Analytical Sciences

Direct Electrochemical Behavior of Cytochrome c on DNA-modified Glassy Carbon Electrode and Its Application to Cytochrome c Biosensor

Yun-Chun LIU, Shi-Qiang CUI, and Zhou-Sheng YANG

School of Chemistry and Materials Science, Anhui Key Laboratory of Functional Molecular Solids, Anhui Normal University, Wuhu 241000, P. R. China

DNA was immobilized on glassy carbon electrodes to fabricate DNA-modified electrodes. The direct electron transfer of horse heart cytochrome c on DNA-modified glassy carbon electrode was achieved. A pair of well-defined redox peaks of cytochrome c appeared at E_pc = -0.017 V and E_pa = 0.009 V (vs. Ag/AgCl) in 10 mM phosphate buffer solution (pH 7.0) at a scan rate of 50 mV/s. The electron transfer coefficient (α) and the standard rate constant of the surface reaction (K_s) of cytochrome c on DNA-modified electrodes could be estimated to be 0.87 and 34.52 s^-1, respectively. The DNA-modified glassy carbon electrode could be applied to detect cytochrome c by means of differential pulse voltammetry (DPV). The cathodic peak current was proportional to the quantity of cytochrome c in the range of 4.0 × 10^-6 M to 1.2 × 10^-5 M. The correlation coefficient is 0.996, and with the detection limit was 1.0 × 10^-6 M (three times the ratio of signal to noise, S/N = 3).

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