DNA-based electrochemical biosensor using chitosan–carbon nanotubes composite film for biodetection of Pirazon

Abstract

The interaction of Pirazon (PIR) with calf thymus ds-DNA (double-stranded Deoxyribonucleic acid) in solution and immobilized DNA on chitosan–carbon nanotubes composite modified gold electrode was investigated by electrochemical and UV-Vis spectroscopy techniques. In solution interactions, spectroscopic results indicate non-intercalative binding of PIR. A competition study with methylene blue, as an intercalative probe, was applied to confirm the binding mode of PIR. PIR showed an oxidation peak at 1.1 V at the bare Au electrode. When ds-DNA was added into the PIR solution, its peak current decreased. Au electrode modified with single wall carbon nanotube (SWCNT) and chitosan (CS) decorated with the ds-DNA were tested to determine PIR content in solution. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to characterize the electrochemical properties of the modified electrode. The modified electrode surface has good reproducibility and stability. The modified electrode exhibited linear detection range, 5×10-9 to 5×10-5 M, with a detection limit of 1×10-10 M.