Abstract
Fabricating dicopper centers in nanozymes offers a promising route to mimic catecholase-like catalysis. However, some dicopper centers often suffer from symmetric configurations, which are prone to weakening the O-O bond polarization, thereby limiting O(2) activation. This results in unsatisfactory intrinsic activities of nanozymes, thus hindering their potential sensing applications. Here, we report a catechol oxidase (CO)-like nanozyme (DTD-Cu) engineered with proximal and asymmetrically coordinated dicopper centers via a N/S-rich ligand. The unique asymmetric N(4)Cu-CuN(4)S configuration facilitates the preferential O(2) adsorption/activation and O-O bond polarization as well as the subsequent 4-electron reduction to H(2)O via a H(2)O(2) intermediate, thus endowing DTD-Cu with dramatically enhanced intrinsic activity, as evidenced by orders-of-magnitude improvements in K (m) and K (cat)/K (m) over most reported CO-like nanozymes and artificial enzymes. Capitalizing on this superior activity, we achieved highly selective and sensitive detection of the cytotoxic tris(2-carboxyethyl)phosphine (TCEP) with a detection limit of 98.6 ppb via a synergistic dual-inhibition mechanism involving both TCEP-induced reduction of the oxidized substrate/ROS and direct TCEP-mediated chelation to the Cu sites.