Nanozymatic Antioxidant System Based on MoS Nanosheets.

The enzymatic antioxidant system (EAS) protects aerobic cells from oxidative stress. However, it is brittle and susceptible of inactivation of reactive oxygen species (ROS) immoderate production. Here, we demonstrated that MoS nanosheets (few-layer MoS), as a multifunctional nanozyme, possess intrinsic activity of mimicking enzymes of superoxide dismutases (SODs), catalases (CATs), and peroxidases (PODs) under physiological conditions (pH 7.4, 25 °C). Further, MoS nanosheets showed POD-like activity by transferring electrons instead of generating ROS. Similar to EAS, a defense termed nanozymatic antioxidant system (NAS) was developed by MoS nanosheets, for regulation of oxidative stress. Surprisingly, this NAS can effectively scavenge other free radicals including hydroxyl radicals (OH), nitrogen-centered free radicals (DPPH), and nitric oxide (NO). To evaluate these unique properties of MoS-based NAS in vivo, Escherichia coli ( E. coli), Staphylococcus aureus ( S. aureus), and A549 cell models were established, respectively. These results showed MoS nanosheets superiorly protect bacteria and cells against oxidative injury caused by HO. This work makes MoS nanosheets promising antioxidants in the pathological processes and expands their application in biocatalysis and nano-biomedicine.