DISPOSABLE SCREEN-PRINTED BIOSENSORS FOR THE DETECTION OF PESTICIDES

摘要

A disposable amperometric biosensor for the detection of pesticides has been prepared using two different enzymatic systems. The carbon-based electrodes were realised with the screen-printing technique that allows to obtain electrodes simply and inexpensively. The first one is a two-enzymes system based on acetylcholinesterase (AchE) and choline oxidase (ChOD). Three different arrangements were tested either with only one of the two enzyme immobilised, either with both. The second one is based on AChE and is a single-enzyme system, with acetylthiocholine (ATCh) as substrate. In both systems the steady-state current was used as a measure of the enzyme activity. In the presence of pesticides, an irreversible inhibition of AChE occurred, resulting in a decrease in the rate of current change. The inhibition assays was performed with the organophosphorus pesticide Paraoxon, which has proved to be a strong inhibitor of cholinesterase enzymes. Two different methods were tested to enhance the inhibition effects. Pesticide was added during the measurement or by a preincubation. When the analysis was performed by 10-min preincubation of the biosensor with sample, Paraoxon in concentration about 30 nM could be detected.