Biphasic,tough composite core/shell PCL/PVA-GEL nanofibers for biomedical application

Emulsion electrospinning using natural and synthetic polymers, including two dissimilar materials is a promising technique for nanofibers fabrication in a core/shell configuration for tissue engineering, controlled or sustained drug delivery and dressing applications. In this study, we designed and fabricated core/shell nanofibers based on polycaprolactone (PCL) as core material and poly(vinyl alcohol) (PVA)-gelatin (GEL) blend as shell materials (PCL/PVA-GEL) to achieve high mechanical properties, good cell growth, and proliferation via emulsion electrospinning. The effect of water to acetic acid ratio in the solvent system (8:2, 7:3, 6:4, 5:5) and also type and concentration (3, 5, 7 w/v %) of surfactant on emulsion stability and nanofibers morphology were investigated. The emulsion containing 2% Tween80 and 1% Span60 as surfactants were selected by considering the stability of emulsion and uniform fiber morphology. In the tensile strength and elongation at break, 53 and 8% increase in the crosslinked wet state of the PCL/PVA-GEL nanofibers compared with PVA-GEL nanofibers were observed respectively. The cell culture results indicated that the PCL/PVA-GEL nanofibers surface has presented suitable interaction with fibroblast cells and cells attached and proliferated well on the fabricated substrate within 24 and 48 hours and also would be a good candidate for biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48713.     

Fabrication and characterization of chitosan/poly(vinyl alcohol) electrospun nanofibrous membranes containing silver nanoparticles for antibacterial water filtration

Electrospun nanofibrous membranes (ENMs) were fabricated based on chitosan/poly(vinyl alcohol) (CS/PVA) with a 70/30 mass ratio containing silver nanoparticles (AgNPs) via the electrospinning method. AgNPs were produced on the surface of CS/PVA nanofibers by adding AgNO₃ to a CS/PVA blend solution as a silver rendering component. The presence of AgNPs in the polymer blend solution was detected by UV spectrophotometry. The morphology of nanofibers before and after cross-linking with glutaraldehyde was investigated by the field emission scanning electron microscopy. The formation and size distribution of AgNPs onto the surface of nanofibers were observed by transmission electron microscopy and confirmed by energy dispersing X-ray spectroscopy. As-spun and cross-linked CS/PVA nanofibers revealed a smooth surface with diameters ranging from 58 to 73 nm and 95 to 109 nm, respectively. The effect of AgNP formation on the chemical structure of nanofibers was explored by Fourier transform infrared spectroscopy. Static and dynamic antibacterial filtration efficiencies of CS/PVA ENMs, containing differing amounts of AgNO₃, have been tested against Escherichia coli, a gram negative bacterium. The antibacterial assessment results exhibited a significant increase in both static and dynamic antibacterial filtration efficiencies of the prepared CS/PVA ENMs by addition of AgNO₃ as a bactericidal agent.     

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.     

Synthesis,antimicrobial, and release behaviors of tetracycline hydrochloride loaded poly (VInyl alcohol)/chitosan/ZrO2 nanofibers

Tetracycline hydrochloride loaded poly (vinyl alcohol)/chitosan/ZrO₂ (Tet‐PVA/CS/ZrO₂) hybrid nanofibers were fabricated via electrospinning technique. The representative weight ratio of PVA/CS at 3 : 1 was chosen to fabricate drug carrier PVA/CS/ZrO₂ nanofibers. The drug carrier showed a decrease in average diameter with the increase of ZrO₂ content at given conditions, and the nanofibers were uneven and interspersed with spindle‐shape beads with ZrO₂ content at 60 wt % and above. The networks linked by hydrogen and Zr–O–C bonds among PVA, CS, and ZrO₂ units resulted in the improving of thermal stability and decreasing of crystallinity of the polymeric matrix. Moreover, the incorporation of ZrO₂ endowed the fibers with ultraviolet shielding effect ranged from 200 to 400 nm. The Tet loading dosage had no obvious effect on the morphology and size of the medicated nanofibers at Tet content below 8 wt %, but interspersed with spindle‐shaped beads when Tet content increased to 10 wt %. The Tet‐PVA/CS/ZrO₂) nanofibers showed well controlled release and better antimicrobial activity against Staphylococcus aureus, and the Tet release from the medicated nanofibers could be described by Fickian diffusion model for M_t /M_∞< 0.6. These medicated nanofibers may have potential as a suitable material in drug delivery and wound dressing. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42506.     

