UiO-66@MnO2: A fluorescent nanozyme for dual-mode sensing of acetylcholinesterase activity and organophosphorus pesticides

The determination of acetylcholinesterase (AChE) activity and organophosphorus pesticides plays a critical role in disease diagnosis, drug screening, and food safety monitoring. In this study, we report a multifunctional UiO-66@MnO 2 nanocomposite that integrates both oxidase-mimicking activity and intrinsic fluorescence, enabling dual-mode colorimetric and fluorescence sensing. MnO 2 nanosheets anchored on the surface of the UiO-66 not only catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) but also efficiently quenched the fluorescence of UiO-66 via Förster resonance energy transfer. Upon the addition of acetylthiocholine and AChE, the enzymatic generated thiocholine reduces MnO 2 , resulting in disassembly of the nanocomposite. This triggers a “turn-off” colorimetric signal and a “turn-on” fluorescence response, enabling sensitive detection of AChE with detection limits as low as 0.076 mU/mL (colorimetric) and 3.8 mU/mL (fluorescence). Furthermore, taking advantage of the inhibitory effect of organophosphorus pesticides on AChE activity, the proposed platform was further successfully extended to detect dipterex, achieving detection limits of 0.032 μM (colorimetric) and 1.1 μM (fluorescence). Moreover, the dual-mode nanozyme sensor was successfully validated in complex biochemical samples, highlighting its considerable potential for applications in bioanalysis, food safety monitoring, and environmental surveillance.