Selenium Bio-Nanocomposite Based on Alteromonas macleodii Mo169 Exopolysaccharide: Synthesis, Characterization, and In Vitro Antioxidant Activity

In this study, the novel exopolysaccharide (EPS) produced by the marine bacterium Alteromonas macleodii Mo 169 was used as a stabilizer and capping agent in the preparation of selenium nanoparticles (SeNPs). The synthesized nanoparticles were well dispersed and spherical with an average particle size of 32 nm. The cytotoxicity of the EPS and the EPS/SeNPs bio-nanocomposite was investigated on human keratinocyte (HaCaT) and fibroblast (CCD-1079Sk) cell lines. No cytotoxicity was found for the EPS alone for concentrations up to 1 g L(−1). A cytotoxic effect was only noticed for the bio-nanocomposite at the highest concentrations tested (0.5 and 1 g L(−1)). In vitro experiments demonstrated that non-cytotoxic concentrations of the EPS/SeNPs bio-nanocomposite had a significant cellular antioxidant effect on the HaCaT cell line by reducing ROS levels up to 33.8%. These findings demonstrated that the A. macleodii Mo 169 EPS can be efficiently used as a stabilizer and surface coating to produce a SeNP-based bio-nanocomposite with improved antioxidant activity.