Structure characterization of Oudemansiella radicata polysaccharide and preparation of selenium nanoparticles to enhance the antioxidant activities

Selenium nanoparticles have attracted worldwide attentions due to their bioactivities and low toxicity, but the application is limited by stability. This study focuses on the synthesis of selenium nanoparticles using polysaccharide as dispersants. Two Oudemansiella radicata polysaccharide fractions (ORP1 and ORP2) were purified by anion exchange and gel filtration chromatography. Monosaccharide composition, methylation analysis, FT-IR and NMR spectra analysis confirmed that the two fractions were mainly composed of →6)-β-D-Glcp-(1→ and →6)-α-D-Galp-(1 → . Selenium nanoparticles (ORP1-SeNPs and ORP2-SeNPs) were prepared by adding ORP1 and ORP2 to the redox system of selenite and ascorbic acid. The synthesis conditions were optimized by single factor experiment and orthogonal experiment. The average diameter of ORP1-SeNPs and ORP2-SeNPs synthesized under the optimal conditions were 106.28 nm and 117.04 nm, and their morphology appear to be monodispersed and spherical. Moreover, stability tests indicated that particle sizes were affected by time and temperature during storage. Compared with selenium nanoparticles without polysaccharide, ORP1-SeNPs and ORP2-SeNPs exhibited higher antioxidant activities by scavenging free radicals (such as DPPH•, ABTS•+ and O2•-).