Sensitive detection of pesticides using a differential ISFET-based system with immobilized cholinesterases

Abstract

Organophosporus pesticides were determined using a simple biosensor design. Enzymatic membranes prepared by cross-linking with BSA were deposited on a sensor chip consisting of two identical pH-FETs working in the differential mode (ENFET with enzyme, REFET without enzyme). Acetyl- and butyrylcholinesterase membranes were tested using acetyl- and butyrylcholine chloride as substrates. The decrease in the substrate steady-state response caused by exposure of the biosensor to pesticides [diisopropyl fluorophosphate (DFP), trichlorfon, paraoxon-methyl] was used to estimate the enzyme inhibition. The optimized parameters for the measurement procedure were determined and the detection limits were found to be 10-12 M for DFP and 10-6 M for paraoxon-methyl and trichlorfon. © 1993.