphous (AM) and semi crystalline (SC) PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was [...] Read more.

Polylactic acid (PLA) and montmorillonite (CB) as filler were studied as coatings for cellulose based packages. Amorphous (AM) and semi crystalline (SC) PLA were used at different concentrations according to a 2 × 6 × 3 full factorial experimental design. CB loading was three concentrations and coating was performed by casting. Contact angle (CA), water vapor (WVP) and grease permeabilities were measured for each resultant package and were compared to commercial materials (Glassine Paper, Grease Proof Papers 1 and 2 produced commercially). Significant differences were found and the main factors were the type and concentration of PLA. The best values were: for grease penetration, +1800 s; WVP from 161.36 to 237.8 g·µm·kPa⁻¹·m⁻²·d⁻¹ and CA from 69° to 73° for PLA–AM 0.5% and CB variable. These parameters are comparable to commercial packages used in the food industry. DSC revealed three different thermal events for PLA–SC and just T_g for PLA–AM. Crystallinity was also verified, obtaining a ΔH_crys of 3.7 J·g⁻¹ for PLA–SC and 14 J·g⁻¹ for PLA–SC–BC, evidencing clay interaction as a crystal nucleating agent. Differences found were explained on terms of the properties measured, where structural and chemical arrays of the coatings play a fundamental role for the barrier properties. Full article

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683 KiB

Open AccessArticle

Biopolymer Electrolyte Based on Derivatives of Cellulose from Kenaf Bast Fiber

by Mohd Saiful Asmal Rani, Siti Rudhziah, Azizan Ahmad and Nor Sabirin Mohamed

Polymers 2014, 6(9), 2371-2385; https://doi.org/10.3390/polym6092371 - 19 Sep 2014

Cited by 134 | Viewed by 13164

Abstract

A cellulose derivative, carboxymethyl cellulose (CMC), was synthesized by the reaction of cellulose from kenaf bast fiber with monochloroacetic acid. A series of biopolymer electrolytes comprised of the synthesized CMC and ammonium acetate (CH₃COONH₄) were prepared by the solution-casting [...] Read more.

A cellulose derivative, carboxymethyl cellulose (CMC), was synthesized by the reaction of cellulose from kenaf bast fiber with monochloroacetic acid. A series of biopolymer electrolytes comprised of the synthesized CMC and ammonium acetate (CH₃COONH₄) were prepared by the solution-casting technique. The biopolymer-based electrolyte films were characterized by Fourier Transform Infrared spectroscopy to investigate the formation of the CMC–CH₃COONH₄ complexes. Electrochemical impedance spectroscopy was conducted to obtain their ionic conductivities. The highest conductivity at ambient temperature of 5.77 × 10⁻⁴ S cm⁻¹ was obtained for the electrolyte film containing 20 wt% of CH₃COONH₄. The biopolymer electrolyte film also exhibited electrochemical stability up to 2.5 V. These results indicated that the biopolymer electrolyte has great potential for applications to electrochemical devices, such as proton batteries and solar cells. Full article

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7275 KiB

Open AccessCommunication

Influence of Surface Treatment on Tensile Properties of Low-Density Polyethylene/Cellulose Woven Biocomposites: A Preliminary Study

by Ahmad Adlie Shamsuri, Muhammad Kamarul Azroy Azid, Azmah Hanim Mohamed Ariff and Ahmad Khuzairi Sudari

Polymers 2014, 6(9), 2345-2356; https://doi.org/10.3390/polym6092345 - 12 Sep 2014

Cited by 17 | Viewed by 8229

Abstract

Cellulose woven (CW) was surface treated by means of hexadecyltrimethylammonium bromide surfactant (HTAB) in aqueous solution medium at elevated temperature. The parameters of the surface treatment that have been studied are HTAB concentration (0.2, 0.4, 0.6, 0.8 and 1.0 wt%) and treatment time [...] Read more.

Cellulose woven (CW) was surface treated by means of hexadecyltrimethylammonium bromide surfactant (HTAB) in aqueous solution medium at elevated temperature. The parameters of the surface treatment that have been studied are HTAB concentration (0.2, 0.4, 0.6, 0.8 and 1.0 wt%) and treatment time (1, 2, 3, 4 and 5 h). The untreated and treated CW filled low-density polyethylene (LDPE) biocomposites were prepared via compression molding technique. The tensile testing results of LDPE/CW biocomposites demonstrated that the optimum HTAB concentration for treatment of CW in 1 h was 0.4 wt%, while the optimum treatment time at 0.4 wt% HTAB was 2 h. The SEM (scanning electron microscope) images indicated that there is no significant difference in the morphology of the untreated and treated CW; however the morphology of the LDPE/treated CW biocomposite showed better interfacial adhesion as compared with the untreated ones. The FTIR (Fourier transform infrared spectroscopy) spectra revealed that the presence of HTAB on the surface of treated CW and also revealed the existence of intermolecular interactions between LDPE and treated CW. In summary, HTAB could potentially be used as a treatment agent for modifying the surface of CW and consequently improved the tensile properties of LDPE/CW biocomposites. Full article

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Open AccessArticle

Casein Films: The Effects of Formulation, Environmental Conditions and the Addition of Citric Pectin on the Structure and Mechanical Properties

by Laetitia M. Bonnaillie, Han Zhang, Serife Akkurt, Kit L. Yam and Peggy M. Tomasula

Polymers 2014, 6(7), 2018-2036; https://doi.org/10.3390/polym6072018 - 14 Jul 2014

Cited by 86 | Viewed by 17202

Abstract

Thin casein films for food packaging applications reportedly possess good strength and low oxygen permeability, but low elasticity and high sensitivity to moisture. Modifying the films to target specific behaviors depending on environmental conditions can enable a variety of commercial applications for casein-based [...] Read more.

