Optimization of polylactic acid-based medical textiles via electrospinning for healthcare apparel and personal protective equipment

Development of sustainable and eco-friendly non-woven textiles is essential to produce environmentally benign personal protective equipment (PPE) for reduction of risk in transmission and infection of bacteria and virus. This study demonstrates about the fabrication of medical textile from polylactic acid (PLA) biopolymer via electrospinning process. Solvent systems from single to binary in different ratios and the operational parameters of electrospinning, i.e. voltage, solution flow rate and distance to collector, were studied to investigate the influence on nanofiber morphology, diameter and electrospinnability. Effects of substrates and electrospinning techniques such as multi-spinneret and wire spinneret were further investigated for scale-up textile production. Thermal properties were characterized by differential scanning calorimetry (DSC). Viscosity and conductivity of polymer solutions were measured. Nanofiber morphology and diameter were investigated by scanning electron microscopy (SEM). The results showed that binary-solvents DMF/acetone (4:6 v/v) and DMAc/acetone (2:8 v/v) gave finest defect-free fibers and electrospinnability. Polymer concentration of 10–12.5% w/v resulted in defect-free nanofibers. Electrospinning parameters were optimum at a voltage of 25 KV, collector distance of 250 mm and flow rate of 1 mL/h. Optimization of solvents and electrospinning parameters improved mean fiber diameter from 929 ± 670 nm to 315 ± 246 nm. In summary, DMF/acetone solvent system was considered the optimized candidate for PLA electrospinning, effective on non-woven substrates and achieved high nanofiber textile productivity of 180 cm²/min with needleless wire spinneret system. The nanofiber textile has high sub-micron particulate filtration efficiency of 80% and 95% with single and dual layers respectively.     

Fabrication of three-dimensional nanofibrous gelatin scaffolds using one-step crosslink technique

Abstract

Electrospun nanofibers have been considered to be an ideal scaffold for tissue engineering, because of the extracellular-matrix-like structure and the well-controlled fabrication. Here, a new method was used to fabricate electrospun three-dimensional macroporous nanofibrous gelatin scaffolds in ethanol bath by one-step crosslink with glutaraldehyde. The mean diameter of the one-step crosslinked fibers was significantly smaller than that of the traditional two-step crosslinked fibers (p?<?0.05), and scaffolds prepared by one-step crosslink were fluffy and porous. No significant difference was found in the degradation rates for both fibers within 14 days. After immersion in PBS for 14 days, numerous two-step crosslinked fibers merged together. By contrast, the morphology and macroporous structure of one-step crosslinked fibers showed no evident change and were generally maintained. Approximate crosslinking degrees of the two-step and one-step crosslinked gelatin fibers were 40% and 54%, respectively (p?<?0.05). Results from fluorescence microscopy and hematoxylin-eosin staining showed that MC3T3-E1 subclone four cells were distributed more evenly and diversely in the one-step crosslinked fiber scaffolds. The one-step crosslinked fibers enhanced the proliferation and differentiation potential of MC3T3-E1 cells. Furthermore, one-step crosslinked fibers were beneficial in repairing defects in the skulls of rats. Thus, one-step crosslink by glutaraldehyde in ethanol bath is a cost-effective and simple method to fabricate three-dimensional macroporous nanofiberous scaffolds. This technique retains the morphology and structure of the gelatin fibers, and enhances the biological performance of scaffolds in vitro and in vivo.     

PEG/PLGA纳米纤维膜的制备及其参数优化

通过静电纺丝法制备的聚乳酸-羟基乙酸共聚物(PLGA)纳米纤维膜是一种具有广阔应用前景的医用可生物降解高分子材料.为探究不同因素对纺丝过程及膜力学性能的影响,本研究采用响应面法中Box-Behnken设计,选取了PEG含量、纺丝速度和电压3个因素作为影响因子,以拉伸强度作为考察对象,通过回归分析建立了二次多元模型.结果表明,PEG含量对力学性能的影响最为显著,其次为电压的二次项;模型预测的拉伸强度值与真实值能较好的拟合,说明该模型能有效地预测PEG/PLGA复合纤维膜的力学性能.     

