Ce-Doped and Defect-Engineered Zr-Based MOF Nanozyme with Enhanced Organophosphorus Hydrolase-like Activity for Detoxification and the Dual-Mode Detection of Nerve Agent Simulants

It is urgently needed to develop a highly efficient sensor that can rapidly degrade and accurately detect extremely toxic nerve agents, considering that intrinsic drawbacks still exist in most reports based on the inhibition of the activity of natural organophosphorus hydrolases (OPHs). Herein, we presented a two-pronged strategy for the design of a functional Zr-based MOF nanozyme, D-UiO-66-NH₂(ZrCe), with enhanced OPH-like activity to realize both the detoxification and detection of a typical nerve agent simulant, dimethyl-4-nitrophenylphosphate (DMNP). On the one hand, the Ce into UiO-66-NH₂ produced more highly effective active sites due to the electronic synergy between bimetallic nodes; on the other hand, the structural defect promoted the exposure of active sites to increase the accessibility of the substrate. Notably, D-UiO-66-NH₂(ZrCe) had excellent affinity for DMNP, with a Michaelis constant (<i>K</i>_m) value as low as 27.84 μM. Capitalizing on this boosted catalytic activity, D-UiO-66-NH₂(ZrCe) can function as an excellent colorimetric and fluorescence sensor for DMNP, as the hydrolysis product <i>p</i>-nitrophenol of DMNP showed a distinct absorption in the visible light region and spontaneously quenched the inherent fluorescence of D-UiO-66-NH₂(ZrCe) through the inner filter effect. This sensor exhibited a wide detection range (0.4-90 μM) and a low detection limit (0.185 μM). Furthermore, a smartphone-integrated portable platform was well established to enable simple, rapid, and efficient detection of DMNP, thus holding great potential in practical applications for the decontamination and identification of nerve agents.