Electrochemical Behavior of Cytochrome c on Exfoliated Graphite Electrode Modified with DNA

DNA was immobilized on exfoliated graphite electrode to fabricate DNA-modified electrode. The direct electron transfer of horse heart cytochrome c on DNA-modified exfoliated graphite electrode was achieved.  A pair of well defined redox peaks of cytochrome c appeared at E_pc = –0.018 V and E_pa = 0.09 V (vs. SCE) in 0.1 M phosphate buffer solution of pH 7.0 at a scan rate of 50 mV/s.  The DNA- modified exfoliated graphite electrode could be applied to detect cytochrome c by means of cyclic voltammetry (CV) and differential pulse voltammetry (DPV).  The peak current increased with increasing amounts of DNA on the surface of an electrode, and then the magnitude of the peak current trended to be unvarying.  It is suggested that the electrochemistry at the EG electrode is essentially governed by favourable electrostatic interactions.