PECTIN AS A STABILIZER OF NANOSIZED SOLS (AQUEOUS DISPERSIONS) OF SELENIUM
Introduction. The radical change in the properties of the substance during the transition to the nanometer range provides ample opportunities to obtain materials with unique reproducible properties for the needs of various industries. Of particular interest in these areas have recently been nanoparticles of selenium - a trace element that plays a vital role in living organisms, as a component of selenium-dependent proteins. The goal of the work is the synthesis of selenium nanoparticles, using apple pectin (Pec) as a stabilizer and dispersant, in the redox system selenic acid - ascorbic acid, their characteristics, and the study of the effect on the growth of some cultures of microorganisms. Materials and methods. SeNPs were characterized by SEM, FTIR, UV-VIS, and DLS methods. Studies of sols antibacterial properties were performed by measuring optical density. Results of research and discussion. The UV-VIS spectrum of the colloidal solution obtained in brick-red color shows a wide maximum of the absorption band in the region of 300-350 nm, which indicates the formation of amorphous nanoselenium. A comparison of the Pec and SeNP-Pec FTIR-spectra shows the appearance of the characteristic absorption band 3403 cm<sup>-1</sup> due to the oscillations of the hydroxyl groups, which means the emergence of a strong hydrogen bond between the hydroxyl groups of pectin and selenium nanoparticles. Thus, we can conclude that the process of stabilization of selenium nanoparticles takes place due to the formation of hydrogen bonds with the participation of hydroxyl and carboxyl groups of pectin molecules. Photographs of selenium nanoparticles obtained by scanning electron microscopy show that the particles have a spherical shape and a size of about 100 nm. The particle size of SeNP-Pec was confirmed by the method of dynamic analysis of scattered light. The curve of distribution is characterized by the presence of one high peak, which indicates a narrow size distribution of nanoparticles, which is about 80 nm. The study of the effect of selenium sols, stabilized with pectin, on the growth activity of E. coli and B. subtilis, showed that the tested sols do not show bactericidal properties, but have an inhibitory effect on growth cultures. In this case, the growth of E. coli under the action of sol decreased by 20%, while the growth of B. subtilis sol decreased by 60%. Conclusions and prospects for further research. A method of chemical synthesis of selenium nanoparticles in the form of aggregatively stable aqueous sols using "green" precursors is proposed. It is based on the reduction of selenic acid with ascorbic acid and using apple pectin (Pec) as a stabilizer. It is shown that the interaction of its molecules with the surface of particles is ensured by the formation of hydrogen bonds. The size of the obtained spherical nanoparticles with amorphous structure, modified with pectin biomolecules, is 80-100 nm. It is shown that the obtained dispersions of nanoparticles do not show bactericidal action against the studied cultures of B. subtilis and E. coli, but inhibit their growth in the liquid medium, a more pronounced inhibitory effect of the sol was found on B. subtilis.