Physical and chemical aspects of the study of clusters, nanostructures and nanomaterials
Founded at 2009


PhC-2022


Development of a manual extruder for liposome homogenization

Abstract: Medications using liposomes are of great interest in pharmaceuticals. They increase the therapeutic index of the drug by enclosing the medicinal substance inside a biocompatible lipid envelope, which releases the solution only in the required area. Such drugs have already shown their effectiveness in the treatment of diseases related to oncology, dermatology, neurology, surgery, etc. To use liposomes for these purposes, it is necessary that their size be in the range from 50 to 200 nm. There are several ways to create vesicles of this size, but mostly they use either ultrasound exposure to a liposome solution or extrusion. The extrusion method is a method that allows to obtain the most homogeneous solution from liposomal particles. For extrusion, a special device – an extruder is required. It is a system that passes a liposomal solution under pressure through a filter with a certain pore size. In this paper, the process of liposome extrusion, types of liposomal extruders are considered and their pros and cons are evaluated, a model of a manual extruder capable of homogenizing up to 20 ml of solution was also developed. Different materials were considered and used for the construction of this device. The inspection of the extruder showed its operability and showed the advantages of using extrusion compared to the ultrasound exposure method.

Study of calcium oxalate nanocrystalline structures and kinetics of calcium oxalate deposition

Abstract: Calcium oxalates, represented by wavellite CaC2O4·H2O and weddellite CaC2O4·2H2O (the most stable forms), are the main components of stones in the genitourinary system, and are also part of dental, gallstones, and other mineral deposits. It is known that modern approaches to the study and modeling of crystallization processes make it possible to analyze the influence of a number of factors (exogenous and endogenous) arising at various levels of organization: from atoms and molecules to macroscopic processes occurring in industrial devices. The process of crystallization, taking into account the variety of acting factors and forms of crystal structures, consists of two main stages: formation of a solid phase nucleus and its growth (formation of a solute crystal). In this work, using modern approaches, the physicochemical and kinetic patterns of crystallization of calcium oxalates under conditions close to physiological are determined. The effect of physiological solution components (organic and inorganic) was studied, the staged mechanism of the solid phase formation was established, and the kinetic parameters of the growth stage were calculated (lgk = 33.1). The inhibitory effect of inorganic additives (Mg2+, Cl), amino acids (glycine, glutamine, aspartic) and the accelerating effect of hydroxyapatite crystals, seed in the form of calcium oxalate and urea crystals on the crystallization process were revealed.

Crystallization of nanocrystalline hydroxylapatite in the presence of albumin

Abstract: Due to the development of modern biotechnologies and nanomaterials, in the near future it is expected to achieve a new, higher quality level in the design and improvement of the characteristics of intraosseous implants used in orthopedics. Calcium phosphate was synthesized from a model solution of synovia in the presence of albumin. Synthetic solid phases were studied using X-ray phase analysis, IR-Fourier spectroscopy, scanning electron microscopy, and energy dispersive analysis. The supernatant was examined for the presence of ions and to calculate the ratio. It was found that albumin does not affect the phase composition of the samples: the sediments are single-phase and consist of B-type hydroxylapatite carbonate. The study of the structure and morphology of the solid phase showed that the presence of proteins leads to formation of composites with a lower specific surface area compared to hydroxylapatite carbonate. The largest crystallite size is observed for the hydroxylapatite carbonate /albumin sample with the albumin concentration of 12 g/l. With the help of the thermal analysis of the fixation of thermal effects five stages of the thermal transformation were identified in the temperature range of 25-1000 °C; for all samples, the main stages are II–III, associated with the thermal destruction of organic additives. The study of the bioactivity of the samples showed that in the case of active resorption, the most soluble were the samples synthesized in the presence of albumin (>7 g/l), and in the case of passive resorption, the hydroxylapatite carbonate/albumin samples (5 and 7 g/l).

Electrical response of lithium niobate and lithium tantalate thin films to modulated thermal radiation

Abstract: In this work, we studied the pyroelectric activity of thin polycrystalline lithium niobate films fabricated by radio frequency magnetron sputtering and laser ablation, and thin polycrystalline lithium tantalate films fabricated by radio frequency magnetron sputtering. Using the dynamic method of studying the pyroelectric effect, it was found that all samples have self-polarization that occurs during the post-growth thermal annealing of the structure. An estimate of the pyroelectric coefficient showed that the values of the pyroelectric coefficient of lithium niobate and lithium tantalate thin films are several times lower than the values of the pyroelectric coefficient for bulk crystals of the corresponding materials. This may be due to the fact that the polarization vector of some grains lies in the film plane, as well as to the traps existing in the film volume and at the film/substrate interface, on which charge carriers recombine and do not participate in the generation of the pyroelectric current.