Facile preparation and characterization of poly(vinyl alcohol)/chitosan/graphene oxide biocomposite nanofibers

Poly(vinyl alcohol) (PVA)/chitosan (CS)/graphene oxide (GO) biocomposite nanofibers have been successfully prepared using aqueous solution by electrospinning. CS colloidal gel in 1% acetic acid can be changed to homogeneous solution by using electron beam irradiation (EBI). The uniform distributions of GO sheets in the nanofibers were investigated by field emission scanning electron microscopy (FESEM) and Raman spectroscopy. FESEM images illustrated that the spread single GO sheet embedding into nanofibers was formed via self-assembly of GO sheet and PVA/CS chains. And the average diameters of the biocomposite nanofibers decreased (200, 173, 160 and 123 nm) with increasing the contents of GO (0.05, 0.2, 0.4 and 0.6 wt%). Raman spectra verified the presence of GO in the biocomposite nanofibrous mats. The mechanical properties of as-prepared materials related with GO contents. It revealed that the highest tensile strength was 2.78 MPa, which was 25% higher than that of neat PVA/CS nanofibers. Antibacterial test demonstrated that the addition of GO to PVA/CS nanofiber had great ability to increase inhibition zone till 8.6 mm. Overall, these features of PVA/CS/GO nanofibers which were prepared by eco-friendly solvent can be a promising candidate material in tissue engineering, wound healing and drug delivery system.     

Bipolymer nanofibers: Engineering nanoscale interface via bubble electrospinning

Modern applications in biomedicine, drug delivery, and tissue engineering demand versatile materials capable of meeting multifaceted requirements. Conventional mono-functional materials fall short of addressing these complex demands. To tackle this challenge, this study introduces an innovative approach utilizing bubble electrospinning for the fabrication of bipolymeric side-by-side nanofibers. These nanofibers incorporate distinct hydrophilic and hydrophobic domains aligned parallel to their axis, achieved through the electrospinning of polyvinyl alcohol (PVA) as the hydrophilic component, alongside either poly(ε-caprolactone) (PCL) or Nylon6 as the hydrophobic component. The optimal diameter of the bubble electrospinning reservoir was theoretically determined via simulation of electric field using Maxwell 3D software and experimentally validated. Successful electrospinning resulted in nanofibers with hydrophilic and hydrophobic domains derived from PVA/Nylon6 and PVA/PCL polymer combinations. This innovative process yielded nanofibers with diameters as fine as 101 nm in the PVA/Nylon6 bipolymeric nanofibers. Transmission electron microscopy images provide compelling insights into the distinct interfaces formed during polymer-polymer interactions within the nanofibers, manifesting the Janus structure. Furthermore, Fourier-transform infrared spectroscopy confirms the presence of both polymers within the nanofiber matrix. This research represents a significant advancement in the efficient production of bipolymer nanofibers, holding promise for a wide range of applications.     

