The development of new methods increasing the biological effectiveness of proton therapy (PT) is of high interest in radiation oncology. The use of binary technologies, in which the damaging effect of proton radiation is further enhanced by the selective accumulation of the radiosensitizer in the target tissue, can significantly increase the effectiveness of radiation therapy. To increase the absorbed dose in a tumor target, proton boron capture therapy (PBCT) was proposed based on the reaction of proton capture on the 11B isotope with the formation of three α-particles. This review summarizes data on theoretical and experimental studies on the effectiveness and prospects of proton boron capture therapy.

This work studies the transport properties of solid-state nanopores. Nanopores with a diameter of 35-40 nm formed in a thin "free-standing" silicon nitride membrane of 300 nm thick. An experimental setup has been developed to study the transport characteristics of single nanopores. Based on the results of electrical measurements, the pore conductivity was calculated for concentrations of KCl electrolyte in the range of 10-4-1M. An increase of nanopore conductivity was observed with an increase of the electrolyte concentration above 10-2 M. This dependence can be explained by the electrical double layer overlapping that leads to appearance of a charged region inside the nanopore.

The potential of standard methods of radiation therapy is limited by the dose that can be safely delivered to the tumor, which could be too low for radical treatment. The dose efficiency can be increased by using radiosensitizers. In this study, we evaluated the sensitizing potential of biocompatible iron oxide nanoparticles coated with a dextran shell in A172 and Gl-Tr glioblastoma cells in vitro. The cells preincubated with nanoparticles for 24 h were exposed to ionizing radiation (X-ray, gamma, or proton) at doses of 0.5–6 Gy, and their viability was assessed by the Resazurin assay and by staining of the surviving cells with crystal violet. A statistically significant effect of radiosensitization by nanoparticles was observed in both cell lines when cells were exposed to 35 keV X-rays. A weak radiosensitizing effect was found only in the Gl-Tr line for the 1.2 MeV gamma irradiation and there was no radiosensitizing effect in both lines for the 200 MeV proton irradiation at the Bragg peak. A slight (ca. 10%) increase in the formation of additional reactive oxygen species after X-ray irradiation was found when nanoparticles were present. These results suggest that the nanoparticles absorbed by glioma cells can produce a significant radiosensitizing effect, probably due to the action of secondary electrons generated by the magnetite core, whereas the dextran shell of the nanoparticles used in these experiments appears to be rather stable under radiation exposure.

Proton boron capture therapy (PBCT) has emerged from particle acceleration research for enhancing the biological effectiveness of proton therapy. The mechanism responsible for the dose increase was supposed to be related to proton-boron fusion reactions ( 11 B + p → 3 α + 8.7 MeV). There has been some experimental evidence that the biological efficiency of protons is significantly higher for boron-11-containing prostate or breast cancer cells. The aim of this study was to evaluate the sensitizing potential of sodium borocaptate (BSH) under proton irradiation at the Bragg peak of cultured glioma cells. To address this problem, cells of two glioma lines were preincubated with 80 or 160 ppm boron-11, irradiated both at the middle of 200 MeV beam Spread-Out Bragg Peak (SOBP) and at the distal end of the 89.7 MeV beam SOBP and assessed for the viability, as well as their ability to form colonies. Our results clearly show that BSH provides for only a slight, if any, enhancement of the effect of proton radiation on the glioma cells in vitro. In addition, we repeated the experiments using the Du145 prostate cancer cell line, for which an increase in the biological efficiency of proton irradiation in the presence of sodium borocaptate was demonstrated previously. The data presented add new argument against the efficiency of proton boron capture therapy when based solely on direct dose-enhancement effect by the proton capture nuclear reaction, underlining the need to investigate the indirect effects of the secondary alpha irradiation depending on the state and treatment conditions of the irradiated tissue.

The paper reports on experiments on the observation of scanning tunnel mi-croscope (STM)-induced light emission (STM-LE) from bare silicon surfaces and modified with STM lithography. We produced nanoscale hillocks (nanokhobs) on a crystalline Si sub-strate, which can be considered as nanoantennas enhancing STM-LE effect. Our experiments show that the nanoknobes formed on the surface of the original substrate did not provide the achievement of the goal. However, in-situ deposition of a 10 nm thick additional layer of un-doped Si resulted in the increase of STM-LE quantum efficiency by an order of magnitude in comparison with original substrate. This effect paves the way for the fabrication of nanoscale electrically-driven light sources required for hybrid optoelectronic chips.

