Production and characterization of polyurethane ultrafine fibre webs containing boric acid by electrospinning

A novel material has been developed by electrospinning of thermoplastic polyurethane (TPU) ultrafine fibre webs containing boric acid (BA). The chemical characterization of the TPU/BA fibrous webs is determined by the energy dispersive spectrometer and the Fourier transform infrared spectroscopy. The morphologies and thermal properties of the webs obtained are investigated by scanning electron microscopy and the differential scanning calorimeter respectively. The electrospun fibrous webs’ air permeability performance and thickness are also measured. The morphologies of TPU fibrous webs change slightly by adding BA, and the fibre structures are maintained. The results obtained demonstrate that the electrospun TPU/BA fibrous webs may have a wide variety of potential applications in protective textiles and high-performance filters.

Search for fibrous aggregates potentially useful in regenerative medicine formed under physiological conditions by self-assembling short peptides containing two identical aromatic amino acid residues

This study investigates the propensity of short peptides to self-organize and the influence of aggregates on cell cultures. The dipeptides were derived from both enantiomers of identical aromatic amino acids and tripeptides were prepared from two identical aromatic amino acids with one cysteine or methionine residue in the C-terminal, N-terminal, or central position. The formation or absence of fibrous structures under physiological conditions was established using Congo Red and Thioflavine T assays as well as by microscopic examination using normal and polarized light. The in vitro stability of the aggregates in buffered saline solution was assessed over 30 days. Materials with potential for use in regenerative medicine were selected based on the cytotoxicity of the peptides to the endothelial cell line EA.hy 926 and the wettability of the surfaces of the films, as well as using scanning electron microscopy. The criteria were fulfilled by H-dPhedPhe-OH, H-dCysdPhedPhe-OH, H-CysTyrTyr-OH, H-dPhedPhedCys-OH, H-TyrTyrMet-OH, and H–TyrMetTyr–OH. Our preliminary results suggest that the morphology and cell viability of L919 fibroblast cells do not depend on the stereochemistry of the self-organizing peptides

Graphene printing for textronic devices

Grafen se dokazao kao izvrstan nanomaterijal za suvremene elektroničke namjene kao što su biosenzori, tranzistori ili grijači. Nastojanja su da se ovaj novi nanomaterijal upotrebljava za razvoj jedinstvenih tekstroničkih uređaja. Trenutno stanje znanosti o materijalima pokazuje mogućnosti dizajna pametnih tekstila s grafenom. Autori iznose rezultate primjene 2D ugljikove strukture u tekstroničkim uređajima. Primjena novorazvijenih tinti i pasta daju zanimljiva svojstva tekstilu kao što su električna vodljivost i osjetljivost na hlapljive organske spojeve.Graphene has been proved to be an excellent nanomaterial for modern electronic applications such as biosensors, transistors or heaters. The natural point of view is to use this new nanomaterial for the development of unique textronic devices. The current state of the art of the materials science shows design possibilities of the smart textiles with graphene. The authors show the results of implementation of 2D carbon structure into the textronic devices. The development inks and pastes give interesting properties of textile such as electro conductivity and sensitive to the volatile organic compounds

Preparation Method of Porous Dressing Materials Based on Butyric-Acetic Chitin Co-Polyesters

A method for obtaining highly porous materials in the form of film, based on the butyric-acetic chitin co-polyesters, containing 90% of butyryl and 10% of acetyl groups, was developed. The highly porous films, with thickness up to 0.11 mm, were obtained by two methods: (a) pouring 5% BAC 90/10 solution in ethanol on the layer of solid salts (porophor agent) which after solidification was eluted with water; (b) application of the suspension of porophor agent in BAC 90/10 solution in the solvent mixture with density similar to bulk porophor agent. In the final stage, the materials were obtained with porosity up to 95⁻99% and tensile strength 5 cN, which can be used as an active layer of medical dressings. The optimised procedure was used in the production of porous medical dressings (Medisorb) on an industrial scale. In the industrial method, NaCl was used as a porophor agent in the solid form and as a 3% solution in polymer. The final materials were characterised by porosity and other functional parameters at the level recommended for medical dressings. Medisorb series materials do not show in vitro cytotoxic activity

Influence of Porous Dressings Based on Butyric-Acetic Chitin Co-Polymer on Biological Processes In Vitro and In Vivo

In spite of intensively conducted research allowing for the development of more and more advanced wound dressing materials, there is still a need for dressings that stimulate not only reparative and regenerative processes, but also have a positive effect on infected and/or difficult-to-heal wounds. Porous dressing materials based on butyric-acetic chitin co-polyester containing 90% of butyryl and 10% of acetyl groups (BAC 90/10) can also be included in the group mentioned above. Two types of dressings were obtained by the salt leaching method, i.e. a porous sponge Medisorb R and Medisorb Ag with an antibacterial additive. The aim of the study was to evaluate biological effects of porous Medisorb R and Medisorb Ag dressings under in vitro and in vivo conditions. In an in vitro biodegradation test, no mass loss of Medisorb R dressing was observed within 14 days of incubation in physiological fluids at 37 °C. However, on the basis of the FTIR (Fourier Transform Infrared Spectroscopy) tests, surface degradation of Medisorb R dressing was observed. Additionally, the antibacterial activity of the porous Medisorb Ag dressing containing microsilver as an antibacterial additive was confirmed. The in vivo studies included inflammatory activity, skin irritation and sensitisation tests, as well an assessment of local effect after contact with subcutaneous tissue up to 6 months and skin wounds up to 21 days. In the in vivo tests, the dressings exhibited neither effects of skin irritation nor sensitisation. Under macroscopic examination, in full thickness defects of subcutaneous tissue and skin, the dressings caused wound healing with no inflammation, undergoing the most gradual biodegradation between weeks 4 and 8, and the observed differences were statistically significant. In the histological assessment, a weakened, limited inflammatory process associated with degradation of the material has been observed. The process of skin wound healing under Medisorb R dressing in the early period was accelerated compared to that observed in the control group with a gauze dressing

