Персона:
Шкирин, Алексей Владимирович

Организационные подразделения

Организационная единица

Институт лазерных и плазменных технологий

Стратегическая цель Института ЛаПлаз – стать ведущей научной школой и ядром развития инноваций по лазерным, плазменным, радиационным и ускорительным технологиям, с уникальными образовательными программами, востребованными на российском и мировом рынке образовательных услуг.

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Шкирин

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Алексей Владимирович

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Теперь показываю 1 - 10 из 28

Только метаданные
Kinetics of the Light-Oxygen Effect in Aqueous Solutions of Proteins
(2020) Suyazov, N. V.; Ivanov, V. E.; Gudkov, S. V.; Shkirin, A. V.; Chirikov, S. N.; Шкирин, Алексей Владимирович; Чириков, Сергей Николаевич
© 2020, Allerton Press, Inc.Abstract: Molecular mechanisms of the participation of proteins in reactive oxygen species (ROS) generation resulting from the singlet-oxygen effect upon laser exposure in solutions of various proteins are considered. The kinetic equations describing ROS generation are derived, and their approximate general solution is found in the analytical form. By comparison of the found kinetic dependences with experimental data, orders and rate constants of corresponding chemical reactions are determined. An analysis of the results makes it possible to consider that fundamental mechanisms of ROS formation reactions in solutions of various proteins are identical.
Только метаданные
Biodegradable stent coatings on the basis of PLGA polymers of different molecular mass, sustaining a steady release of the thrombolityc enzyme streptokinase
(2020) Sevostyanov, M. A.; Baikin, A. S.; Sergienko, K. V.; Shatova, L. A.; Shkirin, A. V.; Шкирин, Алексей Владимирович
© 2020 Elsevier B.V.The work describes synthesis of novel biodegradable polymer membranes based on poly(lactic-co-glycolic acid) (PLGA), as well as testing of their physicochemical properties. The membranes synthesized have been shown to possess the necessary mechanical properties and to be capable of sustained and directed release of large biomacromolecules, in particular, the molecules of streptokinase (m.w. 47 kDa). Streptokinase is a pharmaceutical drug with a high thrombolytic activity. The technology developed allows one to synthesize membranes with a relative elongation of 25 to 165% and a tensile strength of 20 to 55 MPa. The membranes are biodegradable; the rate of the polymer degradation in an isotonic solution is 0.5–1.0% per day. The streptokinase-infused membranes were demonstrated to release the protein in a controlled manner, with ~90% of the enzyme molecules retaining their activity. The rate of streptokinase release from the membranes was in the range of 0.01–0.07 mg/cm2 per day. The polymer films did not exert any short-term toxic effects on the cells cultivated de novo on the film surface. The mitotic index of cells growing on the surface of polymer films was ~1.5%. The implantation of the synthesized polymers in animals – in the form of film samples and as a component of the coating of nitinol stents – had no complications during the postoperative period. The histological examination of the implant-surrounding tissues did not reveal any abnormalities. When the polymers were implanted as separate film samples, only traces of PGLA were detected in the tissues two months after the surgery. The implantation of stents coated with the streptokinase-infused polymers resulted in the formation of a mature and thick connective-tissue capsule. Thus, novel biodegradable PLGA-based polymer membranes have been synthesized and tested in this work – membranes which possess the necessary mechanical properties and are capable of a sustained and directional release of high-molecular biological compounds.
Только метаданные
Characteristics of Protein Aggregation and Flotation in Water and Alcohol-Water Mixture
(2020) Bunkin, N. F.; Penkov, N. V.; Chaikov, L. L.; Ignatiev, P. S.; Shkirin, A. V.; Chirikov, S. N.; Шкирин, Алексей Владимирович; Чириков, Сергей Николаевич
