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12 pages, 4970 KiB

Open AccessArticle

Fabrication and Characterization of Electrospun Poly(Caprolactone)/Tannic Acid Scaffold as an Antibacterial Wound Dressing

by Xuefei Chen, Qianqian Zhang, Yi Wang, Jie Meng, Meiqin Wu, Huaizhong Xu, Lei Du and Xiaohua Yang

Polymers 2023, 15(3), 593; https://doi.org/10.3390/polym15030593 - 24 Jan 2023

Cited by 13 | Viewed by 3056

Abstract

Antibacterial wound dressings are promising materials to treat infected skin wounds, which greatly affect the wound-healing process. In this study, tannic acid (TA), a natural antibacterial agent, was successfully loaded by electrospinning into poly(caprolactone) (PCL) fibers in a high concentration. It is suggested [...] Read more.

Antibacterial wound dressings are promising materials to treat infected skin wounds, which greatly affect the wound-healing process. In this study, tannic acid (TA), a natural antibacterial agent, was successfully loaded by electrospinning into poly(caprolactone) (PCL) fibers in a high concentration. It is suggested that the addition of TA was beneficial for producing uniform and continuous PCL nanofibers. Hydrogen bonds existed between the PCL and TA molecules based on the analysis of FTIR spectra and DSC results. The interactions and continuous network improved the mechanical properties of the scaffolds. Meanwhile, increasing the amount of TA also enhanced the hydrophilicity and water absorption capacity of the scaffold, both of which are beneficial for accelerating wound healing. Moreover, a burst release of the TA in the initial stage and a controlled, steady release behavior over time contributed to the highly antibacterial properties of the PCL/TA scaffolds. The fabrication of the composite scaffold supplies a facile, efficient, and controllable approach to address the issue of antibacterial treatment in wound dressing. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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17 pages, 3533 KiB

Open AccessArticle

Is Graphene Always Effective in Reinforcing Composites? The Case of Highly Graphene-Modified Thermoplastic Nanofibers and Their Unfortunate Application in CFRP Laminates

by Emanuele Maccaferri, Laura Mazzocchetti, Tiziana Benelli, Jacopo Ortolani, Tommaso Maria Brugo, Andrea Zucchelli and Loris Giorgini

Polymers 2022, 14(24), 5565; https://doi.org/10.3390/polym14245565 - 19 Dec 2022

Cited by 5 | Viewed by 2474

Abstract

Graphene (G) can effectively enhance polymers’ and polymer composites’ electric, thermal, and mechanical properties. Nanofibrous mats have been demonstrated to significantly increase the interlaminar fracture toughness of composite laminates, hindering delamination and, consequently, making such materials safer and more sustainable thanks to increased [...] Read more.

Graphene (G) can effectively enhance polymers’ and polymer composites’ electric, thermal, and mechanical properties. Nanofibrous mats have been demonstrated to significantly increase the interlaminar fracture toughness of composite laminates, hindering delamination and, consequently, making such materials safer and more sustainable thanks to increased service life. In the present paper, poly(ethylene oxide) (PEO), polycaprolactone (PCL), and Nylon 66 nanofibers, plain or reinforced with G, were integrated into epoxy-matrix Carbon Fiber Reinforced Polymers (CFRPs) to evaluate the effect of polymers and polymers + G on the laminate mechanical properties. The main aim of this work is to compare the reinforcing action of the different nanofibers (polyether, polyester, and polyamide) and to disclose the effect of G addition. The polymers were chosen considering their thermal properties and, consequently, their mechanism of action against delamination. PEO and PCL, displaying a low melting temperature, melt, and mix during the curing cycle, act via matrix toughening; in this context, they are also used as tools to deploy G specifically in the interlaminar region when melting and mixing with epoxy resin. The high extent of modification stems from an attempt to deploy it in the interlaminar layer, thus diluting further in the resin. In contrast, Nylon 66 does not melt and maintain the nanostructure, allowing laminate toughening via nanofiber bridging. The flexural properties of the nanomodifed CFRPs were determined via a three-point bending (3PB) test, while delamination behavior in Mode I and Mode II was carried out using Double Cantilever Beam (DCB) and End-Notched Flexture (ENF) tests, respectively. The lack of a positive contribution of G in this context is an interesting point to raise in the field of nanoreinforced CFRP. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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13 pages, 3795 KiB

Open AccessArticle

Evaluation of Lapatinib-Loaded Microfibers Prepared by Centrifugal Spinning

by Enikő Bitay, Attila Levente Gergely, József Kántor and Zoltán-István Szabó

Polymers 2022, 14(24), 5557; https://doi.org/10.3390/polym14245557 - 19 Dec 2022

Cited by 5 | Viewed by 2210

Abstract

Lapatinib (Lap) is a lypophilic drug frequently used in cancer treatment; however, due to its limited solubility and permeability, achieving therapeutic dose through oral administration proves to be a challenge. There are various methods for enhancing the solubility of Lap and other similar [...] Read more.

