Etude de différentes méthodes de biofonctionnalisation pour la ...

Iii. Etudes du film Lan gmuir-Blodgett enzymatique
Mixed enzyme Langmuir-Blodgett films for
organophosphorus pesticide ENFET biosensor
K. Wan1, J.M. Chovelon"2, and N. JaffrezicRenauItI*
tFOS, UMR CNRS 5621, Ecole Centrale de Lyon, BP 163, 69131 Ecully Cedex (France)
LACE, UMR CNRS 5634, Université Claude Bernard-Lyon I, 69622 Villeurbanne (France)
* Author to whom correspondence should be addressed
Abstract
LB films containing Butyryicholinesterase (BuChE)
are fabricated to realize an enzymatic
field effect transistor (ENFET) for the detection of organophosphorus pesticides in water. Trichlorfon
as a common pesticide is chosen in our work. The BuChE-immobilized LB films are formed by
adsorbing the enzyme molecules onto a stearylamine monolayer. The surface characteristics of
BuChE/stearylamine LB films obtained under various conditions of the dipping surface pressures are
analyzed qualitatively
by the atomic force microscopy (AFM) and analyzed quantitatively by FTIR
spectroscopy. Enzyme/stearylamine mixed LB films are immobilized onto ISFET surface and treated
by glutaraldehyde vapor to improve the LB film stability. The ENFET thus obtained worked as a
potentiometric biosensor for trichlorfon detection on the basìs of enzyme inhibition. The detection limit
for trichlorfon can reach i07 M.
Keywords: Langmuïr-Blodgett films; organophosphorus pesticide; ENFET biosensor; Fourier
transformed infrared spectroscopy; atomic force microscopy.
1. Introduction
Since pesticides are among the most toxic products of the chemical industry, the detection of the
ground water contamination has been needed for the control of water supply. lt is known that
butyrylcholinesterase (BuChE) and acetyicholinesterase (AChE), the essential enzymes in the nerve
tissue, are inhibited by organophosphorus compounds widely used as pesticides and nerve toxin for
107