聚乙烯醇及其共混液的电纺性研究

研究了聚乙烯醇(PVA)的浓度、纺丝电压和固化距离对PVA静电纺丝的影响。扫描电镜等结果显示:PVA的浓度(质量体积百分数)为5%￣8%、纺丝电压为6.6￣15kV和固化距离为5￣25cm时适合静电纺丝。PVA分别与海藻酸钠、可溶性淀粉和壳聚糖的混合溶液在一定浓度范围内可纺性好,可得到具有较好纤维形态的纤维。     

Electrospinning of chitosan/poly(lactic acid) nanofibers: The favorable effect of nonionic surfactant

To improve the electrospinnability of chitosan (CS), a series of nanofiber membrane blends comprised of CS, poly(lactic acid) (PLA), and nonionic surfactant polyoxyethylene nonylphenol ether (TX‐15), were made. Uniform nanofibers with no bead‐like structures were obtained from solutions of 2% TX‐15 with 6% CS(50)/PLA(50). The diameter was between 200 and 300 nm. We found that with increasing TX‐15 in the blend, the nanofibers displayed more hydrophilicity. Compared to CS/PLA nanofibers, the blend polymers with TX‐15 had better tensile mechanical properties. Finally, all cells examined showed high levels of attachment and spreading on CS/PLA/TX‐15 nanofibers with a TX‐15 content of 0～3%. Thus, the nanofibers were nontoxic. In conclusion, adding PLA and TX‐15 to CS via solution‐blending and electrospinning may be an effective way to toughen CS nanofibers and make them more suitable for drug delivery or tissue engineering applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41098.     

Evaluation of PCL/chitosan electrospun nanofibers for liver tissue engineering

In this investigation, a nanofibrous scaffold was fabricated through electrospinning of polycaprolactone (PCL) and chitosan (CS) using a novel collector to make better orientation and pore size for cell infiltration. PCL/CS nanofibers with 90-rpm collector speed and 40° angle between collector wires of the new collector have fewer diameters with better pore, size and nanofibers orientation. Mechanical properties, roughness parameters, topology, structure, hydrophilicity, and cell growing were considered for liver tissue engineering. The cell culture was done using epithelial liver mouse cells. The developed electrospun PCL/CS scaffold using novel collector would be an excellent matrix for biomedical applications especially liver tissue engineering.     

Ultrasmall Ag nanocrystals supported on chitosan/PVA nanofiber mats with bifunctional properties

Bifunctional nanofiber mats consisting of chitosan (CS), poly(vinyl alcohol) (PVA), and silver nanocrystals (Ag NCs) have been fabricated by a facile electrospinning method. The formation and presence of Ag NCs supported on CS/PVA nanofibers are confirmed by ultraviolet‐visible spectroscopy and X‐ray diffraction. The morphology of the samples is characterized by transmission electron microscopy and scanning electron microscopy. The prepared Ag NCs/CS/PVA nanofiber mats show pronounced antibacterial activity against Escherichia coli and excellent filtration property for suspended particulate matter (SPM) particles. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46504.     

Preparation of chitosan bicomponent nanofibers filled with hydroxyapatite nanoparticles via electrospinning

Chitosan (CS) bicomponent nanofibers with an average diameter controlled from 100 to 50 nm were successfully prepared by electrospinning of CS and poly(vinyl alcohol) (PVA) blend solution. Finer fibers and more efficient fiber formations were observed with increased PVA contents. On this contribution, a uniform and ultrafine nanofibrous CS bicomponent mats filled with hydroxyapatite (HA) nanoparticles were successfully electrospun in a well devised condition. An increase in the contents of HA nanoparticles caused the conductivity of the blend solution to increase from 1.06 mS/cm (0 wt % HA) to 2.27 mS/cm (0.5 wt % HA), 2.35 mS/cm (1.0 wt % HA), respectively, and the average diameter of the composite fibers to decrease from 59 ± 10 nm(0 wt % HA) to 49 ± 10 nm (0.5 wt % HA), 46 ± 10 nm (1.0 wt % HA), respectively. SEM images showed that some particles had filled in the nanofibers whereas the others had dispersed on the surface of fibers, and EDXA results indicated that both the nanoparticles filled in the nanofibers and those adhered to the fibers were HA particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Three‐layered electrospun PVA/PCL/PVA nanofibrous mats containing tetracycline hydrochloride and phenytoin sodium: A case study on sustained control release,antibacterial, and cell culture properties

