A novel morphine electrochemical biosensor based on intercalative and electrostatic interaction of morphine with double strand DNA immobilized onto a modified Au electrode.

The intercalative and electrostatic interaction of morphine with double-stranded DNA (ds-DNA), which was immobilized onto mercapto-benzaldehyde-modified Au electrode, was employed for designing a sensitive biosensor. The interaction of morphine with the immobilized ds-DNA onto the electrode surface has been studied by differential pulse voltammetry (DPV). Under the optimum conditions, a linear dependence for the morphine concentration in the range of 0.05-500 μmol L(-1) and its oxidation signal were observed and a detection limit of 0.01 μmol L(-1) for the morphine was obtained. The reproducibility and applicability of the analysis to real samples were also investigated and results demonstrated that this DNA biosensor could be utilized for the sensitive, rapid, simple, and cost effective determination of morphine in urine and blood plasma samples.