Vol. 137, Issue 2, February 2012, pp. 226-234

Abstract: In this paper, a novel acetylcholinesterase (AChE) biosensor for organophosphorus (OP) pesticides detection was constructed by modifying glassy carbon electrode (GCE) with gold nanoparticles/chitosan dual-layer membranes. The dual-layer membranes were included in chitosan membrane coated with physically bound AChE to recognize pesticides selectively and gold nanoparticles (GNPs) membrane directly deposited on the surface of GCE to enhance electron transfer rate. During the detection, the chitosan membrane was quickly fixed on the surface of GNPs/GCE with O-ring. Since GNPs process high electron-transfer ability, moreover, chitosan membrane can provides a microenvironment around the enzyme molecule to stabilize its biological activity and prevents the enzyme leaking out effectively. The combination of GNPs and chitosan dual-layer membranes promoted electron transfer and catalyzed the electro-oxidation of thiocholine, thus amplified the detection sensitivity. Using dichlorvos omethoate, trichlorfon and phoxim as model compounds, the inhibition rates of these pesticides were proportional to their concentrations in the range of 0.05~10 μg/l, 0.1~50 μg/l, 0.1~50 μg/l, and 0.2~50 μg/l with a detection limit of 30 ng/l for dichlorvos, 80 ng/l for omethoate, 60 ng/l for trichlorfon and 100 ng/l for phoxim respectively. The biosensor exhibited high sensitivity, good reproducibility and stability, and it was suitable for trace detection of OP pesticide residue.

Keywords: Biosensor, Gold nanoparticles, Acetylcholinesterase, Pesticides residues

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