Analyte-Induced Specific Regulation of Light-Responsive\nCOF-Cu Nanozyme Activity for Ultrafast Thiram Colorimetric Sensing

A light-responsive\ncovalent-organic framework (COF) nanozyme, which\nintegrates the advantages of the COF structure and light-stimulated\nnanozyme catalysis, is a class of sensing star materials with wide\napplication prospects. However, the sensing methods based on light-responsive\nCOF nanozymes are relatively single at present. Therefore, it is necessary\nto develop new sensing strategies to broaden its application in chemical\nsensing and achieve highly efficient detection. Here, a Cu<sup>2+</sup>-modified COF composite material (TpDA-Cu) was rationally designed.\nThe addition of Cu significantly inhibits the excellent light-responsive\nnanozyme activity of TpDA itself. However, because of the restoration\nof the enzyme activity by thiram (Tr) and the oxidase mimic activity\nof the newly formed Cu/Tr complex, TpDA-Cu/Tr exhibits stronger light-responsive\nnanozyme activity. Enzyme kinetic data show that compared with TpDA,\nTpDA-Cu/Tr has a larger <i>V</i><sub>max</sub> value, which\ncan achieve efficient catalytic oxidation of 3,3′,5,5′-tetramethylbenzidine\n(TMB). In addition, the strong coordination effect of Tr and TpDA-Cu\nalso plays a key role in achieving ultrafast, sensitive, and selective\ncolorimetric detection of Tr. This work develops a dual activity regulation\nstrategy of light-responsive COF nanozymes based on analyte induction\nand provides a new perspective for the application of light-responsive\nCOF nanozymes in the field of sensing.