Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids
Single Molecule Electrochemical Detection in Aqueous Solutions and Ionic Liquids
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DOI：
10.1021/acs.analchem.5b02569
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发表时间：
2015-10-20
影响因子：
7.4
通讯作者：
Unwin, Patrick R.
中科院分区：
文献类型：
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作者：
Byers, Joshua C.;Nadappuram, Binoy Paulose;Unwin, Patrick R.
单分子电化学检测（SMED）是电分析化学中极具挑战性的一个方面，需要非常规的电化学电池和测量。在这里，SMED报告使用“四探针”（四通道探针）移液池，通过热解沉积碳到两个对角相对的激光拉石英四管移液管和填充电解质溶液的开放通道，和准参考反电极制成。在覆盖两个工作电极的探针的端部处形成弯月面，并且使弯月面与衬底工作电极表面接触。以这种方式，产生纳米间隙电池，由此移液管中的两个碳电极可用于促进单个分子与基底的氧化还原循环。在基板和尖端电极处产生的反相关电流，在特定的距离（通常为几十纳米），与单分子的检测是一致的。在这种液滴形式中实现的低背景噪声为单分子电化学开辟了新的机会，包括使用离子液体以及水溶液，以及由于精确已知的间隙大小而对影响氧化还原循环电流的因素进行定量评估和分析。
Single molecule electrochemical detection (SMED) is an extremely challenging aspect of electroanalytical chemistry, requiring unconventional electrochemical cells and measurements. Here, SMED is reported using a "quad-probe" (four-channel probe) pipet cell, fabricated by depositing carbon pyrolytically into two diagonally opposite barrels of a laser-pulled quartz quadruple-barreled pipet and filling the open channels with electrolyte solution, and quasi-reference counter electrodes. A meniscus forms at the end of the probe covering the two working electrodes and is brought into contact with a substrate working electrode surface. In this way, a nanogap cell is produced whereby the two carbon electrodes in the pipet can be used to promote redox cycling of an individual molecule with the substrate. Anticorrelated currents generated at the substrate and tip electrodes, at particular distances (typically tens of nanometers), are consistent with the detection of single molecules. The low background noise realized in this droplet format opens up new opportunities in single molecule electrochemistry, including the use of ionic liquids, as well as aqueous solution, and the quantitative assessment and analysis of factors influencing redox cycling currents, due to a precisely known gap size.