Thin casein films for food packaging applications reportedly possess good strength and low oxygen permeability, but low elasticity and high sensitivity to moisture. Modifying the films to target specific behaviors depending on environmental conditions can enable a variety of commercial applications for casein-based films. The mechanical properties of solvent-cast (15% solids) calcium-caseinate/glycerol films (CaCas:Gly ratio of 3:1) were characterized as a function of processing and environmental conditions, including film thickness, solution formulation and ambient humidity (from 22% to 70% relative humidity (RH) at ~20 °C). At constant RH, the elongation at break (EAB) had a strong positive dependence on the film thickness. When RH increased, the tensile strength (TS) and modulus (E) decreased approximately linearly, while EAB increased. From 0.05% to 1% (w/w) of citric pectin (CP) was then incorporated into CaCas/Gly films following seven different formulations (mixing sequences), to alter the protein network and to evaluate the effects of CP on the tensile properties of CaCas/Gly/CP films. At constant film thickness and ~60% RH, the addition of 0.1% or 1.0% CP to the films considerably increased or decreased EAB, TS and E in different directions and to different extents, depending on the formulation, while optical micrographs also showed vastly differing network configurations, suggesting complex formulation- and stoichiometry-dependent casein-pectin interactions within the dried films. Depending on the desired film properties and utilization conditions, pectin may be a useful addition to casein film formulations for food packaging applications. Full article

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356 KiB

Open AccessArticle

Effect of Mannitol on Hyaluronic Acid Stability in Two in Vitro Models of Oxidative Stress

by Marguerite Rinaudo, Bernard Lardy, Laurent Grange and Thierry Conrozier

Polymers 2014, 6(7), 1948-1957; https://doi.org/10.3390/polym6071948 - 8 Jul 2014

Cited by 23 | Viewed by 9752

Abstract

In this paper, we propose the evaluation of the mannitol’s ability to reduce hyaluronic acid (HA) degradation using two different models of oxidative stress. Firstly, a solution of hyaluronan and a solution of the same HA including mannitol in PBS buffer were submitted [...] Read more.

In this paper, we propose the evaluation of the mannitol’s ability to reduce hyaluronic acid (HA) degradation using two different models of oxidative stress. Firstly, a solution of hyaluronan and a solution of the same HA including mannitol in PBS buffer were submitted to an oxidative stress generated by the addition of xanthine + xanthine oxidase generating oxygen free radicals. Different enzyme concentrations were used and the HA properties were studied after 24 h of contact at ambient temperature. Decreases of the viscosity of the solution were assessed by rheometry (viscous and elastic module) and that of HA molecular weight was determined by steric exclusion chromatography. Rheologic behavior was assessed on identical HA solutions subjected to another model of oxidative stress imposed by addition of hydrogen peroxide. The influence of mannitol concentration on HA degradation was also demonstrated. Whatever the stress applied, it appears very clearly that mannitol protects hyaluronic acid from mediated oxygen free radicals degradation. These in vitro results suggest that mannitol could be a simple way to significantly increase the intra-articular residence time of the injected hyaluronic acid and therefore might improve viscosupplementation effectiveness. Full article

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418 KiB

Open AccessArticle

Influence of Functionalization Degree on the Rheological Properties of Isocyanate-Functionalized Chitin- and Chitosan-Based Chemical Oleogels for Lubricant Applications

by Rocío Gallego, Mercedes González, Jesús F. Arteaga, Concepción Valencia and José M. Franco

Polymers 2014, 6(7), 1929-1947; https://doi.org/10.3390/polym6071929 - 8 Jul 2014

Cited by 26 | Viewed by 8864

Abstract

This work deals with the influence of functionalization degree on the thermogravimetric and rheological behaviour of NCO-functionalized chitosan- and chitin-based oleogels. Chitosan and chitin were functionalized using different proportions of 1,6-hexamethylene diisocyanate (HMDI) and subsequently dispersed in castor oil to promote the chemical [...] Read more.

This work deals with the influence of functionalization degree on the thermogravimetric and rheological behaviour of NCO-functionalized chitosan- and chitin-based oleogels. Chitosan and chitin were functionalized using different proportions of 1,6-hexamethylene diisocyanate (HMDI) and subsequently dispersed in castor oil to promote the chemical reaction between the –NCO group of the modified biopolymer and the –OH group located in the ricinoleic fatty acid chain of castor oil, thus resulting in different oleogels with specific thermogravimetric and rheological characteristics. Biopolymers and oleogels were characterized through Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Small-amplitude oscillatory shear (SAOS) measurements were performed on the oleogels. Oleogels presented suitable thermal resistance, despite the fact that the inclusion of HMDI moieties in the polymer structure led to a reduction in the onset temperature of thermal degradation. The insertion of low amounts of HMDI in both chitin and chitosan produces a drastic reduction in the values of oleogel viscoelastic functions but, above a critical threshold, they increase with the functionalization degree so that isocyanate functionalization results in a chemical tool to modulate oleogel rheological response. Several NCO-functionalized chitosan- and chitin-based oleogel formulations present suitable thermal resistance and rheological characteristics to be proposed as bio-based alternatives to traditional lubricating greases. Full article

