Composite chitosan/poly(ethylene oxide) electrospun nanofibrous mats as novel wound dressing matrixes for the controlled release of drugs

The aim of this study was to develop novel biomedical electrospun nanofiber mats for controlled drug release, in particular to release a drug directly to an injury site to accelerate wound healing. Here, nanofibers of chitosan (CS), poly(ethylene oxide) (PEO), and a 90 : 10 composite blend, loaded with a fluoroquinolone antibiotic, such as ciprofloxacin hydrochloride (CipHCl) or moxifloxacin hydrochloride (Moxi), were successfully prepared by an electrospinning technique. The morphology of the electrospun nanofibers was investigated by scanning electron microscopy. The functional groups of the electrospun nanofibers before and after crosslinking were characterized by Fourier transform infrared spectroscopy. X‐ray diffraction results indicated an amorphous distribution of the drug inside the nanofiber blend. In vitro drug‐release evaluations showed that the crosslinking could control the rate and period of drug release in wound‐healing applications. The inhibition of bacterial growth for both Escherichia coli and Staphylococcus aureus were achieved on the CipHCl‐ and Moxi‐loaded nanofibers. In addition, both types of CS/PEO and drug‐containing CS/PEO nanofibers showed excellent cytocompatibility in the cytotoxicity assays. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42060.     

Mechanical characterization of high‐performance graphene oxide incorporated aligned fibroporous poly(carbonate urethane) membrane for potential biomedical applications

In this article, we report the development of graphene oxide (GO) reinforced electrospun poly(carbonate urethane) (PCU) nanocomposite membranes intended for biomedical applications. In this study, we aimed to improve the mechanical properties of PCU fibroporous electrospun membranes through fiber alignment and GO incorporation. Membranes with 1, 1.5, and 3% loadings of GO were evaluated for their morphology, mechanical properties, crystallinity, biocompatibility, and hemocompatibility. The mechanical properties were assessed under both static and dynamic conditions to explore the tensile characteristics and viscoelastic properties. The results show that GO presented a good dispersion and exfoliation in the PCU matrix, contributing to an increase in the mechanical performance. The static mechanical properties indicated a 55% increase in the tensile strength, a 127% increase in toughness for 1.5 wt % GO loading and the achievement of a maximum strength reinforcement efficiency value at the same loading. Crystallinity changes in membranes were examined by X‐ray diffraction analysis. In vitro cytotoxicity tests with L‐929 fibroblast cells and percentage hemolysis tests with fresh venous blood displayed the membranes to be cytocompatible with acceptable levels of hemolytic characteristics. Accordingly, these results highlight the potential of this mechanically improved composite membrane's application in the biomedical field. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41809.     

Fabrication of polymer/drug‐loaded hydroxyapatite particle composite fibers for drug sustained release

The aim of this study is to fabricate polymer/hydroxyapatite (HA) particle composite fibers for drug encapsulation and sustained release. Firstly, drug‐loaded hydroxyapatite particles are synthesized in one step, then by electrospinning of the blends of drug‐loaded hydroxyapatite particles and polymer solution the drug‐loaded polymer/hydroxyapatite particle composite fibers are successfully prepared. Effect of loading ratio of drug‐loaded hydroxyapatite particles in the fibers and pH value of the release medium on the drug release kinetics are both investigated, and the results demonstrate that, as compared with the polymer/drug electrospun fibers, the drug in the polymer/drug‐loaded hydroxyapatite particle composite fibers shows a sustained release manner, and the drug release rate can be regulated by both the loading ratio of drug‐loaded hydroxyapatite particles in the composite fibers and pH value of the buffer solution. The results indicate that the developed drug‐loaded polymer/hydroxyapatite particle composite fibers show great potential in bone regeneration and other related biomedical fields. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42871.     

Interplay between physicochemical and mechanical properties of poly(ethylene terephthalate) meshes for hernia repair

Non‐medical‐grade industrial nets are often implemented in developing countries as affordable alternative to surgical meshes for hernia repair. Even if there is clear evidence about their repairing reliability, their physicochemical and mechanical properties have been not fully investigated. This works compares three industrial nets with different textile patterns, and a surgical mesh of the same polymer. Nets are autoclave‐sterilized and characterized through scanning electron microscope, Raman spectroscopy, thermogravimetric analysis , differential scanning calorimetry, and uniaxial tensile tests. Spectral and thermal analyses reveal that all samples are based on poly(ethylene terephthalate). Differences are found in phase conformations with modifications in amorphous, ordered amorphous, and crystalline domains. Changes in material characteristics do not affect mechanical properties, which are mainly ascribable to the textile pattern. Industrial nets show a stiffening behavior different from the almost linear anisotropic response of surgical mesh. However, non‐medical‐grade nets could be potentially applied for surgeries once their biocompatibility and in vivo stability have been evaluated. Non‐medical‐grade industrial nets are used as low‐cost alternative to surgical meshes for hernia repair in less developed countries. Nets sterilization modifies their phase conformation, due to the interaction with water, but do not affect mechanical properties. Even tough industrial nets show a different stiffening behavior, physicochemical characterization confirms a similarity to standard surgical meshes. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46014.     