© 2020, Allerton Press, Inc.Abstract: Investigation of immunoglobulin (IgG) solutions with the concentration of 0.125 mg/mL shows that monomer IgG macromolecules ~10 nm in size form aggregates as large as ~300 nm in water and ~900 nm in the 36.7 vol % ethanol–water mixture (EWM). Shaking results in formation of floating-up bubbles in the solutions of both types. However, efficiency of immunoglobulin bubble flotation in water and EWM is substantially different. This difference can be caused by simultaneous action of two mechanisms for attachment of IgG particles (macromolecules or aggregates) to bubbles in aqueous solutions: direct attraction of IgG particles to the charged surface of a bubble and existence of ion-stabilized nanobubbles with a radius of ~100 nm capable of making up compound particles like nanobubbles–IgG macromolecules/IgG aggregates, which in turn serve as “spatial agents” for flotation of IgG particles on larger bubbles. In the EWM, attachment of IgG particles to floating-up bubbles is ineffective because of weak surface charge of macro- and microbubbles and absence of nanobubbles.
Только метаданные
Rheological Effects of Polymer Membrane Swelling in Water and Their Dependence on Isotopic Composition
(2020) Bunkin, N. F.; Kozlov, V. A.; Kiryanova, M. S.; Pavlenko, A. A.; Shkirin, A. V.; Шкирин, Алексей Владимирович
© 2020, Allerton Press, Inc.Abstract: It is shown that swelling of an initially hydrophobic Nafion plate in a cell of limited volume follows a different way in ordinary water (deuterium concentration 157 ppm) and in deuterium-depleted water (deuterium concentration 1 ppm). Small variations in the deuterium concentration in water turn out to lead to a considerable difference in swelling dynamics of the polymer membrane. For a Nafion plate 175 µm thick, this effect is most distinct at the distance between the windows L = 200 µm.
Только метаданные
Study of the physicochemical and biological properties of the new promising Ti–20Nb–13Ta–5Zr alloy for biomedical applications
(2020) Konushkin, S. V.; Sergiyenko, K. V.; Nasakina, E. O.; Leontyev, V. G.; Shikirin, A. V.; Шкирин, Алексей Владимирович
© 2020 Elsevier B.V.A technology for producing a new homogeneous Ti–20Nb–13Ta–5Zr alloy has been developed. It is shown that the alloy is single-phase with a β-Ti type crystal lattice. The alloy has the required mechanical properties (tensile strength of about 745 MPa). On the surface of plates and wire made of alloy, a relief of micro- and nanoscale is observed. In terms of the ability to generate reactive oxygen species and long-lived reactive protein species, the Ti–20Nb–13Ta–5Zr alloy is more preferable than nitinol. It was established that cell cultures growing on plates or wire made of Ti–20Nb–13Ta–5Zr alloy had a significant mitotic index (2%). The number of viable cells was at least 95–96% of the overall cell count. According to the results of implantation of the alloy in the form of plates or wire ring to animals, it can be concluded that the alloy is biocompatible. The morphology of the surface of the samples did not change after biological experiments. It can be assumed that the alloy Ti–20Nb–13Ta–5Zr is a material potentially suitable for medical applications.
Только метаданные
General Features of Size Distributions and Internal Structure of Particles in Aqueous Nanosuspensions
(2020) Kirichenko, M. N.; Chaikov, L. L.; Krasovskii, V. I.; Bulychev, N. A.; Shkirin, A. V.; Chirikov, S. N.; Шкирин, Алексей Владимирович; Чириков, Сергей Николаевич
© 2020, Allerton Press, Inc.Abstract: Size distributions of nanoparticle aggregates in water suspensions and emulsions are measured for a number of metal oxides, silicon carbide, nanodiamonds, and lubricating cutting fluid. It is found that all these distributions have a similar bimodal form. Estimations of the average distance between the nanoparticles in the aggregates based on various experimental results and theoretical models agree with one another.
Только метаданные
Mesodroplet Heterogeneity of Low-Concentration Aqueous Solutions of Polar Organic Compounds
(2019) Bunkin, N. F.; Lyakhov, G. A.; Ignatiev, P. S.; Kobelev, A. V.; Shkirin, A. V.; Шкирин, Алексей Владимирович
It is found experimentally that a mesoscopic droplet phase is formed in low-concentration aqueous solutions of various polar organic compounds, which are considered in the chemical literature as infinitely soluble in water. The content of dissolved organic molecules in droplets is much higher than in the ambient solution. The droplet size increases with temperature. Theory can explain the mesodroplet formation by the phase separation of a binary mixture affected by the dichotomous noise of twinkling hydrogen bonds between molecules of organic compound and water. The Snyder polarity index, which is used by chemists as a miscibility criterion for molecular compounds, depends in the model on the dipole moments of mixed molecules and the energy and number of hydrogen bonds. With this refinement, it can be used as an estimation criterion for the existence and intensity (i.e., the number of droplets per unit volume of organic aqueous solution) of mesodroplet separation.
