Molecules

Editorial

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5 pages, 210 KiB

Open AccessEditorial

Polylactide-Based Materials: Synthesis and Biomedical Applications

by Marek Brzeziński and Malgorzata Basko

Molecules 2023, 28(3), 1386; https://doi.org/10.3390/molecules28031386 - 1 Feb 2023

Cited by 4 | Viewed by 2031

Abstract

Polylactide (PLA) is a biocompatible polyester that can be obtained by polycondensation of lactic acid or the ring-opening polymerization (ROP) of lactide [...] Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

Research

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15 pages, 2587 KiB

Open AccessArticle

Polylactide Nanoparticles as a Biodegradable Vaccine Adjuvant: A Study on Safety, Protective Immunity and Efficacy against Human Leishmaniasis Caused by Leishmania Major

by Sana Ayari-Riabi, Noureddine Ben khalaf, Balkiss Bouhaouala-Zahar, Bernard Verrier, Thomas Trimaille, Zakaria Benlasfar, Mehdi Chenik and Mohamed Elayeb

Molecules 2022, 27(24), 8677; https://doi.org/10.3390/molecules27248677 - 8 Dec 2022

Cited by 6 | Viewed by 1966

Abstract

Leishmaniasis is the 3rd most challenging vector-borne disease after malaria and lymphatic filariasis. Currently, no vaccine candidate is approved or marketed against leishmaniasis due to difficulties in eliciting broad immune responses when using sub-unit vaccines. The aim of this work was the design [...] Read more.

Leishmaniasis is the 3rd most challenging vector-borne disease after malaria and lymphatic filariasis. Currently, no vaccine candidate is approved or marketed against leishmaniasis due to difficulties in eliciting broad immune responses when using sub-unit vaccines. The aim of this work was the design of a particulate sub-unit vaccine for vaccination against leishmaniasis. The poly (D,L-lactide) nanoparticles (PLA-NPs) were developed in order to efficiently adsorb a recombinant L. major histone H2B (L. major H2B) and to boost its immunogenicity. Firstly, a study was focused on the production of well-formed nanoparticles by the nanoprecipitation method without using a surfactant and on the antigen adsorption process under mild conditions. The set-up preparation method permitted to obtain H2B-adsorbed nanoparticles H2B/PLA (adsorption capacity of about 2.8% (w/w)) with a narrow size distribution (287 nm) and a positive zeta potential (30.9 mV). Secondly, an in vitro release assay performed at 37 °C, pH 7.4, showed a continuous release of the adsorbed H2B for almost 21 days (30%) from day 7. The immune response of H2B/PLA was investigated and compared to H2B + CpG7909 as a standard adjuvant. The humoral response intensity (IgG) was substantially similar between both formulations. Interestingly, when challenged with the standard parasite strain (GLC94) isolated from a human lesion of cutaneous leishmaniasis, mice showed a significant reduction in footpad swelling compared to unvaccinated ones, and no deaths occurred until week 17th. Taken together, these results demonstrate that PLA-NPs represent a stable, cost-effective delivery system adjuvant for use in vaccination against leishmaniasis. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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11 pages, 2211 KiB

Open AccessArticle

PLGA-Lipid Hybrid Nanoparticles for Overcoming Paclitaxel Tolerance in Anoikis-Resistant Lung Cancer Cells

by Sasivimon Pramual, Kriengsak Lirdprapamongkol, Korakot Atjanasuppat, Papada Chaisuriya, Nuttawee Niamsiri and Jisnuson Svasti

Molecules 2022, 27(23), 8295; https://doi.org/10.3390/molecules27238295 - 28 Nov 2022

Cited by 11 | Viewed by 2401

Abstract

Drug resistance and metastasis are two major obstacles to cancer chemotherapy. During metastasis, cancer cells can survive as floating cells in the blood or lymphatic circulatory system, due to the acquisition of resistance to anoikis—a programmed cell death activated by loss of extracellular [...] Read more.

