A Versatile\nVisual Molecular Imprinting-Driven Switchable\nNanozyme Activity-Based Trimodal Assay and Logic Gate Circuits of\nEthyl Carbamate

Concerns regarding the hazard of the carcinogenic ethyl\ncarbamate\n(EC) have driven attempts to exploit efficient, timely, straightforward,\nand economic assays for warning early food safety. Here, we proposed\na novel molecularly imprinted polymer Co@MOF-MIP, with a high peroxidase\n(POD)-like activity and a bright blue fluorescence emission, to develop\na versatile visual assay for colorimetric, fluorescent, and photothermal\ntrimodal detection and logic gate outputting of EC. Briefly, the POD-like\nactivity of Co@MOF-MIP made it to decompose H<sub>2</sub>O<sub>2</sub> into <sup>·</sup>OH for oxidizing colorless 3,3′,5,5′-tetramethylbenzidine\n(TMB) into a blue oxTMB, resulting in a 660 nm irradiated photothermal\neffect and bursting the blue fluorescence of Co@MOF-MIP via inner\nfilter effect, observing a decreased fluorescence signal together\nwith an increased colorimetric and 660 nm irradiated photothermal\nsignals. However, EC could specifically fill the imprinted cavities\nof Co@MOF-MIP to block the catalytic substrates TMB and H<sub>2</sub>O<sub>2</sub> out of Co@MOF-MIP for further reacting with the inside\ncatalytic center of Co<sup>2+</sup>, resulting in the transformation\nsuppressing of TMB into oxTMB, yielding an EC concentration-dependent\ntrimodal responses in fluorescence signal enhancement, colorimetric,\nand 660 nm irradiated photothermal signal decreases. Assisted by the\nportable devices such as smartphones and hand-held thermal imagers,\na visual onsite portable trimodal analytical platform was proposed\nfor EC fast and accurate detection with the low detection limits of\n1.64, 1.24, and 1.78 μg/L in colorimetric, fluorescent, and\nphotothermal modes, respectively. Interestingly, these reactive events\ncould be programmed by the classical Boolean logic gate analysis to\noffer a novel promising avenue for the big data Internet of Things\nmonitoring and warning early residual EC in a more intelligent, dynamical,\nfast, and accurate manner, safeguarding food safety.