The use of electrospun polymeric biodegradable materials for medical applications is becoming increasingly widespread. One of the most important parameters regarding the functionality of nanofiber scaffolds during implantation and the subsequent regeneration of damaged tissues concerns their stability and degradation behavior, both of which are influenced by a wide range of factors (the properties of the polymer and the polymer solution, the technological processing approach, the sterilization method, etc.). This study monitored the degradation of nanofibrous materials fabricated from degradable polyesters as a result of the sterilization method applied (ethylene oxide and gamma irradiation) and the solvent system used to prepare the spun polymer solution. Aliphatic polyesters PCL and PLCL were chosen for this study and selected with respect to the applicability and handling in the surgical setting of these nanofibrous materials for vascular bandaging. The results revealed that the choice of solvent system exerts a significant impact on degradation during sterilization, especially at higher gamma irradiation values. The subsequent enzyme-catalyzed degradation of the materials following sterilization indicated that the choice of the sterilization method influenced the degradation behavior of the materials. Whereas wave-like degradation was evident concerning ethylene oxide sterilization, no such behavior was observed following gamma-irradiation sterilization. With concern for some of the tested materials, the results also indicated the potential for influencing the development of degradation within the bulk versus degradation from the surface of the material. Both the sterilization method and the choice of the spinning solvent system were found to impact degradation, which was observed to be most accelerated in the case of PLCL (L-lactide-co-caprolactone copolymer) electrospun from organic acids and subsequently sterilized using gamma irradiation. Since we planned to use these materials in cardiovascular applications, it was decided that their hemocompatibility would also be tested. The results of these tests revealed that changes in the structures of the materials initiated by sterilization may exert thrombogenic and anticoagulant impacts. Moreover, the microscopic analysis suggested that the solvent system used in the preparation of the materials potentially affects the behavior of erythrocytes; however, no indication of the occurrence of hemolysis was detected.

A membrane composed of PCL and PVA layers enriched with platelet lysate was produced to allow cell adhesion and growth and to serve as a drug delivery system that release bioactive compounds in effective concentrations.

Tissue engineering aims to develop materials that enhance biological activity and promote tissue healing and regeneration.One promising approach is to functionalize nanofibrous materials with antimicrobial substances, such as lipophosphonoxin (LPPO), and use water-soluble polymers like polyvinyl alcohol (PVA) to incorporate bioactive molecules into fibers.However, water-soluble materials often face the issue of "burst release," releasing over 90% of the active substances within the initial 24 hours.This research focuses on preparing functionalized nanofibrous materials based on PVA containing the experimental antimicrobial compound LPPO and subsequent physical stabilization of the materials using the "Heat treatment" method.The applied stabilization successfully reduced the incorporated substance's release rate by up to 50%.The resulting materials have the potential to provide functional cross-linked PVA nanofiber scaffolds for regenerative medicine applications in large and chronic skin injuries.

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.

Tissue engineering and regenerative medicine are ever-growing multidisciplinary fields.Along with the development of tissue carriers, methods for testing the biocompatibility of these materials are also being developed.This work deals with research, development, and optimisation of the preparation of a fibre system intended for monitoring the direct interaction of the 3T3 mouse fibroblast cell line with polymeric materials in real-time (live cell imaging).The fabricated microfiber model (grid) was seeded with the 3T3 mouse fibroblast cell line, and the interaction between the materials and the cells was monitored for three days by optical microscope.The interaction between the materials and the cells was observed during a picture of cells on the fibres.The advantage of this method is the absence of other chemicals like chemicals for the visualisation of cells (fluorescence staining) or chemicals for measuring cell viability because cells adhering to fibres are visible in transmitted light.

Among widely electrospun biodegradable polymer materials are aliphatic polyesters: polycaprolactone, polylactide acid or a copolymer of caprolactone and lactic acid (PLCL).Many different modifications of electrospinning can be used to change the fiber structure and, therefore, to set optimal, especially morphological, material effects for application, testing, or treatment with these means.Structural or shape changes include not only fiber diameters, their distribution, but also fiber orientation, their interconnection, their smooth or rough surface, and also the significant arrangement of the internal networks of polymer chains represented, for example, by the degree of crystallinity.The process and material parameters of the production of nanofibrous materials must still be studied to ensure the resulting properties of the materials lead to predictable effects during its application.A general understanding of the effect of five different solvent systems and especially the effect of air humidity (from 20 to 50% RH) during the needleless electrospinning process on the formation of nanofibrous materials from biodegradable polyesters copolymer (PLCL) is evaluated concerning the actual spinning process and the resulting morphology assessed by SEM.The internal chemical structure or arrangement evaluated using especially DSC, FTIR and GPC is necessary to ensure the reproducibility of the production of materials and thus their application results.

