Green synthesis of ultrasmall selenium nanoparticles (SeNPs) using Hericium erinaceus polysaccharide (HEP) as nanozymes for efficient intracellular antioxidation

[Display omitted] •Green synthesis of ultra-small selenium nanoparticles (SeNPs) has been achieved.•The SeNPs modified with H. erinaceus polysaccharide (HEP) have good dispersibility.•The as-prepared HEP-SeNPs can work as antioxidant nanozymes like CAT, SOD and GPx.•The as-prepared HEP-SeNPs show excellent cytoprotection ability. As one of essential trace elements for the human body, selenium plays an important role in antioxidation by scavenging free radicals. Especially, selenium nanoparticles (SeNPs) nowadays attract increasing attention due to their low toxicity and high biocompatibility. In this work, we introduced a facile method of green synthesis of ultra-small monodisperse SeNPs using Hericium erinaceus polysaccharides (HEP), and investigated the antioxidant property and biocompatibility of the as-prepared SeNPs. Our results showed that the HEP-SeNPs had the excellent antioxidant ability to eliminate reactive oxygen species (ROS) efficiently, and it could act as mimic enzymes or nanozymes such as catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx). The cell experiment confirmed the outstanding cell protection ability against external oxidative stress. Therefore, this work has not only put forward a facile and efficient method of green synthesis of ultra-small selenium nanoparticles with excellent antioxidant capacity and biocompatibility, but also demonstrated the potential application of the HEP-SeNPs as the nanozymes in biological applications such as strong antioxidants.