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Open AccessReview

Low Molecular Weight Chitosan (LMWC)-based Polyplexes for pDNA Delivery: From Bench to Bedside

by Mireia Agirre, Jon Zarate, Edilberto Ojeda, Gustavo Puras, Jacques Desbrieres and Jose Luis Pedraz

Polymers 2014, 6(6), 1727-1755; https://doi.org/10.3390/polym6061727 - 16 Jun 2014

Cited by 45 | Viewed by 11878

Abstract

Non-viral gene delivery vectors are emerging as a safer alternative to viral vectors. Among natural polymers, chitosan (Ch) is the most studied one, and low molecular weight Ch, specifically, presents a wide range of advantages for non-viral pDNA delivery. It is crucial to [...] Read more.

Non-viral gene delivery vectors are emerging as a safer alternative to viral vectors. Among natural polymers, chitosan (Ch) is the most studied one, and low molecular weight Ch, specifically, presents a wide range of advantages for non-viral pDNA delivery. It is crucial to determine the best process for the formation of Low Molecular Weight Chitosan (LMWC)-pDNA complexes and to characterize their physicochemical properties to better understand their behavior once the polyplexes are administered. The transfection efficiency of Ch based polyplexes is relatively low. Therefore, it is essential to understand all the transfection process, including the cellular uptake, endosomal escape and nuclear import, together with the parameters involved in the process to improve the design and development of the non-viral vectors. The aim of this review is to describe the formation and characterization of LMWC based polyplexes, the in vitro transfection process and finally, the in vivo applications of LMWC based polyplexes for gene therapy purposes. Full article

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Open AccessArticle

Chitosan Membranes Exhibiting Shape Memory Capability by the Action of Controlled Hydration

by Cristina O. Correia, Sofia G. Caridade and João F. Mano

Polymers 2014, 6(4), 1178-1186; https://doi.org/10.3390/polym6041178 - 17 Apr 2014

Cited by 20 | Viewed by 7181

Abstract

Chitosan membranes can undergo a glass transition at room temperature triggered by hydration. The mechanical properties of the membranes were followed by a tension test and dynamic mechanical analysis (DMA), with the sample in wet conditions after being immersed in varying compositions of [...] Read more.

Chitosan membranes can undergo a glass transition at room temperature triggered by hydration. The mechanical properties of the membranes were followed by a tension test and dynamic mechanical analysis (DMA), with the sample in wet conditions after being immersed in varying compositions of water/ethanol mixtures. Results show that with the increasing of water content, the Young’s and storage modulus decrease systematically. For water contents of ca. 35 vol%, chitosan (CHT) exhibits a glass transition, showing an elastomeric plateau in the elastic modulus above this hydration level and the occurrence of a peak in the loss factor. Due to the semi-crystalline nature of CHT, membranes of this biomaterial present a shape memory capability induced by water uptake. By fixation of the permanent shape by further covalent cross-linking, the membranes can have different permanent shapes appropriate for different applications, including in the biomedical area. Full article

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Open AccessArticle

All Green Composites from Fully Renewable Biopolymers: Chitosan-Starch Reinforced with Keratin from Feathers

by Cynthia G. Flores-Hernández, Arturo Colín-Cruz, Carlos Velasco-Santos, Víctor M. Castaño, José L. Rivera-Armenta, Armando Almendarez-Camarillo, Perla E. García-Casillas and Ana L. Martínez-Hernández

Polymers 2014, 6(3), 686-705; https://doi.org/10.3390/polym6030686 - 11 Mar 2014

Cited by 83 | Viewed by 14713

Abstract

The performance as reinforcement of a fibrillar protein such as feather keratin fiber over a biopolymeric matrix composed of polysaccharides was evaluated in this paper. Three different kinds of keratin reinforcement were used: short and long biofibers and rachis particles. These were added [...] Read more.

The performance as reinforcement of a fibrillar protein such as feather keratin fiber over a biopolymeric matrix composed of polysaccharides was evaluated in this paper. Three different kinds of keratin reinforcement were used: short and long biofibers and rachis particles. These were added separately at 5, 10, 15 and 20 wt% to the chitosan-starch matrix and the composites were processed by a casting/solvent evaporation method. The morphological characteristics, mechanical and thermal properties of the matrix and composites were studied by scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and dynamic mechanical analysis. The thermal results indicated that the addition of keratin enhanced the thermal stability of the composites compared to pure matrix. This was corroborated with dynamic mechanical analysis as the results revealed that the storage modulus of the composites increased with respect to the pure matrix. The morphology, evaluated by scanning electron microscopy, indicated a uniform dispersion of keratin in the chitosan-starch matrix as a result of good compatibility between these biopolymers, also corroborated by FTIR. These results demonstrate that chicken feathers can be useful to obtain novel keratin reinforcements and develop new green composites providing better properties, than the original biopolymer matrix. Full article

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Open AccessReview

Hyaluronic Acid Bioconjugates for the Delivery of Bioactive Molecules

by Anna Mero and Monica Campisi

Polymers 2014, 6(2), 346-369; https://doi.org/10.3390/polym6020346 - 30 Jan 2014

Cited by 221 | Viewed by 23243

Abstract

Hyaluronic acid (HA) has currently several therapeutic applications: in ophthalmology, osteoarthritis, wound healing, tissue regeneration, postoperative anti-adhesion and anesthetic medicine. In the last ten years, it has also been successfully investigated in the field of drug delivery, in the form of conjugates or [...] Read more.