Biomineralization is a universal process that has implications in a variety of areas, from civil engineering to medicine. While crystallization of amorphous CaCO3 formed in vitro is known to precede the vaterite-calcite/aragonite pathway, this process could be significantly altered when induced by bacteria, particularly within the extracellular matrix (ECM) of microbial cells. We used a combination of SEM, SANS, SAXS, FTIR and XRD methods to investigate the structure of CaCO3 formed during biomineralization induced by planktonic Bacillus cereus. Formation of precipitates in the presence of CaCl2 and urea was observed both during bacterial growth and in the medium devoid of bacteria and ECM (cell-free system). The pathway for polymorphic transformations of CaCO3 from the amorphous phase to vaterite and further to calcite was confirmed for the bacterium-induced mineralization and did not depend on the concentration of Ca2+ and urea. The structure of CaCO3 sediments differed when formed in cell-free and bacterial systems and varied depending on time and the medium composition. The rate of precipitation was accelerated in the presence of DNA, which had little effect on the solid phase structure in the cell-free system, while strongly affecting the structure and polymorphic composition of the precipitates in bacterial culture.

To date, the mechanisms of biomineralization induced by bacterial cells in the context of biofilm formation remain the subject of intensive studies. In this study, we analyzed the influence of the medium components on the induction of CaCO 3 precipitation by the Bacillus cereus cells and composition of the extracellular matrix (ECM) formed in the submerged culture. While the accumulation of extracellular polysaccharides and amyloids appeared to be independent of the presence of calcium and urea during the growth, the accumulation of extracellular DNA (eDNA), as well as precipitation of calcium carbonate, required the presence of both ingredients in the medium. Removal of eDNA, which was sensitive to treatment by DNase, did not affect other matrix components but resulted in disruption of cell network formation and a sixfold decrease in the precipitate yield. An experiment with a cell-free system confirmed the acceleration of mineral formation after the addition of exogenous salmon sperm DNA. The observed pathway for the formation of CaCO 3 minerals in B. cereus planktonic culture included a production of exopolysaccharides and negatively charged eDNA lattice promoting local Ca 2+ supersaturation, which, together with an increase in the concentration of carbonate ions due to pH rise, resulted in the formation of an insoluble precipitate of calcium carbonate. Precipitation of amorphous CaCO 3 on eDNA matrix was followed by crystal formation via the ACC-vaterite-calcite/aragonite pathway and further formation of larger mineral aggregates in complex with extracellular polymeric substances. Taken together, our data showed that DNA in extracellular matrix is an essential factor for triggering the biomineralization in B. cereus planktonic culture.

We developed a technique for the fabrication of single nanopores with gold bow -tie nanoantennas in a free-standing SiN membrane of arbitrary thickness. Single pores with a diameter of 30-50 nm and a length of 300 nm were fabricated. Studies of ion transport in solid-state nanopores upon optical radiation showed that the enhancement of an electromag-netic field by plasmon structures near nanopores leads to the increase in nanochannel conduc-tivity.

A technique for synthesizing nanostructures by current lithography in a scanning tunneling microscope (STM lithography) in layered Au/Si structures has been developed. An experimental dependence of the geometric dimensions of the created nanostructures on the time of current STM lithography has been obtained. A theoretical model for the growth of nanostructures is proposed, which explains the nonlinear dependence of the radius of the obtained nanostructures on time with saturation in the region of large radii. Keywords: Au/Si nanostructures, STM lithography, growth rate, modeling.

A technique for synthesizing nanostructures by current lithography in a scanning tunneling microscope (STM lithography) in layered Au/Si structures has been developed. An experimental dependence of the geometric dimensions of the created nanostructures on the time of current STM lithography has been obtained. A theoretical model for the growth of nanostructures is proposed, which explains the nonlinear dependence of the radius of the obtained nanostructures on time with saturation in the region of large radii. Keywords: Au/Si nanostructures, STM lithography, growth rate, modeling.

The review describes the application of small-angle scattering (SAS) of neutrons and complementary methods to study the structures of biomacromolecules. Here we cover SAS techniques, such as the contrast variation, the neutron spin-echo, and the solution of direct and inverse problems of three-dimensional reconstruction of the structures of macromolecules from SAS spectra by means of molecular modeling. A special section is devoted to specific objects of research, such as supramolecular complexes, influenza virus nucleoprotein, and chromatin.

