Acetylcholine biosensor based on dendrimer layers for pesticides detection

We tested a new design of an enzyme biosensor based on acetylcholinesterase (AChE) and choline oxidase (ChO) immobilized on the supported monomolecular layer composed of poly(amidoamine) (PAMAM) dendrimers of the fourth generation (G4) mixed with 1-hexadecanethiol (HDT). The resulting enzymatic activity, measured amperometrically, was substantially depressed in the presence of the organophosphate pesticide dimethyl-2,2-dichlorovinyl-phosphate (DDVP, Dichlorvos), carbamate pesticides carbofuran and carbamate drug eserine. The detection limits (1.3 x 10(-3) ppb for DDVP, 0.01 ppb for carbofuran and 0.03 for eserine) were considerably lower than so far reported for AChE based amperometric and potentiometric sensors. The relative simple protocol of biosensor preparation, high sensitivity and stability is very promising for determination of environmental pollutants in field conditions.