Hyaluronic acid (HA) has currently several therapeutic applications: in ophthalmology, osteoarthritis, wound healing, tissue regeneration, postoperative anti-adhesion and anesthetic medicine. In the last ten years, it has also been successfully investigated in the field of drug delivery, in the form of conjugates or hydrogel depot systems. HAylation, the covalent conjugation of HA to bioactive molecules, allows the overcoming of disadvantages associated with some pharmaceuticals, such as insolubility, instability and fast kidney clearance. These issues can be addressed also by covalent attachment of polyethylene glycol (PEGylation), but HA has the relevant advantages of biodegradability, high loading and specific targeting. In this review, the novel HA derivatives and the latest advances in HA-based drug delivery with a particular focus on the chemistry of conjugation will be discussed. Although, so far, there are no HA-drug conjugates on the market, several derivatives are presently under clinical investigation, and the promising results encourage further investigations and the exploitation of this versatile polysaccharide. Full article

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2013

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3166 KiB

Open AccessArticle

Extensional Flow Properties of Externally Plasticized Cellulose Acetate: Influence of Plasticizer Content

by Stefan Zepnik, Stephan Kabasci, Rodion Kopitzky, Hans-Joachim Radusch and Thomas Wodke

Polymers 2013, 5(3), 873-889; https://doi.org/10.3390/polym5030873 - 2 Jul 2013

Cited by 35 | Viewed by 12108

Abstract

Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl citrate [...] Read more.

Elongational flow properties of polymer melts are very important for numerous polymer processing technologies such as blown film extrusion or foam extrusion. Rheotens tests were conducted to investigate the influence of plasticizer content on elongational flow properties of cellulose acetate (CA). Triethyl citrate (TEC) was used as plasticizer. Melt strength decreases whereas melt extensibility increases with increasing plasticizer content. Melt strength was further studied as a function of zero shear viscosity. The typical draw resonance of the Rheotens curve shifts to higher drawdown velocity and the amplitude of the draw resonance decreases with increasing TEC content. With respect to foam extrusion, not only are melt strength and melt extensibility important but the elongational behavior at low strain rates and the area under the Rheotens curve are also significant. Therefore, elongational viscosity as well as specific energy input were calculated and investigated with respect to plasticizer content. Preliminary foam extrusion tests of externally plasticized CA using chemical blowing agents confirm the results from rheological characterization. Full article

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Open AccessReview

Functionalized Polymers from Lignocellulosic Biomass: State of the Art

by Elena Ten and Wilfred Vermerris

Polymers 2013, 5(2), 600-642; https://doi.org/10.3390/polym5020600 - 28 May 2013

Cited by 65 | Viewed by 15510

Abstract

Since the realization that global sustainability depends on renewable sources of materials and energy, there has been an ever-increasing need to develop bio-based polymers that are able to replace petroleum-based polymers. Research in this field has shown strong potential in generating high-performance functionalized [...] Read more.

Since the realization that global sustainability depends on renewable sources of materials and energy, there has been an ever-increasing need to develop bio-based polymers that are able to replace petroleum-based polymers. Research in this field has shown strong potential in generating high-performance functionalized polymers from plant biomass. With the anticipated large-scale production of lignocellulosic biomass, lignin, cellulose and hemicellulosic polysaccharides will be abundantly available renewable feedstocks for biopolymers and biocomposites with physico-chemical properties that match or exceed those of petroleum-based compounds. This review examines the state of the art regarding advances and challenges in synthesis and applications of specialty polymers and composites derived from cellulose, hemicellulose and lignin, ending with a brief assessment of genetic modification as a route to tailor crop plants for specific applications. Full article

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2012

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805 KiB

Open AccessArticle

Polysaccharide-Based Hydrogels: The Key Role of Water in Affecting Mechanical Properties

by Daniela Pasqui, Milena De Cagna and Rolando Barbucci

Polymers 2012, 4(3), 1517-1534; https://doi.org/10.3390/polym4031517 - 21 Aug 2012

Cited by 157 | Viewed by 17191

Abstract

Different hydrogels were prepared starting from natural or semi-synthetic polysaccharides (carboxymethylcellulose, hyaluronic acid and chitosan) which were cross-linked by the addition of a cross-linking agent chosen according to the chemical groups present along the polymer chains. The cross-linking reaction allows for the formation [...] Read more.

Different hydrogels were prepared starting from natural or semi-synthetic polysaccharides (carboxymethylcellulose, hyaluronic acid and chitosan) which were cross-linked by the addition of a cross-linking agent chosen according to the chemical groups present along the polymer chains. The cross-linking reaction allows for the formation of a three-dimensional network made of covalent bonds between the polymer chains, which is stable under physiological conditions. The presence of a substantial amount of water within the polysaccharide matrices makes such systems unique among hydrophilic gels. Water itself is responsible for some of their peculiar characteristics, one of which is their injectability which makes these hydrogels suitable for using as matrices for mini-invasive surgery and localized therapy. Full article

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779 KiB

Open AccessReview

Enzyme-Catalyzed Modifications of Polysaccharides and Poly(ethylene glycol)

by H. N. Cheng and Qu-Ming Gu

Polymers 2012, 4(2), 1311-1330; https://doi.org/10.3390/polym4021311 - 21 Jun 2012

Cited by 42 | Viewed by 13045

Abstract

Polysaccharides are used extensively in various industrial applications, such as food, adhesives, coatings, construction, paper, pharmaceuticals, and personal care. Many polysaccharide structures need to be modified in order to improve their end-use properties; this is mostly done through chemical reactions. In the past [...] Read more.