Lapatinib (Lap) is a lypophilic drug frequently used in cancer treatment; however, due to its limited solubility and permeability, achieving therapeutic dose through oral administration proves to be a challenge. There are various methods for enhancing the solubility of Lap and other similar drugs, one being the preparation of amorphous solid dispersions (ASD). In this study, a Lap-loaded polyvinylpyrrolidone (PVP) fiber mat was created with centrifugal spinning from a PVP/Lap solution in dimethyl formamide and ethanol. The production rate was 12.2 g/h dry fibers, and the fibers had an average thickness of 2.55 ± 0.92 μm. In the differential scanning calorimetry (DSC) thermogram of the fiber mat, the melting peak of the crystalline Lap was not visible, suggesting that Lap was in an amorphous state. A dissolution study was carried out in 0.2 M phosphate buffer saline solution at 37 °C. UV spectrophotometry data indicated that in the sample containing the fiber mat, the Lap concentration was 332 μg/mL (66%) in 10 min, decreasing to 227 μg/mL by 45 min. Meanwhile the crystalline Lap formed a 30–40 μg/mL (6–8%) solution in 5 min, maintaining that concentration. We conclude that centrifugal spinning can be an effective and easy method to produce ASDs. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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15 pages, 4874 KiB

Open AccessArticle

Stimulus-Responsive, Gelatin-Containing Supramolecular Nanofibers as Switchable 3D Microenvironments for Cells

by Kentaro Hayashi, Mami Matsuda, Masaki Nakahata, Yoshinori Takashima and Motomu Tanaka

Polymers 2022, 14(20), 4407; https://doi.org/10.3390/polym14204407 - 19 Oct 2022

Cited by 3 | Viewed by 2508

Abstract

Polymer- and/or protein-based nanofibers that promote stable cell adhesion have drawn increasing attention as well-defined models of the extracellular matrix. In this study, we fabricated two classes of stimulus-responsive fibers containing gelatin and supramolecular crosslinks to emulate the dynamic cellular microenvironment in vivo. [...] Read more.

Polymer- and/or protein-based nanofibers that promote stable cell adhesion have drawn increasing attention as well-defined models of the extracellular matrix. In this study, we fabricated two classes of stimulus-responsive fibers containing gelatin and supramolecular crosslinks to emulate the dynamic cellular microenvironment in vivo. Gelatin enabled cells to adhere without additional surface functionalization, while supramolecular crosslinks allowed for the reversible switching of the Young’s modulus through changes in the concentration of guest molecules in culture media. The first class of nanofibers was prepared by coupling the host–guest inclusion complex to gelatin before electrospinning (pre-conjugation), while the second class of nanofibers was fabricated by coupling gelatin to polyacrylamide functionalized with host or guest moieties, followed by conjugation in the electrospinning solution (post-conjugation). In situ AFM nano-indentation demonstrated the reversible switching of the Young’s modulus between 2–3 kPa and 0.2–0.3 kPa under physiological conditions by adding/removing soluble guest molecules. As the concentration of additives does not affect cell viability, the supramolecular fibers established in this study are a promising candidate for various biomedical applications, such as standardized three-dimensional culture matrices for somatic cells and the regulation of stem cell differentiation. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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25 pages, 25985 KiB

Open AccessArticle

Novel Wet Electrospinning Inside a Reactive Pre-Ceramic Gel to Yield Advanced Nanofiber-Reinforced Geopolymer Composites

by Yunzhi Xu, Ping Guo and Ange-Therese Akono

Polymers 2022, 14(19), 3943; https://doi.org/10.3390/polym14193943 - 21 Sep 2022

Cited by 7 | Viewed by 3385

Abstract

Electrospinning is a versatile approach to generate nanofibers in situ. Yet, recently, wet electrospinning has been introduced as a more efficient way to deposit isolated fibers inside bulk materials. In wet electrospinning, a liquid bath is adopted, instead of a solid collector, for [...] Read more.