Sulfobetaine-functionalized electrospun poly(ethylene-co-vinyl alcohol) membranes for blood filtration

Functionalization imparting zwitterionic sulfobetaines has been proven as the most versatile method for improving the hemocompatibility of polymers. In this study, we aimed to enhance the hemocompatibility of electrospun poly(ethylene-co-vinyl alcohol) (EVAL) by photografting with a betaine N-(3-sulfopropyl)-N-methacroyloxyethyl-N,N-dimethyl ammonium betaine (SMDB). SMDB was UV-photografted to electrospun EVAL fibroporous membranes to obtain EVAL-g-PSMDB poly[N-(3-sulfopropyl)-N-methacroyloxyethyl-N,N- dimethylammonium betaine] grafted on EVAL with different extents of grafting. The functionalization was confirmed by analysis of the attenuated total reflectance–Fourier transform infrared spectra. The effects of functionalization on the morphology, wettability, mechanical properties, and hemocompatibility of the electrospun EVAL membranes were also studied by scanning electron microscopy, water contact angle measurement, universal testing machine measurement, and in vitro hemocompatibility evaluation, respectively. The findings highlight that SMDB functionalization significantly reduced protein adsorption, hemolysis, and platelet adhesion. Blood cell consumption studies projected that the SMDB-functionalized EVAL was able to capture leukocytes from blood, and hence, this system has the potential to be used as a filter medium for the selective removal of leukocytes from blood. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47057.     

Preparation and surface modification of electrospun aligned poly(butylene carbonate) nanofibers

In this study, aligned poly(butylene carbonate) nanofibers were fabricated by electrospinning with a high‐speed transfer roller as the receiving device. Cold plasma treatment technology was applied to improve its hydrophilicity and activity to expand its application in biological materials. The morphology of the fibers was investigated with scanning electron microscopy. X‐ray diffraction was used to research the impact of the rotation speed on the crystallization and orientation degree of the crystals. The tensile properties of the materials were evaluated by a universal tester. The surface properties of the fibers pretreated by Helium (He) and those grafted with gelatin were evaluated with water contact angle measurement and X‐ray photoelectron spectroscopy. The experimental results indicate that the order degree of fibers, crystallinity, and orientation of the crystalline region, including the mechanical properties, all increased correspondingly with the rotation speed. After plasma pretreatment, the hydrophilicity was improved significantly, and the grafting reaction was realized successfully. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Crystallinity,reversibility, and injectability of physically crosslinked poly(vinyl alcohol) and poly(ethylene glycol) hydrogels

Crystallite regions within a hydrogel network contribute to its mechanical strength, which is crucial for use in load-bearing applications. However, high amounts of crystallinity can negatively impact the ability for hydrogels to be injected, an attractive property that could replace the need for highly invasive surgical procedures. The reversibility of crystallinity and its lasting impact on the injectability of poly(vinyl alcohol) and poly(ethylene glycol) hydrogels was evaluated in this paper. The relative percent crystallinity in hydrogels was evaluated after storage and autoclaving in syringes in weekly intervals using X-ray diffraction. Results indicate that crystallinity increased over time and significantly decreased after autoclaving for all samples, where postautoclaved samples contained comparable crystallinity percentages to freshly made gels (p > 0.05). Injectability was evaluated using calculated viscosity. Aged samples were able to be injected after autoclaving, yet there was no determination established between viscosity and storage times based on the data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48706.     