Polysaccharides are used extensively in various industrial applications, such as food, adhesives, coatings, construction, paper, pharmaceuticals, and personal care. Many polysaccharide structures need to be modified in order to improve their end-use properties; this is mostly done through chemical reactions. In the past 20 years many enzyme-catalyzed modifications have been developed to supplement chemical derivatization methods. Typical reactions include enzymatic oxidation, ester formation, amidation, glycosylation, and molecular weight reduction. These reactions are reviewed in this paper, with emphasis placed on the work done by the authors. The polymers covered in this review include cellulosic derivatives, starch, guar, pectin, and poly(ethylene glycol). Full article

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Open AccessArticle

Thermal Properties and Thermal Degradation of Cellulose Tri-Stearate (CTs)

by Feng-Yuan Huang

Polymers 2012, 4(2), 1012-1024; https://doi.org/10.3390/polym4021012 - 16 Apr 2012

Cited by 68 | Viewed by 10168

Abstract

Cellulose tri-stearate (CTs) was synthesized employing triﬂuoroacetic anhydride (TFAA), stearic acid (SA), with microcrystal cellulose (MCC) and characterized with FT-IR and ¹H-NMR. The degree of substitution of CTs was determined by the traditional saponiﬁcation method and ¹H-NMR. The thermal properties of [...] Read more.

Cellulose tri-stearate (CTs) was synthesized employing triﬂuoroacetic anhydride (TFAA), stearic acid (SA), with microcrystal cellulose (MCC) and characterized with FT-IR and ¹H-NMR. The degree of substitution of CTs was determined by the traditional saponiﬁcation method and ¹H-NMR. The thermal properties of CTs were investigated by the thermogravimetric analysis (TGA) under Ar flow in dynamic heating conditions. Thermal stability, activation energy, as well as the degradation mechanism of the decomposition process were revealed. The results showed that the thermal stability of CTs is superior to that of raw materials-MCC, and that the degradation of CTs in argon is a first-order weight loss; the initial decomposition temperature and the temperature corresponding to maximum degradation rate (T_p) increase with an increase in heating rate. The activation energy values were calculated with the Ozawa method, Coats-Redfern method and Kinssinger method, respectively. Analyses of experimental results suggest that the degradation mechanism 0.10 < α < 0.80 is F2 type, A3 for α < 0.1, and R3 for α > 0.80. The degradation mechanism of CTs in the whole conversion range is a complex mechanism, and is the combination of A3, F2 and R3. Full article

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Open AccessArticle

Synthesis of Hyperbranched Glycoconjugates by the Combined Action of Potato Phosphorylase and Glycogen Branching Enzyme from Deinococcus geothermalis

by Jeroen van der Vlist, Martin Faber, Lizette Loen, Teunis J. Dijkman, Lia A. T. W. Asri and Katja Loos

Polymers 2012, 4(1), 674-690; https://doi.org/10.3390/polym4010674 - 27 Feb 2012

Cited by 25 | Viewed by 15295

Abstract

Potato phosphorylase is able to synthesize linear polyglucans from maltoheptaose primers. By coupling maltoheptaose to butane diamine, tris(2-aminoethyl)amine and amine functionalized amine functionalized poly ethyleneglycol (PEG), new primer molecules became available. The resulting di-, tri- and macro-primers were incubated with potato phosphorylase and [...] Read more.

Potato phosphorylase is able to synthesize linear polyglucans from maltoheptaose primers. By coupling maltoheptaose to butane diamine, tris(2-aminoethyl)amine and amine functionalized amine functionalized poly ethyleneglycol (PEG), new primer molecules became available. The resulting di-, tri- and macro-primers were incubated with potato phosphorylase and glycogen branching enzyme from Deinococcus geothermalis. Due to the action of both enzymes, hyperbranched polyglucan arms were grown from the maltoheptaose derivatives with a maximum degree of branching of 11%. The size of the synthesized hyperbranched polyglucans could be controlled by the ratio monomer over primer. About 60%–80% of the monomers were incorporated in the glycoconjugates. The resulting hyperbranched glycoconjugates were subjected to Dynamic Light Scattering (DLS) measurements in order to determine the hydrodynamic radius and it became obvious that the structures formed agglomerates in the range of 14–32 nm. Full article

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Open AccessCommentary

Reinforced Materials Based on Chitosan, TiO₂ and Ag Composites

by Khairul Anuar Mat Amin and Marc in het Panhuis

Polymers 2012, 4(1), 590-599; https://doi.org/10.3390/polym4010590 - 16 Feb 2012

Cited by 65 | Viewed by 8600

Abstract

This study investigates the mechanical reinforcement of chitosan with TiO₂ and Ag nanoparticles, as well as their water vapour transmission rates and water resistance behaviour. The mechanical properties of chitosan were improved by addition of TiO₂ or Ag, with significant increases [...] Read more.

