Electrochemical monitoring of the interaction of UO22+ with immobilized DNA

Abstract

Interaction of uranyl ion (UO22+) with immobilized double strand calf thymus DNA (ds-ct-DNA) on zirconium attached gold-mercaptopropionic acid self-assembled monolayer (Au-MPA-Zr(IV) SAM) is monitored by electrochemical techniques. The results show that after 15min proximity of the immobilized DNA with UO22+, the peak currents of the square wave voltammograms are decreased (about 80%), and the equivalent circuit model of electrochemical impedance spectroscopy (EIS) data, requires two constant phase elements (CPE) instead of only one. By using the surface concentration of DNA (≈2.3×10-13mol/cm2) and the number of the anthraquinonedisulfonic acid (AQDS) adsorbed on DNA (1.34×10-10mol/cm2) the ration of AQDS per DNA base pairs is obtained ≈1/30 before proximity to UO22+. Based on EIS technique, we find that the double strand structure of immobilized DNA on the electrode surface has been changed (damaged) by UO22+. This modified electrode has potential of becoming a screening tool for the rapid assessment of the interaction and genotoxicity of existing and new chemicals. © 2013 Elsevier B.V.