Drug resistance and metastasis are two major obstacles to cancer chemotherapy. During metastasis, cancer cells can survive as floating cells in the blood or lymphatic circulatory system, due to the acquisition of resistance to anoikis—a programmed cell death activated by loss of extracellular matrix attachment. The anoikis-resistant lung cancer cells also develop drug resistance. In this study, paclitaxel-encapsulated PLGA-lipid hybrid nanoparticles (PLHNPs) were formulated by nanoprecipitation combined with self-assembly. The paclitaxel-PLHNPs had an average particle size of 103.0 ± 1.6 nm and a zeta potential value of −52.9 mV with the monodisperse distribution. Cytotoxicity of the nanoparticles was evaluated in A549 human lung cancer cells cultivated as floating cells under non-adherent conditions, compared with A549 attached cells. The floating cells exhibited anoikis resistance as shown by a lack of caspase-3 activation, in contrast to floating normal epithelial cells. Paclitaxel tolerance was evident in floating cells which had an IC₅₀ value of 418.56 nM, compared to an IC₅₀ value of 7.88 nM for attached cells. Paclitaxel-PLHNPs significantly reduced the IC₅₀ values in both attached cells (IC₅₀ value of 0.11 nM, 71.6-fold decrease) and floating cells (IC₅₀ value of 1.13 nM, 370.4-fold decrease). This report demonstrated the potential of PLHNPs to improve the efficacy of the chemotherapeutic drug paclitaxel, for eradicating anoikis-resistant lung cancer cells during metastasis. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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12 pages, 1775 KiB

Open AccessArticle

Influence of PCL and PHBV on PLLA Thermal and Mechanical Properties in Binary and Ternary Polymer Blends

by Raasti Naseem, Giorgia Montalbano, Matthew J. German, Ana M. Ferreira, Piergiorgio Gentile and Kenneth Dalgarno

Molecules 2022, 27(21), 7633; https://doi.org/10.3390/molecules27217633 - 7 Nov 2022

Cited by 18 | Viewed by 2531

Abstract

PLLA, PCL and PHBV are aliphatic polyesters which have been researched and used in a wide range of medical devices, and all three have advantages and disadvantages for specific applications. Blending of these materials is an attractive way to make a material which [...] Read more.

PLLA, PCL and PHBV are aliphatic polyesters which have been researched and used in a wide range of medical devices, and all three have advantages and disadvantages for specific applications. Blending of these materials is an attractive way to make a material which overcomes the limitations of the individual polymers. Both PCL and PHBV have been evaluated in polymer blends with PLLA in order to provide enhanced properties for specific applications. This paper explores the use of PCL and PHBV together with PLLA in ternary blends with assessment of the thermal, mechanical and processing properties of the resultant polymer blends, with the aim of producing new biomaterials for orthopaedic applications. DSC characterisation is used to demonstrate that the materials can be effectively blended. Blending PCL and PHBV in concentrations of 5–10% with PLLA produces materials with average modulus improved by up to 25%, average strength improved by up to 50% and average elongation at break improved by 4000%, depending on the concentrations of each polymer used. PHBV impacts most on the modulus and strength of the blends, whilst PCL has a greater impact on creep behaviour and viscosity. Blending PCL and PHBV with PLLA offers an effective approach to the development of new polyester-based biomaterials with combinations of mechanical properties which cannot be provided by any of the materials individually. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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11 pages, 2056 KiB

Open AccessCommunication

Synergistic Flame Retardancy of Phosphatized Sesbania Gum/Ammonium Polyphosphate on Polylactic Acid

by Qing Zhang, Huiyuan Liu, Junxia Guan, Xiaochun Yang and Baojing Luo

Molecules 2022, 27(15), 4748; https://doi.org/10.3390/molecules27154748 - 25 Jul 2022

Cited by 4 | Viewed by 1666

Abstract

Phosphating sesbania gum (DESG) was obtained by modifying sesbania gum (SG) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and endic anhydride (EA). The structure of DESG was determined using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (¹H-NMR). Flame-retardant polylactic acid (PLA) composites [...] Read more.

Phosphating sesbania gum (DESG) was obtained by modifying sesbania gum (SG) with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and endic anhydride (EA). The structure of DESG was determined using Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance spectroscopy (¹H-NMR). Flame-retardant polylactic acid (PLA) composites were prepared by melt-blending PLA with DESG, which acted as a carbon source, and ammonium polyphosphate (APP), which acted as an acid source and a gas source. The flame retardancy of the PLA composite was investigated using vertical combustion (UL-94), the limiting oxygen index (LOI) and the cone calorimeter (CONE) test. Thermal properties and morphology were characterized via thermogravimetric analysis (TGA) and field emission scanning electron microscopy (FESEM), respectively. Experimental results indicated that when the mass ratio of DESG/APP was equal to 12/8 the LOI value was 32.2%; a vertical burning test (UL-94) V-0 rating was achieved. Meanwhile, the sample showed a lowest total heat release (THR) value of 52.7 MJ/m², which is a 32.5% reduction compared to that of neat PLA. Using FESEM, the uniform distribution of DESG and APP in the PLA matrix was observed. The synergistic effect of DESG and APP effectively enhanced the flame retardancy of PLA. Additionally, the synergistic mechanism of DESG and APP in PLA was proposed. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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15 pages, 2739 KiB

