Vol 13, No 1-2 (2018)

The thermal treatment of detonation nanodiamonds samples has been performed using synchronous thermal analysis in an argon flow at atmospheric pressure and 600, 800, 1000, 1200, and 1500°C with heating rates of 2 and 10°C/min. X-ray phase analysis of the stored samples shows the thermal stability of some nanodiamond particles up to 1500°C. An electron microscopic investigation of the heat-treated samples shows the effect of the heating rate on the properties of the detonation nanodiamonds powder. Phase changes in detonation nanodiamonds begin in the temperature range of 600–700°C, while the graphitization of diamond nanoparticles synthesized by detonation occurs at temperatures above 800°C.

The nanoscale profiling modes of epitaxial GaAs layers are experimentally studied through focused ion beams (FIB). The regularities of the influence of ion current and single FIB exposure time on the geometric characteristics of the forming nanosized profile and the etching rate of the surface of GaAs epitaxial layers are determined. It is established that, within the range of FIB modes used, the rate of normal etching of GaAs(001) is on average an order of magnitude lower than the rate of lateral etching. It is shown that the FIB formation of structures with sizes of up to 100 nm atop the GaAs epitaxial layers necessitates the use of ion currents of up to 10² pA and single exposure times at a point from 10 to 100 μs. The results of the present work can be used in the development of technological processes for manufacturing promising elements of nanoelectronics and nanophotonics based on a combination of the FIB method and various types of growth methods.

A method for measuring low concentrations (up to 0.001 mg/mL) of TiO₂ nanoparticles in aerosols using an optical dielectric microcavity is proposed. The method is based on measuring the change in the microcavity Q factor due to the adsorption of particles on its surface. The results of experimental studies of aerosol samples containing TiO₂ nanoparticles with a diameter of 40 nm with different concentrations are presented. The method for calibrating the measurement channel is developed. The basic requirements for the optical dielectric microcavity as a primary measuring transducer are formulated. The influence of the opticalmode volume on the measurement error is estimated.

A radiotracer technique is developed using titanium dioxide nanoparticles labeled by fast protons with the acquisition of a ⁴⁸V radioactive isotope, and the biokinetics of these brookite nanoparticles in the organisms of laboratory rats within the one-time intragastrical injection are studied. The main result of this work is the detection of titanium dioxide in the colon even within 5 days after injecting the slurry in an amount of 0.4% from the total exposition dose, which evidences the accumulation of titanium dioxide nanoparticles in the organ. This means that macro- and nano-fractions of titanium dioxide particles can be potentially dangerous for the colon, exerting a toxic and carcinogenic influence on its epithelial cells. Moreover, some traces of titanium dioxide nanoparticles are found to penetrate into the blood and liver. However, 98% of titanium dioxide is eliminated from the organism with feces within 5 days after injection. Neither kidneys nor brain exhibit the presence of titanium dioxide residues. This effect is due to the agglomeration of titanium dioxide nanoparticles, which is already significant and prompt in the solution for injection. At the same time, despite the ability of agglomerates to dissociate in the acidic medium of the stomach, only a few amounts of titanium dioxide pass into a nanometric form, which then penetrates through the colon into blood.

To investigate the patterns of uptake of PLGA-PEG nanoparticles by human cancer cells, FITC-labeled polymer nanoparticles (FPN) are prepared and their properties are characterized. The amount of internalized FPN is measured by flow cytometry after quenching the fluorescence of the membrane-bound nanoparticles with Trypan Blue. The total uptake of the FPN by COLO 320 HSR and SW837 human cancer cells is shown to be proportional to the nanoparticle concentration and incubation time over a period of 24 h. The highest intracellular accumulation of the FPN is observed at 1 or 4 h, depending on the cell type. The translocation of the biodegradable and biocompatible polymer nanoparticles into the cancer cells that we observe may be the mechanism for enhancing the efficiency of the anticancer drug by loading it into these nanocarriers owing to a prolonged increase in the intracellular concentration of the therapeutic agent and the facilitation of its interaction with intracellular targets.

The nanoscale profiling modes of an (100) n-type silicon substrate surface through the local anodic oxidation (LAO) are studied. The influence of relative humidity and pulse voltage at LAO on the geometric parameters of silicon oxide nanostructures (SONs) and shaped profile nanostructures (SPNs) formed within the liquid etching of SONs is elucidated. It is shown that an increase in LAO voltage pulse amplitude from 10 to 20 V causes a gain in the SON height from 0.6 ± 0.2 to 2.0 ± 0.3 nm at a relative humidity of 70 ± 1%. The results can be applied for the design of technological processes in the element-base fabrication of silicon nanoelectronics using scanning probe nanotechnology.