Pilot Study of Cytoprotective Mechanisms of Selenium Nanorods (SeNrs) under Ischemia-like Conditions on Cortical Astrocytes.

The cytoprotective properties of the trace element selenium, its nanoparticles, and selenium nanocomplexes with active compounds are shown using a number of models. To date, some molecular mechanisms of the protective effect of spherical selenium nanoparticles under the action of ischemia/reoxygenation on brain cells have been studied. Among other things, the dependence of the effectiveness of the neuroprotective properties of nanoselenium on its diameter, pathways, and efficiency of penetration into astrocytes was established. In general, most research in the field of nanomedicine is focused on the preparation and study of spherical nanoparticles of various origins due to the ease of their preparation; in addition, spherical nanoparticles have a large specific surface area. However, obtaining and studying the mechanisms of action of nanoparticles of a new form are of great interest since nanorods, having all the positive properties of spherical nanoparticles, will also have a number of advantages. Using the laser ablation method, we managed to obtain and characterize selenium nanorods (SeNrs) with a length of 1 µm and a diameter of 100 nm. Using fluorescence microscopy and inhibitory analysis, we were able to show that selenium nanorods cause the generation of Ca2+ signals in cortical astrocytes in an acute experiment through the mobilization of Ca2+ ions from the thapsigargin-sensitive pool of the endoplasmic reticulum. Chronic use of SeNrs leads to a change in the expression pattern of genes encoding proteins that regulate cell fate and protect astrocytes from ischemia-like conditions and reoxygenation through the inhibition of a global increase in the concentration of cytosolic calcium ([Ca2+]i). An important component of the cytoprotective effect of SeNrs during ischemia/reoxygenation is the induction of reactive A2-type astrogliosis in astrocytes, leading to an increase in both baseline and ischemia/reoxygenation-induced phosphoinositide 3-kinase (PI3K) activity and suppression of necrosis and apoptosis. The key components of this cytoprotective action of SeNrs are the actin-dependent process of endocytosis of nanoparticles into cells and activation of the Ca2+ signaling system of astrocytes.

Laser Ablation-Generated Crystalline Selenium Nanoparticles Prevent Damage of DNA and Proteins Induced by Reactive Oxygen Species and Protect Mice against Injuries Caused by Radiation-Induced Oxidative Stress.

With the help of laser ablation, a technology for obtaining nanosized crystalline selenium particles (SeNPs) has been created. The SeNPs do not exhibit significant toxic properties, in contrast to molecular selenium compounds. The administration of SeNPs can significantly increase the viabilities of SH-SY5Y and PCMF cells after radiation exposure. The introduction of such nanoparticles into the animal body protects proteins and DNA from radiation-induced damage. The number of chromosomal breaks and oxidized proteins decreases in irradiated mice treated with SeNPs. Using hematological tests, it was found that a decrease in radiation-induced leukopenia and thrombocytopenia is observed when selenium nanoparticles are injected into mice before exposure to ionizing radiation. The administration of SeNPs to animals 5 h before radiation exposure in sublethal and lethal doses significantly increases their survival rate. The modification dose factor for animal survival was 1.2. It has been shown that the introduction of selenium nanoparticles significantly normalizes gene expression in the cells of the red bone marrow of mice after exposure to ionizing radiation. Thus, it has been demonstrated that SeNPs are a new gene-protective and radioprotective agent that can significantly reduce the harmful effects of ionizing radiation.

Fluoroplast Doped by Ag2O Nanoparticles as New Repairing Non-Cytotoxic Antibacterial Coating for Meat Industry.

Foodborne infections are an important global health problem due to their high prevalence and potential for severe complications. Bacterial contamination of meat during processing at the enterprise can be a source of foodborne infections. Polymeric coatings with antibacterial properties can be applied to prevent bacterial contamination. A composite coating based on fluoroplast and Ag2O NPs can serve as such a coating. In present study, we, for the first time, created a composite coating based on fluoroplast and Ag2O NPs. Using laser ablation in water, we obtained spherical Ag2O NPs with an average size of 45 nm and a ζ-potential of -32 mV. The resulting Ag2O NPs at concentrations of 0.001-0.1% were transferred into acetone and mixed with a fluoroplast-based varnish. The developed coating made it possible to completely eliminate damage to a Teflon cutting board. The fluoroplast/Ag2O NP coating was free of defects and inhomogeneities at the nano level. The fluoroplast/Ag2O NP composite increased the production of ROS (H2O2, OH radical), 8-oxogualnine in DNA in vitro, and long-lived active forms of proteins. The effect depended on the mass fraction of the added Ag2O NPs. The 0.01-0.1% fluoroplast/NP Ag2O coating exhibited excellent bacteriostatic and bactericidal properties against both Gram-positive and Gram-negative bacteria but did not affect the viability of eukaryotic cells. The developed PTFE/NP Ag2O 0.01-0.1% coating can be used to protect cutting boards from bacterial contamination in the meat processing industry.

