Ion selective redox cycling in zero-dimensional nanopore electrode arrays at low ionic strength
Ion selective redox cycling in zero-dimensional nanopore electrode arrays at low ionic strength
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DOI：
10.1039/c7nr00206h
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发表时间：
2017-04-28
期刊：
影响因子：
6.7
通讯作者：
Bohn, Paul W.
中科院分区：
文献类型：
--
作者：
Fu, Kaiyu;Han, Donghoon;Bohn, Paul W.
表面电荷特性和双电层（EDL）效应控制离子进出纳米孔的运输，产生选择性渗透浓差极化，其主导纳米电极在低离子强度溶液中的电化学响应。在这项研究中，高度有序的零维纳米孔电极阵列（NEAs），每个纳米孔呈现一对凹进的电极，被制造成将EDL效应与氧化还原循环耦合，从而实现具有改进的灵敏度和选择性的电化学检测。由于氧化还原循环效应，这些NEA表现出高达55倍的电流放大，在去除支持电解质后，其可以进一步增加到500倍。纳米孔几何形状的影响，这是一个决定的EDL效应的大小的关键因素，被充分表征，因为是氧化还原活性物质的电荷的大小和符号的影响。所观察到的极限电流与支持电解质的浓度的变化证实了阳离子的积累和阴离子的排斥在NEAs呈现负表面电荷。利用这一原则，多巴胺选择性地确定在存在下的3000倍过量的抗坏血酸内的NEA。
Surface charge characteristics and the electrical double layer (EDL) effect govern the transport of ions into and out of nanopores, producing a permselective concentration polarization, which dominates the electrochemical response of nanoelectrodes in solutions of low ionic strength. In this study, highly ordered, zero-dimensional nanopore electrode arrays (NEAs), with each nanopore presenting a pair of recessed electrodes, were fabricated to couple EDL effects with redox cycling, thereby achieving electrochemical detection with improved sensitivity and selectivity. These NEAs exhibit current amplification as high as 55-fold due to the redox cycling effect, which can be further increased by similar to 500-fold upon the removal of the supporting electrolyte. The effect of nanopore geometry, which is a key factor determining the magnitude of the EDL effect, is fully characterized, as is the effect of the magnitude and sign of the charge of the redox-active species. The observed changes in limiting current with the concentration of the supporting electrolyte confirm the accumulation of cations and repulsion of anions in NEAs presenting negative surface charge. Exploiting this principle, dopamine was selectively determined in the presence of a 3000-fold excess of ascorbic acid within the NEA.