The main objective of this work was to prepare a tailor‐made electrospun nanofibrous samples based on poly(?‐caprolactone) (PCL) containing tetracycline hydrochloride (TC‐HCl) as a middle layer and poly(vinyl alcohol) (PVA) including phenytoin sodium (PHT‐Na) as lateral layers. The characterizations of the three‐layered electrospun samples were carried out by using SEM, ATR‐FTIR spectroscopy along with swelling/weight loss, UV–vis spectrophotometry as well as HPLC, antibacterial and MTT tests. The SEM micrograph images showed that the average diameter of PCL nanofibers was decreased from 243 ± 7 nm to 181 ± 5 nm by adding TC‐HCl. The hydrolytic degradation of PVA nanofibers in the exposure of phosphate buffer solution (PBS) was confirmed by ATR‐FTIR results in which a change at the intensity of the characteristic peak located at 3333 cm^?1 corresponding to hydroxyl groups (? OH) was observed. The UV–vis outcomes revealed a sustained control release of TC‐HCl from the three‐layered nanofibrous samples (PVA/PCL/PVA) with an amount of about 43% compared to the PCL nanofibers which had an ultimate release of the drug about 79%. Furthermore, the HPLC chromatograms showed the released PHT‐Na from PVA nanofibers about 87%. Finally, the MTT assay along with the antibacterial evaluation exhibited that the surfaces of these electrospun three‐layered nanofibrous samples have no cytotoxicity as well as the controlled release of TC‐HCl from them enabled their prolonged use for preventing the bacterium growth such as S. aureus during 24‐h treatment time. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43309.     

Fabrication of electrospun eggshell membrane nanofibers by treatment with catechin

Optimum processing conditions for the electrospinning of water‐soluble eggshell membrane (S‐ESM) were investigated. Two biocompatible polymers, poly(ethylene oxide) (PEO) and poly(vinyl alcohol) (PVA), were used to improve the processability of S‐ESM for electrospinning in aqueous media. Uniform nanofibers with average diameters of 240 and 335 nm were successfully electrospun for blend ratios at S‐ESM/PEO = 95 : 5 and S‐ESM/PVA = 60 : 40 with a solutes concentration of 20 and 18 wt %, respectively. Insoluble S‐ESM/PEO and S‐ESM/PVA fibers were achieved after treatment with catechin and required no toxic or synthetic additives. FTIR spectra indicated that the hydrogen bond formed between S‐ESM and catechin was the main interaction that improved the insolubility of S‐ESM/PEO and S‐ESM/PVA nanofibers in water. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nano/micro-structured poly(ϵ-caprolactone)/gelatin nanofibers with biomimetically-grown hydroxyapatite spherules: High protein adsorption,controlled protein delivery and sustained bioactive ions release designed as a multifunctional bone regenerative membrane

Bioactive and biodegradable fibrous membranes are highly attractive for periodontal bone regeneration. Herein, we demonstrate a new approach for fabrication of a novel nano/micro-structured fibrous membrane made of biodegradable poly(?-caprolactone)/gelatin (PCL/GEL) nanofibers and biomemtically-grown hydroxyapatite spherules (HAs). The proposed approach includes electrospinning fabrication of PCL/GEL nanofibers containing nanobioglass (NBG) agglomerates and their biomimetic transformation into HAs. The NBG agglomerates (~1.9 μm in diameter) enabled the growth of biomimetic HAs (~4 μm in diameter) around the PCL/GEL nanofibers and generated a unique nano/micro-structure. Interestingly, the biomimetically-grown HAs imparted the PCL/GEL-HAs nanofibrous membrane with several remarkable properties including nano/micro-topography, bone-mimetic composition (Ca/P = 1.60), large specific surface area (~31 m²/g), high protein adsorption capacity (~157 μg protein/mg membrane) and controlled protein delivery with zero-order release kinetics; along with sustained release of therapeutic ions (Ca²⁺ ~ 37 ppm, PO₄^3? ~ 24 ppm, and SiO₄^4? ~ 61 ppm). Furthermore, the PCL/GEL-HAs membrane exhibited enhanced wettability, good biodegradability and adequate mechanical properties. Collectively, the PCL/GEL-HAs demonstrated unique properties and it can be considered as a novel multifunctional bioactive/biodegradable membrane for periodontal bone regeneration.     

