Exopolysaccharide-selenium composite nanoparticle: Characterization, antioxidant properties and selenium release kinetics in simulated gastrointestinal conditions

An exopolysaccharide-selenium nanoparticles (EPS-SeNPs) was successfully synthesized by conjugating with Weissella confusa EPS through the reduction of SeO 3 2− . The EPS-SeNPs composite was comprehensively characterized. These analyses confirmed that the EPS-SeNPs composite had an amorphous nature and a uniform size distribution of around 100 nm. The OH groups in EPS interacted with SeNPs, replacing intermolecular interactions in native EPS, which resulted in the stable dispersion of SeNPs within the EPS network. Furthermore, compared to native EPS, EPS-SeNPs with varying Se/EPS ratios demonstrated enhanced radical scavenging capabilities against ABTS, DPPH, superoxide anion radical (O 2 − ), H 2 O 2 , and hydroxyl group radicals (OH·). This suggests that the conjugation of SeNP improved the antioxidant properties of EPS. Furthermore, the investigation delved into the dynamics and mechanism of selenium liberation from EPS-SeNPs under simulated gastric (SGF) and intestinal fluids (SIF). The EPS-SeNPs experienced a decrease in particle size from 223.03 ± 1.67 nm to 98.40 ± 5.57 nm. The release kinetics of selenium in SIF followed a conventional Fickian diffusion pattern. Notably, EPS-SeNPs demonstrated significant Se release following SIF digestion while exhibiting minimal release after SGF digestion, indicating their potential use as a controlled-release selenium-enriched supplement for addressing selenium deficiency.