Electrospinning is a versatile approach to generate nanofibers in situ. Yet, recently, wet electrospinning has been introduced as a more efficient way to deposit isolated fibers inside bulk materials. In wet electrospinning, a liquid bath is adopted, instead of a solid collector, for fiber collection. However, despite several studies focused on wet electrospinning to yield polymer composites, few studies have investigated wet electrospinning to yield ceramic composites. In this paper, we propose a novel in-situ fabrication approach for nanofiber-reinforced ceramic composites based on an enhanced wet-electrospinning method. Our method uses electrospinning to draw polymer nanofibers directly into a reactive pre-ceramic gel, which is later activated to yield advanced nanofiber-reinforced ceramic composites. We demonstrate our method by investigating wet electrospun Polyacrylonitrile and Poly(ethylene oxide) fiber-reinforced geopolymer composites, with fiber weight fractions in the range 0.1–1.0 wt%. Wet electrospinning preserves the amorphous structure of geopolymer while changing the molecular arrangement. Wet electrospinning leads to an increase in both the fraction of mesopores and the overall porosity of geopolymer composites. The indentation modulus is in the range 6.76–8.90 GPa and the fracture toughness is in the range 0.49–0.76 MPa

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with a clear stiffening and toughening effect observed for Poly(ethylene oxide)-reinforced geopolymer composites. This work demonstrates the viability of wet electrospinning to fabricate multifunctional nanofiber-reinforced composites. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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14 pages, 5976 KiB

Open AccessArticle

Electrospun ZnO/Pd Nanofibers as Extremely Sensitive Material for Hydrogen Detection in Oxygen Free Gas Phase

by Vadim Platonov, Abulkosim Nasriddinov and Marina Rumyantseva

Polymers 2022, 14(17), 3481; https://doi.org/10.3390/polym14173481 - 25 Aug 2022

Cited by 7 | Viewed by 2283

Abstract

The development of safety sensors is an urgent necessity for the successful use of hydrogen in real conditions, which may differ, in particular, by the oxygen content in the surrounding atmosphere. Palladium-modified zinc oxide shows the high sensitivity when detecting hydrogen in air; [...] Read more.

The development of safety sensors is an urgent necessity for the successful use of hydrogen in real conditions, which may differ, in particular, by the oxygen content in the surrounding atmosphere. Palladium-modified zinc oxide shows the high sensitivity when detecting hydrogen in air; however, studies of the sensor properties and the operation mechanism of the ZnO/Pd sensor when reducing gases are detected in an oxygen deficient or inert atmosphere have not been effectuated. In this work, we synthesized the ZnO and ZnO/Pd nanofibers by electrospinning and for the first time determined their sensor properties in the detection of CO, NH₃ and H₂ in different oxygen backgrounds. The microstructure and composition of nanofibers were characterized by electron microscopy, X-ray diffraction, X-ray fluorescent spectroscopy, and X-ray photoelectron spectroscopy. The interaction with the gas phase was investigated in situ by diffuse reflectance IR Fourier transform spectroscopy (DRIFTS). The sensor properties of ZnO and ZnO/Pd nanofibers were studied at 100–450 °C towards CO, NH₃ and H₂ in the N₂/O₂ gas mixtures containing 0.0005–20% O₂. When detecting CO, a decrease in the oxygen concentration from 20 to 0.0005% in the gas phase does not lead to a significant change in the sensor response. At the same time, when detecting NH₃ and especially H₂, a decrease in oxygen concentration down to 0.0005% results in the dramatic increase in the sensor response of ZnO/Pd nanofibers. This result is discussed in terms of palladium hydride formation, modulation of the potential barrier at the ZnO/Pd interface, as well as changes in the concentration of donor defects and charge carriers in the ZnO matrix. Synthesized electrospun ZnO/Pd nanofibers are extremely promising materials for sensors for detecting hydrogen in an oxygen free atmosphere. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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14 pages, 7440 KiB

Open AccessArticle

In Vivo Evaluation of PCL Vascular Grafts Implanted in Rat Abdominal Aorta

by Anna A. Dokuchaeva, Aleksandra B. Mochalova, Tatyana P. Timchenko, Kseniya S. Podolskaya, Oxana A. Pashkovskaya, Elena V. Karpova, Ilya A. Ivanov, Natalya A. Filatova and Irina Yu Zhuravleva

Polymers 2022, 14(16), 3313; https://doi.org/10.3390/polym14163313 - 15 Aug 2022

Cited by 4 | Viewed by 2389

Abstract

Electrospun tissue-engineered grafts made of biodegradable materials have become a perspective search field in terms of vascular replacement, and more research is required to describe their in vivo transformation. This study aimed to give a detailed observation of hemodynamic and structural properties of [...] Read more.

