DEVELOPMENT OF SPECIFIC ELECTROCHEMICAL BIOSENSOR BASED ON CHITOSAN MODIFIED SCREEN PRINTED CARBON ELECTRODE FOR THE MONITORING OF CAPTAN FUNGICIDE

Abstract

Harmful chemicals predominantly used in modern agriculture for pest control have raised a
long-term accumulation in the environment and serious problems concerning food safety and health.
Excellent detection tools for environmental monitoring are thus urgently needed. The recent biosensor
technology is proposed to fulfill this purpose. In this study, an expedient biosensor for captan fungicide
determination has been fabricated using its specific reacting enzyme glutathione-s-transferase (GST)
covalently immobilized on natural biopolymer chitosan (Chi). The screen-printed carbon electrode (SPCE)
has been selected as a basal platform for the biosensor development. Modification of SPCE was made by
self-assembled deposition of 1% chitosan in 1% acetic acid solution onto the basal SPCE. Progressive
characteristics of the assembled SPCE-Chi-GST have been clearly approved by atomic force microscopy,
impedance spectroscopy and cyclic voltammetry (CV). Two sequential oxidation peak currents arose in the
electrochemical behavior analysis of captan in the presence of GST substrate electrolyte solution by CV and
linear sweep voltammetry (LSV). Dose-response to various captan concentrations was investigated in the
range 0 – 20 μg/ml by LSV and a similar good linear relationship between peak current and concentration of
captan could be obtained by both oxidation steps with the limit of detection (LOD) at 0.2 μg/ml. Thus the
sensitive, rapid, inexpensive and miniature quantitative system for captan monitoring could now be
successfully achieved by this proposed biosensor.