Potential of electrospun chitosan fibers as a surface layer in functionally graded GTR membrane for periodontal regeneration

Objective

The regeneration of periodontal tissues lost as a consequence of destructive periodontal disease remains a challenge for clinicians. Guided tissue regeneration (GTR) has emerged as the most widely practiced regenerative procedure. Aim of this study was to electrospin chitosan (CH) membranes with a low or high degree of fiber orientation and examines their suitability for use as a surface layer in GTR membranes, which can ease integration with the periodontal tissue by controlling the direction of cell growth.

Electrospun mupirocin loaded polyurethane fiber mats for anti-infection burn wound dressing application

Wound care treatment is a serious issue faced by the medical staffs due to its variety and complexity. Wound dressings are typically used to manage the various types of wounds. In this study, polyurethane (PU) fibers containing mupirocin (Mu), a commonly used antibiotic in wound care, were fabricated via electrospinning technique. The aim of this study was to develop biomedical electrospun fiber scaffolds for preventing wound infections with good compatibility and to demonstrate their applications as anti-infective burn wound dressings. The surface morphology of fibers was obtained by scanning electron microscopy. FT-IR spectra, water vapor transmission rate, and drug release study in vitro were tested to demonstrate the fiber scaffold characteristic. The prepared PU/Mu composite scaffolds had satisfactory antibacterial activity especially against Staphylococcus aureus. The cell studies revealed that the scaffolds were biocompatible and safe for cell attachment. Histological and immunohistochemical examinations were performed in rats, and the results indicated the histological analysis of tissue stained with H&E showed no obvious inflammation reaction. The results indicated that the electrospun scaffolds were capable of loading and delivering drugs, and could be potentially used as novel antibacterial burn wound dressings.     

TGFβ2 differentially modulates smooth muscle cell proliferation and migration in electrospun gelatin-fibrinogen constructs

A main goal of tissue engineering is the development of scaffolds that replace, restore and improve injured tissue. These scaffolds have to mimic natural tissue, constituted by an extracellular matrix (ECM) support, cells attached to the ECM, and signaling molecules such as growth factors that regulate cell function. In this study we created electrospun flat sheet scaffolds using different compositions of gelatin and fibrinogen. Smooth muscle cells (SMCs) were seeded on the scaffolds, and proliferation and infiltration were evaluated. Additionally, different concentrations of Transforming Growth Factor-beta2 (TGFβ2) were added to the medium with the aim of elucidating its effect on cell proliferation, migration and collagen production. Our results demonstrated that a scaffold with a composition of 80% gelatin-20% fibrinogen is suitable for tissue engineering applications since it promotes cell growth and migration. The addition of TGFβ2 at low concentrations (≤1 ng/ml) to the culture medium resulted in an increase in SMC proliferation and scaffold infiltration, and in the reduction of collagen production. In contrast, TGFβ2 at concentrations >1 ng/ml inhibited cell proliferation and migration while stimulating collagen production. According to our results TGFβ2 concentration has a differential effect on SMC function and thus can be used as a biochemical modulator that can be beneficial for tissue engineering applications.     

Surface-functionalized electrospun nanofibers for tissue engineering and drug delivery

Electrospun nanofibers with a high surface area to volume ratio have received much attention because of their potential applications for biomedical devices, tissue engineering scaffolds, and drug delivery carriers. In order to develop electrospun nanofibers as useful nanobiomaterials, surfaces of electrospun nanofibers have been chemically functionalized for achieving sustained delivery through physical adsorption of diverse bioactive molecules. Surface modification of nanofibers includes plasma treatment, wet chemical method, surface graft polymerization, and co-electrospinning of surface active agents and polymers. A variety of bioactive molecules including anti-cancer drugs, enzymes, cytokines, and polysaccharides were entrapped within the interior or physically immobilized on the surface for controlled drug delivery. Surfaces of electrospun nanofibers were also chemically modified with immobilizing cell specific bioactive ligands to enhance cell adhesion, proliferation, and differentiation by mimicking morphology and biological functions of extracellular matrix. This review summarizes surface modification strategies of electrospun polymeric nanofibers for controlled drug delivery and tissue engineering.     