Electrospun tissue-engineered grafts made of biodegradable materials have become a perspective search field in terms of vascular replacement, and more research is required to describe their in vivo transformation. This study aimed to give a detailed observation of hemodynamic and structural properties of electrospun, monolayered poly-ε-caprolactone (PCL) grafts in an in vivo experiment using a rat aorta replacement model at 10, 30, 60 and 90 implantation days. It was shown using ultrasound diagnostic and X-ray tomography that PCL grafts maintain patency throughout the entire follow-up period, without stenosis or thrombosis. Vascular compliance, assessed by the resistance index (RI), remains at the stable level from the 10th to the 90th day. A histological study using hematoxylin-eosin (H&E), von Kossa and Russell–Movat pentachrome staining demonstrated the dynamics of tissue response to the implant. By the 10th day, an endothelial monolayer was forming on the graft luminal surface, followed by the gradual growth and compaction of the neointima up to the 90th day. The intense inflammatory cellular reaction observed on the 10th day in the thickness of the scaffold was changed by the fibroblast and myofibroblast penetration by the 30th day. The cellularity maximum was reached on the 60th day, but by the 90th day the cellularity significantly (p = 0.02) decreased. From the 60th day, in some samples, the calcium phosphate depositions were revealed at the scaffold-neointima interface. Scanning electron microscopy showed that the scaffolds retained their fibrillar structure up to the 90th day. Thus, we have shown that the advantages of PCL scaffolds are excellent endothelialization and good surgical outcome. The disadvantages include their slow biodegradation, ineffective cellularization, and risks for mineralization and intimal hyperplasia. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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21 pages, 10481 KiB

Open AccessArticle

Pilot-Scale Electrospinning of PLA Using Biobased Dyes as Multifunctional Additives

by Naveen Kumar Balakrishnan, Maike-Elisa Ostheller, Niccolo Aldeghi, Christian Schmitz, Robert Groten and Gunnar Seide

Polymers 2022, 14(15), 2989; https://doi.org/10.3390/polym14152989 - 23 Jul 2022

Cited by 7 | Viewed by 3276

Abstract

Fibers with diameters in the lower micrometer range have unique properties suitable for applications in the textile and biomedical industries. Such fibers are usually produced by solution electrospinning, but this process is environmentally harmful because it requires the use of toxic solvents. Melt [...] Read more.

Fibers with diameters in the lower micrometer range have unique properties suitable for applications in the textile and biomedical industries. Such fibers are usually produced by solution electrospinning, but this process is environmentally harmful because it requires the use of toxic solvents. Melt electrospinning is a sustainable alternative but the high viscosity and low electrical conductivity of molten polymers produce thicker fibers. Here, we used multifunctional biobased dyes as additives to improve the spinnability of polylactic acid (PLA), improving the spinnability by reducing the electrical resistance of the melt, and incorporating antibacterial activity against Staphylococcus aureus. Spinning trials using our 600-nozzle pilot-scale melt-electrospinning device showed that the addition of dyes produced narrower fibers in the resulting fiber web, with a minimum diameter of ~9 µm for the fiber containing 3% (w/w) of curcumin. The reduction in diameter was low at lower throughputs but more significant at higher throughputs, where the diameter reduced from 46 µm to approximately 23 µm. Although all three dyes showed antibacterial activity, only the PLA melt containing 5% (w/w) curcumin retained this property in the fiber web. Our results provide the basis for the development of environmentally friendly melt-electrospinning processes for the pilot-scale manufacturing of microfibers. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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14 pages, 3195 KiB

Open AccessArticle

The Effect of Electrical Polarity on the Diameter of Biobased Polybutylene Succinate Fibers during Melt Electrospinning

by Maike-Elisa Ostheller, Naveen Kumar Balakrishnan, Robert Groten and Gunnar Seide

Polymers 2022, 14(14), 2865; https://doi.org/10.3390/polym14142865 - 14 Jul 2022

Cited by 5 | Viewed by 2509

Abstract

Melt electrospinning is a simple, versatile, and widely used technique for the production of microfibers and sub-microfibers. Polybutylene succinate (PBS) is a promising raw material for the preparation of melt-electrospun fibers at the laboratory scale. The inclusion of additives in the PBS melt [...] Read more.