Только метаданные
The Physical Nature of Mesoscopic Inhomogeneities in Highly Diluted Aqueous Suspensions of Protein Particles
(2019) Bunkin, N. F.; Penkov, N. V.; Ignatiev, P. S.; Kozlov, V. A.; Shkirin, A. V.; Chirikov, S. N.; Шкирин, Алексей Владимирович; Чириков, Сергей Николаевич
The dispersed composition of water samples prepared by the multiple-dilution technique has been investigated opto-physically using two laser diagnostics methods: dynamic light scattering and laser phase microscopy. We studied suspensions of antibodies (Ab) to the human interferon-gamma (IFN) in water with an initial concentration of 0.125 mg ml(-1) (5x10(14) mol cm(-3)), which were subjected to 12 successive 100-multiple volume dilutions (C12) in water. Individual antibodies and particles of about 300 nm in size, which can be considered as aggregates of individual antibodies, have been found in the initial suspensions. It turned out that some mesoparticles with a concentration on the order of 10(3) cm(-3) exist also in suspensions subjected to C12 dilution. These particles have a refractive index close to typical values of protein refractive indices. A possible explanation of the origin of particles with sizes on the order of several hundreds of nanometers, revealed in highly diluted suspensions, is proposed. On the one hand, some of these particles may be aggregates of antibodies from the initial suspension, which remained (due to the flotation effect) in the bulk of the liquid after dilutions. On the other hand, the appearance of solid contaminant particles at the same mesoscopic scale (i.e., on the order of several hundreds of nanometers) cannot be excluded in the dilution process.
Только метаданные
Effect of Gas Type and Its Pressure on Nanobubble Generation
(2021) Bunkin, N. F.; Penkov, N. V.; Goltayev, M. V.; Ignatiev, P. S.; Shkirin, A. V.; Шкирин, Алексей Владимирович
© Copyright © 2021 Bunkin, Shkirin, Penkov, Goltayev, Ignatiev, Gudkov and Izmailov.The dependence of the volume number density of ion-stabilized gas nanobubbles (bubstons) on the type of gas and the pressure created by this gas in deionized water and saline solution has been investigated. The range of external pressures from the saturated water vapor (17 Torr) to 5 atm was studied. It turned out that the growth rate of the volume number density of bubstons is controlled by the magnitude of the molecular polarizability of dissolved gases. The highest densities of bubstons were obtained for gases whose molecules have a dipole moment. At fixed external pressure and the polarizability of gas molecules, the addition of external ions leads to a sharp increase in the content of bubstons.
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Modeling the Kinetics of the Singlet Oxygen Effect in Aqueous Solutions of Proteins Exposed to Thermal and Laser Radiation
(2022) Shkirin, A. V.; Chirikov, S. N.; Suyazov, N. V.; Reut, V. E.; Grigorieva, D. V.; Gorudko, I. V.; Bruskov, V. I.; Gudkov, S. V.; Шкирин, Алексей Владимирович; Чириков, Сергей Николаевич
A system of kinetic equations describing the changes in the concentration of reactive oxygen species (ROS) in aqueous solutions of proteins was obtained from the analysis of chemical reactions involving singlet oxygen. Applying the condition of the stationarity of the intermediate products to the system, we determined the functional dependence of the hydrogen peroxide concentration on the protein concentration under the action of thermal and laser radiation. An approximate analytical solution to the nonlinear system of differential equations that define the ROS concentration dynamics was found. For aqueous solutions of bovine serum albumin (BSA) and bovine gamma globulin (BGG), the orders and rate constants of the reactions describing the ROS conversions were determined by minimizing the sum of squared deviations of the functions found by solving both the static and dynamic problems from experimentally measured dependences. When solving the optimization problem, the Levenberg–Marquardt algorithm was used. © 2022 by the authors.