Investigation of Hypersonic Conic Flows Generated by Magnetoplasma Light-Gas Gun Equipped with Laval Nozzle

This chapter introduces new approach of hypersonic flow generation and experimental study of hypersonic flows over cones with half- angles τ1 = 3◦ and τ2 = 12◦. Mach number of the of the incident flow was M1 = 18. Visualization of the flow structure was made by the schlieren method. Straight Foucault knife was located in the focal plane of the receiving part of a shadow device. Registration of shadow patterns was carried out using high- speed camera Photron Fastcam (300 000 fps) with an exposure time of 1 μs. The Mach number on the cone was calculated from inclination angle of shock wave in the shadowgraph

Application of magnetic nanoparticles, fluorescent nanoparticles and nanozymes in immunoassays

The reported study was funded by RFBR according to the research project № 19-015-00408 А

Magnetic nanoclusters coated with albumin, casein, and gelatin: Size tuning, relaxivity, stability, protein corona, and application in nuclear magnetic resonance immunoassay

The surface functionalization of magnetic nanoparticles improves their physicochemical properties and applicability in biomedicine. Natural polymers, including proteins, are prospective coatings capable of increasing the stability, biocompatibility, and transverse relaxivity (r2) of magnetic nanoparticles. In this work, we functionalized the nanoclusters of carbon-coated iron nanoparticles with four proteins: bovine serum albumin, casein, and gelatins A and B, and we conducted a comprehensive comparative study of their properties essential to applications in biosensing. First, we examined the influence of environmental parameters on the size of prepared nanoclusters and synthesized protein-coated nanoclusters with a tunable size. Second, we showed that protein coating does not significantly influence the r2 relaxivity of clustered nanoparticles; however, the uniform distribution of individual nanoparticles inside the protein coating facilitates increased relaxivity. Third, we demonstrated the applicability of the obtained nanoclusters in biosensing by the development of a nuclear-magnetic-resonance-based immunoassay for the quantification of antibodies against tetanus toxoid. Fourth, the protein coronas of nanoclusters were studied using SDS-PAGE and Bradford protein assay. Finally, we compared the colloidal stability at various pH values and ionic strengths and in relevant complex media (i.e., blood serum, plasma, milk, juice, beer, and red wine), as well as the heat stability, resistance to proteolytic digestion, and shelf-life of protein-coated nanoclusters. © 2019 by the authors. Licensee MDPI, Basel, Switzerland

Nuclear magnetic resonance-based assays in immunodiagnostics

During the research, two different approaches for NMR-based assays were developed. Analytical performance of designed (table) method is acceptable for immunodiagnostics test-systems.This work was supported by Russian Science Foundation (project № 17-15-01116)

Immunoregulatory potential of pregnancy-specific β1-glycoprotein

The embryo, being half an antigenically “foreign” organism, should elicit a maternal immune response. During evolution, however, the mechanisms ensuring successful development of pregnancy have been formed. In particular, among factors providing immune tolerance during pregnancy are some proteins associated with pregnancy. The pregnancy-specific β 1-glycoprotein (PSG, PSG1; SP1; PSβG1) is a dominant fetoplacental protein produced by cyto- and syncytiotrophoblast cells, and it exhibits immunosuppressive properties. Our team of authors possesses a patented method for obtaining native human PSG preparation from blood serum of pregnant women, a mixture of PSG1, PSG3, PSG7, PSG9, and their isoforms and precursors. This review presents an analysis of our results for the period from 2015 to 2020. We studied the immunoregu-latory effects of the obtained PSG preparation at concentrations comparable to those observed in pregnancy (1, 10, 100 |ag/mL). The study was performed with peripheral blood cells obtained from non-pregnant women. It was found that PSG significantly increased the percentage of adaptive Tregs in vitro, as well as expression of CTLA-4, GITR, and production of IL-10 by these cells. It has been shown that PSG has a stimulating effect upon indoleamine-2,3-dioxygenase (IDO) activity of peripheral blood monocytes. For Th17 cells, we have demonstrated that PSG can suppress differentiation and proliferation of these cells, along with reduced production of critical proinflammatory cytokines (IL-8, IL-10, IL-17, IFNγ, MCP-1, TNF α). As for the memory T cells, PSG suppressed CD25 expression and IL-2 production by them, along with simultaneous decreased expression of Gfi1, hnRNPLL genes, thus preventing the formation of the “mature” CD45R0 isoform. PSG has been shown to inhibit naive T cells’ conversion to the terminally differentiated effector subpopulation of helper T cells. When analyzing PSG effects upon cytokine profile of immunocompetent cells, it was found that the protein predominantly suppresses the Th1 cytokine production by the studied cell types, and regulates the Th2 cytokine production in divergent manner. The results obtained are consistent with general concept of immunosuppression during pregnancy. Thus, PSG could be one of the factors preventing formation and implementation of immune response to placental antigens

Prussian Blue Nanozymes with Enhanced Catalytic Activity: Size Tuning and Application in ELISA-like Immunoassay

