A study was carried out on the spectralluminescent properties of fl uorescein after its reaction with various reactive oxygen and halogen species ( O_2^∙-, H2O2, HOCl, HOBr, HOSCN, N-chloramine, taurine N-chloramine, and taurine N-bromamine) as well as in the myeloperoxidase (MPO)–H2O2–Cl–/Br–/SCN– system. Reaction with only HOBr or with the MPO–H2O2–Br system turns fluorescein into a compound with an absorption maximum at 518 nm. The fluorescence maximum is recorded at 540 nm when excited at 520 nm, corresponding to eosin Y (brominated fluorescein). Conditions with phosphatebuffered saline (PBS) at pH 7.4 containing 137 mM NaCl, 5 mM fluorescein, 15–30 mM NaBr, and 25–50 mM H2O2 were found to be optimal for detecting HOBr in solution. A qualitative method for determining the brominating activity of MPO in vitro has been proposed. This method was used to study the effect of physiological and synthetic inhibitors as well as reactive oxygen and halogen species scavengers on the brominating activity of MPO. Our results indicate that fluorescein holds promise for use in a fluorescent method for detecting the brominating activity of mammalian hemecontaining peroxidases.

It has been shown that when drops fall on a solid surface, the physicochemical properties of water change. After drops fall on a solid surface, water saturated with atmospheric gases luminesces in the blue region of the spectrum. The luminescence intensity decreases exponentially after exposure. The concentration of gases (molecular oxygen and carbon dioxide) in water decreases. In this case, both the size and the number of nano-sized gas bubbles in the water do not change. It has been established that when drops fall on a solid surface in water saturated with atmospheric gases, hydrogen peroxide and hydroxyl radicals are formed. As the fall height increases, the intensity of generation of hydrogen peroxide and hydroxyl radical increases. The formation of hydrogen peroxide is probably associated with two independent mechanisms.

The influence of the solution acidity on the interaction between bovine serum albumin (BSA) molecules and gold nanoparticles in solutions has been investigated by absorbance spectroscopy, fluorescence spectroscopy, and dynamic light scattering (DLS). The influence of pH on the processes of aggregation–disaggregation of gold nanoparticles with BSA and without it and on the denaturation of protein solution is demonstrated. It is also shown that BSA molecules can stabilize gold nanoparticles at acidic pH values of 2.0–4.0. The data obtained can be useful for physiologists studying the influence of nanoparticles on different biological media of the body.

The concentration of hydrogen peroxide and hydroxyl radicals in dependence of the intensity (strength) of water drop impact on a solid surface has been measured. The intensity was varied by changing the fall height from 1 to 4 m and the tilt angle of the surface onto which drops fell. It is shown that the content of hydrogen peroxide and hydroxyl radicals in solution increases after the drop impact on the solid surface. Apparently, the main mechanism of the observed effects is the generation of singlet oxygen and its further reduction.

Protein crystal structure studies are an important tool for drug design. The growth of high-quality crystals suitable for X-ray diffraction is the limiting factor and the bottleneck in obtaining the structural data. Here we report the extraction, purification, and crystallization of the protein GTPase Era from the pathogenic bacterium Staphylococcus aureus . In bacterial cells, GTPase Era acts as a ribosome assembly factor. This enzyme is responsible for the cell growth and division. However, its structure is poorly understood. We obtained crystals of Staphylococcus aureus GTPase Era, which can be used in further structural studies by single-crystal X-ray diffraction analysis.

A technique for synthesizing Tb nanoparticles using laser ablation in various liquid media (MQ water, ethanol, isopropyl alcohol, and isobutanol) is considered with the aim of preparing colloidal solutions of Tb nanoparticles, containing different amounts of oxidized particles. The synthesis of nanoparticles in isobutyl alcohol exhibits the lowest percentage of oxidized particles relative to the total number of particles in the resulting colloid, with a final ratio of oxidized Tb2O3 particles to all particles close to 5%. The influence of oxidized particles on the intensity of physicochemical processes (formation of plasma, shock waves, acoustic signals, and chemical products as a result of dissociation of water molecules) occurring during optical breakdown of colloidal solutions, has been investigated. The general tendency of the influence of oxidized particles consists in an increase in the intensity of the aforementioned characteristics upon laser breakdown with an increase in the Tb2O3 fraction with respect to the total number of particles in the colloid. The observed effect is presumably related to the high aggregability of Tb2O3 particles, while the absorption coefficient of particles is of minor importance.

