Coordination Construction of the Dual Superoxide Dismutase Catalytic Center Nanozyme: Synergistic Contribution of the Site, Structure, and Electron Transfer Pathway

Superoxide dismutase (SOD) mimics are limited by a single active center, and their performance is difficult to achieve the activity level of natural SOD. Herein, we exhibit the coordination construction of different SOD active centers (Cu and Mn) and structural regulation of framework carbonization in MOFs. The obtained catalytic activity and excellent biocompatibility are comparable to Cu/Zn-SOD. The improvement of catalytic performance was attributed to the bimetallic sites' synergistic catalysis (enhancing the substrate affinity and accelerating the reaction process) on the one hand and the contribution of framework carbonization on the other hand, which not only regulate the relative position and valence of metal nodes but improve the spatial adaptability of the reaction and reduce the reaction barrier, and the increased conductivity of the framework accelerates the electron transfer process in the reaction. The excellent biocompatibility results from the fixing effect of the carbonized framework on the metal nodes. Mn/Cu-C-N2 was encapsulated in a chitosan film as an antioxidant compared with a pure chitosan film; the anthocyanin content of blueberries increased 2 times after being stored at room temperature for 7 days, and the content was 83% of the fresh blueberries, providing exciting potential for biological applications limited by the performance of SOD nanozymes.