Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials
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Formation of hybrid carriers based on albumin and polyoxometalate for targeted drug delivery

M.O. Tonkushina, I.D. Gagarin, B.T.M.A.. Sharadgah, V.R. Gavrilyuk, K.A. Piunov, A.A. Ostroushko
Ural Federal University

Abstract: The use of proteins to create the targeted drug delivery systems is a promising approach in medicine and has many advantages. The formation of hybrid drug carriers based on proteins and polyoxometalates has a number of additional benefits. Polyoxometalates are able to bind both proteins and molecules of certain drugs to obtain water-soluble products without the use of toxic reagents and organic solvents. The regulation of the experimental conditions allows to control the size of the particles formed in solution. The gradual destruction of polyoxometalate {Mo72Fe30} at blood pH provides a pH-dependent mechanism for drug release from the carrier structure. In our research, we obtained bovine serum albumin associated with coordination complexes {Mo72Fe30}-doxorubicin and {Mo72Fe30}-tetracycline in aqueous solution. A decrease in the rate of the drug release in a phosphate buffer solution at pH 7.4 (blood pH) from the obtained materials compared to systems not containing albumin was observed. The data obtained in this study shed light on the formation patterns of multicomponent supramolecular systems, consisting of polyoxometalates, proteins, and drugs. The results indicate the possibility of creating hybrid carriers for targeted drug delivery based on polyoxometalates and albumin using non-covalent binding.
Keywords: {Mo72Fe30}, doxorubicin, tetracycline, albumin, targeted drug delivery, supramolecular systems

Solid Sr2Ti1-xMnxO4 (x = 0; 0,01; 0,025; 0,05; 0,1) solutions with K2NiF4 structure

T.I. Chupakhina, A.M. Uporova, O.I. Gyrdashova, L.Yu. Buldakova, Y.A. Deeva, I.V. Baklanova, M.Yu. Yanchenko
Institute of Solid State Chemistry of the Ural Branch of RAS

Abstract: Solid of Sr2Ti1-xMnxO4 (x = 0; 0.01; 0.025; 0.05; 0.1) solutions with Raddlesden-Popper structure (An+1BnO3n+1, n = 1, structural type K2NiF4) were obtained by a precursor technology. Formate complexes of the corresponding metals synthesized by an original method were used as precursors. The products of thermolysis of the obtained complexes with an organic ligand are isostructural single-phase samples, which crystallize as agglomerates with an average size of 1 μm. Using energy dispersive X-ray analysis, we established a uniform distribution in the agglomerates of Sr2+, Ti4+ and Mn4+. According to electron spin resonance and optical spectroscopy, manganese in titanium-oxygen polyhedra of Sr2Ti1-xMnxO4 is predominantly in oxidation degree 4+. Increasing the concentration of manganese in the solid solution composition effectively narrows the forbidden band width of strontium titanate from 3.5 eV to 2.5 eV for Sr2Ti0,9Mn0,1O4. The catalytic properties Sr2Ti1-xMnxO4 were analyzed in the oxidation reaction of hydroquinone under irradiation of its aqueous solutions in the ultraviolet and visible spectral ranges. Under the described conditions, all photocatalysts showed a high rate of photooxidation. It was found that the photocatalytic activity of Sr2Ti1-xMnxO4 in 3 consecutive cycles of photooxidation under infrared stimulation exceeds the commercial catalyst Degussa P25 by 4 times.
Keywords: layered wide-gap semiconductors. perovskite, strontium titanate, formate synthesis, photocatalysis, voltammetry. electron microscopy. electron microscopy

Study of the physico-chemical properties of composites obtained by mechanochemical synthesis of nanoscale hydroxyapatite and synthetic zeolites

A.G. Shirokova1, S.A. Bibanaeva1, E.A. Bogdanova1,2, V.M. Skachkov1, O.V. Koryakova3
1 Institute of Solid State Chemistry of the Ural Branch of RAS
2 JSC Giredmet
3 I.Ya. Postovsky Institute of Organic Synthesis of the Ural Branch of RAS

