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Herein, poly(caprolactone)/poly (glycerol sebacate) (PCL/PGS) fibrous structures incorporating hydroxyapatite (HA) and graphene oxide (GO) nanofillers were prepared through two procedures, including electrospinning and simultaneous electrospinning/electrospray procedures. Accordingly, introducing nanofillers into the structures through the simultaneous method led to improving the mechanical strength from 3.69 to 4.95 MPa. The electrospray nanofillers caused improvement of the amorphous regions (up to 83.4%) and increased the degradation rate. Furthermore, the filler-filled electrospun/electrospray sample illustrated the highest cell viability of 94.81 ± 0.5%. The results implied that the simultaneous procedure is promising for fabricating filler-loaded membranes as bone tissue scaffolds. [ABSTRACT FROM AUTHOR]

The purpose of this research is to introduce and design scaffolds composed of polycaprolactone(PCL) and gelatine nanofibers containing both hydroxyapatite and graphene nanoparticles at the same time for using in bone tissue engineering. At first, optimal conditions for the production of PCL/gelatine nanofibrous webs were investigated. In the following step, hydroxyapatite and graphene nanoparticles incorporated into PCL/gelatine nanofibrous webs for comparison with PCL/gelatine nanofibrous webs without adding any particles. Morphological, mechanical and biological tests were done to analyse fabricated structures. 50%PCL/50%gelatin sample has the less fiber diameter in both group with or without adding nanoparticles of hydroxyapatite and graphene. The FTIR analyses revealed characteristic absorption bands for PCL/gelatin/hydroxyapatite/graphene nanofibrous scaffolds is still similar to that of PCL/gelatin sample. Also, blending of PCL with gelatin decreased tensile strength and increased the tensile strain. As the final result, the addition of hydroxyapatite and graphene reduces diameter of nanofiber and improves the biological and mechanical properties and has a good potential using in bone tissue engineering. [ABSTRACT FROM AUTHOR]

The drug release systems are useful in controlling efficacy, improvement of function and reduction of side effects of drugs. Herein, Poly (ε-caprolactone) (PCL)/Poly (N-vinyl-2-pyrrolidone) (PVP) core-shell nanofibers loaded by multi-walled carbon nanotubes (MWCNTs) were produced. The surfaces of nanofibers were coated by polypyrrole (PPy) via vapor phase and chemical method. The chemical method was desirable according to SEM images and electrical conductivity of about 502.89 ± 45.25 S/m. Electrical stimulation was performed in the coated sample and the release of 5-fluorouracil (5FU) was investigated. Drug release of non-coated and coated samples without/with field application was investigated. The results exhibited the electric signal could be considered as a drug release control factor for coated samples with electrical field application. [ABSTRACT FROM AUTHOR]

In this study, composites of knitted fabric made from side-by-side multiple glass and polypropylene yarns have been investigated. These composites have been produced by a new manufacturing method – the hot press method. By using various knitted fabrics made from different components of glass and polypropylene yarns, several types of knitted structures and yarn components were investigated: rib 1-1, full Milano and full cardigan. The mechanical properties of composites were measured in three directions. The results showed that hot-pressed knitted composites of glass and polypropylene yarns have high strength, impact resistance, work-to-break and elongation, simultaneously. The highest bending resistance and maximum stiffness are achieved for rib-knitted composites consisting of 8 wt% glass and 92 wt% polypropylene yarns. The highest impact energy absorption was obtained with 18 wt% glass content and 82 wt% polypropylene matrix.

