Application of gold–silver nanocluster based fluorescent sensors for determination of acetylcholinesterase activity and its inhibitor

AuAg nanoclusters (AuAgNCs) with high fluorescent was synthetize. The fluorescence of the AuAgNCs was quenched by thiocholine (TCh), a product of the catalytic hydrolysis of acetylthiocholine (ATCh) by acetylcholinesterase (AChE). In the presence of paraoxon (a AChE inhibitor), the catalytic hydrolysis of ATCh was blocked, and then the fluorescence of the AuAgNCs was retained to some degree. Based on this mechanism, the AuAgNCs with high fluorescence was first time used to detect the AChE and AChE inhibitors. Under the optimal conditions, the linear range of this method for AChE was 0.4–25 mU/mL with the detection limit of 0.15 mU/mL, which compare favorably to previously reported methods with more widely linear range or much lower detection limit. And for the detection of paraoxon, the corresponding IC50 was estimated to be 1.9 ng/mL. This method was also utilized to detect the paraoxon in apple samples successfully. This study provides a new selective and sensitive fluorescent assay for determination of AChE activity and AChE inhibitor, and expands the application of AuAgNCs in biological analysis.