Prussian blue nanozymes possessing peroxidase-like activity gather significant attention as alternatives to natural enzymes in therapy, biosensing, and environmental remediation. Recently, Prussian blue nanoparticles with enhanced catalytic activity prepared by reduction of FeCl3/K3[Fe(CN)6] mixture have been reported. These nanoparticles were denoted as ‘artificial peroxidase’ nanozymes. Our study provides insights into the process of their synthesis. We studied how the size of nanozymes and synthesis yield can be controlled via adjustment of the synthesis conditions. Based on these results, we developed a reproducible and scalable method for the preparation of ‘artificial peroxidase’ with tunable sizes and enhanced catalytic activity. Nanozymes modified with gelatin shell and functionalized with affine molecules were applied as labels in colorimetric immunoassays of prostate-specific antigen and tetanus antibodies, enabling detection of these analytes in the range of clinically relevant concentrations. Protein coating provides excellent colloidal stability of nanozymes in physiological conditions and stability upon long-term storage. © 2022 by the author. Licensee MDPI, Basel, Switzerland.Russian Science Foundation, RSF: 20-75-00029Funding: This study was supported by the Russian Science Foundation, grant 20-75-00029

Modified Desolvation Method Enables Simple One-Step Synthesis of Gelatin Nanoparticles from Different Gelatin Types with Any Bloom Values

Gelatin nanoparticles found numerous applications in drug delivery, bioimaging, immunotherapy, and vaccine development as well as in biotechnology and food science. Synthesis of gelatin nanoparticles is usually made by a two-step desolvation method, which, despite providing stable and homogeneous nanoparticles, has many limitations, namely complex procedure, low yields, and poor reproducibility of the first desolvation step. Herein, we present a modified one-step desolvation method, which enables the quick, simple, and reproducible synthesis of gelatin nanoparticles. Using the proposed method one can prepare gelatin nanoparticles from any type of gelatin with any bloom number, even with the lowest ones, which remains unattainable for the traditional two-step technique. The method relies on quick one-time addition of poor solvent (preferably isopropyl alcohol) to gelatin solution in the absence of stirring. We applied the modified desolvation method to synthesize nanoparticles from porcine, bovine, and fish gelatin with bloom values from 62 to 225 on the hundreds-of-milligram scale. Synthesized nanoparticles had average diameters between 130 and 190 nm and narrow size distribution. Yields of synthesis were 62–82% and can be further increased. Gelatin nanoparticles have good colloidal stability and withstand autoclaving. Moreover, they were non-toxic to human immune cells. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The reported study was funded by RFBR and Kaliningrad Oblast according to the research project № 19-415-393005 (preparation of fluorescence gelatin nanoparticles and study of their fluorescent properties), by RFBR research project 19-015-00408 (preparation of gelatin nanoparticles by the desolvation method), and by Ministry of Science and Higher Education of the Russian Federation within the framework of the Russian State Assignment under contract No. AAAA-А19-119112290010-7 (assessment of nanoparticles cytotoxicity)

Study of the graphene oxide nanoparticles effect on luminol-dependent chemiluminescence of human leukocytes

Graphene and its derivatives are increasingly used in biomedical research. Therefore, the mechanisms and consequences of the interaction of graphene nanoparticles with living objects are intensively studied. The immune system is involved in protecting the body and regulating its functions, so the question of the effect of graphene and its derivatives on immune cells is crucial. The specific response of monocytes, macrophages, and neutrophils to a stimulus is to increase the production of reactive oxygen species (ROS). Published data on graphene oxide (GO) and polyethylene glycol-modified graphene oxide (GO-PEG) effects on peripheral blood leukocytes are scarce and contradictory. It is due to variations in objects and conditions of study, along with the difference in particle concentrations. Thus, it was essential to evaluate the GO and GO-PEG effect on ROS production by human leukocytes. Our study aimed at the effect of particles of unmodified and PEG-modified graphene oxide (GO and GO-PEG) on the ROS production by peripheral blood leukocytes in not-stimulated and stimulated luminoldependent chemiluminescence (LCL) tests. ROS production was stimulated by opsonized zymosan (OZ). A hydrogen peroxide-luminol system was used for assessing the independent effect of GO nanoparticles on the quenching of ROS luminescence. Pristine GO (Ossila, Great Britain) nanoparticles were PEG-modified (GO-PEG). The average size of the GO flakes was 1-5 µm, the GO-PEG-flakes 569±14 nm, and the amount of PEG covering was ~ 20%. Nanoparticles were used at concentrations of 5; 2.5; 1.25 µg/ml. It has been established that GO-PEG nanoparticles in concentrations of 2.5 and 5 µg/ml suppressed ROS production in the spontaneous LCL test. At the same time, the GO effects showed a visible but a not significant tendency to inhibition of LCL. Similar results were obtained in the stimulated LCL test. However, when analyzing the process kinetics, both GO-PEG and GO decreased the ROS production, but mainly in the first minutes of the test. When analyzing the quenching effect of the LCL reaction in a cell-free system, there was no significant effect of GO and GO-PEG nanoparticles. Thus, the general vector of the obtained effects was associated with the suppression of ROS production. GO-PEG ROS-decreasing effects were more pronounced in comparison with unmodified GO. In general, we have confirmed the antioxidant effects of GO and GO-PEG using the LCL method. We can assume that in addition to the actual antioxidant effect of graphene nanoparticles, ROS production decreases due to the rapid GO uptake and blocking of several intracellular signals that induce an oxidative burst