Antimicrobial modification of polypropylene with silver nanoparticles immobilized on zinc stearate

The microwave synthesis of Ag nanoparticles on zinc stearate (ZnSt/Ag) was performed to obtain an antimicrobial additive for a polypropylene matrix. Thermoplastically prepared polymer composites contained (1, 3, 5 and 10) % of mass fractions of ZnSt/Ag. The effect of the presence of additives on the morphology and mechanical properties of composites was studied by scanning electron microscopy and stress-strain analysis. The antimicrobial activity of the composites was studied according to the ISO 22196 standard. The results showed that sufficient antimicrobial activity of the composites against both Gram-positive and Gram-negative bacterial strains was observed in the case of the composites with the highest filling studied.grant of Technology Agency of the Czech Republic [TE02000006]; Ministry of Education, Youth and Sports of the Czech Republic - Program NPU I [LO1504]; Internal Grant Agency of the Tomas Bata University in Zlin [IGA/CPS/2015/004

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

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

Effect of structure of polymers grafted from graphene oxide on the compatibility of particles with a silicone-based environment and the stimuli-responsive capabilities of their composites

This study reports the utilization of controlled radical polymerization as a tool for controlling the stimuli-responsive capabilities of graphene oxide (GO) based hybrid systems. Various polymer brushes with controlled molecular weight and narrow molecular weight distribution were grafted from the GO surface by surface-initiated atom transfer radical polymerization (SI-ATRP). The modification of GO with poly(n-butyl methacrylate) (PBMA), poly(glycidyl methacrylate) (PGMA), poly(trimethylsilyloxyethyl methacrylate) (PHEMATMS) and poly(methyl methacrylate) (PMMA) was confirmed by thermogravimetric analysis (TGA) coupled with online Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Various grafting densities of GO-based materials were investigated, and conductivity was elucidated using a four-point probe method. Raman shift and XPS were used to confirm the reduction of surface properties of the GO particles during SI-ATRP. The contact angle measurements indicated the changes in the compatibility of GOs with silicone oil, depending on the structure of the grafted polymer chains. The compatibility of the GOs with poly(dimethylsiloxane) was also investigated using steady shear rheology. The tunability of the electrorheological, as well as the photo-actuation capability, was investigated. It was shown that in addition to the modification of conductivity, the dipole moment of the pendant groups of the grafted polymer chains also plays an important role in the electrorheological (ER) performance. The compatibility of the particles with the polymer matrix, and thus proper particles dispersibility, is the most important factor for the photo-actuation efficiency. The plasticizing effect of the GO-polymer hybrid filler also has a crucial impact on the matrix stiffness and thus the ability to reversibly respond to the external light stimulation.Grant Agency of the Czech RepublicGrant Agency of the Czech Republic [16-20361Y]; Ministry of Education, Youth and Sports of the Czech Republic program NPU I [LO1504]; Research & Innovation Operational Programme - ERDF [313021T081]; project VEGAVedecka grantova agentura MSVVaS SR a SAV (VEGA) [2/0129/19]; European UnionEuropean Union (EU) [CZ.02.2.69/0.0/0.0/16_027/0008464]; Operational Program Research and Development for innovations; European Regional Development Fund (ERDF)European Union (EU); national budget of Czech Republic within project CPS -strengthening research capacity [CZ.1.05/2.1.00/19.0409]; National Science Centre, Poland [UMO-2016/23/P/ST5/02131]; European Unions' Horizon 2020 research and innovation programme under Marie Sklodowska-Curie grant [665778

Immobilization of bacteriocin nisin into a poly(vinyl alcohol) polymer matrix crosslinked with nontoxic dicarboxylic acid

This work is focused on novel methodology of poly(vinyl alcohol) crosslinking by non-toxic dicarboxylic acid, glutaric acid. The cross-linked system was used as a matrix for immobilization of bacteriocin nisin. Effect of the crosslinking degree on physico-chemical, morphology, mechanical, and thermal properties of poly(vinyl alcohol) films were investigated by using swelling test, Fourier transform infrared spectroscopy, scanning electron microscopy, stress-strain analysis, differential scanning calorimetry, and thermogravimetry. Release profile of the nisin from the cross-linked poly(vinyl alcohol) was studied by high performance liquid chromatography. Antibacterial activity of the prepared systems was tested by agar diffusion test and dilution and spread plate technique. Results showed suitability of glutaric acid as effective crosslinking agent of poly(vinyl alcohol) that acts synergistically with bacteriocin nisin against the tested Gram-positive and Gram-negative bacterial strains. © 2016 Wiley Periodicals, Inc.LO1504, NPU, Northwestern Polytechnical UniversityMinistry of Agriculture of the Czech Republic [QJ1310254]; Ministry of Education, Youth and Sports of the Czech Republic within the NPU I program [LO1504]; European Regional Development Fund [CZ.1.05/2.1.00/19.0409]; Internal Grant Agency of the Tomas Bata University on Zlin [IGA/CPS/2016/004