Purpose: 5-Fluorouracil (5FU) and Fe3O4 nanoparticles were encapsulated in core-shellpolycaprolactone (PCL)/chitosan (CS) nanofibers as a multi-mode anticancer system to studydrug release sustainability. The structure of the core-shell drug delivery system was alsooptimized according to drug release behavior by artificial intelligence.Methods: The core-shell nanofibers were electrospun by a coaxial syringe. Artificial neuralnetwork (ANN) was used for function approximation to estimate release parameters. A geneticalgorithm was then used for optimizing the structure. Chemical assay of the optimized samplewas performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD),and energy-dispersive X-ray spectroscopy (EDX). vibration sample magnetometer (VSM) testwas conducted to measure the real amount of loaded magnetic nanoparticles. HepG2 cellcytotoxicity was studied and the results for the optimized samples with and without Fe3O4 after72 hours were reported.Results: Feeding ratio of sheath to core and the amount of CS, Fe3O4, and 5FU had a statisticaleffect on nanofibers diameters, which were 300-450 nm. The drug loading efficiency of thesenanofibers was 65-86%. ANN estimated the release parameters with an error of 10%. Thetemperature increased about 5.6°C in the alternative magnetic field (AMF) of 216 kA.m-1~300kHz and 4.8°C in the AMF of 154 kA.m-1~400 kHz after 20 minutes. HepG2 cell cytotoxicityfor the optimized samples with and without Fe3O4 after 72 hours were 39.7% and 38.8%,respectively.Conclusion: Since this core-shell drug release system was more sustainable compared to theblend structure despite the low half-life of 5FU, it is suggested to utilize it as post-surgicalimplants for various cancer treatments such as liver or colorectal cancer in the future. Thissystem is capable of providing chemotherapy and hyperthermia simultaneously. [ABSTRACT FROM AUTHOR]

As a special structure and due to the unique properties of submicron‐scale fibers and electrical conductivity, conductive nanofibers recently attracted further attention in various fields, especially tissue engineering. This study aimed to coat poly (glycerol sebacate) (PGS) nanofiber/poly(caprolactone) (PCL) as a widely used combination in the fields of medicine with poly(pyrrole) (PPy) as a conductive polymer, subsequently studying and optimizing production process variables using response surface methodology (RSM). The samples were examined for morphological and structural, and their electrical conductivity and electroactivity were measured using a four‐point probe system and a cyclic voltammetry, respectively. The electrospinning conditions for constructing the substrate nanofibers with the smallest diameter were optimized. The monomer concentration of 0.05M and the polymerization time of 3.3 h exploiting the RSM were also considered as the optimal conditions for obtaining coated‐nanofibers with the smallest diameter and desired electrical conductivity (0.001 S/cm). The structural findings confirmed the successful synthesis of PGS and PPy. The conductive‐nanofiber produced under optimal conditions revealed good mechanical properties (tensile strength = 3.12 ± 0.19 MPa and elongation at break = 80.26 ± 13.71%). The highest biocompatibility was observed for the sample synthesized with the pyrrole concentration of 0.05M, which can be a suitable candidate for application in cardiac tissue engineering. [ABSTRACT FROM AUTHOR]

The present research is focused on optimization the buckling process factors to produce buckled silk yarn using the Analytic Hierarchy Process (AHP) method to gain the best mechanical properties. To achieve this aim, the improvement of mechanical performance is investigated by surface changes of single yarns due to air-jet buckling process. SEM images of yarns approved the efficiency of buckling process by increasing the yarn diameter. According to the decision matrix, the best conditions of buckling process were related to 40 Psi as air pressure and 80 rpm as speed. In the following step, multi-twisted buckled silk yarn was designed and compared in load at break aspect with native collagenous tissues. To sum up, buckling process and also analytic hierarchy process optimization method are the acceptable approaches to design the best structure of multi-twisted buckled silk yarn that has a good potential as a scaffold in collagenous tissues. [ABSTRACT FROM AUTHOR]

Cartilage is a connective tissue with a slow healing rate due to lack in blood circulation and slow metabolism. Designing tissue engineering scaffolds modified based on its specific features can assist its natural regeneration process. In this study, the chitosan‐gelatin/single‐walled carbon nanotubes functionalized by COOH (SWNTs‐COOH) nanocomposite scaffolds were fabricated through electrospinning. The effect of each component and different duration of cross‐linking were assessed in terms of morphology, porosity, chemical structure, thermal behavior, mechanical properties, wettability, biodegradability, and in vitro cell culture study. Adding SWNTs‐COOH decreased fiber diameter, water contact angle and degradation rate while increased tensile strength, hydrophilicity, stability and cell viability, due to their high intrinsic electrical conductivity, and mechanical properties and the presence of COOH functional groups in its structure. All the sample presented a porosity percentage of more than 80%, which is essential for tissue engineering scaffolds. The presence SWNTs‐COOH did not have any adverse effect on cytocompatibility. The optimal cross‐linking time increased the stability of the scaffolds in PBS. It can be concluded that the chitosan‐gelatin/1wt% SWNTs‐COOH scaffold can be appropriate for cartilage tissue engineering applications. [ABSTRACT FROM AUTHOR]

