The electrochemical behavior of ferrocene and its complex with DNA

The electrochemical behavior of ferrocene (Fc) and its interaction with calf thymus DNA at a rotating disk electrode modified with carbon nanotube (CNT) in Tris-NaCl buffer solution (pH=7.2) have been investigated by using cyclic voltammetry, differential pulse voltammetry, rotating disk electrode measurement, and electrochemical impedance spectrum. It is found that a pair of reversible redox waves for Fc are exhibited in the absence and presence of DNA on the immovable CNT-modified electrode. When the modified electrode is rotating, a distinct limiting diffusion current appears. Nyquist plot of Fc shows a suppressed half-circle in the absence and presence of DNA on the rotating CNT-modified electrode. Moreover, there exists an interaction of Fc with DNA under diffusion control based on the decrease of the peak current and limiting diffusion current with the increase of DNA concentration. On the other hand, the interaction between Fc and DNA under electrochemical control is also studied, the results show that the electrochemical reaction resistance of Fc exhibiting on the rotating disk electrode increases with the addition of DNA, and the rate constant at the formal potential decreases in the presence of DNA compared with that in the absence of DNA.