This study investigates the mechanical reinforcement of chitosan with TiO₂ and Ag nanoparticles, as well as their water vapour transmission rates and water resistance behaviour. The mechanical properties of chitosan were improved by addition of TiO₂ or Ag, with significant increases in Young’s modulus (from 25 MPa to ~300 MPa), tensile strength (from 6 MPa to 18–35 MPa) and toughness (from 1.3 J g⁻¹ to 7–8 J g⁻¹). The water vapour transmission rates (368–413 g m⁻² d⁻¹) were found to be similar for both materials. Inclusion of Ag reduced the water resistance (from 823% to 1,000%), while inclusion of TiO₂ yielded significant improvement in water resistance (from 823% to 100%). Full article

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2011

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221 KiB

Open AccessCommunication

Bacterial Inactivation Kinetics of Dialdehyde Starch Aqueous Suspension

by Le Song, Samuel R. Farrah and Ronald H. Baney

Polymers 2011, 3(4), 1902-1910; https://doi.org/10.3390/polym3041902 - 3 Nov 2011

Cited by 13 | Viewed by 7329

Abstract

The bacterial inactivation kinetics of dialdehyde starch (DAS) aqueous suspension was studied by the relationship between the minimal lethal concentration (MLC) and the inactivation time at four different temperatures. The relationship between MLC and exposure time was found to follow the first-order Chick-Watson [...] Read more.

The bacterial inactivation kinetics of dialdehyde starch (DAS) aqueous suspension was studied by the relationship between the minimal lethal concentration (MLC) and the inactivation time at four different temperatures. The relationship between MLC and exposure time was found to follow the first-order Chick-Watson law. This first-order inactivation kinetics was modeled by pseudo-first order chemical reaction. This model was validated by the successful predication of the bacterial inactivation response at room temperature. Full article

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Open AccessReview

Biomedical Activity of Chitin/Chitosan Based Materials—Influence of Physicochemical Properties Apart from Molecular Weight and Degree of N-Acetylation

by Jolanta Kumirska, Mirko X. Weinhold, Jorg Thöming and Piotr Stepnowski

Polymers 2011, 3(4), 1875-1901; https://doi.org/10.3390/polym3041875 - 3 Nov 2011

Cited by 235 | Viewed by 21721

Abstract

The physicochemical nature of chitin and chitosan, which influences the biomedical activity of these compounds, is strongly related to the source of chitin and the conditions of the chitin/chitosan production process. Apart from widely described key factors such as weight-averaged molecular weight (M [...] Read more.

The physicochemical nature of chitin and chitosan, which influences the biomedical activity of these compounds, is strongly related to the source of chitin and the conditions of the chitin/chitosan production process. Apart from widely described key factors such as weight-averaged molecular weight (M_W) and degree of N-acetylation (DA), other physicochemical parameters like polydispersity (M_W/M_N), crystallinity or the pattern of acetylation (P_A) have to be taken into consideration. From the biological point of view, these parameters affect a very important factor—the solubility of chitin and chitosan in water and organic solvents. The physicochemical properties of chitosan solutions can be controlled by manipulating solution conditions (temperature, pH, ionic strength, concentration, solvent). The degree of substitution of the hydroxyl and the amino groups or the degree of quaternization of the amino groups also influence the mechanical and biological properties of chitosan samples. Finally, a considerable research effort has been directed towards developing safe and efficient chitin/chitosan-based products because many factors, like the size of nanoparticles, can determine the biomedical characteristics of medicinal products. The influence of these factors on the biomedical activity of chitin/chitosan-based products is presented in this report in more detail. Full article

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Open AccessReview

Polysaccharides: The “Click” Chemistry Impact

by Pierre-Henri Elchinger, Pierre-Antoine Faugeras, Benjamin Boëns, François Brouillette, Daniel Montplaisir, Rachida Zerrouki and Romain Lucas

Polymers 2011, 3(4), 1607-1651; https://doi.org/10.3390/polym3041607 - 27 Sep 2011

Cited by 82 | Viewed by 16889

Abstract

Polysaccharides are complex but essential compounds utilized in many areas such as biomaterials, drug delivery, cosmetics, food chemistry or renewable energy. Modifications and functionalizations of such polymers are often necessary to achieve molecular structures of interest. In this area, the emergence of the [...] Read more.

Polysaccharides are complex but essential compounds utilized in many areas such as biomaterials, drug delivery, cosmetics, food chemistry or renewable energy. Modifications and functionalizations of such polymers are often necessary to achieve molecular structures of interest. In this area, the emergence of the “click” chemistry concept, and particularly the copper-catalyzed version of the Huisgen 1,3-dipolar cycloaddition reaction between terminal acetylenes and azides, had an impact on the polysaccharides chemistry. The present review summarizes the contribution of “click” chemistry in the world of polysaccharides. Full article

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Open AccessArticle

Effect of Moisture on the Orientation Birefringence of Cellulose Esters

by Mohd Edeerozey Abd Manaf, Manami Tsuji, Shogo Nobukawa and Masayuki Yamaguchi

Polymers 2011, 3(2), 955-966; https://doi.org/10.3390/polym3020955 - 14 Jun 2011

Cited by 37 | Viewed by 8994

Abstract

Orientation birefringence and its wavelength dispersion are studied for hot-drawn films of cellulose esters such as cellulose triacetate (CTA), cellulose diacetate (CDA), and cellulose acetate propionate (CAP) exposed to three different humidities of environments. Hot-drawn CTA films show negative birefringence that decreases with [...] Read more.

