Poly(2-oxazoline) hydrogels by photoinduced thiol-ene “click” reaction using different dithiol crosslinkers

Fabrication of a library of biocompatible hydrogels by photoinduced thiol-ene “click” reaction is described. The hydrogels are based on two different statistical copolymers consisting of 2-butenyl-2-oxazoline (EnOx) with either 2-methyl-2-oxazoline (MeOx) or 2-ethyl-2-oxazoline (EtOx). Crosslinking is achieved via pendant vinyl groups of EnOx in the copolymers with selected dithiol crosslinkers, namely dithiothreitol, 1,3-propanedithiol, 1,6-hexanedithiol, and 1,9-nonanedithiol by thiol-ene photocoupling. On the basis of different polarity and flexibility of particular dithiols and three different molar ratios to double bonds, it is possible to control swelling and mechanical characteristics of resulting hydrogels. Biocompatibility of all hydrogel types is verified by determination of toxicity of hydrogel extracts and contact direct toxicity towards mice 3T3 fibroblast cell line. The resulting low toxicity of all prepared hydrogels predetermines its utilization in biomedicine.     

The interaction of thin polyaniline films with various H‐phosphonates: Spectroscopy and quantum chemical calculations

The conducting form of polyaniline (PANI) is formed by doping of non‐conducting PANI base usually by protonic acids. An alternative way of doping, consisting in an interaction via hydrogen bonding, has been previously proven for H‐phosphonates. In this study, PANI base films are exposed to various H‐phosphonates, changes in the structure of the films are analyzed by ultraviolet–visible, infrared, and Raman spectroscopies and spectroscopic data are compared with quantum chemical calculations. According to our results, the interaction of the PANI base films with H‐phosphonates is realized by hydrogen bonding between the imine nitrogen of PANI and the hydroxy group of the H‐phosphonate tautomeric form, i.e., phosphite. This is in the contrast to the PANI powders doped with H‐phosphonates where both interacting phosphite and non‐interacting H‐phosphonate forms were observed. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46728.     

Effect of Thermal Treatment on the Amplification and Quantification of Transgenic and Non-transgenic Soybean and Maize DNA

Processing of raw plant materials causes occurrence of degraded DNA in foods. The effect of DNA degradation on amplification and quantification of transgenic and non-transgenic DNA in raw and experimentally thermally processed foods was studied. The degree of DNA degradation was checked by agarose gel electrophoresis and polymerase chain reaction (PCR). Cetyl trimethyl ammonium bromide method yielded DNA of a better quality, while Genespin and Wizard were less appropriate. Baking at 220 °C considerably reduced the size of DNA fragments. In order to measure the length of amplifiable DNA, primers for soybean and maize genes were used. Small DNA fragments ranging from 100 to 200 bp were amplified in all samples. DNA fragments over 1 kbp were amplified only if heating at 220 °C lasted less than 30 min. Baking of flour (220 °C) reduced the size of extracted DNA fragments so that 1,100 bp amplicon was no longer amplifiable, while the amplicons of 913 and 1,100 bp were obtained from the baked bread. When PCR assays targeting maize high mobility group and zein genes were used under the same conditions, analogous results were achieved. Quantification of genetically modified organism content was not influenced by baking.     

Effect of 1-Ethyl-3-methylimidazolium Tetrafluoroborate and Acetate Ionic Liquids on Stability and Amyloid Aggregation of Lysozyme

Amyloid fibrils draw attention as potential novel biomaterials due to their high stability, strength, elasticity or resistance against degradation. Therefore, the controlled and fast fibrillization process is of great interest, which raises the demand for effective tools capable of regulating amyloid fibrillization. Ionic liquids (ILs) were identified as effective modulators of amyloid aggregation. The present work is focused on the study of the effect of 1-ethyl-3-methyl imidazolium-based ILs with kosmotropic anion acetate (EMIM-ac) and chaotropic cation tetrafluoroborate (EMIM-BF₄) on the kinetics of lysozyme amyloid aggregation and morphology of formed fibrils using fluorescence and CD spectroscopy, differential scanning calorimetry, AFM with statistical image analysis and docking calculations. We have found that both ILs decrease the thermal stability of lysozyme and significantly accelerate amyloid fibrillization in a dose-dependent manner at concentrations of 0.5%, 1% and 5% (v/v) in conditions and time-frames when no fibrils are formed in ILs-free solvent. The effect of EMIM-BF₄ is more prominent than EMIM-ac due to the different specific interactions of the anionic part with the protein surface. Although both ILs induced formation of amyloid fibrils with typical needle-like morphology, a higher variability of fibril morphology consisting of a different number of intertwining protofilaments was identified for EMIM-BF_4.     