Open AccessArticle

Creation of a Stable Nanofibrillar Scaffold Composed of Star-Shaped PLA Network Using Sol-Gel Process during Electrospinning

by Karima Belabbes, Coline Pinese, Christopher Yusef Leon-Valdivieso, Audrey Bethry and Xavier Garric

Molecules 2022, 27(13), 4154; https://doi.org/10.3390/molecules27134154 - 28 Jun 2022

Cited by 6 | Viewed by 1676

Abstract

PLA nanofibers are of great interest in tissue engineering due to their biocompatibility and morphology; moreover, their physical properties can be tailored for long-lasting applications. One of the common and efficient methods to improve polymer properties and slow down their degradation is sol-gel [...] Read more.

PLA nanofibers are of great interest in tissue engineering due to their biocompatibility and morphology; moreover, their physical properties can be tailored for long-lasting applications. One of the common and efficient methods to improve polymer properties and slow down their degradation is sol-gel covalent crosslinking. However, this method usually results in the formation of gels or films, which undervalues the advantages of nanofibers. Here, we describe a dual process sol-gel/electrospinning to improve the mechanical properties and stabilize the degradation of PLA scaffolds. For this purpose, we synthesized star-shaped PLAs and functionalized them with triethoxysilylpropyl groups (StarPLA-PTES) to covalently react during nanofibers formation. To achieve this, we evaluated the use of (1) a polymer diluent and (2) different molecular weights of StarPLA on electrospinnability, StarPLA-PTES condensation time and crosslinking efficiency. Our results show that the diluent allowed the fiber formation and reduced the condensation time, while the addition of low-molecular-weight StarPLA-PTES improved the crosslinking degree, resulting in stable matrices even after 6 months of degradation. Additionally, these materials showed biocompatibility and allowed the proliferation of fibroblasts. Overall, these results open the door to the fabrication of scaffolds with enhanced stability and prospective long-term applications. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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15 pages, 3138 KiB

Open AccessArticle

PLLA Coating of Active Implants for Dual Drug Release

by Katharina Wulf, Madeleine Goblet, Stefan Raggl, Michael Teske, Thomas Eickner, Thomas Lenarz, Niels Grabow and Gerrit Paasche

Molecules 2022, 27(4), 1417; https://doi.org/10.3390/molecules27041417 - 19 Feb 2022

Cited by 13 | Viewed by 2698

Abstract

Cochlear implants, like other active implants, rely on precise and effective electrical stimulation of the target tissue but become encapsulated by different amounts of fibrous tissue. The current study aimed at the development of a dual drug release from a PLLA coating and [...] Read more.

Cochlear implants, like other active implants, rely on precise and effective electrical stimulation of the target tissue but become encapsulated by different amounts of fibrous tissue. The current study aimed at the development of a dual drug release from a PLLA coating and from the bulk material to address short-term and long-lasting release of anti-inflammatory drugs. Inner-ear cytocompatibility of drugs was studied in vitro. A PLLA coating (containing diclofenac) of medical-grade silicone (containing 5% dexamethasone) was developed and release profiles were determined. The influence of different coating thicknesses (2.5, 5 and 10 µm) and loadings (10% and 20% diclofenac) on impedances of electrical contacts were measured with and without pulsatile electrical stimulation. Diclofenac can be applied to the inner ear at concentrations of or below 4 × 10⁻⁵ mol/L. Release of dexamethasone from the silicone is diminished by surface coating but not blocked. Addition of 20% diclofenac enhances the dexamethasone release again. All PLLA coatings serve as insulator. This can be overcome by using removable masking on the contacts during the coating process. Dual drug release with different kinetics can be realized by adding drug-loaded coatings to drug-loaded silicone arrays without compromising electrical stimulation. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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15 pages, 3876 KiB