Orientation birefringence and its wavelength dispersion are studied for hot-drawn films of cellulose esters such as cellulose triacetate (CTA), cellulose diacetate (CDA), and cellulose acetate propionate (CAP) exposed to three different humidities of environments. Hot-drawn CTA films show negative birefringence that decreases with increasing wavelength. On the other hand, CDA and CAP films show positive birefringence that increases with increasing wavelength, i.e., the so-called extraordinary wavelength dispersion of birefringence. Upon exposure to high humidity environment, the orientation birefringence of CDA and CAP decreases. The decrease is prominent for the samples containing a large amount of water. CTA, however, shows an increase in magnitude of its negative orientation birefringence with increasing moisture content. The results can be explained by the increase of the polarizability anisotropy perpendicular to the stretching direction in the cellulose esters. It is found from ATR-FTIR measurements that hydrogen bonds are formed between carbonyl groups of cellulose esters and water molecules. Considering that orientation birefringence of cellulose esters is determined mainly by ester groups, the formation of hydrogen bonds contributes to the polarizability anisotropy, thus affecting the orientation birefringence. Full article

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Open AccessArticle

Modulating Biofunctional starPEG Heparin Hydrogels by Varying Size and Ratio of the Constituents

by Petra Birgit Welzel, Silvana Prokoph, Andrea Zieris, Milauscha Grimmer, Stefan Zschoche, Uwe Freudenberg and Carsten Werner

Polymers 2011, 3(1), 602-620; https://doi.org/10.3390/polym3010602 - 14 Mar 2011

Cited by 70 | Viewed by 15069

Abstract

Heparin and four-armed, end-functionalized polyethylene glycol (starPEG) were recently combined in sets of covalently linked biohybrid hydrogel networks capable of directing various therapeutically relevant cell types. To extend the variability and applicability of this novel biomaterials platform, the influence of size and molar [...] Read more.

Heparin and four-armed, end-functionalized polyethylene glycol (starPEG) were recently combined in sets of covalently linked biohybrid hydrogel networks capable of directing various therapeutically relevant cell types. To extend the variability and applicability of this novel biomaterials platform, the influence of size and molar ratio of the two building blocks on the hydrogel properties was investigated in the present study. Heparin and starPEG were converted in various molar ratios and in different molecular weights to tune swelling, stiffness and pore size of the obtained polymer networks. Hydrogels with a range of elastic moduli could be generated by controlling either the crosslinking density or the chain length of the starPEG, whereas altering the molecular mass of heparin did not significantly affect hydrogel strength. The concentration of heparin in the swollen gels was found to be nearly invariant at varying crosslinking degrees for any given set of building blocks but adjustable by the size of the building blocks. Since heparin is the base for all biofunctionalization schemes of the gels these findings lay the ground for an even more versatile customization of this powerful new class of biomaterials. Full article

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Open AccessArticle

Cellulose Chemistry Meets Click Chemistry: Syntheses and Properties of Cellulose-Based Glycoclusters with High Structural Homogeneity

by Kaori Negishi, Yoichi Mashiko, Erika Yamashita, Atsushi Otsuka and Teruaki Hasegawa

Polymers 2011, 3(1), 489-508; https://doi.org/10.3390/polym3010489 - 24 Feb 2011

Cited by 30 | Viewed by 10733

Abstract

b-1,4-Glucans having oligosaccharide appendages (O-/N-linked b-maltoside and O-/N-linked b-lactoside) at 6C positions of all repeating units can be readily prepared from cellulose through a two step strategy composed of: (1) regio-selective and quantitative bromination/azidation to afford [...] Read more.

b-1,4-Glucans having oligosaccharide appendages (O-/N-linked b-maltoside and O-/N-linked b-lactoside) at 6C positions of all repeating units can be readily prepared from cellulose through a two step strategy composed of: (1) regio-selective and quantitative bromination/azidation to afford 6-azido-6-deoxycellulose; and (2) the subsequent Cu⁺-catalyzed coupling with oligosaccharides having terminal alkyne. The resultant cellulose derivatives showed improved water solubility in comparison to native cellulose; they, however, bound to carbohydrate-binding proteins in a rather non-specific manner. Molecular dynamics calculations revealed that these properties are attributable to rigid sheet-like structures of the cellulose derivatives and the subsequent exposure of their hydrophobic moieties to solvents. Full article

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2010

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Open AccessReview

Chitosan-Based Hyaluronic Acid Hybrid Polymer Fibers as a Scaffold Biomaterial for Cartilage Tissue Engineering

by Norimasa Iwasaki, Yasuhiko Kasahara, Shintarou Yamane, Tatsuya Igarashi, Akio Minami and Shin-ichiro Nisimura

Polymers 2011, 3(1), 100-113; https://doi.org/10.3390/polym3010100 - 27 Dec 2010

Cited by 38 | Viewed by 12920

Abstract

An ideal scaffold material is one that closely mimics the natural environment in the tissue-specific extracellular matrix (ECM). Therefore, we have applied hyaluronic acid (HA), which is a main component of the cartilage ECM, to chitosan as a fundamental material for cartilage regeneration. [...] Read more.