Abstract: In this article, the features of synthesis and physicochemical properties of a composite material based on precipitated hydroxyapatite and synthetic aluminosilicate zeolites are investigated. Using modern methods of analysis, both the obtained composite material and individual components included in its composition are certified. The material was synthesized by mixing with simultaneous grinding in a vibration mill of synthetic zeolite and hydroxyapatite, followed by annealing of the resulting mixture. The characteristics of the initial aluminosilicate zeolites and hydroxyapatite were clarified by infared spectroscopy, their interaction during mechanochemical synthesis and subsequent heat treatment of composites obtained on their basis was assessed. X-ray phase analysis of the initial synthetic zeolites indicates the loss of adsorbed and crystallization water and decomposition to complex aluminosilicate oxides of calcium and sodium during heat treatment at 1000 °C. It was also found that although precipitated hydroxyapatite is structurally unstable and its phase composition depends on temperature, the behavior of the composite material obtained on its basis differs significantly during high-temperature treatment. It was proven that thermal annealing of the composite obtained by mechanosynthesis during heat treatment at 1000 °C does not lead to chemical modification of the hydroxyapatite structure and the formation of a new compound due to the introduction of zeolite. Differential thermal analysis showed an increase in the stability of the composite material relative to its individual components. The morphology of the original materials and those subjected to heat treatment was studied using scanning electron microscopy; a change in morphology during sintering was shown. Along with the study of the thermal stability of the materials, an assessment of the linear shrinkage of the samples and their microhardness was carried out. The conducted comprehensive studies made it possible to recommend composites based on precipitated hydroxyapatite, containing 15 wt.% aluminosilicate zeolites in their composition, as promising materials for further study, possessing the best functional characteristics, including strength.
Keywords: synthetic zeolite, hydroxyapatite, infrared spectroscopy, X-ray phase analysis, differential thermal analysis, composite material

Gas sensitivity of WOx/WS2 nanocomposites at room temperature under ultraviolet irradiation

Z.V. Shomakhov1, S.S. Nalimova2, O.D. Zyryanova2, V.M. Kondratev3,4, Z.Kh. Kalazhokov1, C.D. Bui2, V.A. Moshnikov2
1 Kabardino-Balkarian State University named after H.M. Berbekov
2 Saint Petersburg Electrotechnical University «LETI»
3 Moscow Institute of Physics and Technology
4 Alferov University

Abstract: Currently, semiconductor gas sensors are of interest for various applications, including industry, medicine and environmental monitoring. One of the most important tasks in the sensor technology is to reduce the operating temperature of devices. In this paper, it is proposed to use WOx/WS2 nanostructures obtained by a hydrothermal method to solve this problem. The morphology, structure, and composition of the developed nanostructures were studied using scanning electron microscopy, reflected electron diffraction and X-ray photoelectron spectroscopy. It is shown that the nanostructures are formed by 1D and 2D nanoobjects with an average length of 200 nm and are nanocomposites consisting of tungsten oxide WOx and tungsten disulfide WS2. The study of sensory properties when exposed to isopropanol, ethanol and acetone vapors at room temperature was carried out. A reversible change in resistance is demonstrated when these gases appear in the atmosphere. Additionally, exposure to ultraviolet radiation during the measurement process leads to an increase in the response value and speed of the sensor layers in the case of interaction with isopropanol and ethanol vapors.
Keywords: gas sensors, room temperature, nanostructures, tungsten oxide, tungsten disulfide, nanocomposites

Features of determining the parameters of crystal lattice of ice-like associates of water molecules during hydrate formation

N.A. Shostak
Kuban State Technological University

Abstract: This article describes the features of determining the enthalpy characteristics of the hydrate formation process. Aspects of forming hydrate structures from hydrate-forming agent molecules and water are described. It is shown that the processes of the hydrate formation and dissociation have different natures, which are determined by the interaction of the hydrate former with water in one phase state or another: hydrate former – solid phase of water – ice, hydrate former – liquid phase of water, hydrate former in a critical (pseudocritical) state – liquid phase of water. The dependence of the water crystallization temperature on the pressure and nature of the hydrate former is analyzed. The energy processes occurring during the formation of clusters and unit cells of the crystal lattices of hydrate structures due to the release and absorption of the thermal energy are described. Dependences are proposed for calculating the heat of formation of the crystal lattice from ice-like associates of water molecules. It is shown that the process of restructuring the ice lattice into a hydrate lattice can be both exothermic and endothermic.
Keywords: cluster, crystal lattice, hydrate generator, hydrate formation, hydrate structure, ice-like associates, heat of formation