Open AccessArticle

Composite Fiber Spun Mat Synthesis and In Vitro Biocompatibility for Guide Tissue Engineering

by Rodrigo Osorio-Arciniega, Manuel García-Hipólito, Octavio Alvarez-Fregoso and Marco Antonio Alvarez-Perez

Molecules 2021, 26(24), 7597; https://doi.org/10.3390/molecules26247597 - 15 Dec 2021

Cited by 7 | Viewed by 2348

Abstract

Composite scaffolds are commonly used strategies and materials employed to achieve similar analogs of bone tissue. This study aims to fabricate 10% wt polylactic acid (PLA) composite fiber scaffolds by the air-jet spinning technique (AJS) doped with 0.5 or 0.1 g of zirconium [...] Read more.

Composite scaffolds are commonly used strategies and materials employed to achieve similar analogs of bone tissue. This study aims to fabricate 10% wt polylactic acid (PLA) composite fiber scaffolds by the air-jet spinning technique (AJS) doped with 0.5 or 0.1 g of zirconium oxide nanoparticles (ZrO₂) for guide bone tissue engineering. ZrO₂ nanoparticles were obtained by the hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). SEM and fourier-transform infrared spectroscopy (FTIR) analyzed the synthesized PLA/ZrO₂ fiber scaffolds. The in vitro biocompatibility and bioactivity of the PLA/ZrO₂ were studied using human fetal osteoblast cells. Our results showed that the hydrothermal technique allowed ZrO₂ nanoparticles to be obtained. SEM analysis showed that PLA/ZrO₂ composite has a fiber diameter of 395 nm, and the FITR spectra confirmed that the scaffolds’ chemical characteristics are not affected by the synthesized technique. In vitro studies demonstrated that PLA/ZrO₂ scaffolds increased cell adhesion, cellular proliferation, and biomineralization of osteoblasts. In conclusion, the PLA/ZrO₂ scaffolds are bioactive, improve osteoblasts behavior, and can be used in tissue bone engineering applications. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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15 pages, 12579 KiB

Open AccessCommunication

Long-Term Evaluation of Poly(lactic acid) (PLA) Implants in a Horse: An Experimental Pilot Study

by Júlia Ribeiro Garcia Carvalho, Gabriel Conde, Marina Lansarini Antonioli, Clarissa Helena Santana, Thayssa Oliveira Littiere, Paula Patrocínio Dias, Marcelo Aparecido Chinelatto, Paulo Aléscio Canola, Fernando José. Zara and Guilherme Camargo Ferraz

Molecules 2021, 26(23), 7224; https://doi.org/10.3390/molecules26237224 - 29 Nov 2021

Cited by 16 | Viewed by 2817

Abstract

In horses, there is an increasing interest in developing long-lasting drug formulations, with biopolymers as viable carrier alternatives in addition to their use as scaffolds, suture threads, screws, pins, and plates for orthopedic surgeries. This communication focuses on the prolonged biocompatibility and biodegradation [...] Read more.

In horses, there is an increasing interest in developing long-lasting drug formulations, with biopolymers as viable carrier alternatives in addition to their use as scaffolds, suture threads, screws, pins, and plates for orthopedic surgeries. This communication focuses on the prolonged biocompatibility and biodegradation of PLA, prepared by hot pressing at 180 °C. Six samples were implanted subcutaneously on the lateral surface of the neck of one horse. The polymers remained implanted for 24 to 57 weeks. Physical examination, plasma fibrinogen, and the mechanical nociceptive threshold (MNT) were performed. After 24, 28, 34, 38, and 57 weeks, the materials were removed for histochemical analysis using hematoxylin-eosin and scanning electron microscopy (SEM). There were no essential clinical changes. MNT decreased after the implantation procedure, returning to normal after 48 h. A foreign body response was observed by histopathologic evaluation up to 38 weeks. At 57 weeks, no polymer or fibrotic capsules were identified. SEM showed surface roughness suggesting a biodegradation process, with an increase in the median pore diameter. As in the histopathological evaluation, it was not possible to detect the polymer 57 weeks after implantation. PLA showed biocompatible degradation and these findings may contribute to future research in the biomedical area. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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18 pages, 4664 KiB

Open AccessArticle

Shear-Induced Crystallization of Star and Linear Poly(L-lactide)s

by Joanna Bojda, Ewa Piorkowska, Grzegorz Lapienis and Adam Michalski

Molecules 2021, 26(21), 6601; https://doi.org/10.3390/molecules26216601 - 31 Oct 2021

Cited by 2 | Viewed by 2055

Abstract

The influence of macromolecular architecture on shear-induced crystallization of poly(L-lactide) (PLLA) was studied. To this aim, three star PLLAs, 6-arm with M_w of 120 and 245 kg/mol, 4-arm with M_w of 123 kg/mol, and three linear PLLAs with M_w of [...] Read more.

