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.

Metformin mitigates radiation toxicity exerting antioxidant and genoprotective properties.

The antidiabetic drug metformin (MF) exhibits redox-modulating effects in various pathologies associated with oxidative stress and mitigates ionizing radiation-induced toxicity, but the underlying mechanisms remain to be elucidated. Thus, we studied some radiomitigatory effects of MF and explored the possible mechanisms behind them. Highly sensitive luminescence methods and non-competitive enzyme-linked immunosorbent assay (ELISA) were used in in vitro studies, and in vivo the damage to bone marrow cells and its repair were assessed by the micronucleus test. In a solution, MF at concentrations exceeding 0.1 µM effectively intercepts •OH upon X-ray-irradiation, but does not react directly with H2O2. MF accelerates the decomposition of H2O2 catalyzed by copper ions. MF does not affect the radiation-induced formation of H2O2 in the solution of bovine gamma-globulin (BGG), but has a modulating effect on the generation of H2O2 in the solution of bovine serum albumin (BSA). MF at 0.05-1 mM decreases the radiation-induced formation of 8-oxoguanine in a DNA solution depending on the concentration of MF with a maximum at 0.25 mM. MF at doses of 3 mg/kg body weight (bw) and 30 mg/kg bw administered to mice after irradiation, but not before irradiation, reduces the frequency of micronucleus formation in polychromatophilic erythrocytes of mouse red bone marrow. Our work has shown that the radiomitigatory properties of MF are mediated by antioxidant mechanisms of action, possibly including its ability to chelate polyvalent metal ions.

Bacteriostatic and Cytotoxic Properties of Composite Material Based on ZnO Nanoparticles in PLGA Obtained by Low Temperature Method.

A low-temperature technology was developed for producing a nanocomposite based on poly (lactic-co-glycolic acid) and zinc oxide nanoparticles (ZnO-NPs), synthesized by laser ablation. Nanocomposites were created containing 0.001, 0.01, and 0.1% of zinc oxide nanoparticles with rod-like morphology and a size of 40-70 nm. The surface of the films from the obtained nanomaterial was uniform, without significant defects. Clustering of ZnO-NPs in the PLGA matrix was noted, which increased with an increase in the concentration of the dopant in the polymer. The resulting nanomaterial was capable of generating reactive oxygen species (ROS), such as hydrogen peroxide and hydroxyl radicals. The rate of ROS generation increased with an increase in the concentration of the dopant. It was shown that the synthesized nanocomposite promotes the formation of long-lived reactive protein species, and is also the reason for the appearance of a key biomarker of oxidative stress, 8-oxoguanine, in DNA. The intensity of the process increased with an increase in the concentration of nanoparticles in the matrix. It was found that the nanocomposite exhibits significant bacteriostatic properties, the severity of which depends on the concentration of nanoparticles. In particular, on the surface of the PLGA-ZnO-NPs composite film containing 0.001% nanoparticles, the number of bacterial cells was 50% lower than that of pure PLGA. The surface of the composite is non-toxic to eukaryotic cells and does not interfere with their adhesion, growth, and division. Due to its low cytotoxicity and bacteriostatic properties, this nanocomposite can be used as coatings for packaging in the food industry, additives for textiles, and also as a material for biomedicine.

Development of a Biocompatible PLGA Polymers Capable to Release Thrombolytic Enzyme Prourokinase.

The novelty of the work lies in the creation and study of the physical and biological properties of biodegradable polymer coatings for stents based on poly(lactic-co-glycolic acid) (PLGA). Polymer coatings are capable of prolonged and directed release of molecules with a high molecular weight, in particular, protein molecules of prourokinase (m.w. 54 kDa). A technology has been developed to create coatings having a relative elongation of 40% to 165% and a tensile strength of 25-65 MPa. Coatings are biodegradable; the rate of degradation of the polymer in an isotonic solution varies in the range of 0.05%-1.0% per day. The created coatings are capable of controlled release of the protein of prourokinase, while about 90% of the molecules of prourokinase retain their enzymatic activity. The rate of release of prourokinase can vary from 0.01 to 0.08 mg/day/cm2. Coatings do not have a short-term toxic effect on mammalian cells. The mitotic index of cells growing on coatings is approximately 1.5%. When implanting the developed polymers in animals in the postoperative period, there are no complications. Histological examination did not reveal pathological processes. When implanting individual polymers 60 days after surgery, only traces of PLGA are detected. Thus, a biodegradable composite mechanically resistant polymer capable of prolonged release of the high molecular weight prourokinase enzyme has been developed.

Formation of long-lived reactive species of blood serum proteins induced by low-intensity irradiation of helium-neon laser and their involvement in the generation of reactive oxygen species.

It was demonstrated that low-intensity radiation of helium-neon (He-Ne) laser at 632.8nm, which leads to the transition of oxygen to a singlet state, causes the formation of reactive oxygen species (ROS) - hydrogen peroxide, hydroxyl and superoxide (hydroperoxide) radicals - in aqueous solutions. The oxygen effect - dependence of hydrogen peroxide formation on the concentration of molecular oxygen - was shown, and the participation of singlet oxygen, hydroxyl radicals and superoxide (hydroperoxide) radicals in this process was testified. Laser radiation-induced ROS in solutions of blood serum proteins, bovine serum albumin and bovine gamma-globulin, cause the formation of long-lived reactive protein species (LRPS) with a half-life of about 4h. The generation of LRPS caused by laser irradiation results in prolonged several-hour generation of ROS - hydrogen peroxide, hydroxyl and superoxide radicals. As affected by LRPS, coupled radical reactions lead to conversion of dissolved molecular oxygen to hydrogen peroxide. Irradiation with light sources away from the oxygen absorption band is not attended by formation of ROS and LRPS. A consideration is provided for the possible molecular mechanisms of ROS formation under the influence of He-Ne laser irradiation, the role of proteins in their generation and the biological significance of these processes.

Formation of long-lived reactive species of blood serum proteins by the action of heat.

It has been previously established that heat induces the formation of reactive oxygen species (ROS) in aqueous solutions. In biological systems, ROS cause oxidative damage predominantly to proteins due to their abundance and sensitivity to oxidation. Proteins oxidized by the action of X-rays represent long-lived reactive species, which trigger the secondary generation of ROS (Bruskov et al. (2012) [25]). Here we studied the possibility of formation of long-lived species of the blood serum proteins bovine serum albumin and bovine gamma-globulin in air-saturated solutions under the action of heat. It is shown that heat induces the generation of long-lived protein species, which in turn generate ROS ((1)О2, (·)O2(-), (·)OН, and H2O2). The formation of the long-lived reactive species of BSA and BGG with a half-life of about 4h induced by moderate hyperthermia was revealed using the chemiluminescence of protein solutions. It was found that long-lived reactive species of BSA and BGG cause prolonged generation of H2O2. The results obtained suggest that H2O2 produced by proteins after heating represents a messenger in signaling pathways and produces therapeutic effects in living organisms.