Electrospun Composite Fibers Research Articles

High-filler content electrospun fibers from biodegradable polymers and hydroxyapatite: Toward improved scaffolds for tissue engineering.

One of the key challenges in tissue engineering area is the creation of biocompatible scaffolds that support cell growth and mimic the structural and mechanical properties of native tissues. Among various materials used for scaffold fabrication, composite materials based on biodegradable polymers reinforced with bioactive inorganic fillers have attracted significant attention due to their properties. One of the important problems with the preparation of composite electrospun fibers is the low filler content in the fiber. This study aims to select the best composition for electrospun polymer fibers in terms of potential application in tissue engineering. The effect of the viscosity of polymer solution/dispersion and filler content on the structure and properties of the fibers was determined. Morphology and filler content were compared. Series of electrospun composite fibers were fabricated from poly(ĺ-caprolactone) (PCL), poly(L-lactic acid) (PLLA) and hydroxyapatite (HAP), containing from 10 wt% to 40 wt% HAP. The properties of the resulting composites were studied using scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and viscosimetry measurements. The addition of HAP to the polymer solution caused a significant increase in viscosity, but the results showed that it is possible to obtain composite electrospun fibers even with 40 wt% filler content. Scanning electron microscopy analysis shows randomly oriented electrospun fibers with an average diameter in the range of 3.8-8.5 ěm for solution and dispersion with high viscosity (1,210-2,000 mPa·s) and significantly larger diameters (approx. 12 ěm) for the PCL solution (326 mPa·s). It is possible to transform the composite dispersion from biopolymers and HAP into nonwoven fabrics at up to 40 wt% filler content. Due to their unique properties, such materials are promising for application in tissue engineering.

Electrospun PVP Fibers as Carriers of Ca2+ Ions to Improve the Osteoinductivity of Titanium-Based Dental Implants.

Although titanium and its alloys are widely used as dental implants, they cannot induce the formation of new bone around the implant, which is a basis for the functional integrity and long-term stability of implants. This study focused on the functionalization of the titanium/titanium oxide surface as the gold standard for dental implants, with electrospun composite fibers consisting of polyvinylpyrrolidone and Ca2+ ions. Polymer fibers as carriers of Ca2+ ions should gradually dissolve, releasing Ca2+ ions into the environment of the implant when it is immersed in a model electrolyte of artificial saliva. Scanning electron microscopy, energy dispersive X-ray spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy confirmed the successful formation of a porous network of composite fibers on the titanium/titanium oxide surface. The mechanism of the formation of the composite fibers was investigated in detail by quantum chemical calculations at the density functional theory level based on the simulation of possible molecular interactions between Ca2+ ions, polymer fibers and titanium substrate. During the 7-day immersion of the functionalized titanium in artificial saliva, the processes on the titanium/titanium oxide/composite fibers/artificial saliva interface were monitored by electrochemical impedance spectroscopy. It can be concluded from all the results that the composite fibers formed on titanium have application potential for the development of osteoinductive and thus more biocompatible dental implants.

Fabrication of Magnetic Poly(L-lactide) (PLLA)/Fe3O4 Composite Electrospun Fibers.

Electrospinning technology is widely used for preparing biological tissue engineering scaffolds because of its advantages of simple preparation, accurate process parameters, and easy control. Poly(L-lactide) (PLLA) is regarded as a promising biomass-based polymer for use in electrospinning. The incorporation of Fe3O4 nanoparticles (NPs) could improve the osteogenic differentiation and proliferation of cells in the presence or absence of a static magnetic field (SMF). In this work, these two materials were blended together to obtain electrospun samples with better dispersibility and improved magnetic properties. First, composite PLLA and Fe3O4 NP fibers were prepared by means of electrospinning. The influence of electrospinning conditions on the morphology of the composite fibers was then discussed. Changes in magnetic properties and thermal stability resulting from the use of different PLLA/Fe3O4 mass ratios were also considered. Next, the morphology, crystal state, thermodynamic properties, and magnetic properties of the electrospun samples were determined using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and vibration sample magnetization (VSM). The results showed that the fibers prepared using PLLA with Mn = 170,000 exhibited good morphology when electrospun at 12 KV. The magnetic properties of PLLA/Fe3O4 composite electrospun fibers increased with the NP content, with the exception of thermal stability. The results of the present study may help to promote the further development of PLLA/Fe3O4 composite materials in the biomedical field.

