Abstract: Acetylcholinesterase (AChE) liposomes bioreactor (ALB), prepared by encapsulating the enzyme AChE into L-α- phosphatidylcholine liposomes, was spherical in shape. A novel AChE biosensor based on multilayer films containing SiO2, chitosan (CS) and ALB was developed. The results showed that ALB had a mean diameter of (7.26 ± 0.75) μm. The biosensor based on six bilayers of multilayer films was the best. The properties of the biosensor were evaluated by electrochemical measurements. Based on the inhibition of organophosphate pesticides on the AChE activity, by using dichlorvos as a model organophosphorus compound, we observed that the inhibition of dichlorvos was proportional to its concentration within the range from 0.25 to 1.75 μmol/L and from 2.00 to 10.00 μmol/L, and the corresponding equations were I = 28.58C + 5.35 and I = 2.38C + 51.25, with a detection limit (LOD) of (0.72 ± 0.065) μg/L estimated at a signal-to-noise ratio of 3. The fabrication of the biosensor was simple, with fast response and acceptable selectivity.

Key words: food safety, pesticide residue, biosensor, SiO2, liposome