A novel dual-impedance-analysis EQCM system--investigation of bovine serum albumin adsorption on gold and platinum electrode surfaces.
A novel dual-impedance-analysis EQCM system--investigation of bovine serum albumin adsorption on gold and platinum electrode surfaces.
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DOI：
10.1016/s0021-9797(03)00196-6
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发表时间：
2003-06
影响因子：
9.9
通讯作者：
Q. Xie;Canhui Xiang;Yu Yuan;Youyu Zhang;L. Nie;S. Yao
中科院分区：
文献类型：
--
作者：
Q. Xie;Canhui Xiang;Yu Yuan;Youyu Zhang;L. Nie;S. Yao
石英晶体微天平（QCM）阻抗法和电化学阻抗谱（EIS）法在界面研究中有着广泛的应用。本文提出了一种在QCM阻抗测量仪和EIS测量仪之间，通过在压电石英晶体（PQC）上串联一个合适的电容，实现QCM阻抗和EI同时、无干扰、高精度测量的新方法。在银沉积过程中，QCM阻抗和EIS的组合和单独测量给出了彼此可比的结果，证明了所提出的方法的可靠性。研究了在Britton-Robinson（B-R）缓冲溶液中牛血清白蛋白（BSA）在金电极和铂电极上的吸附行为，并以Fe（CN）63−/Fe（CN）64−电对为电化学探针表征BSA的吸附行为。虽然裸Au和Pt电极上的Fe（CN）63−/Fe（CN）64−电对的可逆性随着溶液pH从pH 7.0降低到pH 7.2而变化很小，但在BSA修饰的Au电极上，该电对的标准速率常数（ks）随着溶液pH低于pH 7.5而突然增加，但在BSA修饰的Pt电极上，该电对的标准速率常数（ks）随着溶液pH而下降。通过对QCM阻抗数据和EI数据的分析，发现在pH = 4.5时，BSA溶液的共振频率、双电层电容、BSA吸附层电容、BSA溶液在277.5和224.5 nm处的峰吸光度、在含有亚铁氰化物的BR溶液中，BSA吸附层可以有效地抑制亚铁氰化物氧化过程中的金腐蚀。对这些发现作了一些初步解释。该方法在表面科学中具有广泛的应用前景。
Both quartz crystal microbalance (QCM) impedance and electrochemical impedance spectroscopy (EIS) methods are widely used in interface studies. This paper presents details about a new strategy for simultaneous, mutual-interference-free and accurate measurements of QCM impedance and EI, through connecting a suitable capacitance in series with the piezoelectric quartz crystal (PQC) between QCM impedance and EIS measurement instruments. Combined and individual measurements of QCM impedance and EIS during silver deposition gave results comparable with each other, demonstrating the reliability of the proposed method. Bovine serum albumin (BSA) adsorption on gold and platinum electrodes in Britton–Robinson (B–R) buffers was investigated, and the Fe(CN)63−/Fe(CN)64−couple was used as an electrochemical probe to characterize BSA adsorption. While the reversibility of Fe(CN)63−/Fe(CN)64−couple on bare Au and Pt electrodes changed very slightly with decreasing solution pH from pH∼7 to pH∼2, the standard rate constant (ks) of this couple increased abruptly with solution pH below pH∼4.5 at a BSA-modified Au electrode, but decreased with solution pH at a BSA-modified Pt electrode. By analyzing the QCM impedance data with a modified BVD equivalent circuit and the EI data with a modified Randle's equivalent circuit, inflexion changes at pH∼4.5 were all found at pH-dependent responses of the resonant frequency, the double-layer capacitance, the capacitance of the adsorbed BSA layer, the peak-absorbance values of BSA solutions at 277.5 and 224.5 nm, and so on. It was also found that a BSA adsorption layer can effectively inhibit gold corrosion during ferrocyanide oxidation in a ferrocyanide-containing BR solution. Some preliminary explanations of these findings have been given. The proposed method is highly recommended for wider applications in surface science.