Enhancing piezoelectric effect of PVDF electrospun fiber through NiO nanoparticles for wearable applications

Flexible electrospun fiber-based piezoelectric nanogenerator (PENG) has attracted a lot of interest due to its ability of generating electrical energy from mechanical energy sources. The present work aims to improve the piezoelectric output of PENG devices based on electrospun polyvinylidene fluoride (PVDF) doped with nickel oxide nanoparticles (NiO NPs) in different concentrations (2, 4, 6, 8 and 10 wt.-%). Crystalline phase changes and β-crystalline content in electrospun fibers were evaluated using XRD and FTIR-ATR, respectively. Surface morphology and surface roughness of the electrospun fibers were observed using FE-SEM and AFM, respectively. The hydrophobic nature of the fibers was analyzed using a wettability test. PENG output voltage and short-circuit current performance of neat PVDF and PVDF doped with NiO (PN) composite electrospun fibers were calculated using a customized variable-pressure setup with an optimized force of 1.0 kgf and 1.0 Hz frequency. Neat PVDF-based PENG exhibited only 1.7 V and 0.7 μA, whereas, PVDF doped with 6 wt.-% NiO NP (PN-6) based PENG generated a high output voltage of 5.5 V and 1.83 μA current. The optimized PN-6 PENG device is demonstrated for use in wearable devices towards identifying certain body movements like tapping, wrist movement, walking and running.

Activated carbon-decorated electrospun polystyrene fibers for highly efficient removal of hazardous crystal violet dye from water

This study focuses on the synthesis of activated carbon (AC) from pomegranate peels biowaste and successful incorporation into polystyrene fibers (PSFs) by electrospinning process, yielding composite electrospun fiber membrane known as AC-PSFs. To gain insights into the characteristics of the fabricated electrospun fiber composite, a comprehensive characterization was conducted. To verify the role of AC in enhancing adsorption performance of PSFs to remove cationic crystal violet dye (CV) from aqueous solutions, batch adsorption technique was used. Notably, the AC-PSFs composite, containing 10% of AC, exhibited 465% high adsorption capacity compared to neat PSFs. The maximum Langmuir adsorption capacities obtained for CV dye was 65.14, 67.16 and 71.28 mg/g for PSFs and 388, 394.61 and 402.78 mg/g for AC-PSFs, at a temperature of 298, 303, and 308 K, respectively. The adsorption of CV dye onto PSFs and AC-PSFs closely followed the Langmuir isotherm model, while the kinetic adsorption fitted well with PSO model. AC-PSFs is a highly reusable adsorbent, retaining a 99% removal efficiency after using it for ten consecutive cycles, exemplifying its significant potential for long-term applications. Furthermore, the fabricated AC-PSFs composite offers the advantages of facile fabrication, excellent reusability, and easy handle, thereby establishing itself as a promising adsorbent for the efficient removal of cationic dyes from polluted water.

In Vitro Properties of Electrospun Composite Fibers Containing Boric Acid and Enhanced with Epidermal Growth Factor for Wound Dressing Applications

