2-Methylimidazole-doped nanozymes with enhanced laccase activity for the (+)-catechins detection in dairy products.

In this work, 2-methylimidazole (MI) was doped into the Bpy-Cu nanozyme as a second ligand to form a novel laccase-mimicking enzyme (MI-Bpy-Cu). By comparison, MI-Bpy-Cu nanozyme was identified to have excellent laccase-mimicking activity, high stability and catalytic kinetic properties. It may be that the incorporation of 2-methylimidazole helped the nanozymes to build a structure closer to natural laccase and accelerate the electron transfer rate, thereby achieving the purpose of enhancing the activity. Furthermore, we observed that MI-Bpy-Cu nanozymes could oxidize the colorless (+)-Catechin to generate a yellow radical product, and a novel colorimetric sensing strategy for (+)-Catechin was successfully developed. The method had excellent selectivity and anti-interference properties, and also had good application in the analysis of (+)-Catechin in dairy products.