Electrochemical monitoring of the interaction of UO22Â + with immobilized DNA

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 15 min 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− 13 mol/cm2) and the number of the anthraquinonedisulfonic acid (AQDS) adsorbed on DNA (1.34 × 10− 10 mol/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.