Voltammetric Determination of 6-mercaptopurine at Co(III) Trisphenanthroline Complex and DNA Decorated with Grpahene Oxide Modified Glassy Carbon Electrode

A Cobalt (III) trisphenanthroline complex ([Co(phen)3] 3+ ) has been adsorption assembled on a glassy carbon electrode (GCE) modified with DNA decorated with graphene oxide (GO) by multiple sweep voltammetry. In the present protocol, GO is served as a functional unit of DNA to greatly improve the efficient immobilization of DNA on the GC electrode and also offer a favorable microenvironment to keep the DNA structure of double-stranded (dsDNA), which facilitates the intercalation of redoxactive [Co(phen)3] 3+ . The evidences from scanning electron microscope, X-ray diffraction, cyclic voltammetry, electrochemical impedance spectroscopy, emission spectroscopy and differential pulse voltammetry reveal that [Co(phen)3] 3+ can be assembled on the surfaces of GO-decorated dsDNA driven by electrostatic attraction, intercalation and π-stacking interaction. Furthermore, the highly stable [Co(phen)3] 3+ /GO-dsDNA/GCE is used to the highly selective determination of 6- mercaptopurine (6-MP) in the human blood with satisfactory. The reduction peak current was linear to 6-MP concentration in the range from 5×10 -8 to 2×10 -6 M 6-MP, and the detection limit is 1.5×10 -8 M ( S / N = 3)