Effect of Sodium Salicylate on the Viscoelastic Properties and Stability of Polyacrylate-Based Hydrogels for Medical Applications

Investigation was made into the effect exerted by the presence of sodium salicylate (0-2 wt.%), in Carbomer-based hydrogel systems, on processing conditions, rheological and antimicrobial properties in tests against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacterial strains, and examples of yeast (Candida albicans) and mould (Aspergillus niger). In addition, the work presents an examination of long-term stability by means of aging over one year the given hydrogels at 8 degrees C and 25 degrees C. The results show that 0.5wt.% NaSal demonstrated a noticeable effect on the hydrogel neutralization process, viscosity, and antimicrobial properties against all of the tested microorganisms. The long-term stability studies revealed that hydrogels can maintain antimicrobial activity as well as viscosity to a degree that would be sufficient for practical use.Ministry of Agriculture of the Czech Republic [QJ1310254]; Ministry of Education, Youth and Sports of the Czech Republic [LO1504

The effect of plasma pretreatment and cross-linking degree on the physical and antimicrobial properties of nisin-coated PVA films

Stable antimicrobial nisin layers were prepared on the carrying medium-polyvinyl alcohol (PVA) films, crosslinked by glutaric acid. Surface plasma dielectric coplanar surface barrier discharge (DCSBD) modification of polyvinyl alcohol was used to improve the hydrophilic properties and to provide better adhesion of biologically active peptide-nisin to the polymer. The surface modification of films was studied in correlation to their cross-linking degree. Nisin was attached directly from the salt solution of the commercial product. In order to achieve a stable layer, the initial nisin concentration and the following release were investigated using chromatographic methods. The uniformity and stability of the layers was evaluated by means of zeta potential measurements, and for the surface changes of hydrophilic character, the water contact angle measurements were provided. The nisin long-term stability on the PVA films was confirmed by tricine polyacrylamide gel electrophoresis (SDS-PAGE) and by antimicrobial assay. It was found that PVA can serve as a suitable carrying medium for nisin with tunable properties by plasma treatment and crosslinking degree. © 2018 by the authors.Czech Science Foundation (Grant Agency of the Czech Republic) [17-10813S

Isolation and thermal stabilization of bacteriocin nisin derived from whey for antimicrobial modifications of polymers

This work describes novel alternative for extraction of bacteriocin nisin from a whey fermentation media and its stabilization by using polyethylene glycol as matrix with high practical applicability. This product was compared with commercially available nisin product stabilized by sodium chloride and nisin extracted and stabilized by using ammonium sulfate and polysorbate 80. The stability of samples was tested by means of long-term storage at -18, 4, 25, and 55 degrees C up to 165 days. The nisin content in the samples was determined by high-performance liquid chromatography and electrophoresis. In addition, effect of whey fortification with lactose on nisin production and antibacterial activity studied against Staphylococcus aureus was tested. Results show that stabilization by polyethylene glycol provides enhanced nisin activity at 55 degrees C after 14 days and long-term stability at 25 degrees C with keeping antibacterial activity.Ministry of Agriculture of the Czech Republic [QJ1310254]; Ministry of Education, Youth and Sports of the Czech Republic [LO1504]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2017/005]QJ1310254, MZe, Ministerstvo Zemědělství; LO1504, MEYS, Ministry of Education, Youth and Science; IGA/CPS/2017/00

Degradable poly(ethylene oxide)-like plasma polymer films used for the controlled release of nisin

Poly(ethylene oxide) (PEO)-like thin films were successfully prepared by plasma-assisted vapor thermal deposition (PAVTD). PEO powders with a molar weight (Mw) between 1500 g/mol and 600,000 g/mol were used as bulk precursors. The effect of Mw on the structural and surface properties was analyzed for PEO films prepared at a lower plasma power. Fourier transform (FTIR-ATR) spectroscopy showed that the molecular structure was well preserved regardless of the Mw of the precursors. The stronger impact of the process conditions (the presence/absence of plasma) was proved. Molecular weight polydispersity, as well as wettability, increased in the samples prepared at 5 W. The influence of deposition plasma power (0-30 W) on solubility and permeation properties was evaluated for a bulk precursor of Mw 1500 g/mol. The rate of thickness loss after immersion in water was found to be tunable in this way, with the films prepared at the highest plasma power showing higher stability. The effect of plasma power deposition conditions was also shown during the permeability study. Prepared PEO films were used as a cover, and permeation layers for biologically active nisin molecule and a controlled release of this bacteriocin into water was achieved. © 2020 by the authors.Czech Science FoundationGrant Agency of the Czech Republic [GA17-10813S]; TBU in Zlin [IGA/CPS/2020/001

Polyester urethane (PLA/PEG) polymer based films prepared by plasma assisted vapour thermal deposition

Polyester urethane polymer was synthesized as linked biocompatible poly (lactide)/poly (ethylene oxide) polymers. The bulk polymer was subsequently used as precursor material for plasma assisted vapour thermal deposition of thin plasma polymer films under varying RF discharge power. The effect of plasma polymerization on the final physico-chemical characteristics was investigated. The chemical analysis of the films was performed using X-ray photoelectron spectroscopy and infrared spectroscopy. Structural analysis of plasma polymer thin film revealed the similar molecular structure as in case of precursor since PEU-characteristic bonds were preserved after the plasma polymerization. Surface properties analysed by a contact angle measurement revealed an increase of wettability in the samples prepared at higher RF power. At the same time a surface energy evaluated according to acid-base model decreased. The results indicate that plasma polymer films properties could be tuned depending on applied deposition conditions. © NANOCON 2019.All right reserved.Czech Science FoundationGrant Agency of the Czech Republic [GA17-10813S

