Colloidal selenium nanoparticles functionalized with some polymers: Synthesis, characterization, and applications

Selenium nanoparticles (Se NPs) have attracted attention due to their small size, low toxicity, antimicrobial activity, and many other properties and widespread uses. In addition to these advantages, it is important to enrich and functionalize Se NPs with some capping agents to further improve their properties and increase their applicability. Therefore, in this thesis, the synthesis and characterization of Se NPs using natural biopolymers chitosan (Ch) and sodium alginate (Alg) and synthetic polymers polyvinyl alcohol (PVA) and polyvinylpyrrolidone (PVP) and their potential to be used as an antibacterial agent were systematically studied. In addition, the effects of capping agents on the physicochemical properties of Se NPs were investigated. The synthesis of Se NPs was carried out by reduction of sodium selenite (Na2SeO3) as the selenium source with ascorbic acid (VC) as the reducing agent in the presence of polymer solutions (Ch, Alg, PVA, and PVP), which contained quercetin or not. The formation, shape, and size of SeNPs were evaluated using ultraviolet-visible (UV-Vis) and Fourier transform infrared (FTIR) spectroscopies and scanning electron microscopy (SEM). The SEM analysis revealed that the Se NPs were spherical, and their diameters changed depending on the polymer used. While the presence of functional groups of the coating substances in Se NPs was determined by FTIR analysis, it was observed from XRD measurements that Se NPs had an amorphous structure. Zeta potential measurements showed that Se NPs were stable, and their surface charge varied with the functional groups of the polymer. The antibacterial activity of all SeNPs was determined against S. aureus bacterium by broth microdilution method. The results of the microdilution assay revealed that all Se NPs examined had highly significant antibacterial activity.