The influence of macromolecular architecture on shear-induced crystallization of poly(L-lactide) (PLLA) was studied. To this aim, three star PLLAs, 6-arm with M_w of 120 and 245 kg/mol, 4-arm with M_w of 123 kg/mol, and three linear PLLAs with M_w of 121, 240 and 339 kg/mol, were synthesized and examined. The PLLAs were sheared at 170 and 150 °C, at 5/s, 10/s and 20/s for 20 s, 10 s and 5 s, respectively, and then cooled at 10 or 30 °C/min. Shear-induced crystallization during cooling was followed by a light depolarization method, whereas the crystallized specimens were examined by DSC, 2D-WAXS, 2D-SAXS and SEM. The effect of shear depended on the shearing conditions, cooling rate and polymer molar mass but it was also affected by the macromolecular architecture. The shear-induced crystallization of linear PLLA with M_w of 240 kg/mol was more intense than that of the 6-arm polymer with similar M_w, most possibly due to its higher M_z. However, the influence of shear on the crystallization of the star polymers with M_w close to 120 kg/mol was stronger than on that of their linear analog. This was reflected in higher crystallization temperature, as well as crystallinity achieved during cooling. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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13 pages, 3014 KiB

Open AccessArticle

Modification of Polylactide Nonwovens with Carbon Nanotubes and Ladder Poly(silsesquioxane)

by Mariia Svyntkivska, Tomasz Makowski, Ewa Piorkowska, Marek Brzezinski, Agata Herc and Anna Kowalewska

Molecules 2021, 26(5), 1353; https://doi.org/10.3390/molecules26051353 - 3 Mar 2021

Cited by 7 | Viewed by 2312

Abstract

Electrospun nonwovens of poly(L-lactide) (PLLA) modified with multiwall carbon nanotubes (MWCNT) and linear ladder-like poly(silsesquioxane) with methoxycarbonyl side groups (LPSQ-COOMe) were obtained. MWCNT and LPSQ-COOMe were added to the polymer solution before the electrospinning. In addition, nonwovens of PLLA grafted to modified MWCNT [...] Read more.

Electrospun nonwovens of poly(L-lactide) (PLLA) modified with multiwall carbon nanotubes (MWCNT) and linear ladder-like poly(silsesquioxane) with methoxycarbonyl side groups (LPSQ-COOMe) were obtained. MWCNT and LPSQ-COOMe were added to the polymer solution before the electrospinning. In addition, nonwovens of PLLA grafted to modified MWCNT were electrospun. All modified nonwovens exhibited higher tensile strength than the neat PLA nonwoven. The addition of 10 wt.% of LPSQ-COOMe and 0.1 wt.% of MWCNT to PLLA increased the tensile strength of the nonwovens 2.4 times, improving also the elongation at the maximum stress. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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15 pages, 1614 KiB

Open AccessArticle

Poly(Ethylene Glycol)-b-Poly(D,L-Lactide) Nanoparticles as Potential Carriers for Anticancer Drug Oxaliplatin

by Yulia A. Kadina, Ekaterina V. Razuvaeva, Dmitry R. Streltsov, Nikita G. Sedush, Eleonora V. Shtykova, Alevtina I. Kulebyakina, Alexander A. Puchkov, Dmitry S. Volkov, Alexey A. Nazarov and Sergei N. Chvalun

Molecules 2021, 26(3), 602; https://doi.org/10.3390/molecules26030602 - 24 Jan 2021

Cited by 22 | Viewed by 3575

Abstract

Nanoparticles based on biocompatible methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG₁₁₃-b-P(D,L)LA_n) copolymers as potential vehicles for the anticancer agent oxaliplatin were prepared by a nanoprecipitation technique. It was demonstrated that an increase in the hydrophobic PLA block length [...] Read more.

