Acetylcholine enzyme sensor for determining methamidophos insecticide Evaluation of some genetically modified acetylcholinesterases from Drosophila melanogaster

A sensitive screen-printed amperometric sensor suitable for rapid determination of the concentration of the insecticide methamidophos was developed. It was based on the principle of inhibition of acetylcholinesterase (AChE) activity. The first part of the study was focused on the screening of several genetically modified AChEs in order to select the most sensitive enzyme towards the methamidophos. Values for the bimolecular constant ki were also determined. In a second part of the study, we compared the lowest detectable methamidophos concentrations using different immobilised AChEs. The lowest detectable concentration in a standard solution was 1.4ppb for the AChE(Dros)-B03 mutant compared to 4.8ppb for the wild type AChE and 53ppb for the electric eel source.