Highly toxic organophosphorus nerve agents often exist in the form of gas in the environment and can damage human neuroregulatory system by inhibiting the activity of acetylcholinesterase (AChE). However, fluorescent probes based on small organic molecules bring a secondary burden to environment, and their sensitivity and specificity for sarin simulant diethyl chlorophosphate (DCP) detection are unsatisfactory. Nanozyme cascade systems with signal amplification can be used for highly sensitive identification of analytes, but are rarely used in ratiometric analysis of DCP. Combination of enzyme cascades and ratiometric fluorescence ensures the accuracy and sensitivity of the output signal. We prepared a self-assembled nanohybrid (Ag–AuNCs@UiO-66-NH) by metal-organic framework material and gold nanoclusters. On the one hand, UiO-66-NH with enzyme-like activity was used to hydrolyze DCP into diethyl phosphate (DEP) and chloridion (Cl). Cl hindered aggregation-induced enhanced emission (AIEE) of AuNCs by binding with Ag and decreased the fluorescence of AuNCs. On the other hand, ligand metal charge transfer effect (LMCT) of UiO-66-NH was blocked by DCP to enhance the fluorescence of UiO-66-NH. Combining ratiometric analysis and nanozyme cascade reaction, an ultra-sensitive fluorescence sensor for detecting DCP was constructed, and ensured the accuracy of experimental results. In addition, Ag–AuNCs@UiO-66-NH was embedded into the agarose hydrogel substrate, the resulting agarose hydrogel film allowed quantitative assessment of DCP vapor and high sensitivity was demonstrated (detection limit as low as 1.02 ppb). A strategy combining enzyme cascade with ratiometric fluorescence was proposed, which improved the accuracy and sensitivity of the analysis results. The soft-solid platform based on agarose hydrogel film was constructed to realize the quantitative monitoring of sarin simulant gas. The LOD value obtained in this work is much lower than the immediately life-threatening or health threatening concentration of sarin.

中文翻译：

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UiO-66-NH2引发级联反应：构建用于超灵敏检测神经毒剂模拟物的比率荧光传感器

高毒有机磷神经毒剂常以气体形式存在于环境中，可通过抑制乙酰胆碱酯酶（AChE）的活性来损害人体神经调节系统。然而，基于有机小分子的荧光探针给环境带来了二次负担，其对沙林模拟物氯磷酸二乙酯（DCP）检测的灵敏度和特异性并不令人满意。具有信号放大功能的纳米酶级联系统可用于高灵敏度的分析物鉴定，但很少用于 DCP 的比率分析。酶级联和比例荧光的结合确保了输出信号的准确性和灵敏度。我们通过金属有机骨架材料和金纳米团簇制备了自组装纳米杂化物（Ag–AuNCs@UiO-66-NH）。一方面，利用具有类酶活性的UiO-66-NH将DCP水解成磷酸二乙酯（DEP）和氯离子（Cl）。 Cl 通过与 Ag 结合阻碍 AuNC 的聚集诱导增强发射（AIEE）并降低 AuNC 的荧光。另一方面，UiO-66-NH的配体金属电荷转移效应（LMCT）被DCP阻断，增强了UiO-66-NH的荧光。结合比例分析和纳米酶级联反应，构建了检测DCP的超灵敏荧光传感器，保证了实验结果的准确性。此外，将Ag-AuNCs@UiO-66-NH嵌入琼脂糖水凝胶基质中，所得琼脂糖水凝胶膜可以对DCP蒸气进行定量评估，并表现出高灵敏度（检测限低至1.02 ppb）。提出了酶级联与比率荧光相结合的策略，提高了分析结果的准确性和灵敏度。构建基于琼脂糖水凝胶膜的软固体平台，实现沙林模拟气体的定量监测。这项工作中获得的 LOD 值远低于立即危及生命或健康的沙林浓度。