Fabrication and characterization of chitosan/kefiran electrospun nanofibers for tissue engineering applications

Chitosan (CS)-based nanofibrous scaffolds are very promising in tissue engineering applications. However, electrospinning of CS is not possible unless using toxic solvents such as trifluoroacetic acid or by blending with other polymers. In the present study, we investigated CS-based nanofibers' fabrication by blending it with kefiran as a natural polysaccharide. A series of solutions with various CS to kefiran ratios were prepared and underwent electrospinning. The effects of main process parameters, including applied voltage and needle tip-to-collector distance on nanofibers' diameter and morphology, were also studied. Nanofibers containing 80% CS and 20% Kefiran with an average diameter of 81 ± 17 nm were successfully electrospun. Thermogravimetric analysis indicated the presence of both polymers in blend nanofibers. The diameter of CS/kefiran nanofibers increased with enhanced applied voltage, while needle tip-to-collector distance did not significantly affect the mean diameters. Appropriate viability of l929 cells on the obtained scaffolds was demonstrated utilizing Alamar blue assay. Also, cell attachment onto the fiber surface was confirmed by scanning electron microscopy. Results indicated that CS/kefiran nanofibrous scaffolds would be promising for tissue engineering applications.     

Reversible control of biomaterial properties for dynamically tuning cell behavior

In the past decade, significant advances in chemistry and manufacturing have enabled the development of increasingly complex and controllable biomaterials. A key innovation is the design of dynamic biomaterials that allow for user-specified, reversible, temporal control over material properties. In this review, we provide an overview of recent advancements in reversible biomaterials, including control of stiffness, chemistry, ligand presentation, and topography. These systems have wide-ranging applications within biomedical engineering, including in vitro disease models and tissue-engineered scaffolds to guide multistep biological processes.     

Novel bilayer electrospun poly(caprolactone)/ silk fibroin/ strontium carbonate fibrous nanocomposite membrane for guided bone regeneration

In this study, a thin layer with a thickness of about 120 μm of poly(caprolactone) (PCL) was fabricated by electrospinning method. Then, a fibrous nanocomposite composed of PCL/silk fibroin/strontium carbonate (PCL/SF/SrCO₃) was electrospun on the prepared layer. Then, they were characterized. The mechanical properties, water uptake, degradation rate, wettability, porosity, and bioactivity of the electrospun membrane were scrutinized in vitro. Cytotoxicity of the samples was assessed by using osteoblast-like cells (SAOS-2) and L929 fibroblasts. Moreover, the cell adhesion, alkaline phosphatase (ALP) activity, and calcium deposition through alizarin red staining were conducted. Results revealed that the bilayer structure doubled the optimum mechanical properties and the addition of SrCO₃ up to 15%–20% increased ALP activity, calcium deposition, and bioactivity. According to the results, the nanofibrous bilayer membrane containing 20 wt% SrCO₃, 20 wt% SF, and 60 wt% PCL was chosen as the optimum sample. Therefore, this membrane could be applied in guided bone regeneration (GBR).     

Influence of polycaprolactone/polyglycolide blended electrospun fibers on the morphology and mechanical properties of polycaprolactone

Polycaprolactone (PCL) and polyglycolide (PGA) are two biopolymers that have been used as in situ biomedical devices for various applications. The obstacle of creating a composite that captures the benefit of PCL's long degradation time, while acquiring the strength from PGA is overcoming the lack of surface adhesion between the two biopolymers for stress transfer to occur. This study investigates the use of miscible PCL‐PGA blended fibers, created by electrospinning, to increase the interfacial bonding of fibers to the PCL matrix of the polymer–polymer composite. The use of the blended fibers will thereby create the ability of load transfer from the long‐term PCL matrix to the stronger PCL‐PGA fiber reinforcement. The incorporation of the PCL‐PGA fibers was able to increase the tensile yield strength and Young's modulus over that of the bulk PCL, while decreasing the percent elongation at break. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40224.     

Shape‐memory behaviors of electrospun chitosan/poly(ethylene oxide) composite nanofibrous membranes

With aim of constructing a class of functional environmentally friendly materials, we electrospun chitosan (CS) blends with various contents of poly(ethylene oxide) (PEO) into a series of composite nanofibrous membranes exhibiting shape‐memory behaviors. In the present composite system, CS and PEO served as hard and soft domains, respectively. The CS, presenting no thermal transition, and the PEO, with apparent melting–crystallization, were demonstrated by differential scanning calorimetry testing. Characterizations also revealed that the morphologies of the CS/PEO membranes were controlled by the mass ratios of CS/PEO. The composite fibrous membranes showed great mechanical performances and thermal stabilities as well. Moreover, CS/PEO possessed excellent shape‐memory behaviors. Such fibrous membranes could complete their shape‐recovery processes within 20 s at the temperature of 20°C above the melting transition temperature (T_m). Both the shape fixity and shape‐recovery ratios were higher than 90%, even after five cycles. The CS/PEO fibrous membranes present significant potential applications in the field of biotechnology and tissue engineering, such as in scaffolds and smart tubes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42532.     

