Nanochemistry Research Institute, Department of Chemistry, Curtin University, G.P.O. Box U1987, Perth, Western Australia 6845, Australia.
Anal Chem. 2013 Feb 5;85(3):1389-94. doi: 10.1021/ac302222u. Epub 2013 Jan 17.
The impact of surfactant addition to the organic phase on the electroactivity of proteins at the aqueous-organogel interface was examined by voltammetry. The presence of bis(2-ethylhexyl)sulfosuccinate (AOT) in the organogel phase, as the sodium salt, caused marked changes in the peak currents for myoglobin detection. The protein desorption voltammetric peak exhibited a 6-fold increase in the current compared to the corresponding experiment without surfactant. Interfacial coverage showed a 17-fold increase in the adsorbed protein at the interface, from 50 pmol cm(-2), in the absence of surfactant, to 850 pmol cm(-2), in the presence of 10 mM surfactant. Additionally, the presence of the surfactant resulted in a second pair of adsorption/desorption peaks at lower potentials and in a change in the capacitance of the system. The formation of surfactant-protein and surfactant-protein-organic anion deposits is proposed on the basis of these features, leading to increased voltammetric signals for myoglobin, hemoglobin, and cytochrome c. The mechanism of protein-surfactant interaction was probed by using the surfactant as the anion in the organic phase electrolyte salt. Repetitive cyclic voltammetry of cytochrome c showed that in the presence of surfactant there was an enhancement of the signal, caused by a buildup of the protein-surfactant-electrolyte anion assembly at the interface. These findings provide the basis for surfactant-modified interfaces to enhance the electroanalytical performance for protein detection.
通过伏安法研究了表面活性剂添加到有机相后对水-有机凝胶界面上蛋白质电活性的影响。二(2-乙基己基)磺基琥珀酸钠（AOT）作为钠盐存在于有机凝胶相中，导致肌红蛋白检测的峰电流发生明显变化。与没有表面活性剂的相应实验相比，蛋白质解吸伏安峰的电流增加了 6 倍。界面覆盖度显示，在没有表面活性剂的情况下，界面上吸附的蛋白质从 50 pmol cm(-2)增加到 850 pmol cm(-2)，增加了 17 倍。此外，表面活性剂的存在导致在较低电位下出现第二对吸附/解吸峰，并改变了系统的电容。基于这些特征，提出了表面活性剂-蛋白质和表面活性剂-蛋白质-有机阴离子沉积物的形成，从而导致肌红蛋白、血红蛋白和细胞色素 c 的伏安信号增强。通过将表面活性剂用作有机相电解质盐中的阴离子来探测蛋白质-表面活性剂相互作用的机制。细胞色素 c 的重复循环伏安法表明，在表面活性剂存在的情况下，由于界面处蛋白质-表面活性剂-电解质阴离子组装的积累，信号增强。这些发现为表面活性剂修饰界面提供了基础，以增强蛋白质检测的电化学生物传感器性能。
