Department of Chemistry, Graduate School of Physical Sciences, Shahajalal University of Science and Technology, Sylhet-3114, Bangladesh.
Analyst. 2014 Feb 7;139(3):569-75. doi: 10.1039/c3an01826a.
Generator-collector electrode systems are based on two independent working electrodes with overlapping diffusion fields where chemically reversible redox processes (oxidation and reduction) are coupled to give amplified current signals. A generator-collector trench electrode system prepared from two tin-doped indium oxide (ITO) electrodes placed vis-à-vis with a 22 μm inter-electrode gap is employed here as a sensor in aqueous media. The reversible 2-electron anthraquinone-2-sulfonate redox system is demonstrated to give well-defined collector responses even in the presence of oxygen due to the irreversible nature of the oxygen reduction. For the oxidation of dopamine on ITO, novel "Piranha-activation" effects are observed and chemically reversible generator-collector feedback conditions are achieved at pH 7, by selecting a more negative collector potential, again eliminating possible oxygen interference. Finally, dopamine oxidation in the presence of ascorbate is demonstrated with the irreversible oxidation of ascorbate at the "mouth" of the trench electrode and chemically reversible oxidation of dopamine in the trench "interior". This spatial separation of chemically reversible and irreversible processes within and outside the trench is discussed as a potential in situ microscale sensing and separation tool.
发生器-收集器电极系统基于两个具有重叠扩散场的独立工作电极，其中化学可逆的氧化还原过程（氧化和还原）耦合以产生放大的电流信号。这里采用由两个掺锡氧化铟（ITO）电极制备的发生器-收集器沟槽电极系统作为在水介质中的传感器，两个电极相对放置，电极之间的间隙为 22μm。由于氧还原的不可逆性，即使存在氧，可逆的 2 电子蒽醌-2-磺酸盐氧化还原系统也能给出明确的收集器响应。对于 ITO 上多巴胺的氧化，观察到了新颖的“Piranha 激活”效应，并且通过选择更负的收集器电位，在 pH 7 下实现了化学可逆的发生器-收集器反馈条件，再次消除了可能的氧干扰。最后，在存在抗坏血酸的情况下证明了多巴胺的氧化，其中在沟槽电极的“口”处不可逆地氧化抗坏血酸，并且在沟槽“内部”中化学可逆地氧化多巴胺。讨论了在沟槽内外的化学可逆和不可逆过程的这种空间分离作为潜在的原位微尺度传感和分离工具。