Biodegradable nanofiber materials are widely used for biomedical applications such as tissue engineering.These materials are characterized by submicron fibre diameter, small pore size, and large specific surface area (surface to volume ratio), and this structure is very similar to the natural extracellular matrix and is a favorable environment for the growth of eukaryotic cells.These days research focuses on other modifications of nanofiber structures for upgrades these structures or to create specific properties e.g.antimicrobial character.Fibre morphology and structure are able modified during their preparation, a suitable method for that is electrospinning technology and post-process modification.Electrospun materials with nanofiber backbone decorated with protruding periodic pattern of polymer crystals are termed nanofiber shishkebabs.The shish-kebab structure can be formed by post-process recrystallization in suitable liquids (dilute polymer solution, partial solvent, or a mixture of solvent and non-solvent, solvent or partial solvent, or dilute polymer solution evaporation.The crystal period can be controlled to be a few hundreds of nanometres.Partial enzyme-catalyzed degradation of electrospun nanofibers is another method to prepare a similar structure.In this case, amorphous parts of polymer nanofibers are preferentially degraded, and the remaining macromolecules form new structures, mainly crystal structures resembling nanofiber shish-kebab.The aim of this study was preparation, description, and characterization of mentioned structure.

Scaffolds made of degradable polymers, such as collagen, polyesters or polysaccharides, are promising matrices for fabrication of bioartificial vascular grafts or patches. In this study, collagen isolated from porcine skin was processed into a gel, reinforced with collagen particles and with incorporated adipose tissue-derived stem cells (ASCs). The cell-material constructs were then incubated in a DMEM medium with 2% of FS (DMEM_part), with added polyvinylalcohol nanofibers (PVA_part sample), and for ASCs differentiation towards smooth muscle cells (SMCs), the medium was supplemented either with human platelet lysate released from PVA nanofibers (PVA_PL_part) or with TGF-β1 + BMP-4 (TGF + BMP_part). The constructs were further endothelialised with human umbilical vein endothelial cells (ECs). The immunofluorescence staining of alpha-actin and calponin, and von Willebrand factor, was performed. The proteins involved in cell differentiation, the extracellular matrix (ECM) proteins, and ECM remodelling proteins were evaluated by mass spectrometry on day 12 of culture. Mechanical properties of the gels with ASCs were measured via an unconfined compression test on day 5. Gels evinced limited planar shrinkage, but it was higher in endothelialised TGF + BMP_part gel. Both PVA_PL_part samples and TGF + BMP_part samples supported ASC growth and differentiation towards SMCs, but only PVA_PL_part supported homogeneous endothelialisation. Young modulus of elasticity increased in all samples compared to day 0, and PVA_PL_part gel evinced a slightly higher ratio of elastic energy. The results suggest that PVA_PL_part collagen construct has the highest potential to remodel into a functional vascular wall.

The use of Intraoperative Cell Salvage (ICS) is currently limited in oncological surgeries, due to safety concerns associated with the ability of existing devices to successfully remove circulating tumour cells. In this work, we present the first stages towards the creation of an alternative platform to current cell savers, based on the extremely selective immunoaffinity membrane chromatography principle. Non-woven membranes were produced via electrospinning using poly(vinyl alcohol) (PVA), and further heat treated at 180 °C to prevent their dissolution in aqueous environments and preserve their fibrous morphology. The effects of the PVA degree of hydrolysis (DH) (98 % vs 99 %), method of electrospinning (needleless DC vs AC), and heat treatment duration (1-8 h) were investigated. All heat treated supports maintained their cytocompatibility, whilst tensile tests indicated that the 99 % hydrolysed DC electrospun mats were stronger compared to their 98 % DH counterparts. Although, and at the described conditions, AC electrospinning produced fibres with more than double the diameter compared to those from DC electrospinning, it was not chosen for subsequent experiments because it is still under development. Evidence of unimpeded passage of SY5Y neuroblastoma cells and undiluted defibrinated sheep's blood in flow-through filtration experiments confirmed the successful creation of 3D networks with minimum resistance to mass transfer and lack of non-specific cell binding to the base material, paving the way for the development of novel, highly selective ICS devices for tumour surgeries.

