A facial and efficient method for the screening of acetylcholinesterase (AChE) inhibitors by capillary electrophoresis was developed. Based on the specific affinity of concanavalin A (Con A) for binding to the glycosyl group of AChE, enzyme molecules were oriented-immobilized on the surface of gold nanoparticles (AuNPs@Con A@AChE). Then, these modified nanoparticles were bounded to the capillary inlet (about 1.0 cm) by electrostatic self-assembly to obtain the oriented-immobilized enzyme microreactor (OIMER). Compared to an IMER with a free enzyme, the peak area of the product obtained by the OIMER increased by 52.6%. The Michaelis-Menten constant (Km) was as low as (0.061 ± 0.003) mmol/L. The method exhibits good repeatability with a relative standard deviation (RSD) of 1.3% for 100 consecutive runs. The system was successfully applied to detect the IC50 values of donepezil and four components from Chinese medicinal plants. This work demonstrates the potential of this method as a low cost, simple, and accurate screening method for other enzyme inhibitors.
Keywords: acetylcholinesterase; capillary electrophoresis; enzyme inhibitor screening; gold nanoparticles; oriented-immobilized enzyme microreactor.