Nanoparticles based on biocompatible methoxy poly(ethylene glycol)-b-poly(D,L-lactide) (mPEG₁₁₃-b-P(D,L)LA_n) copolymers as potential vehicles for the anticancer agent oxaliplatin were prepared by a nanoprecipitation technique. It was demonstrated that an increase in the hydrophobic PLA block length from 62 to 173 monomer units leads to an increase of the size of nanoparticles from 32 to 56 nm. Small-angle X-ray scattering studies confirmed the “core-corona” structure of mPEG₁₁₃-b-P(D,L)LA_n nanoparticles and oxaliplatin loading. It was suggested that hydrophilic oxaliplatin is adsorbed on the core-corona interface of the nanoparticles during the nanoprecipitation process. The oxaliplatin loading content decreased from 3.8 to 1.5% wt./wt. (with initial loading of 5% wt./wt.) with increasing PLA block length. Thus, the highest loading content of the anticancer drug oxaliplatin with its encapsulation efficiency of 76% in mPEG₁₁₃-b-P(D,L)LA_n nanoparticles can be achieved for block copolymer with short hydrophobic block. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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16 pages, 2871 KiB

Open AccessArticle

High-Toughness Poly(lactic Acid)/Starch Blends Prepared through Reactive Blending Plasticization and Compatibilization

by Huan Hu, Ang Xu, Dianfeng Zhang, Weiyi Zhou, Shaoxian Peng and Xipo Zhao

Molecules 2020, 25(24), 5951; https://doi.org/10.3390/molecules25245951 - 16 Dec 2020

Cited by 26 | Viewed by 3030

Abstract

In this study, poly(lactic acid) (PLA)/starch blends were prepared through reactive melt blending by using PLA and starch as raw materials and vegetable oil polyols, polyethylene glycol (PEG), and citric acid (CA) as additives. The effects of CA and PEG on the toughness [...] Read more.

In this study, poly(lactic acid) (PLA)/starch blends were prepared through reactive melt blending by using PLA and starch as raw materials and vegetable oil polyols, polyethylene glycol (PEG), and citric acid (CA) as additives. The effects of CA and PEG on the toughness of PLA/starch blends were analyzed using a mechanical performance test, scanning electron microscope analysis, differential scanning calorimetry, Fourier-transform infrared spectroscopy, X-ray diffraction, rheological analysis, and hydrophilicity test. Results showed that the elongation at break and impact strength of the PLA/premixed starch (PSt)/PEG/CA blend were 140.51% and 3.56 kJ·m⁻², which were 13.4 and 1.8 times higher than those of pure PLA, respectively. The essence of the improvement in the toughness of the PLA/PSt/PEG/CA blend was the esterification reaction among CA, PEG, and starch. During the melt-blending process, the CA with abundant carboxyl groups reacted in the amorphous region of the starch. The shape and crystal form of the starch did not change, but the surface activity of the starch improved and consequently increased the adhesion between starch and PLA. As a plasticizer for PLA and starch, PEG effectively enhanced the mobility of the molecular chains. After PEG was dispersed, it participated in the esterification reaction of CA and starch at the interface and formed a branched/crosslinked copolymer that was embedded in the interface of PLA and starch. This copolymer further improved the compatibility of the PLA/starch blends. PEGs with small molecules and CA were used as compatibilizers to reduce the effect on PLA biodegradability. The esterification reaction on the starch surface improved the compatibilization and toughness of the PLA/starch blend materials and broadens their application prospects in the fields of medicine and high-fill packaging. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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Review

Jump to: Editorial, Research

23 pages, 6089 KiB

Open AccessEditor’s ChoiceReview

Poly(Lactic Acid)-Based Graft Copolymers: Syntheses Strategies and Improvement of Properties for Biomedical and Environmentally Friendly Applications: A Review

by Jean Coudane, Hélène Van Den Berghe, Julia Mouton, Xavier Garric and Benjamin Nottelet

Molecules 2022, 27(13), 4135; https://doi.org/10.3390/molecules27134135 - 28 Jun 2022

Cited by 23 | Viewed by 5699

Abstract

As a potential replacement for petroleum-based plastics, biodegradable bio-based polymers such as poly(lactic acid) (PLA) have received much attention in recent years. PLA is a biodegradable polymer with major applications in packaging and medicine. Unfortunately, PLA is less flexible and has less impact [...] Read more.