Melt electrospinning is a simple, versatile, and widely used technique for the production of microfibers and sub-microfibers. Polybutylene succinate (PBS) is a promising raw material for the preparation of melt-electrospun fibers at the laboratory scale. The inclusion of additives in the PBS melt can reduce the final fiber diameter, but economically feasible larger-scale processes remain challenging. The fiber diameter can also be reduced by machine optimization, although this is expensive due to the complexity of melt-electrospinning devices. Changes in electrical field polarity have provided a low-cost strategy to reduce the diameter of fibers produced by solution-electrospinning, but there is little information about the effect of this parameter on the final diameter of melt-electrospun fibers. We therefore determined the effect of field polarity on the diameter of melt-electrospun PBS fibers at the laboratory scale and investigated the transferability of these results to our 600-nozzle pilot-scale device. Changing the polarity achieved a significant reduction in fiber diameter of ~50% at the laboratory scale and ~30% at the pilot scale, resulting in a minimum average fiber diameter of 10.88 µm. Although the effect of field polarity on fiber diameter was similar at both scales, the fibers in the web stuck together at the laboratory scale but not at the pilot scale. We have developed an inexpensive method to reduce the diameter of melt-electrospun PBS fibers and our data provide insight into the transferability of melt electrospinning from the laboratory to a pilot-scale machine. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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12 pages, 7030 KiB

Open AccessArticle

A U-Shaped Optical Fiber Temperature Sensor Coated with Electrospinning Polyvinyl Alcohol Nanofibers: Simulation and Experiment

by Yen-Lung Chou, Hsin-Yi Wen, Yu-Qiao Weng, Yi-Ching Liu, Chao-Wei Wu, Hsiang-Cheng Hsu and Chia-Chin Chiang

Polymers 2022, 14(10), 2110; https://doi.org/10.3390/polym14102110 - 22 May 2022

Cited by 15 | Viewed by 2791

Abstract

This study describes the fabrication of an electrospun, U-shaped optical fiber sensor for temperature measurements. The sensor is based on single mode fibers and was fabricated into a U-shaped optical fiber sensor through flame heating. This study applied electrospinning to coat PVA, a [...] Read more.

This study describes the fabrication of an electrospun, U-shaped optical fiber sensor for temperature measurements. The sensor is based on single mode fibers and was fabricated into a U-shaped optical fiber sensor through flame heating. This study applied electrospinning to coat PVA, a polymer, onto the sensor layer to reduce its sensitivity to humidity. The sensor is used to measure temperature variations ranging from 30 °C to 100 °C. The objectives of this study were to analyze the sensitivity variation of the sensor with different sensor layer thicknesses resulting from different electrospinning durations, as well as to simulate the wavelength signals generated at different electrospinning durations using COMSOL. The results revealed that the maximum wavelength sensitivity, transmission loss sensitivity, and linearity of the sensor were 25 dBm/°C, 70 pm/°C, and 0.956, respectively. Longer electrospinning durations resulted in thicker sensor layers and higher sensor sensitivity, that wavelength sensitivity of the sensor increased by 42%. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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14 pages, 4628 KiB

Open AccessArticle

Variable Direct Electromechanical Properties of As-Electrospun Polystyrene Microfiber Mats with Different Electrospinning Conditions

by Chonthicha Iumsrivun, Kazuki Matsuda, Shunsaku Ohkubo and Yuya Ishii

Polymers 2022, 14(9), 1840; https://doi.org/10.3390/polym14091840 - 29 Apr 2022

Cited by 4 | Viewed by 2096

Abstract

As-electrospun microfiber mats comprising atactic polystyrene (aPS), a low-cost commodity polymer, have demonstrated beneficial electromechanical properties. However, the variability of the electromechanical properties of fiber mats produced using different electrospinning conditions has not been investigated. Therefore, herein, the direct electromechanical properties of aPS [...] Read more.

As-electrospun microfiber mats comprising atactic polystyrene (aPS), a low-cost commodity polymer, have demonstrated beneficial electromechanical properties. However, the variability of the electromechanical properties of fiber mats produced using different electrospinning conditions has not been investigated. Therefore, herein, the direct electromechanical properties of aPS fiber mats produced using different deposition times (t_dep) and electrospinning voltages (V_ES) are investigated. The resulting apparent piezoelectric d constant (d_app) of the fiber mats demonstrates a specific peak value for t_dep as high as ~1600 pC N⁻¹ under 1-kPa pressure application after ~0.2-kPa pre-pressure application, although the d_app of the fiber mats produced with some conditions is nearly zero pC·N⁻¹. Furthermore, the peak position of d_app with t_dep is fundamentally determined with σ_Eff0/Y_D(h-h_pre) [σ_Eff0: effective surface charge density, Y_D(h-h_pre): secant modulus of elasticity]. Charge distribution models for fiber mats with different t_dep are established. The models explain the characteristics of the significant changes in Y_D(h-h_pre) and σ_Eff0 with t_dep. These findings provide significant directions for the production of fiber mats with improved direct electromechanical properties. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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14 pages, 2115 KiB

Open AccessArticle

Sustainable Packaging Material Based on PCL Nanofibers and Lavandula luisieri Essential Oil, to Preserve Museological Textiles

by Ester F. Ferreira, Cláudia Mouro, Lúcia Silva and Isabel C. Gouveia

Polymers 2022, 14(3), 597; https://doi.org/10.3390/polym14030597 - 2 Feb 2022

Cited by 8 | Viewed by 2653

Abstract

The connection with textiles is one of the oldest traditions in humanity, and in the historical scenario, textiles and clothing deal with material culture. Therefore, preservation is of the utmost importance to keep this important heritage. Packaging and protection of museological textiles is [...] Read more.

