Abstract:An efficient and convenient method for determining aflatoxin B1 （AFB1） was established. With acetylcholine thio （ATCh） as the substrate， the effect of AFB1 on the bioactivity of acetylcholinesterase （AChE）was studied. The results indicated that thiocholine（TCh） could be adsorbed on the surface of gold nanoparticles （AuNPs） in the form of Au-S covalent form， which led to the polymerization of AuNPs and the gradual color change from burgundy to blue-gray in visible light. Meanwhile， the local surface plasmon resonance absorption peaks at the wavelength of 522 nm decreased in turn. When AFB1 was present in a sample， the biological activity of AChE was inhibited， which reduced hydrolysis of ATCh to TCh. Based on the determination of the change of UV-vis absorption peaks at 522 nm before and after the inhibition， a rapid， simple， and sensitive colorimetric method for the visualization of AFB1 was constructed， which realized and the detection of trace AFB1 in samples. The optimal reaction conditions were as follows： pH7.4， AChE concentration of 2 500 mU/mL， substrate concentration of 5 μmol/L， and reaction time of 60 min. The linear range of AFB1 was 0.1-20 ng/mL， and the limit of detection was 0.03 ng/mL. The spiked recovery of the actual peanut oil samples ranged from 93.4% to 104.9%. The results indicated that the established method had high sensitivity and accuracy for the determination of AFB1 in food.