Building hydrophobic substrate pocket to boost activity of laccase-like nanozyme through acetonitrile-mediated strategy.

Nanozymes, as promising alternatives to natural enzymes, offer several advantages with biocatalytic functions but remain inferior in catalytic activity. It is crucial to focus on factors that affect the enzymatic activity of nanozymes and develop strategies to make them more competitive with natural enzymes. Herein, CuVO nanorods are confirmed to own the intrinsic laccase-like activity, and an acetonitrile (MeCN)-mediated strategy is proposed for reaction acceleration by mimicking the enzymatic substrate pocket. In the presence of MeCN, the interaction between substrates and nanozymes gets efficiently promoted by the bridging function of cyano-group, where the utilization of Cu active sites is greatly improved due to the condensed hydrophobic substrate layers formed in the vicinity of CuVO nanorods by the solvent effect of MeCN. Theoretical calculations also disclose that the addition of MeCN endows 2,4-dichlorophenol (2,4-DP) with a lower free-energy barrier in adsorption and activation on the surface of CuVO nanozyme. Benefiting from the improved activity, a sensitive colorimetric sensing platform for 2,4-DP is constructed with the limit of detection as low as 0.48 μM. Our finding lays a theoretical foundation for achieving high-performance catalytical activity of the nanozymes based on the modulation of the reaction microenvironment, effectively alleviating the complex engineering process of nanozymes.