As a potential replacement for petroleum-based plastics, biodegradable bio-based polymers such as poly(lactic acid) (PLA) have received much attention in recent years. PLA is a biodegradable polymer with major applications in packaging and medicine. Unfortunately, PLA is less flexible and has less impact resistance than petroleum-based plastics. To improve the mechanical properties of PLA, PLA-based blends are very often used, but the outcome does not meet expectations because of the non-compatibility of the polymer blends. From a chemical point of view, the use of graft copolymers as a compatibilizer with a PLA backbone bearing side chains is an interesting option for improving the compatibility of these blends, which remains challenging. This review article reports on the various graft copolymers based on a PLA backbone and their syntheses following two chemical strategies: the synthesis and polymerization of modified lactide or direct chemical post-polymerization modification of PLA. The main applications of these PLA graft copolymers in the environmental and biomedical fields are presented. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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27 pages, 7095 KiB

Open AccessReview

Stereocomplex Polylactide for Drug Delivery and Biomedical Applications: A Review

by Seung Hyuk Im, Dam Hyeok Im, Su Jeong Park, Justin Jihong Chung, Youngmee Jung and Soo Hyun Kim

Molecules 2021, 26(10), 2846; https://doi.org/10.3390/molecules26102846 - 11 May 2021

Cited by 38 | Viewed by 4484

Abstract

Polylactide (PLA) is among the most common biodegradable polymers, with applications in various fields, such as renewable and biomedical industries. PLA features poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) enantiomers, which form stereocomplex crystals through racemic blending. PLA emerged as a promising material [...] Read more.

Polylactide (PLA) is among the most common biodegradable polymers, with applications in various fields, such as renewable and biomedical industries. PLA features poly(D-lactic acid) (PDLA) and poly(L-lactic acid) (PLLA) enantiomers, which form stereocomplex crystals through racemic blending. PLA emerged as a promising material owing to its sustainable, eco-friendly, and fully biodegradable properties. Nevertheless, PLA still has a low applicability for drug delivery as a carrier and scaffold. Stereocomplex PLA (sc-PLA) exhibits substantially improved mechanical and physical strength compared to the homopolymer, overcoming these limitations. Recently, numerous studies have reported the use of sc-PLA as a drug carrier through encapsulation of various drugs, proteins, and secondary molecules by various processes including micelle formation, self-assembly, emulsion, and inkjet printing. However, concerns such as low loading capacity, weak stability of hydrophilic contents, and non-sustainable release behavior remain. This review focuses on various strategies to overcome the current challenges of sc-PLA in drug delivery systems and biomedical applications in three critical fields, namely anti-cancer therapy, tissue engineering, and anti-microbial activity. Furthermore, the excellent potential of sc-PLA as a next-generation polymeric material is discussed. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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20 pages, 705 KiB

Open AccessReview

Strategies for Enhancing Polyester-Based Materials for Bone Fixation Applications

by Raasti Naseem, Charalampos Tzivelekis, Matthew J. German, Piergiorgio Gentile, Ana M. Ferreira and Kenny Dalgarno

Molecules 2021, 26(4), 992; https://doi.org/10.3390/molecules26040992 - 13 Feb 2021

Cited by 23 | Viewed by 4565

Abstract

Polyester-based materials are established options, regarding the manufacturing of bone fixation devices and devices in routine clinical use. This paper reviews the approaches researchers have taken to develop these materials to improve their mechanical and biological performances. Polymer blending, copolymerisation, and the use [...] Read more.

Polyester-based materials are established options, regarding the manufacturing of bone fixation devices and devices in routine clinical use. This paper reviews the approaches researchers have taken to develop these materials to improve their mechanical and biological performances. Polymer blending, copolymerisation, and the use of particulates and fibre bioceramic materials to make composite materials and surface modifications have all been studied. Polymer blending, copolymerisation, and particulate composite approaches have been adopted commercially, with the primary focus on influencing the in vivo degradation rate. There are emerging opportunities in novel polymer blends and nanoscale particulate systems, to tune bulk properties, and, in terms of surface functionalisation, to optimise the initial interaction of devices with the implanted environment, offering the potential to improve the clinical performances of fracture fixation devices. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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28 pages, 4610 KiB

Open AccessReview

Crosslinking of Polylactide by High Energy Irradiation and Photo-Curing

by Melania Bednarek, Katarina Borska and Przemysław Kubisa

Molecules 2020, 25(21), 4919; https://doi.org/10.3390/molecules25214919 - 23 Oct 2020

Cited by 40 | Viewed by 4926

Abstract

Polylactide (PLA) is presently the most studied bioderived polymer because, in addition to its established position as a material for biomedical applications, it can replace mass production plastics from petroleum. However, some drawbacks of polylactide such as insufficient mechanical properties at a higher [...] Read more.