The connection with textiles is one of the oldest traditions in humanity, and in the historical scenario, textiles and clothing deal with material culture. Therefore, preservation is of the utmost importance to keep this important heritage. Packaging and protection of museological textiles is imperative due to the risks that these articles suffer, mainly concerning the attack of microorganisms that promote the acceleration of their degradation, and it is still necessary to create a proper packing material. In the present work we describe a bibliographic review about the museological scenario, focused on the packaging for preservation of textile articles, as well as the techniques usually used in preventive material conservation. Future perpsctives for the improvement in the conservation of museological textiles are also given. This research aims to produce a sustainable material based on polycaprolactone (PCL), with and without antimicrobial function by incorporating Lavandula luisieri essential oil (EO), in the form of a non-woven substrate for museological packaging. A comparison was made with the most frequently used materials, such as raw cotton and a non-woven polyester. The results demonstrated that both PCL and PCL + EO obtained a good characterization for museological application with good breaking strength and excellent whiteness index. In addition, PCL + EO showed a high bacterial reduction when compared with other protective materials frequently used in museums. Therefore, these findings emphasize the potential use of this material as an innovative protective antibacterial museological packaging solution, able to safeguard and preserve textile museum and clothing collections for longer and for future generations. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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17 pages, 5057 KiB

Open AccessArticle

Electrospun 5-Chloro-7-iodo-8-hydroxyquinoline (Clioquinol)-Containing Poly(3-hydroxybutyrate)/Polyvinylpyrrolidone Antifungal Materials Prospective as Active Dressings against Esca

by Milena Ignatova, Nasko Nachev, Mariya Spasova, Nevena Manolova, Iliya Rashkov and Mladen Naydenov

Polymers 2022, 14(3), 367; https://doi.org/10.3390/polym14030367 - 18 Jan 2022

Cited by 8 | Viewed by 2286

Abstract

Esca is a grapevine disease known for centuries which pertains to the group of so-called vine trunk diseases. Phaeomoniella chlamydospora (P. chlamydospora) and Phaeoacremonium aleophilum (P. aleophilum) are the two main fungal pathogens associated with esca. Novel fibrous materials with antifungal properties based [...] Read more.

Esca is a grapevine disease known for centuries which pertains to the group of so-called vine trunk diseases. Phaeomoniella chlamydospora (P. chlamydospora) and Phaeoacremonium aleophilum (P. aleophilum) are the two main fungal pathogens associated with esca. Novel fibrous materials with antifungal properties based on poly(3-hydroxybutyrate) (PHB), polyvinylpyrrolidone (PVP) and 5-chloro-7-iodo-8-hydroxyquinoline (clioquinol, CQ) were developed. One-pot electrospinning (“in” strategy) or electrospinning in conjunction with electrospraying (“on” strategy) were applied to obtain the materials. The materials’ morphology and their surface chemical composition were examined using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR). CQ incorporated in the bulk of the fibers or in PVP particles deposited on the fibers was in the amorphous phase, which was confirmed by differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The in vitro release of CQ depended on the composition of the electrospun materials and on their design. The performed microbiological screening revealed that, unlike the non-loaded mats, the fibrous mats loaded with CQ were effective in inhibiting the growth of the pathogenic P. chlamydospora and P. aleophilum fungi. Therefore, the created materials are promising as active dressings for grapevine protection against esca. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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18 pages, 2526 KiB

Open AccessArticle

Antimicrobial Food Packaging Based on Prodigiosin-Incorporated Double-Layered Bacterial Cellulose and Chitosan Composites

by Lúcia F. A. Amorim, Cláudia Mouro, Martijn Riool and Isabel C. Gouveia

Polymers 2022, 14(2), 315; https://doi.org/10.3390/polym14020315 - 13 Jan 2022

Cited by 44 | Viewed by 4629

Abstract

Nowadays, food packaging systems have shifted from a passive to an active role in which the incorporation of antimicrobial compounds into biopolymers can promote a sustainable way to reduce food spoilage and its environmental impact. Accordingly, composite materials based on oxidized-bacterial cellulose (BC) [...] Read more.