Slow release of levofloxacin conjugated on silica nanoparticles from poly(ɛ-caprolactone) nanofibers

Composite levofloxacin (LVF)/nanofibers have been fabricated through electrospinning. Slow release was achieved by covalently binding LVF to mesoporous silica nanoparticles (MSN) through a cleavable thioester bond and then blending the MSN into poly(?-caprolactone) (PCL) nanofibers. Conjugated LVF–MSN was characterized by FTIR, DSC, TGA, and solid-state C¹³ NMR. The structure of composite nanofibers was studied by scanning electron microscopy (SEM). Drug release profiles showed that burst release was decreased from 59% in the uniform PCL/LVF electrospun mats to 20% in the PCL/conjugated LVF–MSN mats after 1 day in phosphate buffer at 37°C, and gradual release in the latter was observed over the next 13 days. This slow release is due to the cleavable bond between LVF and MSN that can be hydrolyzed over a time and results in slow release of LVF. The results indicate that confining drug-conjugated MSN into nanofibers are effective ways to slow down the burst release of the drug.     

PCL/poloxamer 188 blend microsphere for paclitaxel delivery: Influence of poloxamer 188 on morphology and drug release

A novel controlled release system, paclitaxel‐loaded poly (ε‐caprolactone) (PCL)/poloxamer 188 (Pluronic F68, F68) blend microspheres is proposed in the present work. F68 was incorporated into PCL matrices as both a pore‐forming agent and a drug releasing enhancer. Paclitaxel‐loaded PCL/F68 blend microspheres with different amounts of F68 were prepared by the oil‐in water (O/W) emulsion/solvent evaporation method. Characterization of the microspheres followed to examine the particle size, the drug encapsulation efficiency, the surface morphology, and in vitro release behavior. The influences of F68 on microsphere morphology and paclitaxel release are discussed. The porosity of the surface of PCL/F68 blend microspheres and the release rate of paclitaxel from the PCL/F68 blend microspheres increased as the initial amount of blended F68 increased. Faster and controlled release was achieved in comparison with the PCL microspheres. Through this study, the developed microporous PCL/F68 blend microspheres could be used as a drug delivery system to enhance and control drug release in the future. © 2007 Wiley Periodicals, Inc. JAppl Polym Sci 104: 1895–1899, 2007     

Polyvinyl alcohol-collagen-hydroxyapatite biocomposite nanofibrous scaffold: Mimicking the key features of natural bone at the nanoscale level

Polyvinyl alcohol (PVA) nanofibers, PVA/Type I Collagen (Col) and their composites with hydroxyapatite nanoparticles (nano-HAp) were prepared by electrospinning techniques. The composite nanofibrous membranes were subjected to detailed analysis. Morphological investigations show that the generated nanofibers (NFs) have uniform morphology with an average diameter of ∼160 nm for pure PVA, ∼176 nm for PVA/n-HAp, ∼245 nm for PVA/Col and ∼320 nm for PVA/Col/n-HAp. It is of interest to observe that large numbers of HAp nanorods are preferentially oriented parallel to the longitudinal direction of the electrospun PVA and/or PVA/Col NFs. FTIR and thermal analysis demonstrated that there was strong intermolecular hydrogen bonding between the molecules of PVA/Col/n-HAp. Furthermore, the obtained PVA/Col/nHAp NFs scaffold (7 cm × 11 cm) has a porous structure with adjustable pore size and shape. The pore size is in the range of 650 μm with a porosity of 49.5%. On the other hand, mechanical characterizations revealed that the incorporating of 5 wt% n-HAp into the matrix of PVA/Col nanofibers could significantly improve the rigidity of the resultant biocomposite nanofibrous scaffold. These results strongly suggest a huge potential of the prepared scaffold for bone tissue engineering.     