Polylactide (PLA) is presently the most studied bioderived polymer because, in addition to its established position as a material for biomedical applications, it can replace mass production plastics from petroleum. However, some drawbacks of polylactide such as insufficient mechanical properties at a higher temperature and poor shape stability have to be overcome. One of the methods of mechanical and thermal properties modification is crosslinking which can be achieved by different approaches, both at the stage of PLA-based materials synthesis and by physical modification of neat polylactide. This review covers PLA crosslinking by applying different types of irradiation, i.e., high energy electron beam or gamma irradiation and UV light which enables curing at mild conditions. In the last section, selected examples of biomedical applications as well as applications for packaging and daily-use items are presented in order to visualize how a variety of materials can be obtained using specific methods. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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44 pages, 6091 KiB

Open AccessReview

Biocompatible Polymers Combined with Cyclodextrins: Fascinating Materials for Drug Delivery Applications

by Bartłomiej Kost, Marek Brzeziński, Marta Socka, Małgorzata Baśko and Tadeusz Biela

Molecules 2020, 25(15), 3404; https://doi.org/10.3390/molecules25153404 - 28 Jul 2020

Cited by 45 | Viewed by 5528

Abstract

Cyclodextrins (CD) are a group of cyclic oligosaccharides with a cavity/specific structure that enables to form inclusion complexes (IC) with a variety of molecules through non-covalent host-guest interactions. By an elegant combination of CD with biocompatible, synthetic and natural polymers, different types of [...] Read more.

Cyclodextrins (CD) are a group of cyclic oligosaccharides with a cavity/specific structure that enables to form inclusion complexes (IC) with a variety of molecules through non-covalent host-guest interactions. By an elegant combination of CD with biocompatible, synthetic and natural polymers, different types of universal drug delivery systems with dynamic/reversible properties have been generated. This review presents the design of nano- and micro-carriers, hydrogels, and fibres based on the polymer/CD supramolecular systems highlighting their possible biomedical applications. Application of the most prominent hydrophobic aliphatic polyesters that exhibit biodegradability, represented by polylactide and polycaprolactone, is described first. Subsequently, particular attention is focused on materials obtained from hydrophilic polyethylene oxide. Moreover, examples are also presented for grafting of CD on polysaccharides. In summary, we show the application of host-guest interactions in multi-component functional biomaterials for controlled drug delivery. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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34 pages, 12314 KiB

Open AccessReview

Supramolecular Interactions in Hybrid Polylactide Blends—The Structures, Mechanisms and Properties

by Anna Kowalewska and Maria Nowacka

Molecules 2020, 25(15), 3351; https://doi.org/10.3390/molecules25153351 - 23 Jul 2020

Cited by 12 | Viewed by 3950

Abstract

The conformation of polylactide (PLA) chains can be adjusted by supramolecular interactions (the formation of hydrogen bonds or host-guest complexes) with appropriate organic molecules. The structures formed due to those intermolecular interactions may act as crystal nuclei in the PLA matrix (“soft templating”). [...] Read more.

The conformation of polylactide (PLA) chains can be adjusted by supramolecular interactions (the formation of hydrogen bonds or host-guest complexes) with appropriate organic molecules. The structures formed due to those intermolecular interactions may act as crystal nuclei in the PLA matrix (“soft templating”). In this review, the properties of several supramolecular nucleating systems based on synthetic organic nucleators (arylamides, hydrazides, and 1,3:2,4-dibenzylidene-d-sorbitol) are compared to those achieved with biobased nucleating agents (orotic acid, humic acids, fulvic acids, nanocellulose, and cyclodextrins) that can also improve the mechanical properties of PLA. The PLA nanocomposites containing both types of nucleating agents/additives are discussed and evaluated in the context of their biomedical applicability. Full article

(This article belongs to the Special Issue Polylactide-Based Materials: Synthesis and Biomedical Applications)

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