Nowadays, food packaging systems have shifted from a passive to an active role in which the incorporation of antimicrobial compounds into biopolymers can promote a sustainable way to reduce food spoilage and its environmental impact. Accordingly, composite materials based on oxidized-bacterial cellulose (BC) and poly(vinyl alcohol)-chitosan (PVA-CH) nanofibers were produced by needleless electrospinning and functionalized with the bacterial pigment prodigiosin (PG). Two strategies were explored, in the first approach PG was incorporated in the electrospun PVA-CH layer, and TEMPO-oxidized BC was the substrate for nanofibers deposition (BC/PVA-CH_PG composite). In the second approach, TEMPO-oxidized BC was functionalized with PG, and afterward, the PVA-CH layer was electrospun (BC_PG/PVA-CH composite). The double-layer composites obtained were characterized and the nanofibrous layers displayed smooth fibers with average diameters of 139.63 ± 65.52 nm and 140.17 ± 57.04 nm, with and without pigment incorporation, respectively. FTIR-ATR analysis confirmed BC oxidation and revealed increased intensity at specific wavelengths, after pigment incorporation. Moreover, the moderate hydrophilic behavior, as well as the high porosity exhibited by each layer, remained mostly unaffected after PG incorporation. The composites’ mechanical performance and the water vapor transmission rate (WVTR) evaluation indicated the suitability of the materials for certain food packaging solutions, especially for fresh products. Additionally, the red color provided by the bacterial pigment PG on the external surface of a food packaging material is also a desirable effect, to attract the consumers’ attention, creating a multifunctional material. Furthermore, the antimicrobial activity was evaluated and, PVA-CH_PG, and BC_PG layers exhibited the highest antimicrobial activity against Staphylococcus aureus and Pseudomonas aeruginosa. Thus, the fabricated composites can be considered for application in active food packaging, owing to PG antimicrobial potential, to prevent foodborne pathogens (with PG incorporated into the inner layer of the food packaging material, BC/PVA-CH_PG composite), but also to prevent external contamination, by tackling the exterior of food packaging materials (with PG added to the outer layer, BC_PG/PVA-CH composite). Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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12 pages, 3322 KiB

Open AccessArticle

Fabrication of Electrospun Ni_0.5Zn_0.5Fe₂O₄ Nanofibers Using Polyvinyl Pyrrolidone Precursors and Electromagnetic Wave Absorption Performance Improvement

by Kyeong-Han Na, Kyong-Pil Jang, Sung-Wook Kim and Won-Youl Choi

Polymers 2021, 13(23), 4247; https://doi.org/10.3390/polym13234247 - 3 Dec 2021

Cited by 8 | Viewed by 2216

Abstract

Ni_0.5Zn_0.5Fe₂O₄ nanofibers with an average diameter of 133.56 ± 12.73 nm were fabricated by electrospinning and calcination. According to our thermogravimetric—differential thermal analysis and X-ray diffraction results, the calcination temperature was 650 °C. The microstructure, crystal [...] Read more.

Ni_0.5Zn_0.5Fe₂O₄ nanofibers with an average diameter of 133.56 ± 12.73 nm were fabricated by electrospinning and calcination. According to our thermogravimetric—differential thermal analysis and X-ray diffraction results, the calcination temperature was 650 °C. The microstructure, crystal structure, and chemical composition of the nanofibers were observed using field-emission scanning electron, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Commercial particle samples and samples containing 10 wt% and 20 wt% nanofibers were fabricated, and the electromagnetic properties were analyzed with a vector network analyzer and a 7.00 mm coaxial waveguide. Regardless of the nanofiber content, Ni_0.5Zn_0.5Fe₂O₄ was dominantly affected by the magnetic loss mechanism. Calculation of the return loss based on the transmission line theory confirmed that the electromagnetic wave return loss was improved up to −59.66 dB at 2.75 GHz as the nanofiber content increased. The absorber of mixed compositions with Ni_0.5Zn_0.5Fe₂O₄ nanofibers showed better microwave absorption performance. It will be able to enhance the performance of commercial electromagnetic wave absorbers of various types such as paints and panels. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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24 pages, 2875 KiB

Open AccessReview

Electro Fluid Dynamics: A Route to Design Polymers and Composites for Biomedical and Bio-Sustainable Applications

by Nergis Zeynep Renkler, Iriczalli Cruz-Maya, Irene Bonadies and Vincenzo Guarino

Polymers 2022, 14(19), 4249; https://doi.org/10.3390/polym14194249 - 10 Oct 2022

Cited by 10 | Viewed by 2591

Abstract

In the last two decades, several processes have been explored for the development of micro and/or nanostructured substrates by sagely physically and/or chemically manipulating polymer materials. These processes have to be designed to overcome some of the limitations of the traditional ones in [...] Read more.