Anna A. Oleshkevich, Specific features of change in enzymate activity in

A method has been developed to obtain composite membranes based on porous glass. Inside the nanopores of glass membranes, gold nanoparticles are formed that have plasmon resonance. The average size of the obtained particles was 20–25 nm. The obtained membranes are promising for the development of new-generation sensors and investigation of the impact of plasmon resonance effect on ion transport inside nanopores.

Within the framework of this study, a method was developed for obtaining composite membranes based on porous glass. Gold nanoparticles with plasmon resonance were formed inside the nanopores of glass membranes. The average particle size of the obtained particles was 20-25 nm. The obtained membranes are promising for the development of new generation sensors and for studying the effect of plasmon resonance on the transport of ions inside nanopores.

Fucoidans, sulfated polysaccharides found in cell walls of brown algae, are considered as a promising antimicrobial component for various applications in medicine and the food industry. In this study, we compare the antibacterial properties of two fractions of fucoidan from the brown algae Fucus vesiculosus gathered in the littoral of the Barents Sea and sampled at different stages of purification. The crude fraction of fucoidan was isolated from algae by extraction with aqueous ethanol and sonication. The purified fraction was obtained by additional treatment of the crude fraction with a solution of calcium chloride. The structural features of both fractions were characterized in detail and their antibacterial effects against several Gram-positive and Gram-negative bacteria were compared by photometry, acridine orange staining assay, and atomic force microscopy. Fucoidan inhibited growth in all of the above microorganisms, showing a bacteriostatic effect with minimum inhibitory concentrations (MIC) in the range between 4 and 6 mg/mL, with E. coli being the most sensitive to both fractions. Changes in the chemical composition after treatment of the crude fraction with a solution of calcium chloride led to a decrease in the content of sulfates and uronic acids and diminished antibacterial activity.

Proton therapy is used today to treat many cancers and is particularly appropriate in situations where surgery options are limited, and conventional radiotherapy presents unacceptable risks to patients. A few years ago, it was suggested that an increase of up to a factor of two of the doses at the proton Bragg peak could be achieved if boron is accumulated in the tumor tissues. The mechanism responsible for a higher dose was suggested to be related to proton-boron fusion reactions, leading to the production of high Linear Energy Transfer (LET) α-particles. Nowadays there are single works showing the effectiveness of proton beam irradiation boron-11-containing cancer cells. A limited number of the studies devoted to the application of 11B(p,3a) nuclear reaction in proton therapy and lack of consistency in their results do not allow to judge about the prospects of the boron-containing drugs utilization in proton therapy to increase its antitumor efficacy. In this work, we experimentally test the possibility to enhance proton biological effectiveness in boron-11-containing cancer cells in vitro. Human glioblastoma cells were preincubated with boron compound (Na2B4O7, sodium tetraborate) and irradiated with increasing doses 2-8 Gy at the proton Bragg peak. To test whether the physical nuclear reaction 11B(p,3a) results in an enhancement of the cancer cell death by high-energy proton beam irradiation, cell lines were also irradiated with graded doses 2-8 Gy using γ-ray source. The ability of boron compound to activate the cancer cell death with protons at the Bragg peak irradiation was shown in vitro. At the same time, weaker similar effect was determined for gamma-irradiation that may indicate not only the physical nature of influence boron at irradiated cancer cell viability but a specific biological effect. The data suggest that the combined effect of proton therapy with 11B on glioma cells increases their sensitivity to proton irradiation with low toxicity of the boron compound for cells of normal morphology.

Various methods of synthesis of CuInSe2 remain relevant because it is one of the most effective materials for solar energy. An effective method for the preparation of the CuInSe2 nanodispersed selenium precursor for microwave synthesis is considered. Colloidal selenium solutions were obtained using laser ablation in various liquid media: water, ethanol, triethylene glycol, polyethylene glycol–400 (PEG-400), and a 1% solution of PEG-1500 in PEG-400. The optical properties of the obtained colloidal selenium solutions were studied. Electron microscopy of selenium particles was conducted. Trends of ablation rate change and physicochemical properties of dispersed selenium particles in the variety of liquid media listed above are discussed. The possibility of synthesizing CuInSe2 using the obtained precursor was verified.