The study is aimed at elucidating the effect of selenium nanoparticles (SeNPs) on the death of cells in the primary culture of mouse cerebral cortex during oxygen and glucose deprivation (OGD). A primary cell culture of the cerebral cortex containing neurons and astrocytes was subjected to OGD and reoxygenation to simulate cerebral ischemia-like conditions in vitro. To evaluate the neuroprotective effect of SeNPs, cortical astrocytes and neurons were incubated for 24 h with SeNPs, and then subjected to 2-h OGD, followed by 24-h reoxygenation. Vitality tests, fluorescence microscopy, and real-time PCR have shown that incubation of primary cultured neurons and astrocytes with SeNPs at concentrations of 2.5–10 µg/ml under physiological conditions has its own characteristics depending on the type of cells (astrocytes or neurons) and leads to a dose-dependent increase in apoptosis. At low concentration SeNPs (0.5 µg/ml), on the contrary, almost completely suppressed the processes of basic necrosis and apoptosis. Both high (5 µg/ml) and low (0.5 µg/ml) concentrations of SeNPs, added for 24 h to the cells of cerebral cortex, led to an increase in the expression level of genes Bcl-2, Bcl-xL, Socs3, while the expression of Bax was suppressed. Incubation of the cells with 0.5 µg/ml SeNPs led to a decrease in the expression of SelK and SelT. On the contrary, 5 µg/ml SeNPs caused an increase in the expression of SelK, SelN, SelT, SelP. In the ischemic model, after OGD/R, there was a significant death of brain cells by the type of necrosis and apoptosis. OGD/R also led to an increase in mRNA expression of the Bax, SelK, SelN, and SelT genes and suppression of the Bcl-2, Bcl-xL, Socs3, SelP genes. Pre-incubation of cell cultures with 0.5 and 2.5 µg/ml SeNPs led to almost complete inhibition of OGD/R-induced necrosis and greatly reduced apoptosis. Simultaneously with these processes we observed suppression of caspase-3 activation. We hypothesize that the mechanisms of the protective action of SeNPs involve the activation of signaling cascades recruiting nuclear factors Nrf2 and SOCS3/STAT3, as well as the activation of adaptive pathways of ESR signaling of stress arising during OGD and involving selenoproteins SelK and SelT, proteins of the Bcl-2 family ultimately leading to inactivation of caspase-3 and inhibition of apoptosis. Thus, our results demonstrate that SeNPs can act as neuroprotective agents in the treatment of ischemic brain injuries.

Микролинзовая микроскопия – это относительно новое и многообещающее решение для преодоления дифракционного предела в оптической микроскопии. Благодаря использованию сфер из титаната бария возможно получение оптических изображений с разрешением в десятки нанометров. Совмещенная зондовая и микролинзовая микроскопия позволяет осуществлять регистрацию широкого спектра физических и биохимических параметров изучаемых образцов. Существенным достоинством метода является возможность наблюдения биоматерии как с использованием меток и маркеров, а также, что очень существенно, и без них. Это недостижимо для многих других традиционных методов исследования. Использование лазера на парах меди в оптической установке дает возможность исследовать биологические объекты с низкой интенсивностью света.

The fragmentation of colloidal gold solution in pure water by nanosecond Nd:YAG laser radiation is found to be characterized by a threshold value of nanoparticle concentration, below which the colloidal solution remains stable. Above the threshold, large agglomerates of particles are intensively formed in the colloidal solution; this process manifests itself both in the absorption spectra and in the particle-size distribution. It is shown that the limiting concentration depends linearly on the average size of gold nanoparticles. The critical concentration for 7-nm nanoparticles is approximately 2 × 10 11 mL –1 , whereas the corresponding concentration for nanoparticles 17 nm in diameter is an order of magnitude lower: 2 × 10 10 mL –1 .

The effect of a static magnetic field with induction up to 7 T on the concentration of dissolved molecular oxygen, the concentration of hydrogen peroxide, the redox potential, and the electrical conductivity of aqueous solutions with a low concentration of active impurities is studied. It was shown that the concentration of dissolved molecular oxygen in water under the exposure of a magnetic field with induction up to 7 T does not change significantly, while the concentration of hydrogen peroxide increases linearly. It has been established that the pH value of water with field amplification in this induction range tends to decrease within 10%. With an increase in induction, an increase in the redox potential of water is observed. The change in its value is approximately 7 mV/T. It was shown that, with an increase in induction up to 2 T, the electrical resistivity of the water under study drops to about 0.6 MΩ cm, while at higher values of induction it practically does not change.