The Development of New Nanocomposite Polytetrafluoroethylene/Fe2O3 NPs to Prevent Bacterial Contamination in Meat Industry.

The bacterial contamination of cutting boards and other equipment in the meat processing industry is one of the key reasons for reducing the shelf life and consumer properties of products. There are two ways to solve this problem. The first option is to create coatings with increased strength in order to prevent the formation of micro damages that are favorable for bacterial growth. The second possibility is to create materials with antimicrobial properties. The use of polytetrafluoroethylene (PTFE) coatings with the addition of metal oxide nanoparticles will allow to the achieving of both strength and bacteriostatic effects at the same time. In the present study, a new coating based on PTFE and Fe2O3 nanoparticles was developed. Fe2O3 nanoparticles were synthesized by laser ablation in water and transferred into acetone using the developed procedures. An acetone-based colloidal solution was mixed with a PTFE-based varnish. Composites with concentrations of Fe2O3 nanoparticles from 0.001-0.1% were synthesized. We studied the effect of the obtained material on the generation of ROS (hydrogen peroxide and hydroxyl radicals), 8-oxoguanine, and long-lived active forms of proteins. It was found that PTFE did not affect the generation of all the studied compounds, and the addition of Fe2O3 nanoparticles increased the generation of H2O2 and hydroxyl radicals by up to 6 and 7 times, respectively. The generation of 8-oxoguanine and long-lived reactive protein species in the presence of PTFE/Fe2O3 NPs at 0.1% increased by 2 and 3 times, respectively. The bacteriostatic and cytotoxic effects of the developed material were studied. PTFE with the addition of Fe2O3 nanoparticles, at a concentration of 0.001% or more, inhibited the growth of E. coli by 2-5 times compared to the control or PTFE without NPs. At the same time, PTFE, even with the addition of 0.1% Fe2O3 nanoparticles, did not significantly impact the survival of eukaryotic cells. It was assumed that the resulting composite material could be used to cover cutting boards and other polymeric surfaces in the meat processing industry.

A Polytetrafluoroethylene (PTFE) and Nano-Al2O3 Based Composite Coating with a Bacteriostatic Effect against E. coli and Low Cytotoxicity.

The problem of bacterial contamination through surfaces is important for the food industry. In this regard, there is a growing interest in new coatings based on nanoparticles that can provide a long-term antibacterial effect. Aluminum oxide nanoparticles are a good candidate for such coatings due to their availability and good biocompatibility. In this study, a coating containing aluminum oxide nanoparticles was produced using polytetrafluoroethylene as a polymer matrix-a polymer that exhibits excellent mechanical and physicochemical properties and it is not toxic. The obtained coatings based on "liquid Teflon" containing various concentrations of nanoparticles (0.001-0.1 wt%) prevented the bacterial growth, and they did not exhibit a cytotoxicity on animal cells in vitro. Such coatings are designed not only to provide an antibacterial surface effect, but also to eliminate micro damages on surfaces that inevitably occur in the process of food production.

Effect of Laser-Induced Optical Breakdown on the Structure of Bsa Molecules in Aqueous Solutions: An Optical Study.

The influence of laser radiation of a typical surgical laser on the physicochemical properties of the Bovine Serum Albumin (BSA) protein was studied. It was established that the physicochemical characteristics of optical breakdown weakly depend on the concentration of protein molecules. At the same time, the patterns observed for an aqueous solution of BSA irradiated with a laser for different time periods were extremely similar to the classical ones. It was established that after exposure to laser radiation, the optical density of protein solutions increases. At the same time, the intensity of BSA fluorescence due to aromatic amino acid residues decreases insignificantly after exposure to laser radiation. In this case, the position of the excitation and emission maximum does not change, and the shape of the fluorescence spot on 3D maps also does not change significantly. On the Raman spectrum after exposure to laser radiation, a significant decrease in 1570 cm-1 was observed, which indicates the degradation of α-helices and, as a result, partial denaturation of BSA molecules. Partial denaturation did not significantly change the total area of protein molecules, since the refractive index of solutions did not change significantly. However, in BSA solutions, after exposure to laser radiation, the viscosity increased, and the pseudoplasticity of aqueous solutions decreased. In this case, there was no massive damage to the polypeptide chain; on the contrary, when exposed to optical breakdown, intense aggregation was observed, while aggregates with a size of 400 nm or more appeared in the solution. Thus, under the action of optical breakdown induced by laser radiation in a BSA solution, the processes of partial denaturation and aggregation prevail, aromatic amino acid residues are damaged to a lesser extent, and fragmentation of protein molecules is not observed.