The Chitosan Implementation into Cotton and Polyester/Cotton Blend Fabrics

Chitosan is an environmentally friendly agent that is used to achieve the antimicrobial properties of textiles. Nowadays, the binding of chitosan to the textiles has been thoroughly researched due to the increasing demands on the stability of achieved properties during the textile care processes. Most crosslinking agents for chitosan are not safe for humans or environment, such as glutaric aldehyde (GA) and formaldehyde derivatives. Eco-friendly polycarboxyilic acids (PCAs) are usually used in after-treatment. In this work, chitosan powder was dissolved in citric acid with sodium hydrophosphite (SHP) as a catalyst. Standard cotton (CO) and polyester/cotton (PES/CO) fabrics were pretreated in 20% NaOH, similar to mercerization, in order to open the structure of the cotton fibers and hydrolyze polyester fibers, continued by finishing in the gelatin chitosan bath. Afterwards, the hot rinsing process, followed by drying and curing, closed the achieved structure. The main objective was to achieve durable antimicrobial properties to multiple maintenance cycles CO and PES/CO fabric in order to apply it in a hospital environment. The characterization of fabrics was performed after treatment, first and fifth washing cycles according ISO 6330:2012 by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FTIR-ATR), electrokinetic analysis (EKA), by the determination of tensile properties and mechanical damage (wear), and the antimicrobial activity. The application of 20% NaOH led to the swelling and mercerization of cotton cellulose, and hydrolysis of polyester, resulting in better mechanical properties. It has been confirmed that the chitosan particles were well implemented into the cotton fiber and onto to the polyester component of PES/CO blend. The presence of chitosan was confirmed after five washing cycles, but in lower quantity. However, achieved antimicrobial activity is persistent

Modifikace kyseliny polymléčné plastifikací pro aplikace v obalovém průmyslu

Plastic products, especially in the packaging industry, have become the main commodities penetrating virtually every aspect of our lives. Unfortunately, their omnipresence is not neutral to the natural environment. Pollution in the form of microplastics is a global problem. Therefore, green technologies that enter into the circular economy become an important topic. As part of the research work, the modification of poly(lactic acid) has been studied for use in the packaging industry. Due to its intrinsic rigidity, plasticizing substances had to be introduced in PLA in order to improve its plastic deformability. Both high-molecular compounds such as ethoxylated lauryl alcohol, block copolymer of ethylene oxide and propylene oxide, and ethoxylated stearic acid as well as low-molecular compounds such as di-2-ethylhexyl adipate, di-2-ethylhexyl sebacate, and triethyl citrate were used. The samples extruded from plasticized polymers were characterized using differential scanning calorimetry, thermal gravimetric analysis, and mechanical properties including Young's modulus. The melt flow rate (MFR) and molar mass distribution were determined. For all modified samples the glass transition temperature, depending on the plasticizer used, was shifted towards lower values compared to the base polymer. The best result was obtained for di-2-ethylhexyl adipate (ADO) and di-2-ethylhexyl sebacate (SDO). The elongation at break increased significantly for ADO at about 21%. The highest elongation was obtained for SDO (about 35%), although it obtained a higher glass temperature. The degradation of the polymer was not observed for both plasticizers. For these plasticizers (ADO and SDO) it also lowered Young's module by about 26%, and at the infrared spectrum deformation of peaks were observed, which may indicate the interaction of the ester carbonyl group of PLA with plasticizers. Therefore it can be concluded that they are good modifiers. The selected plasticizers that are used in the production of food contact materials, in particular in the production of PVC (polyvinyl chloride) food films, also exhibited great potential to be applied to PLA food films, and exhibit better properties than the citrate, which are indicated in many publications as PLA plasticizers.Kyselina polymléčná byla plastifikována různými změkčovadly za účelem zlepšení jejích vlastností jako obalového materiálu. Hlavním cílem bylo vyvinutí materiálu schopného nahradit tradiční obalové materiály s negativním dopadem na životní prostředí

Conjugates of Chitosan and Calcium Alginate with Oligoproline and Oligohydroxyproline Derivatives for Potential Use in Regenerative Medicine

New materials that are as similar as possible in terms of structure and biology to the extracellular matrix (external environment) of cells are of great interest for regenerative medicine. Oligoproline and oligohydroxyproline derivatives (peptides 2–5) are potential mimetics of collagen fragments. Peptides 2–5 have been shown to be similar to the model collagen fragment (H-Gly-Hyp-Pro-Ala-Hyp-Pro-OH, 1) in terms of both their spatial structure and biological activity. In this study, peptides 2–5 were covalently bound to nonwovens based on chitosan and calcium alginate. Incorporation of the peptides was confirmed by Fourier transform -infrared (FT-IR) and zeta potential measurements. Biological studies (cell metabolic activity by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and Live/Dead assay) proved that the obtained peptide-polysaccharide conjugates were not toxic to the endothelial cell line EA.hy 926. In many cases, the conjugates had a highly affirmative influence on cell proliferation. The results of this study show that conjugates of chitosan and calcium alginate with oligoproline and oligohydroxyproline derivatives have potential for use in regenerative medicine