An impedimetric biosensor based on poly(l-lysine)-decorated multiwall carbon nanotubes for the determination of diazinon in water and fruits

A new electrochemical biosensor is developed for the detection of diazinon. For this purpose, a glassy carbon electrode is modified with MWCNTs and poly- l -lysine to immobilize a double-strain DNA (ds-DNA) on the surface of the electrode. In the first step, the interaction of diazinon with ds-DNA is transduced by electrochemical impedance spectroscopy and UV–Vis spectroscopy to monitor the intercalation of diazinon with DNA helix. This interaction leads to reduced interfacial charge-transfer resistance ( R ct ). The difference in the R ct before and after the interaction is considered as a suitable signal for diazinon detection. The proposed biosensor has a low detection limit (0.3 nmol L −1 ), a wide linear dynamic range (0.001‒100 µmol L −1 ), and high selectivity for the determination of diazinon. Finally, the performance of the biosensor for detecting of diazinon is verified in real samples such as river water, agricultural wastewater, lettuce juice, and tomato juice.