Eudragit E100/poly(ethylene oxide) electrospun fibers for DNA removal from aqueous solution

The development of new strategies for production of low-cost deoxyribonucleic acid (DNA) adsorbents based on electrospun fibers of block copolymers [Eudragit E-100/poly(ethylene oxide) (PEO)] is a promising way for fast retrieval of free of degradation double-stranded DNA chains from aqueous solution. The adsorption takes place through electrostatic interaction between DNA and oppositely charged electrospun fibers that provide high surface area for DNA adsorption. The adsorption capacity observed for electrospun fibers of Eudragit E100/PEO (considering as target molecules the salmon sperm DNA) was in order of 44.31 mg g⁻¹, following the Langmuir model in a typical adsorption at solid/liquid interface (pseudo-second-order model), that characterizes the electrospun fibers as promising templates for removal of biologic components and further use in molecular biology techniques, as DNA amplification by polymerase chain reaction. The reuse and integrity of membranes after long period of adsorption were tested, confirming the potential of material as adsorbent. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47479.     

The use of poly (ε‐caprolactone) to enhance the mechanical strength of porous Si‐substituted carbonate apatite

Poly(ε‐caprolactone) (PCL)/silicon‐substituted carbonate apatite (Si‐CO3Ap) composite derived from the interconnected porous Si‐CO3Ap reinforced with molten PCL was prepared. PCL was used to improve the mechanical properties of a porous apatite by a simple polymer infiltration method, in which the molten PCL was deposited through the interconnected channel of porous Si‐CO3Ap. The PCL covered and penetrated into the pores of the Si‐CO3Ap to form an excellent physical interaction with Si‐CO3Ap leading to a significant increase in diametral tensile strength from 0.23 MPa to a maximum of 2.04 MPa. The Si‐CO3Ap/PCL composite has a porosity of about 50–60% and an interconnected porous structure, with pore sizes of 50–150 μm which are necessary for bone tissue formation. These results could pave the way for producing a porous, structured biocomposite which could be used for bone replacement. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Chitosan modified by poly(ethylene oxide): Film and mixture properties

Chitosan + poly(ethylene oxide) mixtures and films prepared from these mixtures were studied by rheological, absorption of solvent vapors, SANS, and mechanical testing methods. At a stoichiometric chitosan:poly(ethylene oxide) monomer:monomer composition, the mechanical properties of chitosan + poly(ethylene oxide) film are the best as compared with those of the initial components or of other compositions. This film composition is shown to be less heterogeneous. Chitosan and poly(ethylene oxide) are proved to be slightly incompatible polymers. This is supposed to induce the two components to align and to order at their stoichiometric composition, leading to the improvement in the mechanical properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1114–1122, 2002; DOI 10.1002/app.10319     

Fabrication and characterization of electrospun psyllium husk-based nanofibers for tissue regeneration

The present study reports for first time the blending of psyllium husk (PH) powder/gelatin (G) in the polymer-rich composition of polyvinyl alcohol (PVA) to make an electrospinnable solution. The composite was prepared in 3 different ratios viz., 100% (wt/wt) (PVA + PH), 75% + 25% (PVA + 75PH + 25G) (wt/wt) and 50% + 50% (PVA + 50PH + 50G) (wt/wt) in 6% PVA solution. Optimum electrospinning parameters were evaluated for all the prepared blends. The fabricated nanofibers were characterized by scanning electron microscopy (SEM), attenuated total reflectance-Fourier transform infrared, differential scanning calorimetry, porosity percentage, and fiber orientation using ImageJ software. A qualitative in vitro degradation study at room temperature is supported by SEM images. The cellular interactions were characterized by MTT assay of NIH-3T3 fibroblast cells for 2 and 4 days with an optimum cell growth of >50% by fourth day of culture and long-term cultivation of L929-RFP cells was observed for 10 days. The nanofibers were formed in the range of 49–600 nm. PVA + 75PH + 25G when cultured with L929-RFP cells exhibited highest fluorescence intensity and thus supported cellular proliferation significantly. Based on the results obtained from various analyses, we anticipate that fabricated psyllium-based nanofiber can be used as a promising candidate for wound healing and other biomedical applications.     