The requirements of the wound microenvironment, involving pH regulation, mechanical compatibility with skin, and prevention of bacterial attachment, highlight crucial considerations for advanced wound dressings. This study focused on electrospinning of poly(L-lactide-co-ε-caprolactone) (PLCL) enriched with 3–5% boric acid particles. The fibers were also supplemented with epidermal growth factor (EGF) prior to in vitro cell culture experiments. The results revealed that the fibers, with micro-to-nano thickness, displayed unique morphologies as boric acid particles interacted with the PLCL. Boric acid-containing fibers showed lower swelling rates compared to pure PLCL fibers that achieved a swelling rate of 151 ± 10.3%. Nevertheless, they maintained slightly acidic conditions and adequate oxygen conductivity in vitro. The water vapor transmission rate (WVTR) of fibers produced using a 5% boric acid-added PLCL was measured at 557 ± 20.9 g/m2day at 24 h, demonstrating competitive performance with commercial products. The incorporation of 5% boric acid in PLCL fibers significantly improved their maximum tensile stress, reaching 11.31 ± 0.82 MPa, as opposed to pure PLCL, which attained 6.92 ± 2.08 MPa. The Young's modulus values were determined as 190.53 ± 64.80 MPa for pure PLCL and 224.74 ± 91.66 MPa for PLCL containing 5% boric acid. In vitro fibroblast cell (3T3) proliferation on all fiber types did not show a significant difference compared to control. Fluorescent microscopy displayed a good adhesion and spread of cells on boric acid containing fibers. The addition of boric acid drastically reduced the attachment of Escherichia coli. The findings demonstrated the promising potential of electrospun PLCL fibers with incorporated boric acid as wound dressings.

Parameters’ Influence on Electrospun Polystyrene-Grubbs’ Catalyst Composite Fibers Morphology

Electrospinning represents a simple, cost-effective technique that allows the production of continuous fibers, with diameters ranging from the micrometer to the nanometer scale. Mixing particles in the polymer feed solution could result in composite fibers, with various potential applications, depending on the particle filler. The influence of electrospinning parameters on the fiber morphology must be investigated to obtain undamaged fibers without large agglomerates. This research presents polystyrene (PS)-based electrospun composite fibers, containing the first- and the second-generation Grubbs’ catalyst (G1 and G2). Loading of both catalysts was 1[Formula: see text]wt.% in the composite fibers, and the influence of different solution flow rates on fiber diameter, shape and regularity was investigated. Applied flow rates were 5, 10, 15 and 20[Formula: see text]ml/h for both composites (PS-G1 and PS-G2). Software analysis of field emission scanning electron microscopy (FESEM) images has revealed that flow rate has a higher influence on the diameter increase in PS-G1 compared to PS-G2, due to a difference in electrostatic forces and polymer-catalyst interactions. In both composites, 10[Formula: see text]ml/h was the threshold for producing smooth and undamaged fibers, further enhanced in PS-G2, where large agglomerates were observed at 20[Formula: see text]ml/h. Furthermore, in both composites, fiber diameter distribution was significantly wider at higher flow rates, which is not a desirable feature in composites. The presented results demonstrated the synergy between different parameters that influence the formation and morphology of electrospun PS-based composites and could help in the future design and processing of continuous composite fibers.

DNA data storage in electrospun and melt-electrowritten composite nucleic acid-polymer fibers

Incorporating biomolecules as integral parts of computational systems represents a frontier challenge in bio- and nanotechnology. Using DNA to store digital data is an attractive alternative to conventional information technologies due to its high information density and long lifetime. However, developing an adequate DNA storage medium remains a significant challenge in permitting the safe archiving and retrieval of oligonucleotides. This work introduces composite nucleic acid-polymer fibers as matrix materials for digital information-bearing oligonucleotides. We devised a complete workflow for the stable storage of DNA in PEO, PVA, and PCL fibers by employing electrohydrodynamic processes to produce electrospun nanofibers with embedded oligonucleotides. The on-demand retrieval of messages is afforded by non-hazardous chemical treatment and subsequent PCR amplification and DNA sequencing. Finally, we develop a platform for melt-electrowriting of polymer-DNA composites to produce microfiber meshes of programmable patterns and geometries.

