Mn−Ce Symbiosis: Nanozymes with Multiple Active Sites Facilitate Scavenging of Reactive Oxygen Species (ROS) Based on Electron Transfer and Confinement Anchoring

Abstract

Regulating appropriate valence states of metal active centers, such as Ce³⁺/Ce⁴⁺ and Mn³⁺/Mn²⁺, as well as surface vacancy defects, is crucial for enhancing the catalytic activity of cerium-based and manganese-based nanozymes. Drawing inspiration from the efficient substance exchange in rhizobia-colonized root cells of legumes, we developed a symbiosis nanozyme system with rhizobia-like CeO_x nanoclusters robustly anchored onto root-like Mn₃O₄ nanosupports (CeO_x/Mn₃O₄). The process of "substance exchange" between Ce and Mn atoms-reminiscent of electron transfer-not only fine-tunes the metal active sites to achieve optimal Ce³⁺/Ce⁴⁺ and Mn³⁺/Mn²⁺ ratios but also enhances the vacancy ratio through interface defect engineering. Additionally, the confinement anchoring of CeO_x on Mn₃O₄ ensures efficient electron transfer in catalytic reactions. The final CeO_x/Mn₃O₄ nanozyme demonstrates potent catalase-like (CAT-like) and superoxide dismutase-like (SOD-like) activities, excelling in both chemical settings and cellular environments with high reactive oxygen species (ROS) levels. This research not only unveils a novel material adept at effectively eliminating ROS but also presents an innovative approach for amplifying the efficacy of nanozymes.