Direct electrochemical behavior of cytochrome c on DNA modified glassy carbon electrode and its application to nitric oxide biosensor

Cytochrome c/DNA modified electrode was achieved by coating calf thymus DNA onto the surface of glassy carbon electrode firstly, then immobilizing cytochrome c on it by multi-cyclic voltammetric method and characterized by the electrochemical impedance. The electrochemical behavior of cytochrome c on DNA modified electrode was explored and showed a quasi-reversible electrochemical redox behavior with a formal potential of 0.045 ± 0.010 V (versus Ag/AgCl) in 0.10 M, pH 5.0, acetate buffer solution. The peak currents were linearly with the scan rate in the range of 20-200 mV/s. Cytochrome c/DNA modified electrode exhibited elegant catalytic activity for the electrochemical reduction of NO. The catalytic current is linear to the nitric oxide concentration in the range of 6.0 × 10⁻⁷ to 8.0 × 10⁻⁶ M and the detection limit was 1.0 × 10⁻⁷ M (three times the ratio of signal to noise, S/N = 3).