Yury N. Osin

Cellular imaging by green luminescence of Tb(III)-doped aminomodified silica nanoparticles

The work introduces Tb(III)-centered luminescence of amino-modified silica nanoparticles doped with Tb(III) complexes for cellular imaging. For these purposes water-in-oil procedure was optimized for synthesis of 20 and 35nm luminescent nanoparticles with amino-groups embedded on the surface. The obtained results indicate an impact of the nanoparticle size in decoration, aggregation behavior and luminescent properties of the nanoparticles in protein-based buffer solutions. Formation of a protein-based corona on the nanoparticles surface was revealed through the effect of the nanoparticles on helical superstructure of BSA. This effect is evident from CD spectral data, while no any size impact on the adsorption of BSA onto aminomodified silica surface was observed. Cellular uptake of the nanoparticles studied by confocal and TEM microscopy methods indicates greater cellular uptake for the smaller nanoparticles. Cytotoxicity of the nanoparticles was found to agree well with their cellular uptake behavior, which in turn was found to be greater for the smaller nanoparticles.

Physical Background for Luminescence Thermometry Sensors Based on Pr3

The main goal of this study was creating multifunctional nanoparticles based on rare-earth doped LaF3 nanocrystals, which can be used as fluorescence thermal sensors operating over the 80–320 K temperature range including physiological temperature range (10–50°C). The Pr3

Coprecipitation Method of Synthesis, Characterization, and Cytotoxicity of Pr3+:LaF3 (CPr = 3, 7, 12, 20, 30%) Nanoparticles

The Pr3+:LaF3 (CPr = 3, 7, 12, 20, 30%) nanoparticles were characterized by means of high-resolution transmission electron microscopy, X-ray diffraction, optical spectroscopy, energy dispersive X-ray spectroscopy, dynamic light scattering, and MTT assay. It was revealed that the average diameter of all the NPs is around 14–18 nm. The hydrodynamic radius of the Pr3+:LaF3 (CPr = 7%) nanoparticles strongly depends on the medium. It was revealed that hydrodynamic radii of the Pr3+:LaF3 (CPr = 7%) nanoparticles in water, DMEM, and RPMI-1640 biological mediums were 18 ± 5, 41 ± 6, and 186 ± 8 nm, respectively. The Pr3+:LaF3 (CPr = 7%) nanoparticles were nontoxic at micromolar concentrations toward COLO-320 cell line. The lifetime curves were fitted biexponentially, and for the Pr3+:LaF3 (CPr = 7%) NPs, the luminescence lifetimes of Pr3+ ions were 480 ± 2 and 53 ± 5 nanosec.

The Percolation Phenomenon and Fractal Dimension of Natural Silicates

Many physical effects, such as dc conductivity and percolation, depend on the morphology of the silicate structure and its relationship to adsorbed water. These effects play an important role in numerous technological applications, in geology, oil-extracting industry, and other practical fields. In this study, all the samples: natural montmorillonite, kaolinite, and сlinoptilolite with different exchangeable cations in their structures, – were stored in ambient air humidity. The investigation was carried by using two separate techniques, namely Dielectric Spectroscopy and a fractal analysis of electron micrographs. The aims of this work were to analyze the complex relaxation behavior of the relaxation process in temperature range –70°C ÷ +70°C and to determine the fractal dimensions of silicates from the dielectric response at percolation. Dielectric measurements in the frequency range of 1 Hz ÷ 1 MHz were performed using a BDS 80 Dielectric Spectrometer based on an Alpha Impedance Analyzer (Novocontrol). The micrographs were analyzed using a special Matlab based program. The analysis of aspects of the dielectric relaxation spectra related to percolation was used for the determination of the numerical characteristics of geometric heterogeneity of natural silicates. The percolation temperatures of the studied samples were determined. The percolation phenomenon in the silicates is related to the transfer of the electric excitation within the developed network of open pores due to the migration of protons and ions along the surface of connected pores on the outer surfaces of the granules. The analysis of these processes allows one to extract the fractal dimensions associated with the migration of charge carriers within the porous medium. Fractal dimensions of the silicates calculated in two ways: from dielectric spectroscopy study and from fractal analysis of the micrographs, – are in good agreement with each other. It was demonstrated that conventional method of the spatial fractal dimension determination using fractal analysis of electron micrographs leads to overestimation in the case of spatial fractal bounded by a surface fractal. The dielectric spectroscopy method is free from such overestimation.