A new starch based wound dressing modified by graphene oxide/silver nanowire nanoparticles

Considering the special effect of wound treatment in the field of medicine, antibacterial wound dressings preparation is one of the main challenges in successful wound healing. In this research, a starch (St)/polyvinyl alcohol (PVA) nanofiberous mat modified with graphene oxide (GO)-silver nanowire (AgNW) hybrid was fabricated. Initially, silver nanowires were synthesized by the polyol method, then GO-AgNW nanoparticle was prepared as a biocompatible and antibacterial biofilm. Reducing the diameter of nanofibers due to the addition of starch and GO-AgNW nanoparticles leads to fibroblast proliferation, increased collagen secretion, reduced inflammation and wound closure. Nanofibrous mats showed significant antibacterial activity against Staphylococcus aureus and Escherichia coli microorganisms. The largest zone of bacterial inhibition was obtained for Starch/PVA nanofibers containing 8% GO-AgNWs hybrid (27.11 and 24.62 mm). The use of GO-AgNW nanoparticles without drugs is an important point due to the strong antibacterial property of silver nanowire. The measured contact angle of nanofibrous mats was in the range of 57.8° as a desirable level of hydrophilicity for wound dressings. The degree of swelling obtained about 491.12%, and the water vapor transmission rate of 2549 ± 36 (g/m2.day) as a proof for accelerating wound healing. Finally, the results indicated that St/PVA/GO-AgNWs composite electrospun fibers could be a suitable candidate for the treatment of infectious wounds, surgical wounds, minor burns, etc.

Pitch/Metal Oxide Composite Fibers via Electrospinning for Environmental Applications

This study investigates the synthesis and application of composite electrospun fibers incorporating coal tar pitch (CTP) and various nanomaterial additives, with a specific focus on their potential for eco-bio-applications. The research underscores the environmentally viable aspects of CTP following a thermal treatment process that eliminates volatile components and sulfur, rendering it amenable for fiber electrospinning and subsequent carbonization. Composite fibers were fabricated by integrating CTP with nanomaterials, including nickel oxide (NiO), titanium dioxide (TiO2), activated carbon (AC), and magnetite (Fe3O4). The C/NiO composite fibers exhibit notable acetone sensing capabilities, specifically displaying a rapid response time of 40.6 s to 100 ppm acetone at 220 °C. The C/TiO2 composite fibers exhibit a distinct “beads-on-a-string” structure and demonstrate a high efficiency of 96.13% in methylene blue decomposition, highlighting their potential for environmental remediation applications. Additionally, the C/AC composite fibers demonstrate effective adsorption properties, efficiently removing manganese (II) ions from aqueous solutions with an 88.62% efficiency, thereby suggesting their utility in water purification applications. This research employs an interdisciplinary approach by combining diverse methods, approaches, and materials, including the utilization of agricultural waste materials such as rice husks, to create composite materials with multifaceted applications. Beyond the immediate utility of the composite fibers, this study emphasizes the significance of deploying environmentally responsible materials and technologies to address pressing eco-bio-challenges.

Electrospun composite fibers of poly(lactic acid) and halloysite for the sustained co-delivery of drugs with opposite water affinities

A dual drug delivery system capable of simultaneous release in a sustained manner a hydrophilic and a hydrophobic drug was prepared, consisting of electrospun poly(lactic acid) (PLA) fibers embedded with halloysite nanotubes (Hal). The hydrophobic drug (dexamethasone, DEX) was directly dissolved in the polymer solution and the hydrophilic drug (gentamicin sulfate, GS) was pre-loaded into Hal. Prior to drug loading, Hal were subjected to an acid treatment to enhance their drug loading capacity. The efficacy of the treatment was confirmed by the increase of the BET surface area and pore volume, determined by nitrogen adsorption/desorption isotherm measurements, and by an increase in GS drug loading (from 18% w/w to 25% w/w), determined by thermogravimetry. Morphologically, the fibers with or without Hal exhibited similar smooth surfaces, with no obvious signs of Hal in the composite fibers, indicating that Hal were well embedded in the fibers. In vitro release tests showed the ability of the composite electrospun fibers to release the two loaded drugs simultaneously in a sustained manner for three weeks, in a biphasic pattern characterized by a burst release in the first 2–3 days followed by a gradual, almost constant release. Furthermore, the antibacterial activity of all GS loaded fibers against Staphylococcus aureus was confirmed by a disc diffusion test. In conclusion, the developed electrospun fibers based on a “nanoparticles in micro/nanofibers” structure proved to be an effective system for the sustained co-delivery of two drugs with opposite water affinities.

