酶抑制结合聚集诱导发光用于中药中有机磷农药快速检测研究

Pesticide residue in Traditional Chinese Medicine (TCM) affected the safety of TCM. The analysis of organophosphorus pesticides (OPs) has received increasing attention due to their potential harm to humans and other creatures. Therefore, there is an urgent need to develop rapid detection techniques of OPs. Enzyme inhibition is one of the most popular rapid detection methods. However, the conventional UV spectrophotometry has low sensitivity and narrow linearity region, and the fluorophores have the drawbacks of aggregation caused quenching (ACQ). The newly emerged aggregation-induced emission fluorogens (AIEgens) are featured with high emission efficiency in the aggregated state, which provide unique opportunities for various sensing applications with advantages of high signal-to-noise ratio, strong photostability, and good portability. In order to deal with these difficulties faced by conventional method, an on-site rapid detection method of OPs in TCM was developed based on enzyme inhibition combined with aggregation induced emission (AIE). In this study, tetraphenylethene derivative (TPE), silica nanopheres (SiO2 NPs), MnO2 nanosheets were synthesized. TPE can be aggregated and emitted strong fluorescence on SiO2 NPs due to the electrostatic adsorption. The fluorescence can be effectively quenched by MnO2 nanosheets, which form a AIE fluorescence sensor. Thiocholine, which was produced from acetylthiocholine by the hydrolysis of acetycholinesterase (AChE), could cause the decomposition of MnO2 nanosheets and the corresponding recovery of fluorescence quenching. Based on the irreversibly inhibited effect of OPs on the catalytic activity of AChE, a AIE-based sensing platform for OPs determination is expect be established. In addition, AIE based test strips are expected to be developed for portable detection. It is expected that AIE sensor developed from this work will have a great potential for applications in TCM safety and monitoring.

有机磷农药使用广泛、毒性强、检出频率高，严重影响中药质量安全，因此中药中有机磷农药的快速检测十分必要。酶抑制快速检测应用普遍，但紫外分光光度法灵敏度低、线性范围窄；荧光法的荧光材料易聚集发生自淬灭，导致灵敏度降低。“聚集诱导发光”（AIE）材料在聚集态或固态发光增强，能够提高信号/噪声比，具有较好的光稳定性和便携性。本项目拟针对传统快检方法出现的难题，利用酶抑制和AIE探针，建立有机磷农药AIE检测方法，满足中药市场快速检测需求。项目拟制备四苯基乙烯衍生物（AIE分子）、二氧化硅纳米颗粒和二氧化锰纳米片。前两者通过静电吸附作用聚集发光，后者淬灭荧光，三者形成AIE探针。硫代胆碱（乙酰胆碱酯酶水解产物）能分解后者，从而使荧光恢复。有机磷农药抑制酶活性，其浓度和AIE强度呈一定相关关系。在此基础上，利用AIE材料固态发光特性，制备试纸条，最终实现有机磷农药便携式现场快速检测。

有机磷农药使用广泛、毒性强、检出频率高，影响中药质量安全，因此中药中有机磷农药的快速检测十分必要。有机磷农药的快速检测一般是基于酶抑制的比色检测或者分光光度法，但现有的比色检测易受基质的影响，分光光度法灵敏度低、线性范围窄。另外一方面，新开发的荧光分析法的荧光材料易聚集发生自淬灭，导致灵敏度降低。聚集诱导发光(AIE)材料在聚集态或固态发光增强，能够提高信号/噪声比，具有较好的光稳定性和便携性。本项目制备了1,2-双[4-(3-磺酸丙氧基)苯基]-1,2-二苯乙烯钠盐(BSPOTPE)、二氧化硅纳米粒和二氧化锰纳米片，并对他们进行了表征。由于静电相互作用，二氧化硅纳米粒使BSPOTPE产生聚集诱导发光(AIE)，二氧化锰纳米片能够使荧光淬灭，基于他们的相互作用，建立一种AIE荧光探针。硫代乙酰胆碱在乙酰胆碱酯酶的作用下分解为硫代胆碱，其可以使二氧化锰纳米片分解，并使AIE探针荧光恢复。有机磷农药可以抑制乙酰胆碱酯酶活性，从而使荧光恢复的程度减少。试验结果表明，荧光恢复的减弱程度(I)与反应溶液中有机磷（以对氧磷为例）浓度的对数值(LogC)成线性相关的关系。中药中有机磷农药经过提取、净化前处理后，加入到酶反应体系中，经过与标准比色试纸条对比，可以实现半定量的可视化检测。本方法能够实现有机磷农药的快速可视化检测，为中药等复杂基质的农药检测提供一条新途径。