An ideal scaffold material is one that closely mimics the natural environment in the tissue-specific extracellular matrix (ECM). Therefore, we have applied hyaluronic acid (HA), which is a main component of the cartilage ECM, to chitosan as a fundamental material for cartilage regeneration. To mimic the structural environment of cartilage ECM, the fundamental structure of a scaffold should be a three-dimensional (3D) system with adequate mechanical strength. We structurally developed novel polymer chitosan-based HA hybrid fibers as a biomaterial to easily fabricate 3D scaffolds. This review presents the potential of a 3D fabricated scaffold based on these novel hybrid polymer fibers for cartilage tissue engineering. Full article

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Open AccessReview

Cellulosic Bionanocomposites: A Review of Preparation, Properties and Applications

by Gilberto Siqueira, Julien Bras and Alain Dufresne

Polymers 2010, 2(4), 728-765; https://doi.org/10.3390/polym2040728 - 13 Dec 2010

Cited by 1120 | Viewed by 44817

Abstract

Cellulose is the most abundant biomass material in nature. Extracted from natural fibers, its hierarchical and multi-level organization allows different kinds of nanoscaled cellulosic fillers—called cellulose nanocrystals or microfibrillated cellulose (MFC)—to be obtained. Recently, such cellulose nanoparticles have been the focus of an [...] Read more.

Cellulose is the most abundant biomass material in nature. Extracted from natural fibers, its hierarchical and multi-level organization allows different kinds of nanoscaled cellulosic fillers—called cellulose nanocrystals or microfibrillated cellulose (MFC)—to be obtained. Recently, such cellulose nanoparticles have been the focus of an exponentially increasing number of works or reviews devoted to understanding such materials and their applications. Major studies over the last decades have shown that cellulose nanoparticles could be used as fillers to improve mechanical and barrier properties of biocomposites. Their use for industrial packaging is being investigated, with continuous studies to find innovative solutions for efficient and sustainable systems. Processing is more and more important and different systems are detailed in this paper depending on the polymer solubility, i.e., (i) hydrosoluble systems, (ii) non-hydrosoluble systems, and (iii) emulsion systems. This paper intends to give a clear overview of cellulose nanoparticles reinforced composites with more than 150 references by describing their preparation, characterization, properties and applications. Full article

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Open AccessArticle

Preparation and Characterization of Insoluble Silk Fibroin/Chitosan Blend Films

by Mariana Agostini de Moraes, Grinia Michelle Nogueira, Raquel Farias Weska and Marisa Masumi Beppu

Polymers 2010, 2(4), 719-727; https://doi.org/10.3390/polym2040719 - 13 Dec 2010

Cited by 81 | Viewed by 11667

Abstract

The aim of this study was to prepare and characterize membranes of silk fibroin (SF) and chitosan (CHI) blends. Moreover, a conformation transition of SF to a more stable form induced by the addition of CHI was verified. Blend membranes were prepared, after [...] Read more.

The aim of this study was to prepare and characterize membranes of silk fibroin (SF) and chitosan (CHI) blends. Moreover, a conformation transition of SF to a more stable form induced by the addition of CHI was verified. Blend membranes were prepared, after pH adjustment, in different ratios, and physical integrity, crystallinity, structural conformation and thermal stability were characterized. The results of crystallographic analysis (XRD) indicated the tendency to higher structural organization caused by the addition of CHI. Fourier transformed infrared spectroscopy (FTIR) showed that SF is present in a more stable form in the presence of a CHI content of only 25 wt%. Thermal analysis indicated that SF is thermally stable and that when its proportion in the blend increases, the temperature at which degradation is initiated also increases. Full article

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Open AccessArticle

Periodate Oxidation of Methylcellulose: Characterization and Properties of Oxidized Derivatives

by Marguerite Rinaudo

Polymers 2010, 2(4), 505-521; https://doi.org/10.3390/polym2040505 - 29 Oct 2010

Cited by 34 | Viewed by 12090

Abstract

In this paper, the behavior of oxidized methylcelluloses is compared with that of the initial methylcellulose, an amphiphilic cellulose derivative. Methylcelluloses are important for many applications in the cosmetic and food industries. The mechanism of thermo-gelation of methylcellulose is briefly explained as well [...] Read more.

In this paper, the behavior of oxidized methylcelluloses is compared with that of the initial methylcellulose, an amphiphilic cellulose derivative. Methylcelluloses are important for many applications in the cosmetic and food industries. The mechanism of thermo-gelation of methylcellulose is briefly explained as well as the method of oxidation of polysaccharides. Then, our experiments involve the preparation of oxidized methylcelluloses: three degrees of oxidation are prepared and the new polymers are characterized by NMR, IR, SEC and rheology. Oxidation with periodate theoretically allows introduction of two aldehydic groups on C2–C3 glycol positions of anhydroglucose units. This reaction not only enhances the flexibility of the cellulosic backbone, but also causes a decrease in the molecular weight. In particular, the rheological behavior of methylcellulose and oxidized methylcellulose as a function of temperature is examined. The oxidized methylcelluloses prepared, being rich in aldehyde functions, become interesting intermediaries to prepare new cellulose derivatives. In this paper, three examples of reductive amination based on the reaction of modified methylcelluloses and −NH₂ groups of different molecules are described: β-alanine produces a polyelectrolyte; chitosan and hyaluronan-ADH (derivative obtained with adipic dihydrazide allowing introduction of −NH₂functions on HA backbone) are crosslinked and give new biocompatible hydrogels. Full article

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