A fluorescent microspheres-based microfluidic test system for the detection of immunoglobulin G to SARS-CoV-2

Background: The pandemic of the new coronavirus infection, COVID-19, is currently ongoing in the world. Over the years, the pathogen, SARS-CoV-2, has undergone a series of mutational genome changes, which has led to the spread of various genetic variants of the virus. Meanwhile, the methods used to diagnose SARS-CoV-2, to establish the disease stage and to assess the immunity, are nonspecific to SARS-CoV-2 variants and time-consumable. Thus, the development of new methods for diagnosing COVID-19, as well as their implementation in practice, is currently an important direction. In particular, application of systems based on chemically modified fluorescent microspheres (with a multiplex assay for target protein molecules) opens great opportunities. Aim: development of a microfluidic diagnostic test system based on fluorescent microspheres for the specific detection of immunoglobulins G (IgG) to SARS-CoV-2. Methods: A collection of human serum samples was characterized using enzyme-linked immunosorbent assay (ELISA) and commercially available reagent kits. IgG to SARS-CoV-2 in the human serum were detected by the developed immunofluorescent method using microspheres containing the chemically immobilized RBD fragment of the SARS-CoV-2 (Kappa variant) viral S-protein. Results: The level of IgG in the blood serum of recovered volunteers was 9-300 times higher than that in apparently healthy volunteers, according to ELISA (p0.001). Conjugates of fluorescent microspheres with the RBD-fragment of the S-protein, capable of specifically binding IgG from the blood serum, have been obtained. The immune complexes formation was confirmed by the fluorescence microscopy data; the fluorescence intensity of secondary antibodies in the immune complexes formed on the surface of microspheres was proportional to the content of IgG (r 0.963). The test system had a good predictive value (AUC 70.3%). Conclusion: A test system has been developed, based on fluorescent microspheres containing the immobilized RBD fragment of the SARS-CoV-2 S-protein, for the immunofluorescent detection of IgG in the human blood serum. When testing the system on samples with different levels of IgG to SARS-CoV-2, its prognostic value was shown. The obtained results allow us to present the test system as a method to assess the level of immunoglobulins to SARS-CoV-2 in the human blood serum for the implementation in clinical practice. The test system can also be integrated into various microfluidic systems to create chips and devices for the point-of-care diagnostics

Analysis of the Studies Published on Business Strategy Game and Learning Strategic Management in the Web of Science Database

Although the variety of computer-based games offered for strategic management, ease of use and the number of games available in the market has decreased due to multiple factors, it has also increased. Depending on the criterion of the objectively measured learning outcomes, various games that have been studied to date yield higher results than those obtained by case approach as an alternative teaching strategy. Very little research has been conducted on factors that facilitate play, leading to effective learning outcomes in a business gaming environment. The general purpose of this research is to determine the work conducted on Business Strategy Game (BSG) and Learning Strategic Management. This study was conducted using qualitative research method, document analysis and related content analysis, studying the keywords ‘Business Strategy Game and Learning Strategic Management’ in the Web of Science database, based on the analysis of the documents. The studies in the Web of Science database were analysed according to years, the Web of Science categories, the research area, country/types and writing languages. The analysis of the studies in the Web of Science database for BSG and learning strategic management emerged with the resulting content. A total of 39 studies were carried out and it was concluded that the most common transactions were made in 2019. However, the first study was conducted in 1995. In the literature review, the year 2019 has the most reads, which were mostly published articles. According to the Web of Science field type, it is concluded that there are studies mostly in the Education and Educational Research field and it was also concluded that 38 of these studies were written in English

On the Development and Application of Multiple Cases for Accreditation of Health Care Professionals

The sequence for the development of the multiple case methodology (training technology) for accreditation of health care professionals has been presented. The multidimensionality of cases allows to cover all functions of professional standards. To improve the technique reliability, the multiple-choice tests have been offered. The requirement of local independence of tasks has been implemented. The results of approbation of cases with participation of 114 graduates (6th year) of 5 medical universities have been analysed. The interpretation of the analysis results and their use for assessing the professional readiness of health care professionals have been offered

Silicon–Gold Nanoparticles Affect Wharton’s Jelly Phenotype and Secretome during Tri-Lineage Differentiation