Effects of gamma irradiation on the thermal and mechanical properties of chitosan/PVA nanofibrous mats

Chitosan/poly(vinyl alcohol) (PVA) nanofibrous mats were prepared by the electrospinning method. The morphology and structure of electrospun nanofibers were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. SEM images showed that the uniform and bead-free fibers were obtained at concentrations greater than 8 wt%. Chitosan/PVA mats were irradiated with different doses (50–200 kGy) of ⁶⁰Co gamma rays. The effect of irradiation dose on the mechanical and thermal properties of these films was also investigated. Increasing the irradiation dose led to a decrease in tensile strength. FT-IR and DSC demonstrated that there were strong intermolecular hydrogen bonds between the chitosan and PVA molecules.     

A novel honey‐based nanofibrous scaffold for wound dressing application

In this study, nanofiber meshes were produced from aqueous mixtures of poly(vinyl alcohol) (PVA) and honey via electrospinning. The Electrospinning process was performed at different PVAs to honey ratios (100/0, 90/10, 80/20, 70/30, and 60/40). Dexamethasone sodium phosphate was selected as an anti‐inflammatory drug and incorporated in the electrospinning solutions. Its release behavior was determined. Uniform and smooth nanofibers were formed, independent of the honey content. In case honey content increased up to 40%, some spindle‐like beads on the fibers were observed. The diameter of electrospun fibers decreased as the ratio of honey increased. The release characteristics of the model drug from both the PVA and PVA/honey (80/20) nanofibrous mats were studied and statistical analysis was performed. All electrospun fibers exhibited a large initial burst release at a short time after incubation. The release profile was similar for both PVA and PVA/honey (80/20) drug‐loaded nanofibers. This study shows that an anti‐inflammatory drug can be released during the initial stages and honey can be used as a natural antibiotic to improve the wound dressing efficiency and increase the healing rate. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci, 2013     

Electrospun Poly(ε-Caprolactone)/Silk Fibroin Coaxial Core-Sheath Nanofibers Applied to Scaffolds and Drug Carriers

Developing biologically mimetic nanofibers (NFs) is crucial for their applications as scaffolds in tissue engineering and drug carriers. Herein, we present a strategy to facilely fabricate core-sheath NFs using coaxial electrospinning technique. Poly(ε-caprolactone) (PCL) and silk fibroin (SF) were employed as component materials to construct PCL/SF NFs with PCL cores uniformly encapsulated by SF sheaths. Scanning electron microscopy and transmission electron microscopy demonstrate a uniform core-sheath structure of the coaxial NFs. The engineered core-sheath structure confers the composite NFs with greatly improved properties including surface hydrophilicity and mechanical properties. In vitro cell culture validates that the core-sheath NFs are favorable to the cultured rat pheochromocytoma cells (PC 12) attachment. To further demonstrate the advantage of the coupled structural integrity, the PCL/SF core-sheath NFs were compared with the NFs produced from PCL and SF blend. Results showed that the PCL/SF NFs possessed a tensile strength of ~6.93 ± 0.52 MPa and an elongation at break of ~294.31 ± 24.17%, whereas the blend NFs possessed ~5.55 ± 0.50 MPa and ~88.05 ± 13.98%, respectively. Dexamethasone-phosphate sodium (DEX) was employed as a model drug, whereby the in vitro release study indicates that the NFs exhibit an ideal releasing profile, capable of releasing DEX continuously over a period of 450 h. The constructed PCL/SF core-sheath NFs are promising candidates for biomedical applications. POLYM. ENG. SCI., 60:802–809, 2020. © 2020 Society of Plastics Engineers