Electrochemical probe of natural DNA attached onto the gold–thiol SAMs via Zr(IV) ion glue

Attachment of natural double strand calf thymus DNA onto gold–mercaptopropionic acid self-assembled monolayer electrode via Zr(IV) ion glue, Au–MPA–Zr(IV)-ds-ct-DNA SAM, is studied. The sequential assembly of the layers on the Au surface is traced by electrochemical methods including cyclic and square wave voltammetries in the presence of methylene blue. The results show that DNA is attached to Zr(IV) via its phosphate groups without any contribution from its bases. Effects of the MB concentration on the behavior of adsorbed MB, ionic strength on the MB adsorption, and pH on the amount of immobilized DNA are studied. The proposed method for the preparation of the new template, the Au–MPA–Zr(IV)-ds-ct-DNA, is relatively simple and fast. Long-term stability of this electrode is tested by keeping the template at pH 3, and carrying out a daily electrochemical study at pH 7.4. Under these circumstances, the Au–MPA–Zr(IV)-ds-ct-DNA electrode showed stable behavior for one week.