Multiple studies have demonstrated that various nanoparticles (NPs) stimulate osteogenic differentiation of mesenchymal stem cells (MSCs) and inhibit adipogenic ones. The mechanisms of these effects are not determined. The aim of this paper was to estimate Wharton’s Jelly MSCs phenotype and humoral factor production during tri-lineage differentiation per se and in the presence of silicon–gold NPs. Silicon (SiNPs), gold (AuNPs), and 10% Au-doped Si nanoparticles (SiAuNPs) were synthesized by laser ablation, characterized, and studied in MSC cultures before and during differentiation. Humoral factor production (n = 41) was analyzed by Luminex technology. NPs were nontoxic, did not induce ROS production, and stimulated G-CSF, GM-CSF, VEGF, CXCL1 (GRO) production in four day MSC cultures. During MSC differentiation, all NPs stimulated CD13 and CD90 expression in osteogenic cultures. MSC differentiation resulted in a decrease in multiple humoral factor production to day 14 of incubation. NPs did not significantly affect the production in chondrogenic cultures and stimulated it in both osteogenic and adipogenic ones. The major difference in the protein production between osteogenic and adipogenic MSC cultures in the presence of NPs was VEGF level, which was unaffected in osteogenic cells and 4–9 times increased in adipogenic ones. The effects of NPs decreased in a row AuNPs > SiAuNPs > SiNPs. Taken collectively, high expression of CD13 and CD90 by MSCs and critical level of VEGF production can, at least, partially explain the stimulatory effect of NPs on MSC osteogenic differentiation

Stimulation of Cysteine-Coated CdSe/ZnS Quantum Dot Luminescence by meso-Tetrakis (p-sulfonato-phenyl) Porphyrin

Abstract Interaction between porphyrins and quantum dots (QD) via energy and/or charge transfer is usually accompanied by reduction of the QD luminescence intensity and lifetime. However, for CdSe/ZnS-Cys QD water solutions, kept at 276 K during 3 months (aged QD), the significant increase in the luminescence intensity at the addition of meso-tetrakis (p-sulfonato-phenyl) porphyrin (TPPS4) has been observed in this study. Aggregation of QD during the storage provokes reduction in the quantum yield and lifetime of their luminescence. Using steady-state and time-resolved fluorescence techniques, we demonstrated that TPPS4 stimulated disaggregation of aged CdSe/ZnS-Cys QD in aqueous solutions, increasing the quantum yield of their luminescence, which finally reached that of the fresh-prepared QD. Disaggregation takes place due to increase in electrostatic repulsion between QD at their binding with negatively charged porphyrin molecules. Binding of just four porphyrin molecules per single QD was sufficient for total QD disaggregation. The analysis of QD luminescence decay curves demonstrated that disaggregation stronger affected the luminescence related with the electron-hole annihilation in the QD shell. The obtained results demonstrate the way to repair aged QD by adding of some molecules or ions to the solutions, stimulating QD disaggregation and restoring their luminescence characteristics, which could be important for QD biomedical applications, such as bioimaging and fluorescence diagnostics. On the other hand, the disaggregation is important for QD applications in biology and medicine since it reduces the size of the particles facilitating their internalization into living cells across the cell membrane

A sol-gel synthesis and gas-sensing properties of finely dispersed ZrTiO4

The transparent titanium-zirconium-containing gel was obtained using heteroligand coordination compounds (namely, alkoxoacetylacetonates) as the precursors. The high-dispersive system “ZrTiO4 – carbon”, formed after drying of such gel and carbonization of the obtained xerogel, was used to study the evolution of microstructure for the product (ZrTiO4) during thermal treatment in air for 1 h in the temperature range from 500 °C to 1000°С. It was stated that the formation of crystalline phase occurred in the narrow range 690-730°С. The thermal treatment at 500 °C and 600°С allowed obtaining micro- and mesoporous X-ray amorphous products of the composition ZrTiO4, with the specific surface area falling in the range 82–150m2/g. At the higher temperatures the single-phase nanocrystalline powder was prepared (the specific surface area amounted to 2.5–15m2/g). Particle coarsening took place more extensively at temperatures ≥700°С was shown. For the ZrTiO4 nanopowder crystallized under the mildest conditions at the temperature of 700 °C, chemoresistive gas-sensitive properties were studied for the first time. The material showed a high reproducible response at 1–20% O2 and 200–10,000 ppm H2 at a relatively low detection operating temperature of 450 °C

Gut Microbiota as a Mediator of Essential and Toxic Effects of Zinc in the Intestines and Other Tissues

The objective of the present study was to review the existing data on the association between Zn status and characteristics of gut microbiota in various organisms and the potential role of Zn-induced microbiota in modulating systemic effects. The existing data demonstrate a tight relationship between Zn metabolism and gut microbiota as demonstrated in Zn deficiency, supplementation, and toxicity studies. Generally, Zn was found to be a significant factor for gut bacteria biodiversity. The effects of physiological and nutritional Zn doses also result in improved gut wall integrity, thus contributing to reduced translocation of bacteria and gut microbiome metabolites into the systemic circulation. In contrast, Zn overexposure induced substantial alterations in gut microbiota. In parallel with intestinal effects, systemic effects of Zn-induced gut microbiota modulation may include systemic inflammation and acute pancreatitis, autism spectrum disorder and attention deficit hyperactivity disorder, as well as fetal alcohol syndrome and obesity. In view of both Zn and gut microbiota, as well as their interaction in the regulation of the physiological functions of the host organism, addressing these targets through the use of Zn-enriched probiotics may be considered an effective strategy for health management