Atomically Dispersed Cu Nanozyme with Intensive Ascorbate Peroxidase Mimic Activity Capable of Alleviating ROS-Mediated Oxidation Damage.

Ascorbate peroxidase (APX) as a crucial antioxidant enzyme has drawn attentions for its utilization in preventing cells from oxidative stress responses by efficiently scavenging H 2 O 2 in plants. For eliminating the specific inactivation of natural APXs and regulating the catalytic activity, single-atom nanozymes are considered as promising classes of alternatives with similar active sites and maximal atomic utilization efficiency to natural APXs. Herein, graphitic carbon nitride (g-C 3 N 4 ) anchored with isolated single copper atoms (Cu SAs/CN) is designed as an efficient nanozyme with intrinsic APX mimetic behavior. The engineered Cu SAs/CN exhibits comparable specific activity and kinetics to the natural APXs. Based on the density functional theory (DFT), Cu-N 4 moieties in the active center of Cu SAs/CN are determined to exert such favorable APX catalytic performance, in which the electron transfer between Cu and coordinated N atoms facilitates the activation and cleavage of the adsorbed H 2 O 2 molecules and results in fast kinetics. The constructed Cu SAs/CN nanozyme with superior APX-like performance and high biocompatibility can be applied for effectively protecting the H 2 O 2 -treated cells against oxidative injury in vitro. These findings report the single-atom nanozymes as a successful paradigm for guiding nanozymes to implement APX mimetic performance for reactive oxygen species-related biotherapeutic.