Anti-amyloidogenic activity of glutathione-covered gold nanoparticles

This study is an investigation of the effect of biocompatible glutathione-covered gold nanoparticles (AuSG_7) with an average size of 3 nm on the amyloid fibrils of hen egg-white lysozyme. The anti-amyloid activity of AuSG_7 nanoparticles on this protein was monitored with thioflavin T assay, atomic force microscopy and transmission electron microscopy. The study found that AuSG_7 nanoparticles in vitro depolymerize the amyloid aggregates and inhibit lysozyme aggregate formation. The ability to inhibit amyloid formation and promote amyloid disassembly has concentration-dependent characteristics: the concentration of nanoparticles at which inhibition is half maximal (IC₅₀) was found to be 6.19 μg/mL, and the concentration at which depolymerization is half maximal (DC₅₀) was found to be 8.26 μg/mL.     

Magnetic Properties of ZnFe<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles Synthesized by Starch-Assisted Sol–Gel Auto-combustion Method

In this paper, ZnFe₂O₄ spinel ferrite nanoparticles with different grain sizes at different annealing temperatures have been synthesized using the starch-assisted sol–gel auto-combustion method. The synthesized nanoparticles were characterized by conventional powder X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, and vibrating sample magnetometer. The X-ray diffraction (XRD) patterns demonstrated that the ZnFe₂O₄ nanoparticles consist of single-phase spinel structure with crystallite sizes 4.81, 8.72, 12.06, 29.32, and 72.60 nm annealed at 400, 600, 800, 1000, and 1200 °C, respectively. Field emission scanning electron microscopy reveals that particles are of spherical morphology at lower annealing temperature and hexagonal-like morphology at higher temperature. An infrared spectroscopy study shows the presence of two principal absorption bands in the frequency range around 525 cm^?1 (ν ₁) and around 350 cm^?1 (ν ₂), which indicate the presence of tetrahedral and octahedral group complexes, respectively, within the spinel ferrite nanoparticles. Raman spectroscopy study also indicated the change in octahedral and tetrahedral site-related Raman modes in zinc ferrite nanoparticles with change of particle size. The nanocrystalline ZnFe₂O₄ samples (4.81, 8.72, 12.06, 29.32 nm) show ferrimagnetic behavior, and bulk sample (72.60 nm) shows paramagnetic behavior. This change in magnetic behavior is due to change of cation distribution in ZnFe₂O₄ nanoparticles with decrease of particle size.     

Acidic leaching both of zinc and iron from basic oxygen furnace sludge

During the steel production in the basic oxygen furnace (BOF), approximately 7-15 kg of dust per tonne of produced steel is generated. This dust contains approximately 1.4-3.2% Zn and 54-70% Fe. Regarding the zinc content, the BOF dust is considered to be highly problematic, and therefore new technological processes for recycling dusts and sludge from metallurgical production are still searched for. In this study the hydrometallurgical processing of BOF sludge in the sulphuric acid solutions under atmospheric pressure and temperatures up to 100 °C is investigated on laboratory scale. The influence of sulphuric acid concentration, temperature, time and liquid to solid ratio (L:S) on the leaching process was studied. The main aim of this study was to determine optimal conditions when the maximum amount of zinc passes into the solution whilst iron remains in a solid residue.     

Structure and stability of thin polyaniline films deposited in situ on silicon and gold during precipitation and dispersion polymerization of aniline hydrochloride

Fresh and one-year-old thin polyaniline films prepared during the in-situ precipitation and dispersion polymerizations of aniline hydrochloride on gold and silicon supports in forms of emeraldine salt and base were characterized by UV-visible, Fourier-transform infrared, and Raman spectroscopies. Raman microscope has been used for the analysis of molecular structure. It has been shown that the films prepared by dispersion polymerization are thinner and more resistant to heating. In all cases, the films prepared on silicon were more stable against aging in air than those prepared on gold, which are, on the other hand, more stable against chemical deprotonation. The role of aniline oligomers adsorbed in the early stages of aniline oxidation on the silicon and gold substrates in the molecular structure and stability of the films has been discussed.     

Inhibitory effect of organic acids on arcobacters in culture and their use for control of Arcobacter butzleri on chicken skin

The inhibitory effects of 17 organic acids (C₂-C₁₆ fatty acids, sorbic, benzoic, phenylacetic, fumaric, succinic, lactic, malic and citric) on Arcobacter butzleri, Arcobacter cryaerophilus and Arcobacter skirrowii were investigated by determining their IC₅₀ values, defined as the concentration of acid at which the target DNA sequence was expressed at 50% of the positive control level in cultures incubated at 30 °C for 24 h. DNA was analysed by real-time PCR. The Arcobacter strains tested were inhibited by all the organic acids, with the sensitivities in the order A. skirrowii > A. cryaerophilus > A. butzleri. Eight acids with IC₅₀ values of < 1 mg/mL against A. butzleri were tested for their effects on A. butzleri inoculated on chicken carcasses at a concentration of 5 log CFU/g of skin. Inoculated halved carcasses were immersed in solutions of the acids at 5 mg/mL for 1 min. Samples of skin were collected from carcass halves after storage at 4 °C for 0, 1, 2 or 3 days for enumeration of arcobacters on Muller-Hinton agar. All eight tested acids suppressed bacterial proliferation. The highest inhibitory activities were observed for benzoic, citric, malic and sorbic acids. Subsequent sensory analysis revealed benzoic acid to be the most suitable organic acid for chicken skin treatment.