In this work, a generalized method for measuring the Poisson's ratio of fabrics is presented. The basis of this method is the two-dimensional nature of the fabric deformation. Through this method, the measurement error is very low compared to conventional methods. In the following, the error of measurement in the conventional methods has been proved theoretically then an experiment with five different knitted fabrics and an elastic sheet is designed. In addition, an algorithm based on the image processing technique is presented to measure longitudinal, transverse and area strain. The results of fabrics showed that the theoretical prediction about the error of conventional methods was predicted correctly. In the case of the elastic sheet, the same result has been found, but it was not significant statistically. It is suggested that the proposed method is capable of replacing all available methods of measuring the Poisson's ratio of fabrics and structures like them. [ABSTRACT FROM AUTHOR]

Herein, we fabricated poly (caprolactone)/Gelatin (PCL/Gel) nanofibrous scaffolds and graphene oxide (GO 0.3, 0.6 and 1% w/w) was incorporated into scaffolds. Morphological, structural, mechanical and in vitro analyses of the samples were performed. The diameter of PCL nanofibers was increased by adding Gel and GO, especially by adding 1%w/w of GO (210 ± 20 nm versus 482 ± 104 nm). Mechanical properties and hydrophilicity were improved. All scaffolds were nontoxic and the most biocompatibility values obtained were 91.71 ± 0.1% and 94.29 ± 1.1%, which were related to PCL/Gel and PCL/Gel/GO0.3, respectively. Among all samples, PCL/Gel/GO0.3 showed the highest cell area (0.973 ± 0.041). [ABSTRACT FROM AUTHOR]

Research in the field of tissue engineering, especially heart tissue engineering, is growing rapidly. Herein, the morphological, chemical, mechanical and biological properties of poly (caprolactone) (PCL)/poly (glycerol sebacate) (PGS) and PCL/PGS/graphene nanofibrous scaffolds are investigated. Initially, PGS pre‐polymer is synthesized and characterized by nuclear magnetic resonance and Fourier transform infrared spectroscopies. Then, in order to use the benefits of PGS, this polymer is mixed with PCL. Blending PGS with PCL resulted in the enhancement of ultimate elongation and reduction in the elastic modulus due to the intrinsic properties of PGS. The hydrophobicity of PCL nanofibers is reduced by adding PGS as hydrophilic polymer (105 ± 3° vs. 44 ± 2°). Also, the addition of graphene to the blend nanofibers is balanced the hydrophilicity. Degradation rate of pure PCL nanofibers is very slow but it is increased in the presence of PGS. All nanofibrous scaffolds are biocompatible and non‐toxic. The highest cell adhesion (covered area = 0.916 ± 0.032) and biocompatibility (98.79 ± 1%) are related to PCL/PGS loaded with 1% wt of graphene (PCL/PGS/graphene 1). Thus, this sample can be a good candidate for further examinations of cardiac tissue engineering. [ABSTRACT FROM AUTHOR]

Poly(glycerol sebacate) (PGS) is an attractive polymer that has many applications in medical fields, especially in tissue engineering. In this study, the influence of solvent system on electrospinnability, forming of bead‐free nanofibers and the morphology of PGS nanofibers was investigated and discussed. Among different solvents, the acidic solvent as a benign solvent was used for electrospinning. The steps were as follows: (a) Synthesis the PGS pre‐polymer and analysis its chemical structure by Fourier‐transform infrared spectroscopy (FTIR); (b) Electrospinning of the PGS by mixing PCL in eight different solvent systems; (c) evaluation the morphology of produced nanofibers using the scanning electron microscope (SEM); (d) the study of biocompatibility of produced nanofibers by MTT assay. The average diameter of nanofibers in different solvent systems turned out to vary from 260 ± 63 to 4588 ± 970 nm and nanofibers with different morphologies were produced by changing the solvent system. Among the produced straight nanofibers, the best samples were FA30,15 (formic acid), FA/AC30,15 (formic acid/Acetone), FA/AA30,15 (formic acid/acetic acid), CF/DMF20,15 (chloroform/N,N‐dimethylformamide), FA/AA35,15, and CF/DMF23,15, respectively (based on size and morphology). Also, the produced nanofibers in CF/ET (chloroform/ethanol) had a rough surface. When AA was used as solvent and polymer concentration was kept 35% w/v, sponge‐like scaffold was produced. Moreover, spring‐like nanofibers were fabricated by using DMF, (at 30% w/v) and AC (in all polymer concentrations). MTT results also demonstrated that CF/DMF20,15 as produced sample via hazardous solvents (class 3) is biocompatible. These scaffolds can be used in different tissue engineering applications according to their morphology. [ABSTRACT FROM AUTHOR]

