Electrochemical Comparison of the Interaction of 5-Nitrouracil with Single- or Double-Stranded DNA at mercury and glassy carbon electrodes

Abstract

The interaction of the 5-Nitrouracil (5NU), with ss-, and ds-DNA was investigated electrochemically in absence and presence of copper ions by using cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) at hanging mercury drop electrode (HMDE) and glassy carbon electrode (GCE) surfaces. It was found that, in absence of copper ions, the addition of ss- or ds-DNA to a buffered solution of 5NU results in a decrease on the 5NU redox peak current with a remarkable change in the peak potential (ca. 150 mV vs. Ag/AgCl) at both electrodes. This means that, an interaction of 5NU molecules with both ss- and ds-DNA was observed. The results also demonstrate that a distinguish between ss-, and ds-DNA can be achieved in presence of copper ion through their interaction with 5NU. The binding constants of 5NU with ds-DNA at HMDE and GCE were determined through the changes on the 5NU redox peak currents (at HMDE, 1.45x10^5 and at GCE, 2.65x10^5). The calibration plot for the DNA determination was obtained through the corresponding decreases on the DPSV peak current of 5NU to different additions of DNA (ss- or ds-DNA) concentration levels at the optimum conditions.