The concentration dependences of molecular oxygen and hydrogen in aqueous solutions are studied with multiple dilutions and turbulent stirring accompanying the dilution procedure. Deionized water was saturated with molecular hydrogen and molecular oxygen by bubbling. The gas concentration was measured by polarographic methods. Upon reaching a specific number of dilutions, the concentration of impurities in the aqueous solution ceases to depend on the number of dilutions. The ability to observe this effect is determined by the sensitivity of the measurement method. The composition of the aqueous solutions can change under conditions of mechanical action. Mixing stimulates the capture of molecular oxygen from the atmosphere. The effect is more pronounced with turbulent stirring than with laminar.

The influence of iron and copper nanoparticles of different sizes on the physico-chemical processes occurring in colloidal solutions during laser breakdown has been investigated. The water dissociation occurring under the action of breakdown plasma is characterized by generation of hydroxyl radicals. It is found that both the material of nanoparticles and their size affect the processes of hydroxyl radical generation under the action of laser breakdown plasma.

The purpose of this investigation is to create a scientific basis and technology of the production of fluoropolymer photoconversion films for greenhouses to improve the performance of greenhouses in the area of risk farming. The aim basis of photoconversion technology in greenhouses is reduced to photoconversion of UV radiation into blue-violet, and green and yellow light into red light necessary for plants. In other words, when sunlight passes through fluoropolymer photoconversion films, the intensity of the blue-violet and red regions of the spectrum should increase, and the intensity of the UV, green and yellow regions of the spectrum should drop. The article presents the manufacturing technology of fluoropolymer photoconversion films and examples of its use in greenhouses.

This paper examines the effect of electromagnetic waves, with maxima in the green or red regions of the spectrum, on the morphofunctional state of multipotent mesenchymal stromal cells. The illumination regimes used in our experiments did not lead to any substantial heating of the samples; the physical parameters of the lighting were carefully monitored. When the samples were illuminated with a green light, no significant photostimulatory effect was observed. Red light, on the other hand, had an evident photostimulatory effect. It is shown that photostimulation with a red light decreases the enzymatic activities of mitochondrial dehydrogenases and enhances the viability of cells, their proliferative activity, and their ability to form bone tissue. It is also established that red light stimulates cell proliferation, while not activating the genes that increase the risk of the subsequent malignant transformation of cells or their death. This paper discusses the possible role of hydrogen peroxide in the processes examined.

The formation of selenium nanoparticles by laser ablation of its target in pure water and water containing biocompatible surfactants has been experimentally investigated. Experiments were performed using three different techniques: ablation in a stationary liquid, ablation in a continuous-flow cell, and laser fragmentation of the obtained mixture of selenium micro- and nanoparticles. The mass and size distribution functions of selenium nanoparticles were determined by sedimentation analysis. A production rate of 20mg min−1 was implemented for selenium nanoparticles. These nanoparticles (less than 100 nm in diameter) were found to be amorphous.

High-throughput synthesis of selenium (Se) nanoparticles in the form of colloidal solutions was carried out by 1030 nm laser ablation of a bulk Se target in deionized water and isopropyl alcohol by laser pulses of variable pulse widths (0.3–8.6 ps). The extinction coefficient of the colloidal solutions exhibits an overall decreasing trend with the increase of the laser pulse width in deionized water, also demonstrating a local minimum at 2–4 ps. This can be explained by the growing ablation thresholds, related to the bigger impact of thermal processes during the transition from femto- to picosecond temporal stages.

The effect of laser pulsewidth, tuned in the range tau = 0.3-10 ps, on infrared (IR) laser ablation (LA) thresholds of bulk gold, silver and silicon in air and in liquid environments (deionized water, isopropyl alcohol (IPA)) was studied in this work. The influence of laser pulsewidth on the morphology and yield of the ejected nanoparticles (NPs), as well as its impact on the efficiency of NP generation, was studied by UV-vis spectral measurement of the extinction coefficient spectra of NP colloids, fabricated by multi-pass ablation of bulk targets in both solvents at different pulse duration values, by analytical disc centrifuge and by high-resolution scanning electron mi-croscopy. The ablation thresholds are raising with the increase of laser pulsewidth, exhibiting sublinear dependences. The extinction coefficient dependence on tau exhibited a non-monotonous character in case of water medium for all materials, and was gradually descending in case of LA in IPA. Additional MD-TTM (molecular dynamics-two-temperature model) modeling was performed for single-shot laser exposition of bulk Au target in air with tau = 0.3 ps and 4 ps, which allowed distinguishing the main mechanisms of the material removal, the formation of NPs, and the observed crater topography. The performed simulations supported the trend on the ablation threshold increase with the increase of laser pulse duration.