Aligned and random nanofibrous substrate for the in vitro culture of Schwann cells for neural tissue engineering

The current challenge in peripheral nerve tissue engineering is to produce an implantable scaffold capable of bridging long nerve gaps that will produce results similar to autograft without requiring the harvest of autologous donor tissue. Aligned and random polycaprolactone/gelatin (PCL/gelatin) nanofibrous scaffolds were fabricated for the in vitro culture of Schwann cells that assist in directing the growth of regenerating axons in nerve tissue engineering. The average fiber diameter attained by electrospinning of polymer blend (PCL/gelatin) ranged from 232 ± 194 to 160 ± 86 nm with high porosity (90%). Blending PCL with gelatin resulted in increased hydrophilicity of nanofibrous scaffolds and yielded better mechanical properties, approaching those of PCL nanofibers. The biocompatibility of fabricated nanofibers was assessed for culturing and proliferation of Schwann cells by MTS assay. The results of the MTS assay and scanning electron microscopy confirmed that aligned and random PCL/gelatin nanofibrous scaffolds are suitable substrates for Schwann cell growth as compared to PCL nanofibrous scaffolds for neural tissue engineering.     

Mechanical properties of electrospun fibrinogen structures

Fibrin and fibrinogen have a well-established track record in tissue engineering due to their innate ability to induce improved cellular interaction and subsequent scaffold remodeling compared to synthetic scaffolds. Use of fibrinogen as a primary scaffold component, however, has been limited by traditional processing techniques that render scaffolds with insufficient mechanical properties. The goal of this study was to demonstrate, based on mechanical properties, that electrospun fibrinogen overcomes these limitations and can be successful as a tissue engineering scaffold or wound dressing. Electrospun fibrinogen scaffolds were characterized for fiber diameter and pore area and subsequently tested for uniaxial mechanical properties while dry and hydrated. In addition, uniaxial mechanical testing was conducted on scaffolds treated to regulate scaffold degradation in serum-containing media by supplementing the media with aprotinin or cross-linking the scaffolds with glutaraldehyde vapor. A linear relationship between electrospinning solution concentration and measured fiber diameter was seen; fiber diameters ranged from 120 to 610 nm over electrospinning concentrations of 80 to 140 mg/ml fibrinogen, respectively. Pore areas ranged from 1.3 microm(2) to 13 microm(2) over the same fibrinogen concentrations. Aprotinin in the culture media inhibited scaffold degradation in a predictable fashion, but glutaraldehyde vapor fixation produced less reliable results as evidenced by mechanical property testing. In conclusion, the mechanical characteristics of electrospun fibrinogen strongly support its potential use as a tissue engineering scaffold or wound dressing.     

Directed differentiation and neurite extension of mouse embryonic stem cell on aligned poly(lactide) nanofibers functionalized with YIGSR peptide

End-functional PLLA nanofibers were fabricated into mats of random or aligned fibers and functionalized post-spinning using metal-free “click chemistry” with the peptide Tyr-Ile-Gly-Ser-Arg (YIGSR). Fibers that were both aligned and functionalized with YIGSR were found to significantly increase the fraction of mouse embryonic stem cells (mESC) expressing neuron-specific class III beta-tubulin (TUJ1), the level of neurite extension and gene expression for neural markers compared to mESC cultured on random fiber mats and unfunctionalized matrices. Precise functionalization of degradable polymers with bioactive peptides created translationally-relevant materials that capitalize on the advantages of both synthetic and natural systems, while mitigating the classic limitations of each.