Electrochemical actuators made of conducting polymers are one of the major types of artificial muscles that have attracted much attention in recent years. However, these artificial muscles suffer from potential drop along the length, which undermines their performance in applications requiring longer muscles. This study is aimed at enhancing the performance of this type of artificial muscles through overcoming the potential drop along the length. This is implemented using copper electroplating and creating a full-length highly conductive nanofibrous layer. Polyurethane/copper/polypyrrole (PU/Cu/PPy) nanofibrous artificial muscles were fabricated by combining electrospinning, electroplating and electrochemical polymerization. The copper electroplating affected many features of the PU nanofibrous layer including surface morphology of nanofibers, thermal, mechanical and electrical properties. Average diameter of the PU nanofibers was measured as 306 ± 48 nm, which increased significantly by increasing the duration of copper electroplating. By copper electroplating for 20 s, the onset temperature of nanofibers thermal decomposition was increased from 249 to 302 °C. Additionally, using this process, the sample Young's modulus was increased from 2.20 ± 0.21 to 62.32 ± 5.42 MPa while its elongation at break was decreased from 173.84 ± 14.22 to 94.81 ± 10.96. After copper electroplating for duration as low as 20 s, the electrical conductivity of nanofibers was increased by more than 200 times from 48.90 ± 1.10 to 10 103.06 ± 14.28 S cm−1. Electrochemical polymerization of pyrrole on the surface of metalized nanofibers increased the average diameter of produced nanofibers to 1030 ± 102 nm. Providing an electrical connection along the entire length of artificial muscle resulted in enhanced electroactive property and hence final bending actuation of 88° for a cycle potential between −0.8 V and 0.5 V at a scan rate of 5 mV s−1 was observed. The nanofibrous artificial muscle fabricated by the proposed method has immense potential for use in practical applications. [ABSTRACT FROM AUTHOR]

In this study, solvent‐free nanofibrous electrolytes were fabricated through an electrospinning method. Polyethylene oxide (PEO), lithium perchlorate and ethylene carbonate were used as polymer matrix, salt and plasticizer respectively in the electrolyte structures. Keggin‐type hetero polyoxometalate (Cu‐POM@Ru‐rGO, Ni‐POM@Ru‐rGO and Co‐POM@Ru‐rGO (POM, polyoxometalate; rGO, reduced graphene oxide)) nanoparticles were synthesized and inserted into the PEO‐based nanofibrous electrolytes. TEM and SEM analyses were carried out for further evaluation of the synthesized filler structures and the electrospun nanofibre morphologies. The fractions of free ions and crystalline phases of the as‐spun electrolytes were estimated by obtaining Fourier transform infrared and XRD spectra, respectively. The results showed a significant improvement in the ionic conductivity of the nanofibrous electrolytes by increasing filler concentrations. The highest ionic conductivity of 0.28 mS cm−1 was obtained by the introduction of 0.49 wt% Co‐POM@Ru‐rGO into the electrospun electrolyte at ambient temperature. Compared with solution‐cast polymeric electrolytes, the electrospun electrolytes present superior ionic conductivity. Moreover, the cycle stability of the as‐spun electrolytes was clearly improved by the addition of fillers. Furthermore, the mechanical strength was enhanced with the insertion of 0.07 wt% fillers to the electrospun electrolytes. The results implied that the prepared nanofibres are good candidates as solvent‐free electrolytes for lithium ion batteries. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Summary: Insertion of conductive fillers into solvent‐free polymer electrolytes enhances electrochemical behavior of the electrolyte membranes leading to higher ionic conductivity, lower capacity fading, and so on. Although, the presence of the conductive fillers in the polymer matrixes increases the risk of electrical shorting, herein, polyethylene oxide (PEO)‐based core‐shell nanofibers were prepared via a simple electrospinning method. In the core‐shell electrospun fibers, ethylene carbonate (EC) and lithium perchlorate (LiClO4) were used as a plasticizer and as a lithium salt, respectively. The core component was enwrapped by the PEO/EC/LiClO4 shell part incorporated with SiO2 nanoparticles. Various properties of the fabricated membranes were evaluated by changing the ratio of multiwall carbon nanotubes (MWCNTs) in the core part of the nanofibers. The morphology and core‐shell structure of the electrospun fibers were studied by FESEM and TEM images. According to FTIR and XRD results, addition of the EC plasticizer and the fillers into the as‐spun fibers increased the fraction of free ions and the amorphous regions. From electrochemical impedance spectroscopy studies, the ionic conductivity enhanced by insertion of the plasticizer molecules and the filler particles into the core‐shell structures. The highest ionic conductivities of 0.09 and 0.21 mS.cm−1 were obtained for the free‐filler and the filler‐loaded nanofibrous membranes, respectively. The prepared mats obeyed the Arrhenius behavior (R2~1). Dielectric studies confirmed the obtained data from the ionic conductivities. Furthermore, the capacity residual was enhanced from 69% to 85% by incorporation of the MWCNTs filler into the core component of the electrospun nanofibers. The presented results may facilitate development of versatile nanofibrous membranes embedded with the conductive fillers as solvent‐free electrolytes applicable in lithium‐ion batteries. [ABSTRACT FROM AUTHOR]