In the last two decades, several processes have been explored for the development of micro and/or nanostructured substrates by sagely physically and/or chemically manipulating polymer materials. These processes have to be designed to overcome some of the limitations of the traditional ones in terms of feasibility, reproducibility, and sustainability. Herein, the primary aim of this work is to focus on the enormous potential of using a high voltage electric field to manipulate polymers from synthetic and/or natural sources for the fabrication of different devices based on elementary units, i.e., fibers or particles, with different characteristic sizes—from micro to nanoscale. Firstly, basic principles and working mechanisms will be introduced in order to correlate the effect of selected process parameters (i.e., an applied voltage) on the dimensional features of the structures. Secondly, a comprehensive overview of the recent trends and potential uses of these processes will be proposed for different biomedical and bio-sustainable application areas. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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20 pages, 3526 KiB

Open AccessReview

Electrospinning of Biomedical Nanofibers/Nanomembranes: Effects of Process Parameters

by Balaji Ayyanar Chinnappan, Marimuthu Krishnaswamy, Huaizhong Xu and Md Enamul Hoque

Polymers 2022, 14(18), 3719; https://doi.org/10.3390/polym14183719 - 6 Sep 2022

Cited by 63 | Viewed by 6708

Abstract

Nanotechnology has attracted great attention from researchers in modern science because nanomaterials have innovative and superior physical, chemical, and biological properties, and they can be altered and modified accordingly. As particles get smaller, their surface area increases compared to their volume. Electrospinning is [...] Read more.

Nanotechnology has attracted great attention from researchers in modern science because nanomaterials have innovative and superior physical, chemical, and biological properties, and they can be altered and modified accordingly. As particles get smaller, their surface area increases compared to their volume. Electrospinning is one of the advanced techniques to produce ultrathin nanofibers and membranes, and it is one of the best ways to create continuous nanomaterials with variable biological, chemical, and physical properties. The produced fibers can be utilized in various domains such as wound dressing, drug release, enzyme immobilization, etc. This review examines the biomedical nanofibers/membranes produced by electrospinning techniques to investigate the effects of process parameters (e.g., solution characteristics, applied voltage, and ambient conditions) on nanofiber characteristics (physical, chemical, and mechanical properties). The solution parameters like (i) optimum concentration, (ii) higher molecular weight, and (iii) higher conductivity produce uniform nanofibers, smoother nanofibers, and a smaller and more uniform fiber diameter, respectively. In addition, process parameters such as (i) higher voltage and (ii) slower flow rate produce more polymer ejection from the nozzle and enhance the smoother fiber production, respectively. The optimum tip-to-collector distance is considered to be 13–15 cm. The ambient conditions such as (i) higher humidity and (ii) higher temperature produce thicker and thinner nanofibers, respectively. The controlled parameters through optimization process determine the size and quality of the fibers. The effects of each parameter are discussed in this review. The applications of nanofibers are also discussed. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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18 pages, 4009 KiB

Open AccessReview

Functionalization of Electrospun Nanofiber for Bone Tissue Engineering

by Xuan Yan, Haiyan Yao, Jun Luo, Zhihua Li and Junchao Wei

Polymers 2022, 14(14), 2940; https://doi.org/10.3390/polym14142940 - 20 Jul 2022

Cited by 16 | Viewed by 3235

Abstract

Bone-tissue engineering is an alternative treatment for bone defects with great potential in which scaffold is a critical factor to determine the effect of bone regeneration. Electrospun nanofibers are widely used as scaffolds in the biomedical field for their similarity with the structure [...] Read more.

Bone-tissue engineering is an alternative treatment for bone defects with great potential in which scaffold is a critical factor to determine the effect of bone regeneration. Electrospun nanofibers are widely used as scaffolds in the biomedical field for their similarity with the structure of the extracellular matrix (ECM). Their unique characteristics are: larger surface areas, porosity and processability; these make them ideal candidates for bone-tissue engineering. This review briefly introduces bone-tissue engineering and summarizes the materials and methods for electrospining. More importantly, how to functionalize electrospun nanofibers to make them more conducive for bone regeneration is highlighted. Finally, the existing deficiencies of functionalized electrospun nanofibers for promoting osteogenesis are proposed. Such a summary can lay the foundation for the clinical practice of functionalized electrospun nanofibers. Full article

(This article belongs to the Special Issue Fabrication and Application of Electrospun Nanofibers)

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