Search for: All records

Abstract Electrospun fish gelatin (FGel) nanofibers (NF) mimic the natural bodies extracellular matrix's (ECM) structure and are an attractive material for many biomedical applications. However, FGel poor mechanical properties and rapid dissolution in an aqueous media paired with usually low productivity of the typical electrospinning process necessitate further effort in overcoming these issues. In this study, alternating field electrospinning (AFES) fabricates cold water fish skin gelatin nanofibrous materials (FGel NFM) with up to 10 wt.% Dextran (DEX) or acetyl glucosamine (AGA) from pure aqueous solutions at process productivity of 7.92–8.90 g∙h⁻¹. Thermal crosslinking of as‐spun materials resulted in FGel‐based NFM with 125–325 nm fiber diameters. DEX (MW500k and MW75k) and AGA additives cause different effects on FGel fiber diameters, structure, tensile and degradation behavior, and in vitro performance. All tested materials reveal favorable, but not the same, cellular response through the formation of a confluent layer on the NFM surface regardless of the fibers’ composition despite the significant difference in FGel NFM structure and properties. Results show that AFES and thermal crosslinking of FGel‐based NFM can lead to a sustainable “green” fabrication technology of mono‐ and polysaccharide modified FGel‐based NFM scaffolds with the parameters attuned to targeted biomedical applications. 

Abstract Electrospinning is increasingly used as a staple technology for the fabrication of nano‐ and micro‐fibers of different materials. Most processes utilize direct current (DC) electrospinning, and a multitude of DC‐electrospinning tools ranging from research to commercial production systems is currently available. Yet, there are numerous studies performed on electrospinning techniques utilizing non‐DC, periodic electric fields, or alternating current (AC) electrospinning. Those studies demonstrate the strong potential of AC‐electrospinning for the sustainable production of various nanofibrous materials and structures. Although tremendous progress is achieved in the development of AC‐electrospinning over the last 10 years, this technique remains uncommon. This paper reviews the AC‐electrospinning concepts, instrumentation, and technology. The main focus of this review is the most studied, “electric wind” driven AC‐electrospinning technique tentatively named alternating field electrospinning (AFES). The latter term emphasizes the role of the AC electric field's confinement to the fiber‐generating electrode and the absence of a counter electrode in such an electrospinning system. The synopses of AFES process parameters, fiber‐generating spinneret designs, benefits and obstacles, advancements in AC electrospun nano/micro‐fibrous materials/structures and their applications are given, and future directions are discussed. 

Abstract Nanofibers made by blending natural and synthetic biopolymers have shown promise for better mechanical stability, ECM morphology mimicry, and cellular interaction of such materials. With the evolution of production methods of nanofibers, alternating field electrospinning (a.k.a. alternating current (AC) electrospinning) demonstrates a strong potential for scalable and sustainable fabrication of nanofibrous materials. This study focuses on AC‐electrospinning of poorly miscible blends of gelatin from cold water fish skin (FGEL) and polycaprolactone (PCL) in a range of FGEL/PCL mass ratios from 0.9:0.1 to 0.4:0.6 in acetic acid single‐solvent system. The nanofiber productivity rates of 7.8–19.0 g/h were obtained using a single 25 mm diameter dish‐like spinneret, depending on the precursor composition. The resulting nanofibrous meshes had 94%–96% porosity and revealed the nanofibers with 200–750 nm diameters and smooth surface morphology. The results of FTIR, XRD, and water contact angle analyses have shown the effect of FGEL/PCL mass ratio on the changes in the material wettability, PCL crystallinity and orientation of PCL crystalline regions, and secondary structure of FGEL in as‐spun and thermally crosslinked materials. Preliminary in vitro tests with 3 T3 mouse fibroblasts confirmed favorable and tunable cell attachment, proliferation, and spreading on all tested FGEL/PCL nanofibrous meshes. 

Abstract With the increasing interest in biopolymer nanofibers for diverse applications, the characterization of these materials in the physiological environment has become of equal interest and importance. This study performs first‐time simulated body fluid (SBF) degradation and tensile mechanical analyses of blended fish gelatin (FGEL) and polycaprolactone (PCL) nanofibrous meshes prepared by a high‐throughput free‐surface alternating field electrospinning. The thermally crosslinked FGEL/PCL nanofibrous materials with 84–96% porosity and up to 60 wt% PCL fraction demonstrate mass retention up to 88.4% after 14 days in SBF. The trends in the PCL crystallinity and FGEL secondary structure modification during the SBF degradation are analyzed by Fourier transform infrared spectroscopy. Tensile tests of such porous, 0.1–2.2 mm thick FGEL/PCL nanofibrous meshes in SBF reveal the ultimate tensile strength, Young's modulus, and elongation at break within the ranges of 60–105 kPa, 0.3–1.6 MPa, and 20–70%, respectively, depending on the FGEL/PCL mass ratio. The results demonstrate that FGEL/PCL nanofibrous materials prepared from poorly miscible FGEL and PCL can be suitable for selected biomedical applications such as scaffolds for skin, cranial cruciate ligament, articular cartilage, or vascular tissue repair. 

Blended nanofibrous biomaterials from natural and synthetic sources show promise for better biointegration. This study explores high-yield alternating field electrospinning (AFES) of blended cold-water fish skin gelatin (FGEL) and polycaprolactone (PCL) nanofibrous meshes with up to 30 wt% PCL at 7.8–14.4 g/h fiber productivity, depending on the composition. FGEL/PCL nanofibers reveal smooth surface morphology and 237–313 nm average diameters after thermal crosslinking. FTIR analysis indicated little FGEL/PCL interaction and notable changes in PCL crystallinity in the crosslinked nanofibers. A 14-days in-vitro analysis shows good cellular viability and nanofibrous FGEL/PCL mesh stability. Results demonstrate that AFES provides efficient, scalable production of blended FGEL/PCL nanofibrous biomaterials with suitable characteristics. 

Cotton is grown in about 90 countries and accounts for 24% of the fibers used in the global production of textiles. In 2018/2019, 25.8 Mt of cotton were produced around the world. Since this natural product consists mainly of cellulose, it can be used as a raw material in the so-called “sugar economy”. This paper discusses a model procedure for thermally assisted acidic hydrolysis of cotton into glucose and subsequent oxidation of the glucose into calcium gluconate over Pd-Au/SiO2 catalyst. In the first step, H2SO4 was used as a catalyst for hydrolysis. The cotton hydrolysates were neutralized using CaCO3 and applied as a substrate in the second step, where glucose was oxidized over Pd-Au/SiO2 prepared by ultrasound assisted co-impregnation. With the appropriate Au/Pd molar ratio, small crystallites of palladium and gold were created which were active and selective towards the formation of gluconate ions. This approach to the transformation of glucose represents as a viable alternative to biological processes using fungal and bacterial species, which are sensitive to the presence of inhibitors such as furfurals and levulinic acid in hydrolysates.