Impedance characterization of adsorption process of calmodulin on Au substrate and its combination with Ca²⁺

In this paper, the adsorption process of calmodulin (CaM) on Au substrate was first investigated with electrochemical impedance spectroscopy (EIS) method. The result reveals that the adsorption of the protein-calmodulin contains two steps, i.e., one short quick step followed by a slow one. The complexation of calmodulin with Ca²⁺ was also first probed using EIS technique, in which the complexation of CaM with Ca²⁺ could be reflected by the change of apparent membrane capacitance(C_app) clearly. In all above measurements, a redox couple Fe(CN)₆^3-/ Fe(CN)₆^4- was used as probing-pin to reflect all the changes occurring in the above process. Our work suggests that some biological processes of CaM could be studied using EIS method conveniently.