Laser-Induced Optical Breakdown of an Aqueous Colloidal Solution Containing Terbium Nanoparticles: The Effect of Oxidation of Nanoparticles.

The influence of the number of oxidized terbium nanoparticles on the intensity of physicochemical processes occurring during optical breakdown in aqueous colloidal solutions of nanoparticles has been studied. It is shown that the effect of the number of oxidized terbium nanoparticles on the physicochemical processes occurring during optical breakdown depends significantly on the fluence of laser radiation. At a fluence of less than 100-110 J/cm2, plasma formation processes occur more intensively on less-oxidized (metal) nanoparticles. At a fluence of more than 100-110 J/cm2, the processes of plasma formation during optical breakdown occur much more intensively on more-oxidized nanoparticles. It has been established that the dependence of the rate of laser-induced decomposition of water on the concentration of nanoparticles is two-phase. The rate of generation of water decomposition products increases with an increase in the concentration of nanoparticles up to 109 NP/mL. With a further increase in the concentration of nanoparticles, the rate of generation of water decomposition products decreases. In this case, more than 99% of the decomposition products of water are formed due to the action of plasma, and the share of ultraviolet and ultrasound formed during optical breakdown is approximately 0.5% on each.

Effect of Mechanical Shaking on the Physicochemical Properties of Aqueous Solutions.

Long-lived luminescence in the blue region was found to occur in deionized water saturated with atmospheric gases following mechanical shaking. Luminescence intensity decreased exponentially after the cessation of stress. During vigorous mechanical shaking, we observed gas bubbles in solution, and the liquid-gas interface area increased noticeably. At the same time, the concentration of molecular oxygen decreased, which could not be attributed to the water warming up with exposure to mechanical stress. However, deaerated water rapidly became saturated with gases following mechanical stress. The recommendation that cell culture media should be mixed after they are removed from the fridge in order to allow saturation with oxygen is probably misleading. It was shown that gases existed in water both in the form of individual molecules and nanobubbles. Mechanical stress did not influence the number or size of nanobubbles. While gas nanobubbles were absent in freshly prepared deaerated water, they appeared following exposure to mechanical stress. In addition, in mechanically treated gas-saturated water, there was seemingly an equilibrium shift towards the decomposition of carbonic acid to water and carbon dioxide. At the same time, the pH of water tended to increase immediately after mechanical stress. It was demonstrated that reactive oxygen species (ROS) form in gas-saturated water under mechanical stress (30 Hz, amplitude of 5 mm). The relative generation rate of hydrogen peroxide and of the hydroxyl radical was 1 nM/min and 0.5 nM/min, respectively. It was found that with an increase in the frequency of mechanical action (f), the rate of ROS generation increased in proportion to f 2. The major pathways for hydrogen peroxide generation are probably associated with the formation of singlet oxygen and its further reduction, and the alternative pathway is the formation of hydrogen peroxide as a result of hydroxyl radical recombination.

The Effect of Gold Nanoparticle Concentration and Laser Fluence on the Laser-Induced Water Decomposition.

This Article covers the influence of the concentration of gold nanoparticles on laser-induced water decomposition. It was established that addition of gold nanoparticles intensifies laser-induced water decomposition by almost 2 orders of magnitude. The water decomposition rate was shown to be maximal at a nanoparticle concentration around 1010 NP/mL, whereas a decrease or increase of nanoparticle concentration leads to a decrease of water decomposition rate. It was demonstrated that, if the concentration of nanoparticles in water-based colloid was less than 1010 NP/mL, laser irradiation of the colloid caused formation of molecular hydrogen, hydrogen peroxide, and molecular oxygen. If the concentration of nanoparticles exceeded 1011 NP/mL, only two products, molecular hydrogen and hydrogen peroxide, were formed. Correlations between the water decomposition rate and the main optical and acoustic parameters of optical breakdown-generated plasma were investigated. Variants of laser-induced decomposition of colloidal solutions of nanoparticles based on organic solvents (ethanol, propanol-2, butanol-2, diethyl ether) were also analyzed.