Interaction study of ss-DNA and Yb 3+ ions in aqueous solutions by electrochemical and spectroscopic techniques

Abstract

In this work, for the first time the electrochemical behavior of the Yb 3+ and Yb 3+ ion interactions with short single strand DNA (ssDNA) sequence at two pHs was studied. Then the UV–vis spectroscopic method was used for supporting these pieces of evidence. The interaction between Yb 3+ and ssDNA has different binding modes at different pHs. The ratio between [Yb 3+] and [ssDNA] is dependent to pH and pK a of DNA bases. In pH 3.7, Yb 3+ binds to ssDNA mainly by electrostatic attraction. Binding number, n, of 2 of Yb 3+ per ssDNA and binding constant were obtained with Cyclic Voltammetry (CV) and differential pulse voltammetry (DPV) methods, respectively. In this pH, the bases of ssDNA are totally protonated and Yb 3+ interacts electrostatically with phosphate groups. The UV–vis study showed similar results. The results at pH 5.5 show that Yb 3+ can bind to ssDNA with electrostatic and covalent bonds. In this pH, besides phosphate groups, the bases can be interacted to Yb 3+, too. The binding number 4 of Yb 3+ per ssDNA was obtained. Computational studies were done and confirmed the result of experimental data. The agreement mutually verifies the accuracy of the methods.