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Electrospinning is a widely employed manufacturing platform for tissue engineering applications because it produces structures that closely mimic the extracellular matrix. Herein, we demonstrate the potential of poly(vinyl alcohol) (PVA) electrospun nanofibers as scaffolds for tissue engineering. Nanofibers were created by needleless direct current electrospinning from PVA with two different degrees of hydrolysis (DH), namely 98% and 99% and subsequently heat treated at 180 °C for up to 16 h to render them insoluble in aqueous environments without the use of toxic cross-linking agents. Despite the small differences in the PVA chemical structure, the changes in the material properties were substantial. The higher degree of hydrolysis resulted in non-woven supports with thinner fibres (285 ± 81 nm c.f. 399 ± 153 nm) that were mechanically stronger by 62% (±11%) and almost twice as more crystalline than those from 98% hydrolysed PVA. Although prolonged heat treatment (16 h) did not influence fibre morphology, it reduced the crystallinity and tensile strength for both sets of materials. All samples demonstrated a lack or very low degree of haemolysis (<5%), and there were no notable changes in their anticoagulant activity (≤3%). Thrombus formation, on the other hand, increased by 82% (±18%) for the 98% hydrolysed samples and by 71% (±10%) for the 99% hydrolysed samples, with heat treatment up to 16 h, as a direct consequence of the preservation of the fibrous morphology. 3T3 mouse fibroblasts showed the best proliferation on scaffolds that were thermally stabilised for 4 and 8 h. Overall these scaffolds show potential as 'greener' alternatives to other electrospun tissue engineering materials, especially in cases where they may be used as delivery vectors for heat tolerant additives. [ABSTRACT FROM AUTHOR]

Nanoparticles are extremely promising components that are used in diagnostics and medical therapies. Among them, silica nanoparticles are ultrafine materials that, due to their unique physicochemical properties, have already been used in biomedicine, for instance, in cancer therapy. The aim of this study was to investigate the cytotoxicity of three types of nanoparticles ( SiO 2 , SiO 2 - SH , and SiO 2 - COOH ) in relation to red blood cells, as well as the impact of silicon dioxide nanoparticles on biological membranes and liposome models of membranes. The results obtained prove that hemolytic toxicity depends on the concentration of nanoparticles and the incubation period. Silica nanoparticles have a marginal impact on the changes in the osmotic resistance of erythrocytes, except for SiO 2 - COOH , which, similarly to SiO 2 and SiO 2 - SH , changes the shape of erythrocytes from discocytes mainly towards echinocytes. What is more, nanosilica has an impact on the change in fluidity of biological and model membranes. The research gives a new view of the practical possibilities for the use of large-grain nanoparticles in biomedicine. [ABSTRACT FROM AUTHOR]

The study focuses on a comparison of the electrospinning of various polylactide and polycaprolactone (PLCL) copolymers and poly-L-lactide (PLLA) and polycaprolactone (PCL) homopolymers. The chemical characterisation, electrospinnability, fibrous morphology, degradation rate and interactions with fibroblasts were assessed with respect to copolymers and homopolymers with both lower (around 50,000) and higher (around 95,000) molecular weights. The research investigated commercially available as well as synthesised copolymers. The results revealed that the electrospinnability of polymeric solutions depends on both the molecular weight and the PLA/PCL ratio in the final copolymer. It was determined that PLCL copolymers with a higher content of PCL (≥20%) were not spinnable via the electrospinning process. With the exception of PCL, the resulting fibrous materials were found to be homogeneous and with fibre diameters of slightly more than 1 µm with respect to both the tested molecular weights. The degradation rate was tested under simulation conditions via the utilisation of the lipase and Proteinase K enzymes. The degree of degradation was found to depend on the molecular weight, the crystallinity of the polymer and the specificity of the enzyme applied. While lipase was responsible for the degradation of the PCL polymer, it exerted a minor impact on the PLLA and the copolymers. Proteinase K degraded all the tested polymers with a higher specificity towards PLLA and the PLCL copolymers. All the tested polymers were affected by the surface erosion degradation process via fibrous morphology changes and mass loss with no accompanying shift in the molar mass. The electrospun PLLA materials supported both fibroblast adhesion and proliferation. All the tested materials were determined to be cytocompatible with 3T3 mouse fibroblasts. [ABSTRACT FROM AUTHOR]

The study involved the electrospinning of the copolymer poly(L-lactide-co-ε-caprolactone) (PLCL) into tubular grafts. The subsequent material characterization, including micro-computed tomography analysis, revealed a level of porosity of around 70%, with pore sizes of 9.34 ± 0.19 μm and fiber diameters of 5.58 ± 0.10 μm. Unlike fibrous polycaprolactone, the electrospun PLCL copolymer promoted fibroblast and endothelial cell adhesion and proliferation in vitro. Moreover, the regeneration of the vessel wall was detected following implantation and, after six months, the endothelialization of the lumen and the infiltration of arranged smooth muscle cells producing collagen was observed. However, the degradation rate was found to be accelerated in the rabbit animal model. The study was conducted under conditions that reflected the clinical requirements-the prostheses were sutured in the end-to-side fashion and the long-term end point of prosthesis healing was assessed. The regeneration of the vessel wall in terms of endothelialization, smooth cell infiltration and the presence of collagen fibers was observed after six months in vivo. A part of the grafts failed due to the rapid degradation rate of the PLCL copolymer.