基于ITO电极的细胞色素c吸附层的直接电化学

采用未经修饰的铟锡氧化物(ITO)工作电极直接探测到了细胞色素c(Cytc)吸附层的氧化还原峰,并得出了Cytc的表面浓度,随着溶液浓度从2μmo·lL-1增大到10μmo·lL-1,Cytc的表面浓度相应地从0.35×10-12mo·lcm-2增大到1.53×10-12mo·lcm-2.实验获得的表面浓度倒数与溶液浓度倒数的准线性关系说明Cytc在ITO表面的吸附基本满足Langmuir等温吸附理论.对Cytc溶液的循环伏安测试结果表明参与电极反应的Cytc包括游离分子和吸附分子,前者的贡献大于后者,电极反应主要受扩散控制并呈准可逆过程.根据Nicholson方法估算得到反应物的标准异相速率常数的平均值为1.65×10-3cm·s-1.实验结果显示在室温下放置1h后Cytc吸附层电化学活性部分丧失,在80℃下放置1h后吸附层完全失活.失活的Cytc吸附层对铁氰化钾溶液在Au电极上的电极反应具有明显的阻碍作用.

Direct Electrochemistry of Cytochrome c Adlayer on the ITO Electrode

The electrochemical redox reaction of a cytochrome c(Cyt c)adlayer on an indium tin oxide(ITO)electrode was directly monitored and the surface concentrations of Cyt c versus solution concentrations were obtained from cyclic voltammograms.The results indicate that the surface concentration increases from 0.35×10-12 to 1.53×10-12 mol·cm-2 when the solution concentration is increased from 2 to 10μmo·lL-1.A quasi-linear relationship between the reciprocals of surface concentration and solution concentration was observed,indicating that Cyt c adsorption on the ITO electrode closely obeys the Langmuir isothermal adsorption model.The cyclic voltammograms of the Cyt c solutions with the ITO electrode reveal that both adsorbed and dissociated Cyt c molecules are involved in the electrode reaction and that the contribution of dissociated molecules is much larger than that of adsorbed ones.The electrode reaction is basically diffusion controlled and quasi-reversible.Based on the Nicholson method,the average standard heterogeneous rate constant was determined to be 1.65×10-3 cm·s-1.The electrochemical activity of the Cyt c adlayer was partially lost when it was kept at 25℃ for 1 h,and was completely lost at 80℃.The denatured Cyt c adlayer on a gold electrode can effectively inhibit the electrode reaction of K 3 Fe(CN) 6 solution.