Fluorescence sensor for facile and visual detection of organophosphorus pesticides using AIE fluorogens-SiO2-MnO2 sandwich nanocomposites.

Organophosphorus pesticides (OPs) are frequently for pest control in the agriculture industry. Accumulation of OPs is harmful to the environment and human health. Thus, facile and portable detection of organophosphorus pesticides is of great importance. Among these methods, the fluorescence assay holds the advantages of high sensitivity, simplicity, nondestructive properties. Conventional fluorophores have the drawbacks of poor photostability and low signal-to-noise ratio due to their aggregation-caused quenching drawbacks at high concentration or in the aggregate state. Aggregation-induced emission fluorogens (AIEgens) are one key to develop next-generation fluorescence sensor due to their high emission efficiency in the aggregated state. 1,2-bis[4-(3-sulfonatopropoxyl) phenyl]-1,2-diphenylethene (BSPOTPE) is a typical AIE molecule containing two hydroxyl group. In this study, a fluorescence sensor based on BSPOTPE-SiO2-MnO2 sandwich nanocomposites was fabricated. Thiocholine (TCh), which produced from acetylthiocholine(ATCh) by the hydrolysis of acetylcholinesterase (AChE), can "turn on" the fluorescence sensor. Based on the inhibition effect of OPs on AChE activity and the corresponding "turn off" effect on the fluorescence sensor, an AIE-based assay for OPs determination was developed. The fabricated sensor for paraoxon determination has a good linear relationship in the range of 1-100 μg/L and the LOD of 1 μg/L. Moreover, a simple, convenient fluorescence strip for visual semi-quantitative of OPs was fabricated, indicating this "on-off" fluorescent sensor is promising for on-site and infield detection.