Construction and characterization of Laminaria polysaccharide functionalized selenium nanoparticles based on an activity-oriented approach

Laminaria polysaccharides (LP) have been shown to effectively stabilize selenium nanoparticles (SeNPs), forming LP–SeNP complexes with enhanced bioactivity. However, the correlation between their bioactivity and physicochemical properties remains inadequately explored. This study used chemical reduction with LP as stabilizer to investigate how LP-to-selenium mass ratio (LPSMR), reaction time, and temperature influence particle size, selenium content, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of LP–SeNPs. The results showed that enhanced DPPH scavenging correlated with higher selenium content and smaller particle size, primarily modulated by LPSMR and temperature. Under optimal conditions (LPSMR of 1; temperature of 25°C), the resulting LP–SeNPs exhibited uniform morphology with a particle size of 81.41 nm and selenium content of 653.91 mg/g. This stability was achieved through non-covalent interactions between LP and SeNPs, providing superior light and acid resistance compared to unmodified SeNPs. Notably, LP–SeNPs showed synergistic antioxidant effects, with lower half-maximal inhibitory concentration (IC₅₀) values for scavenging DPPH, hydroxyl, and superoxide anion radicals than LP or SeNPs alone, and enhanced hypoglycemic activity. Cytotoxicity assays confirmed LP–SeNPs had reduced toxicity compared to Na₂SeO₃ and selenopeptide. These findings provide insights into the structure-activity relationships of LP–SeNPs and support their potential application as antioxidant and hypoglycemic agents.