Preservative agent composition with antimicrobial and barrier properties

Kompozice obsahuje hydrogelovou matrici tvořenou síťovanou polymerní strukturou na bázi alespoň jednoho vodorozpustného polymeru (3D polymerní síť, v níž jsou řetěze polymeru, resp. polymerů kovalentně pospojovány příčnými vazbami) ze skupin zahrnující kopolymery kyseliny akrylové a deriváty celulózy a v koncentraci 0,001 až 10 % hmotn., vztaženo na hmotnost suché hydrogelové matrice, biologicky aktivní aditivum tvořené kyselinou mléčnou. Výhodná koncentrace kyseliny mléčné je 0,5 až 10 % hmotn.Composition contains hydrogel matrix, with net-based polymeric structure on the basis of at least one water-soluble polymer (3D polymer net, in which there are polymer chains, more precisely polymers covalently bonded by cross links) from the group containing copolymers of acrylic acid and cellulose derivatives and concentration 0.001 to 10% weight, applying to the weight of dry hydrogel matrix, biologically active additive made of lactic acid. Favourable concentration of the lactic acid is 0.5 to 10% of weight

Core–shell PLA–PVA porous microparticles as carriers for bacteriocin nisin

This work is focused on preparation of novel porous type of core–shell-structured microparticles based on polylactide (shell) and poly(vinyl alcohol) cross-linked with glutaric acid (GA) (core) prepared by water-in-oil-in-water solvent evaporation technique. The microparticle systems were used as delivery systems for immobilisation of model antibacterial agent–nisin. The effect of cross-linking and the initial amount of nisin on their morphology was investigated using scanning electron microscopy, BET analysis, zeta potential measurement and Fourier transform infra-red spectroscopy. Encapsulation efficiency and release profile of nisin from the microparticles were studied by high performance liquid chromatography. Antibacterial activity of the prepared systems was tested by dilution and spread plate technique. Results showed the microparticles in the size range of 9–16 μm in diameter with spherical multi-hollow core–shell structure. The presence of cross-linking agent GA influences the release profile of the peptide and has synergistic effect on Listeria monocytogenes growth reduction. © 2017 Informa UK Limited, trading as Taylor & Francis Group.CZ.1.05/2.1.00/19.0409, MŠMT, Ministerstvo Školství, Mládeže a Tělovýchovy; LO1504, MŠMT, Ministerstvo Školství, Mládeže a TělovýchovyMinistry of Agriculture of the Czech Republic [QJ1310254]; Ministry of Education, Youth and Sports of the Czech Republic [LO1504, CZ.1.05/2.1.00/19.0409]; Internal Grant Agency of the Tomas Bata University in Zlin [IGA/CPS/2017/005

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

Antibacterial polymer composites based on low-density polyethylene and essential oils immobilized on various solid carriers

In this study, we investigated the antibacterial modification of polymers with biologically active substances in essential oils [EOs; linalool, 4-allylanisole (ALY), and trans-anethole]. These compounds were thermoplastically incorporated into a low-density polyethylene matrix via solid inert carriers [wood flour (WF) and talc and molecular sieves] with physically immobilized EOs. The concentrations of the antibacterial modifiers on the carriers and in the resulting composites were determined with three chromatographic techniques (gas chromatography with mass spectrometry, pyrolysis and gas chromatography with mass spectrometry, and high-performance liquid chromatography). The effects of such modifications to the mechanical properties of the prepared composites were studied by stress-strain analysis. Interactions on the polymer matrix carriers were observed by scanning electron microscopy. The prepared composites were also tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains. The highest efficiency of isothermal immobilization was found for systems consisting of ALY and WF. This finding was in accordance with microbiological studies. The phase of immobilizing the EOs did not influence the mechanical properties of the studied composites. © 2015 Wiley Periodicals, Inc.Ministry of Education, Youth, and Sports of the Czech Republic within the NPU I program [LO1504]; EUPRO [LE12002]; Internal Grant Agency of Tomas Bata University in Zlin [IGA/CPS/2015/003]; Ministry of Higher Education, Science, and Technology of the Republic of Slovenia [P4-0015

Influence of gamma rays on the physico-chemical, release and antibacterial characteristics of low-density polyethylene composite films incorporating an essential oil for application in food-packaging

We investigated the effect of gamma irradiation on the properties of low-density polyethylene composite films incorporated with the antimicrobial terpene 4-allylanisole (ALY), and the volatile release of ALY. For comparison, wood flour and molecular sieves were used as solid carriers for ALY at loading ratios of 20 and 30 wt.%. Infrared spectroscopy indicated that a proportion of ALY underwent structural change during melt-compounding and irradiation at high doses (> 10 kGy). Thermal and mechanical properties of composites prepared did not alter remarkably after irradiation. The release study of ALY showed that using wood flour and irradiation reduced the volatilization of ALY from the polymer matrix; however, the effect exerted by irradiation treatment was less noticeable than that of the carrier type. The antibacterial activity study demonstrated that irradiation only exerted a pronounced negative effect on samples that contained 30 wt.% of ALY/wood flour when irradiated at 30 and 50 kGy. © 2018 Elsevier LtdMinistry of Education, Youth and Sports of the Czech Republic [LO1504, CZ.1.05/2.1.00/19.0409