Nanozymatic Antioxidant System Based on MoS2 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 MoS2 nanosheets (few-layer MoS2), 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 degrees C). Further, MoS2 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 MoS2 nanosheets, for regulation of oxidative stress. Surprisingly, this NAS can effectively scavenge other free radicals including hydroxyl radicals ((OH)-O-center dot), nitrogen-centered free radicals ((DPPH)-D-center dot), and nitric oxide ((NO)-N-center dot). To evaluate these unique properties of MoS2-based NAS in vivo, Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), and A549 cell models were established, respectively. These results showed MoS2 nanosheets superiorly protect bacteria and cells against oxidative injury caused by H2O2. This work makes MoS2 nanosheets promising antioxidants in the pathological processes and expands their application in biocatalysis and nano-biomedicine.