Poly(ε-caprolactone)/bioactive glass composite electrospun fibers for tissue engineering applications.

In this work, composite electrospun fibers containing innovative bioactive glass nanoparticles were produced and characterized. Poly(ε-caprolactone), benign solvents, and sol-gel B- and Cu-doped bioactive glass powders were used to fabricate fibrous scaffolds. The retention of bioactive glass nanoparticles in the polymer matrix, the electrospinnability of this novel solution and the obtained electrospun composites were extensively characterized. As a result, composite electrospun fibers characterized by biocompatibility, bioactivity, and exhibiting overall properties adequate for both hard and soft tissue engineering applications, have been produced. The addition of these bioactive glass nanoparticles was, indeed, able to impart bioactive properties to the fibers. Cell culture studies show promising results, demonstrating proliferation and growth of cells on the composite fibers. Wettability, degradation rate, and mechanical performance were also tested and are in line with previous results.

Novel Electrospun Composite Membranes Based on Polyhydroxybutyrate and Poly(vinyl formate) Loaded with Protonated Montmorillonite for Organic Dye Removal: Kinetic and Isotherm Studies.

The use of biodegradable polyesters derived from green sources and their combination with natural abundantly layered aluminosilicate clay, e.g., natural montmorillonite, meets the requirements for the development of new sustainable, disposable, and biodegradable organic dye sorbent materials. In this regard, novel electrospun composite fibers, based on poly β-hydroxybutyrate (PHB) and in situ synthesized poly(vinyl formate) (PVF), loaded with protonated montmorillonite (MMT-H) were prepared via electrospinning in the presence of formic acid, a volatile solvent for polymers and a protonating agent for the pristine MMT-Na. The morphology and structure of electrospun composite fibers were investigated through SEM, TEM, AFM, FT-IR, and XRD analyses. The contact angle (CA) measurements showed increased hydrophilicity of the composite fibers incorporated with MMT-H. The electrospun fibrous mats were evaluated as membranes for removing cationic (methylene blue) and anionic (Congo red) dyes. PHB/MMT 20% and PVF/MMT 30% showed significant performance in dye removal compared with the other matrices. PHB/MMT 20% was the best electrospun mat for adsorbing Congo red. The PVF/MMT 30% fibrous membrane exhibited the optimum activity for the adsorption of methylene blue and Congo red dyes.

Formic Acid Electrospun Composite Fibers Based on Poly Β-Hydroxybutyrate/ In Situ Poly(Vinyl Formate), Loaded with Natural Montmorillonite as Potential Dye Sorbents

Formic Acid Electrospun Composite Fibers Based on Poly Β-Hydroxybutyrate/ In Situ Poly(Vinyl Formate), Loaded with Natural Montmorillonite as Potential Dye Sorbents

Effects of the methyl methacrylate addition, polymerization temperature and time on the MBG@PMMA core-shell structure and its application as addition in electrospun composite fiber bioscaffold

Mesoporous bioactive glass (MBG) possesses a high specific surface area and excellent biocompatibility making it a promising biomaterial. In the present study, poly(methyl methacrylate) (PMMA) was coated on MBG to obtain a MBG@PMMA core-shell structure to further expand the potential applications of MBG. Changes in the MMA to MBG ratio, polymerization temperature and time were investigated to determine their effects on the core-shell structure. The as-prepared core-shell powders were evaluated using scanning electron microscopy, transmission electron microscopy, and Fourier-transform infrared spectroscopy to determine the optimal core-shell structure for electrospinning application. Electrospun composite fiber scaffolds prepared by adding MBG with or without an optimized PMMA shell were examined through microstructural observation, mechanical testing, Raman spectroscopy, and in vitro bioactivity evaluation. Experimental results showed that optimized MBG@PMMA core-shell powder was prepared using MMA: MBG = 3: 1, with polymerization at 70 °C for 4 h. The spherical core-shell powder exhibited a relatively smooth surface and the flake- or cotton-like shell structure was beneficial to electrospinning. Electrospun composite fiber scaffold prepared using MBG@PMMA powder exhibited superior mechanical performance and excellent biocompatibility compared to its shell-less MBG counterpart.

