A sensitive and selective fluorescent probe for acetylcholinesterase: Synthesis,performance, mechanism and application

The detection of acetylcholinesterase (AChE) activity is of great significance for studying the physiological functions of AChE and clinical diagnosis of pesticide poisoning. Herein, a small-molecule fluorescent probe BDFA was rationally designed and readily synthesized via a one-step reaction, which enables qualitative and quantitative detection of AChE. BDFA emits a slight fluorescence in an aqueous medium, while the fluorescence is significantly enhanced under the catalysis of AChE. Mechanism studies reveal that BDFA eliminates the N, N-dimethyl carbamate protective group in the presence of AChE and then spontaneously undergoes intramolecular cyclization conversion to generate an intense fluorescent product. Based on the above mechanism, BDFA exhibits a sensitive, selective, rapid and stable “turn-on” fluorescence response to AChE, without interference from pH, ions, thiols, amino acids and other enzymes. The fluorescence intensity of BDFA at 525 nm has a linear relationship with the AChE concentration in the range of 0.0045–1.0 U/mL, and the detection limit is 4.5 mU/mL. Moreover, BDFA is suitable for rapidly diagnosing AChE activity in blood samples, thus providing an efficient and convenient tool for diagnosing organophosphorus and carbamate pesticide poisoning. Compared with the reported AChE fluorescent probes, BDFA exhibits apparent advantages including simple synthesis, low detection limit and fast response speed.