Improving the electrochemical properties of membranes in lithium‐ion batteries (LIBs) is very important. Many attempts have been made to optimize ionic conductivity of membranes. The aim of this study was fabricating composite nanofiber membranes of poly(vinylidene fluoride) (PVDF), containing titanium dioxide (TiO2) and graphene oxide (GO) nanoparticles to use in LIBs as separators. The morphology, crystallinity, porosity, pore size, electrolyte uptake, ionic conductivity, and electrochemical stability of the membranes were investigated using scanning electron microscopy, wide‐angle X‐ray diffraction, Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and linear sweep voltammetry. The electrolyte uptake and ionic conductivity of the PVDF/TiO2/GO composite nanofiber membranes containing 2 wt % GO were 494% and 4.87 mS cm−1, respectively, which were higher than those of the other fabricated membranes as well as the commercial Celgard membrane. This could be attributed to the increased porosity, larger surface area, and higher amorphous regions of the PVDF/TiO2/GO composite nanofiber membranes as a result of the synergistic effects of the nanoparticles. In this work, suitable optimized membranes with greater electrochemical stability compared with the other membranes were presented. Also, it was demonstrated that the incorporation of the TiO2 and GO nanoparticles into the PVDF nanofiber membranes led to a porous structure where the electrolyte uptake enhanced. These properties made these membranes promising candidates for being used as separators in LIBs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48775. [ABSTRACT FROM AUTHOR]

In this study, polyamide6 (PA6) nanofiber mats were fabricated through the electrospinning process. The nanofibers were coated by polyaniline (PANI) using the in situ polymerization of aniline in the presence of graphene oxide. The composite of the PANI/graphene oxide–coated nanofiber mat was treated with hydrazine monohydrate to reduce graphene oxide to graphene, and this was followed by the reoxidation of PANI. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), wide angle X‐ray diffraction (WAXD), thermal gravimetric analysis (TGA), tensile strength tests, electrical conductivity measurements, cyclic voltammetry (CV), and charge/discharge measurements were conducted on the composite PA6/graphene nanofiber mats. It was found that the surface of the PA6 nanofibers was coated uniformly with the granular PANI and graphene oxide. Besides, the composite nanofibers showed good tensile and thermal properties. Their electrical conductivity and specific capacitance, when used as a separator in the cell, were 1.02 × 10−4 S/cm and 423.28 F/g, respectively. Therefore, the composite PANI/reduced graphene oxide–coated PA6 nanofiber mats could be regarded as suitable candidates for application in energy storage devices. [ABSTRACT FROM AUTHOR]