The prevalence of chronic wounds is increasing due to the population ageing and specific illnesses like diabetes mellitus and vascular diseases.Nanofibrous membranes fabricated using synthetic polymers are promising materials to enhance skin wound healing.PCL and PVA membranes are being studied to be used as scaffolds for skin tissue engineering and hydrogels for controlled drug delivery, respectively.The present study considers the development of a multi-layered membrane made of PCL and PVA loaded with platelet lysate (PL).PCL nanofibers allowed cell adhesion and growth, whereas PVA acted as a hydrogel that releases the bioactive compounds of platelet lysate.The cytocompatibility of the membranes containing PL and without it was demonstrated on two cell types involved in wound healing, i.e. keratinocytes and fibroblasts.Both cell types were able to adhere and proliferate on the membranes.In addition, the membrane containing PL enhanced the proliferation of fibroblasts.A co-culture study was also performed by seeding each cell type on one side of the membrane.The cells were co-cultured for 7 days and the results showed that PL increased the proliferation of cells achieving a monolayer of keratinocytes or fibroblasts on each side of the membrane.Thus, the beneficial effect of PCL-PVA+PL membranes on monocultures and co-cultures of skin cells was demonstrated, and these membranes can be considered potential scaffolds for treatment of chronic wounds.

Threads are the basic textile linear structure used in many areas.The variability of the thread structure made possible by special constructions brings great possibilities of variability.It is also possible to introduce nanofiber material into the yarn construction as a cover for central microfiber yarns, and these can be further intertwined into more complex yarn constructions.Continuous production of so-called composite yarns containing central microfiber yarns and nanofiber wrappers is made possible by alternating current electrospinning.Subsequent braiding of these composite yarns allows the protection of nanofiber packages and the variability of the overall construction of the resulting yarns.This paper introduces the creation of yarns and various types of basic as well as braided yarns with nanofibers.Selected sutures were further subjected to in-vitro testing to verify cytocompatibility for application in hygiene such as dental sutures or medicine as surgical sutures.

Platelet lysate (PL) provides a natural source of growth factors and other bioactive molecules, and the local controlled release of these bioactive PL components is capable of improving the healing of chronic wounds. Therefore, we prepared composite nanofibrous meshes via the needleless electrospinning technique using poly(vinyl alcohol) (PVA) with a high molecular weight and with a high degree of hydrolysis with the incorporated PL (10% w/w). The morphology, wettability and protein release from the nanofibers was then assessed from the resulting composite PVA–PL nanomats. The bioactivity of the PVA–PL nanomats was proved in vitro using HaCaT keratinocytes, human saphenous endothelial cells (HSVECs) and 3T3 fibroblasts. The PVA–PL supported cell adhesion, proliferation, and viability. The improved phenotypic maturation of the HaCaT cells due to the PVA–PL was manifested via the formation of intermediate filaments positive for cytokeratin 10. The PVA–PL enhanced both the synthesis of the von Willebrand factor via HSVECs and HSVECs chemotaxis through membranes with 8 µm-sized pores. These results indicated the favorable effects of the PVA–PL nanomats on the three cell types involved in the wound healing process, and established PVA–PL nanomats as a promising candidate for further evaluation with respect to in vivo experiments.

Electrospun PLCL nanofibrous materials produced by direct current (DC) or alternating current (AC) electrospinning are good candidates for absorbable reinforcement for cardiovascular surgery composite bandages.For an appropriate description of the fiber layers and prediction of its relevant biomechanical characteristics, the knowledge of fiber orientation in the electrospun layers is essential.In this study, the different orientation of fibres in AC and DC electrospun materials was achieved only by changing the rewinding speed of the supporting material, as the easy way for the production of relatively large samples with controlled fiber orientation.The fiber orientation was measured on scanning electron microscope images at different magnification using an open-source image processing software FIJI/Image J with the implementation of the "OrientationJ" plugin.Subsequently, the fiber layers were compared in terms of fiber orientation.Optimal image parameters for the measurement and the best unidirectional oriented-aligned samples were determined

Nanofibrous materials have great potential for use in tissue engineering due to their structure, which mimics the extracellular fibrous matrix. Increasing their biological activity is currently the main goal in the development of these scaffolds. From the standpoint of promoting healing and tissue regeneration, the use of human platelets containing hundreds of biologically active molecules is promising. The present work deals with the preparation of PVA-based nanofibrous material containing native platelet-derived proteins that are released in a sustained manner. The needleless electrospinning process of preparation of material that does not affect the activity of incorporated proteins has been optimized, and the resulting material can be produced on a large scale with a protein loading efficiency of 0.64%. The reasonable fiber diameter distribution (370 +/- 150 nm) with low defects ensures a homogeneous distribution of proteins. The use of high molecular weight PVA (125 000 g/mol) with a high degree of hydrolysis (98-98.8%) resulted in a 40% reduction in PVA solubility without the need for subsequent covalent crosslinking. This, in turn, results in a sustained release of proteins, where after an initial burst release of 90% of the proteins, 10% is gradually released over the next 7 days. Our results demonstrate the potential use of the platelet-lysate loaded PVA material in tissue engineering.

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