Multifunctional silk fibroin – Poly(L-lactic acid) porous nanofibers: Designing adjustable nanopores to control composite properties and biological responses

Nano-scale renewable porous materials have a wide range of applications in the biomedical field such as tissue engineering and biosensors due to their high biocompatibility and large surface area. In this study, a composite of silk fibroin and poly(L-lactic acid) was electrospun together to form a porous nanofiber biomaterial with 11 blending ratios to tune the porosity of the single fibers (19.3–49%). This is highly advantageous as porous fibers effectively promoted cell attachment and proliferation while also manipulating cell growth. The protein-polymer molecular interactions, structures and crystal contents, as well as the melting and glass transition behaviors of the composites were determined. Results reveal that varying silk fibroin content can directly tune the nanopore structure of each individual fiber. The composite nanofibers have a much higher thermal stability when compared to the pure silk or PLA nanofibers. Besides, as the SF concentration increased from 0% to 100%, the hydrophilicity of the electrospun composite fibers increased (contact angle decreased from 135° to 103°), and the enzymatic degradation residues also increased from 20% to 95%. This study provides a unique method for tuning nano-fabrication properties of electrospun protein-polymer fibers that can be widely useful in the fields of biomedicine and sustainable materials.

Poly(L-lactic acid)/poly(ethylene oxide) based composite electrospun fibers loaded with magnesium-aluminum layered double hydroxide nanoparticles

Two types of MgAl layered double hydroxide nanoparticles, MgAl LDH, at Mg:Al ratio of 2:1 and 3:1were prepared and used as inorganic fillers to improve the mechanical properties of poly(lactic acid)/poly(ethylene oxide) (PLA/PEO) electrospun composite fibers. Their detailed structural characterization was performed using X-ray diffraction (XRD) and transmission electron spectroscopy (TEM) techniques. Spectroscopic, thermal, mechanical, and morphological properties of the electrospun composite fibers, and cell proliferation on their surface, were examined. XRD and TEM analyses showed that the LDH nanoparticles were 50 nm in size and the Mg:Al ratio did not affect the average spacing between crystal layers. Fourier transform infrared (FTIR) and thermal analyses (TA) revealed the compatibility of the filler and the polymer matrix. The nanoparticles considerably improved the mechanical properties of the electrospun mats. The tensile strength and elongation at break values of the composite samples increased from 0.22 MPA to 0.40 MPa and 12.2 % to 45.66 %, respectively, resulting from the interaction between LDH and the polymer matrix. Scanning electron microscopy (SEM) and MTT analyses demonstrated that the electrospun composite fibers supported the SaOS-2 cells attachment and proliferation on the fiber surfaces, along with their suitable cytocompatibility.

Conductive electrospun composite fibers based on solid-state polymerized Poly(3,4-ethylenedioxythiophene) for simultaneous electrochemical detection of metal ions.

Conductive composite fibers containing poly (3,4-ethylenedioxythiophene) (PEDOT) and silver nanoparticles (AgNPs) were fabricated by emulsion electrospinning of 2,5-dibromo-3,4-ethylenedioxythiophene (DBEDOT) in toluene together with aqueous solution of poly (vinyl alcohol) (PVA) and silver nanoparticles (AgNPs) in the presence of sodium dodecylsulfate followed by heat treatment at 70°C to convert DBEDOT to conductive PEDOT via solid state polymerization (SSP). The composite fibers were characterized by scanning electron microscopy, transmission electron microscopy, x-ray photoelectron spectroscopy and thermogravimetric analysis. The PEDOT/PVA/AgNPs composite fibers deposited on a screen-printed carbon electrode (SPCE) surface exhibited good electrochemical response and was applied for simultaneous detection of heavy metal ions in a mixture, namely Zn(II), Cd(II), and Pb(II) via square wave anodic stripping voltammetry (SWASV). With added Bi+3 into the detection system, the bismuth film formed on the electrode allows effective alloy formation with the deposited heavy metals obtained upon reduction of the heavy metal ions, the detection of heavy metal ions after stripping was successfully accomplished with a linear range of 10-80ppb and limits of detections (LOD) of 6, 3 and 8ppb for Zn(II), Cd(II), and Pb(II), respectively.

