Organophosphorus\nHydrolase-like Nanozyme with an Activity-Quenched\nAggregation-Induced Emission Effect: A Self-Reporting and Specific\nAssay of Nerve Agents

Given the promising prospect of aggregation-induced emission\nluminogens\n(AIEgens) in fluorescence assays, it is interesting and significant\nto endow AIEgens with molecular recognition capability (such as enzyme-like\nactivity). Here, an AIE nanomaterial with intrinsic enzyme-like activity\n(named as “AIEzyme”) is designed and synthesized via\na facile coordination polymerization of Zr<sup>4+</sup> and AIE ligands.\nAIEzyme possesses enhanced and stable fluorescence in different solvents\nbecause of the AIE effect of ligands in the rigid structure of a coordination\npolymer. On the other hand, the organophosphorus hydrolase (OPH)-mimicking\nactivity of AIEzyme exhibits excellent affinity and specific activity.\nInterestingly, the OPH-like activity can quench the inherent fluorescence\nof AIEzyme by the hydrolysate of a typical organophosphorus nerve\nagent (OPNA), diethyl-4-nitrophenylphosphate. Due to the sensitive\nactivity-induced quenching effect for AIE, the self-reporting fluorescence\nassay method based on AIEzyme was established, which shows ultrahigh\nsensitivity, high selectivity, good storage stability, and acceptable\nreliability for a real sample assay. Moreover, the simultaneous colorimetric\nmethod broadens the detection range and the application scenarios.\nThe proposed assay method avoided the interference of O<sub>2</sub> during detection because the OPH-like activity does not derive from\nthe generation of ROS. As a bonus, AIEzyme can also be used for the\ndegradation of OPNAs by OPH-like activity, and the process can be\nself-monitored by AIE quenching. This work would provide a new opportunity\nfor expanding the application of AIEgens and artificial enzymes by\nendowing AIEgens with enzyme-like activity.