Nanofiber films of chloroacetated natural rubber/poly(vinyl alcohol) by electrospinning technique: Silica effects on biodegradation

Green electrospinning technique was employed to prepare chloroacetated natural rubber (CNR)/poly(vinyl alcohol) (PVA) nanofiber films by varying the addition of PVA in the range 2.5–55 wt % followed by encapsulation of 2.5 wt % fumed silica (FS). In this study, the risk of using organic solvents was eliminated using CNR in latex. The encapsulated electrospun fiber mats showed a fairly homogenous composition with enhanced water absorption ability of 703.54% ± 33.95%. The FS improved the interfacial adhesion and contributed to enhancing the intermolecular interaction between the two polymers. The mean diameter of the nanofibers decreased from 64.0 ± 19.0 to 41.0 ± 13.0 nm and significant improvement in the hydrolytic and enzymatic degradation rate was observed implying that FS can facilitate the degradation rate. Furthermore, loading of PVA and encapsulation of FS resulted in an improved stiffness of CNR at room temperature and storage modulus increased to 2.48 and 2.12 MPa, respectively. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46432.     

Self-expandable hydrogel biliary stent design utilizing the swelling property of poly(vinyl alcohol) hydrogel

We have developed a novel self-expandable biliary stent comprising poly(vinyl alcohol) (PVA). The swelling ratio of the dried PVA hydrogels decreased from 6.7 to 2.6 as the saponification degree increased from 95 to 99.9, whereas the storage modulus and tear strength increased from 17 to 400 kPa and from 0.5 to 10 N mm⁻¹, respectively. The dimensional ratios of the inner- and outer-diameter and the length of the dried tube-shaped hydrogels (saponification degree of 98.5) prepared by simple air drying isotropically increased 1.4–1.5 times in physiological saline. Meanwhile, the dimensional ratios of the dried hydrogels prepared by drying under extension increased by twice, whereas the length decreased slightly, indicating anisotropic swelling. The radial force of the reswollen tube-shaped hydrogels (6.6 ± 0.6 mN mm⁻²) was significantly higher than that of a conventional metallic stent (4.4 ± 0.3 mN mm⁻²), suggesting that PVA hydrogels were applicable as self-expandable stents. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48851.     

Crosslinked,electrospun chitosan–poly(ethylene oxide) nanofiber mats

Mechanical characterization of nanofiber mats is an underexplored area in biomaterial engineering. In this study, a chitosan–poly(ethylene oxide) copolymer blend was electrospun and crosslinked with glutaraldehyde (GA) for various time periods. The tensile and compressive mechanical integrity of the nanofibers was analyzed with increasing exposure to vapor crosslinking. Solubility, scanning electron microscopy characterization, Fourier transform infrared, uniaxial tensile tests, and nanoindentation analyses were used to identify these trends. The mechanical studies confirmed that the GA vapor crosslinking increased the stiffness and decreased the ductility of the electrospun mats. Increased exposure time to crosslinking led to changes in the mat surface color and resistance to dissolution. Scanning electron microscopy fiber counts verified that exposure to GA vapor crosslinking increased the average fiber diameter. By the use of vapor phase deposition, mechanical properties continued to change throughout the study. The crosslinking exposure time could be chosen to accommodate in vivo mechanical loading. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Antioxidant,antifungal, water binding,and mechanical properties of poly(vinyl alcohol) film incorporated with essential oil as a potential wound dressing material

In this study, the properties of poly (vinyl alcohol) (PVA) films incorporated with Zataria multiflora essential oil (ZMO) as a potential antioxidant/antibacterial material was investigated. PVA films were prepared from PVA solutions (2% w/v) containing different concentrations of ZMO. Water solubility, moisture absorption, water swelling, and water vapor permeability for pure PVA films were 57 ± 1.1, 99 ± 3.2%, 337 ± 8%, and 0.453 ± 0.015 g mm/m² h, respectively. Incorporation of ZMO into PVA films caused a significant decrease in water swelling and moisture absorption and increase in solubility and water vapor permeability. Tensile strength, elastic modulus, and elongation at break for pure PVA films were 13.5 ± 0.61 MPa, 15.2 ± 0.8 MPa, and 216 ± 4%, respectively. Incorporation of ZMO into the PVA films caused a significant decrease in tensile strength and elastic modulus and increase in elongation at break of the films. Pure PVA film showed UV‐visible light absorbance ranging from 280 to 440 nm with maximum absorbance at 320 nm. Addition of ZMO caused a significant increase in light absorbance and opacity. PVA films exhibited no antioxidant and antifungal activities, whereas PVA/ZMO films exhibited excellent antioxidant and antifungal properties. Although the bioactivity PVA films were improved by the addition of ZMO, however, the mechanical properties and water binding capacity of the films were weaken slightly. Thus, ZMO emulsified in the ethanol not compatible with PVA matrix and more suitable emulsifier was needed in order to obtain strong film with higher mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40937.