Physicochemical and functional properties of chitosan-stabilized selenium nanoparticles under different processing treatments

Selenium nanoparticles (Se0NPs) have been well-characterized; however, whether processing affects their physicochemical and functional properties remains unknown. Here, chitosan (low and high molecular weight; CS(L) and CS(H), respectively) was used to stabilize Se0NPs, and the effects of heating (37 ℃, 70 ℃, and 95 ℃), freeze-drying-rehydration, and freeze-thawing on CS-Se0NPs physicochemical stability, Se release, antioxidant capacity, and antibacterial activity were evaluated. The results demonstrated that all treatments could cause CS-Se0NPs aggregation and Se release to varying degrees. Aggregation of CS-Se0NPs decreased their antibacterial activity, while Se release increased their antioxidant capacity with negligible effects on antibacterial activities. None of the CS-Se0NPs could tolerate freeze-thawing. CS(H)-Se0NPs exhibited better rehydration and heating stability than CS(L)-Se0NPs, although "rod-like" triclinic crystalline Se in CS(H)-Se0NPs, produced by 95℃ heating, decreased both antioxidant and antibacterial activities. Thus, these results provide a theoretical basis for the development and suitable application of CS-Se0NPs.