Fabrication and stabilization of biocompatible selenium nanoparticles by carboxylic curdlans with various molecular properties

•Selenium nanoparticles (SeNPs) were prepared and stabilized by carboxylic curdlans.•SeNPs showed homogeneous and monodisperse spherical structure with size of∼50–90nm.•Cur-8-capped SeNPs (SeNPs@Cur-8) showed smaller particle size and greater stability.•SeNPs@Cur-8 possessed strong antioxidant efficacy and low cytotoxic activity in vitro.•SeNPs@Cur-8 can be explored as biocompatible NPs for food and medical applications. In this study, carboxylic curdlans (Cur-4, Cur-8, and Cur-24) with different molecular properties and chain conformations were used as stabilizer and capping agent to fabricate stable and water-dispersible selenium nanoparticles (SeNPs). Results showed that molecular properties and chain conformations of carboxylic curdlans remarkably influenced the size, morphology, structure, and stability of SeNPs and the carboxylic curdlan was ligated to SeNPs via OH⋯Se interaction. The as-prepared SeNPs was amorphous and showed homogeneous and monodisperse spherical structure with size of ∼50–90nm. The Cur-8-decorated SeNPs (SeNPs@Cur-8) exhibited smaller particle size (∼56nm) and greater stability than those of the others. The carboxylic curdlan-stabilized SeNPs exhibited excellent antioxidant capacities compared to the control SeNPs. Specifically, SeNPs@Cur-8 with smaller particle size possessed strong antioxidant efficacy. SeNPs@Cur-8 also exhibited low cytotoxic activity against SPCA-1 and HeLa cell lines in vitro.