Metal-ligand dual-site SAzyme with uricase-like mechanism for specific uric acid oxidation

In nature, coenzyme-independent oxidases have evolved in selective catalysis using isolated substrate-binding pockets. Single-atom artificial enzymes (SAzymes) are promising to simulating enzyme-like active centers, but owing to the lack of recognition sites, the specificity requiring in identifying multiple substrates simultaneously is a formidable task. Here we report an unprecedented metal (Ni)-ligand (3,3'-diaminobenzidine, DAB) dual-site SAzyme (Ni-DAB) that exhibited remarkably selectivity in uric acid (UA) oxidation. Experiments and theoretical calculations confirmed that like uricase Ni-DAB had an synergistic isolated dual sites, in which the Ni metal center and the C atom in the ligand served as the specific UA and O2 binding sites, respectively. As a potential application, a Ni-DAB-based biofuel cell using human urine was constructed. This work unlocks a new approach of synergistic isolated dual sites in boosting the selectivity of artificial enzymes.