Characterization of Piezoelectric Properties of Ag-NPs Doped PVDF Nanocomposite Fibres Membrane Prepared by Near Field Electrospinning.

In this study, Near-field electrospinning (NFES) technique is used with a cylindrical collector to fabricate a large area permanent piezoelectric micro and nanofibers by a prepared solution. NFES requires a small electric field to fabricate fibers Objective: The objective of this paper to investigate silver nanoparticle (Ag-NP)/ Polyvinylidene fluoride (PVDF) composite as the best piezoelectric material with improved properties to produced tremendously flexible and sensitive piezoelectric material with pertinent conductance Methods: In this paper, we used controllable electrospinning technique based on Near-field electrospinning (NFES). The process parameter for Ag-NP/PVDF composite electrospun fiber based on pure PVDF fiber. A PVDF solution concentration of 18 wt.% and 6 wt.% silver nitrate, which is relative to the weight of PVDF wt.% with 1058 μS conductivity fibers, have been directly written on a rotating cylindrical collector for aligned fiber PVDF/Ag-NP fibers are patterned on fabricated copper (Cu) interdigitated electrodes were implemented on a thin flexible polyethylene terephthalate (PET) substrate and Polydimethylsiloxane (PDMS) used as a package to enhance the durability of the PVDF/ Ag-NP device. A notable effect on the piezoelectric response has been observed after Ag-NP addition, confirmed by XRD characterization and tapping test of Ag-NP/PVDF composite fiber. The morphology of the PVDF/Ag-NP fibers and measure diameter by scanning electron microscopy (SEM) and Optical micrograph (OM), of fiber. Finally, a diameter of PVDF/Ag-NP fibers up to ~7 μm. The high diffraction peak at 2θ = 20.5˚ was investigated by X-ray diffraction (XRD) in the piezoelectric crystal β-phase structure. Further addition of silver nanoparticles (Ag- NPs) in the PVDF solution resulted in enhancing the electromechanical conversion of the fibers from ~0.1 V to ~1 V. In conclusion, we can say that confirmed and validated the addition of Ag-NP in PVDF could enhance the piezoelectric property by using NFES technique with improved crystalline phase content can be useful for a wide range of power and sensing applications like biomedical devices and energy harvesting, among others.

In situ preparation of nanohydroxyapatite/alginate composites as additives to PVA electrospun fibers as new bone graft materials

Aiming at new fibers containing hydroxyapatite (HAp) nanocrystal composites for bone graft applications, we successfully induced in situ growth of the ceramic phase in alginate gel (HAL) added them as dried materials at 0.1, 0.25 and 0.5% (w/w) to PVA matrices to prepare electrospun fibers. X-ray diffraction pattern and transmission electron microscopy showed rod-like alginate coated hydroxyapatite nanocrystals with diameter and length of (10 ± 2) nm and (34 ± 7) nm, respectively. Morphological analysis showed that electrospun composite fibers presented a fiber diameter range of (97–170) nm with a greater homogeneity of size distribution and no grain accumulation in 12% PVA fibers containing 0.1% HAL. All the samples showed mechanical strength limits within those expected for bone graft materials but the best tensile strength response among the electrospun scaffolds [(15.2 ± 2.5) MPa] was observed for PVA fiber (12%) containing 0.1% HAL. The swelling ratio of all the composite fibers show that the presence of HAL composites induce a homogeneous swelling throughout the 4-week period, compared to bare fibers. We observe that the presence of HAL composites within the PVA fibers induced a greater degradation rate (54–62) % in one month) compared to PVA bare fibers and we attribute this property to the presence of alginate molecules. Biological assays using human gingival fibroblast cells demonstrated that all the fibrous membranes support cell adhesion and proliferation demonstrating their biocompatibility. The fibers and fibrous scaffolds prepared in the present study show very good morphological and mechanical properties as well as biocompatibility, fundamental conditions for applications as bone graft precursor materials.