Nanostructured films of plasma polymerized hexamethyldisilazane and lactic acid deposited by atmospheric plasma JET

In this work, composite layers of hexamethyldisilazane (HMDSN) and lactic acid (LA) were prepared using chemical vapor deposition process by a nitrogen atmospheric pressure plasma jet source. The HMDSN vapours were introduced into the plasma jet. Varying LA admixture was added into the jet in the form of aerosol. The chemical composition, morphology and wettability of resulting films were studied. Infrared spectra and XPS analysis show both Si-O like and hydrocarbon structures. With increasing amount of LA admixture, the oxidation of the layers increases. The morphology of the films was measured with SEM. The films prepared with no LA have a foam-like structure. With increasing amount of LA the structure changes into more fractal-like. The X-ray diffraction analysis suggests the presence of amorphous SiO2 domains in the films. The films exhibited superhydrophobic properties that can be modified by the post-treatment of the samples in DBD discharge. © NANOCON 2019.All right reserved.Czech Science FoundationGrant Agency of the Czech Republic [17-10813S

Nisin immobilization on plasma treated polyvinyl alcohol films

Nisin protein attachment on chemically crosslinked polyvinyl alcohol surface activated in atmospheric Dielectric Coplanar Surface Barrier Discharge was carried out in this work. Plasma activated PVA surfaces show improved level of nisin attachment in comparison with untreated films. In addition, the extent of the nisin surface immobilization and its release strongly depends on crosslinking degree of PVA substrate

Hydrogel composition containing biologically active additive

Hydrogelová kompozice obsahuje hydrogelovou matrici, která je tvořena síťovanou polymerní strukturou na bázi vodorozpustných polymerů a v koncentraci 0,001 až 10 hmot. %, vztaženo na hmotnost suché hydrogelové matrice, a biologicky aktivní aditivum tvořené alespoň jednou biologicky aktivní látkou izolovanou z mléka nebo jeho derivátů. Hydrogelovou matricí je s výhodou síťovaná polymerní struktura na bázi alespoň jednoho polymeru ze skupiny zahrnující kopolymery kyseliny akrylové, kopolymery kyseliny methakrylové, deriváty celulózy a vinylové polymery. Biologicky aktivní látkou izolovanou z mléka nebo jeho derivátů je především látka ze skupiny glykoproteinů, imunoglobulinů a/nebo polypeptidů

Plasma polymers with controlled degradation behaviour

Classical “wet“chemistry methods can produce polymers with well-defined molecular structure, but many types of polymers are difficult to prepare with significant degree of crosslinking without residues of the crosslinking agent. On the other hand, plasma polymers usually have very high degree of crosslinking but nearly random molecular structure. Plasma assisted vapour thermal deposition combines both methods. Classical polymers are heated in a crucible at low pressure and the released oligomeric fragments of the polymer chain are repolymerized in a glow discharge into a thin film. The number of well-preserved monomeric units between the crosslinks can be tuned e.g. from units to tens. Poly-lactic acid (PLA) belongs to a special class of biodegradable polymeric materials. In this work, plasma assisted vapour thermal deposition was utilized to prepare PLA plasma polymers. Molar weights and chemical composition of the “precursor” polymer and of the thin films have been characterized. As the measure of degradability, behaviour of the polymers during hydrolysis has been studied using spectroscopic ellipsometry and liquid chromatography. Possibility to prepare plasma polymer films with controlled degradability was demonstrated. © 2018 TANGER Ltd. All Rights Reserved.Czech Science Foundation (Grant Agency of the Czech Republic) [17-10813S

Thin films of cross-linked polylactic acid as tailored platforms for controlled drug release

Drug-loaded polymers are desirable for the controlled administration of bioactive molecules to biological media because polymer viscoelasticity can be translated into benefits of tissue-contacting materials. Here, we report on plasma-assisted deposition of polyester thin films performed via thermal evaporation of polylactic acid (PLA). The films can be produced with the chemical composition and polymer topology precisely tuned by the discharge power. At low power, weakly cross-linked films are produced with the chemical motif resembling that of PLA, the molar mass distribution peaking at ~350 g × mol−1 and skewing to larger species. At high power, highly cross-linked films are produced with a worse resemblance to PLA. The films swell and dissolve in water, releasing oligomers with the dissolution kinetics spanning over a broad time scale of 10−1–104 s. The released oligomers undergo hydrolysis at the time scale of days and with the final product of lactic acid, meeting the biocompatibility demands. When dissolving, the films expose micrometre-sized pores or buckling instabilities, depending on the discharge power. The phenomenon can be used for controlled release of nisin, an antibacterial peptide so that an hour-delayed release is achieved via the pore-mediated diffusion, whereas a minute-delayed release is achieved through the buckling. Nisin-loaded polyester plasma polymer films are effective against Micrococcus luteus, the bactericidal activity correlating with the drug release kinetics. Hence, the film design holds promise for developing advanced wound dressing materials and other tissue-contacting devices with tunable therapeutic effect. © 2021 Elsevier B.V.Czech Science FoundationGrant Agency of the Czech Republic [GA17-10813S]; Charles University [SVV 260 579/2021]; Ministry of Industry and Trade of the Czech Republic [TRIO FV10400]Univerzita Karlova v Praze, UK: SVV 260 579/2021; Grantová Agentura České Republiky, GA ČR: GA17-10813S; Ministerstvo Průmyslu a Obchodu, MPO: TRIO FV1040