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

摘要

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.