Coupling of Independent Electrochemical Reactions and Fluorescence at Closed Bipolar Interdigitated Electrode Arrays
Coupling of Independent Electrochemical Reactions and Fluorescence at Closed Bipolar Interdigitated Electrode Arrays
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DOI：
10.1002/celc.201500366
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发表时间：
2016-03
期刊：
影响因子：
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通讯作者：
Wei Xu;Chaoxiong Ma;P. Bohn
中科院分区：
文献类型：
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作者：
Wei Xu;Chaoxiong Ma;P. Bohn
双极电极 (BPE) 两端发生的电化学反应必然耦合，从而使一端的电子转移事件能够通过光学方式读出，例如，通过耦合到另一端的荧光反应。为了探索该技术研究多个氧化还原事件的潜力，在封闭的 BPE 配置中制造了平行 BPE 叉指电极阵列 (IDEA) 阵列，并分别与单独的分析和报告微流体通道集成。该装置最初使用分析通道中的 Fe(CN)63/4− 与弱发射刃天青和强发射试卤灵耦合作为荧光氧化还原报告对进行评估。然后，该装置用于研究具有集成 pH 调节电极 (PME) 的结构中的质子耦合电子转移反应，即对苯二酚 (QH2) 氧化。将 pH 敏感染料荧光素共同引入分析通道，以监测 PME 对溶液 pH 值的调节及其与 QH2 氧化的耦合，从而允许在分析通道中直接监测溶液 pH 值的变化以及 QH2 氧化速率，并与报告通道中的荧光进行比较。此外，PME 处产生的 OH− 扩散产生了空间 pH 分布，该分布通过荧光素发射可视化，并且由于每个 BPE 处 QH2 的氧化强烈依赖于局部 pH，因此通过报告通道中相应 BPE 数字的相反极处的耦合荧光反应。因此，BPE IDEA 支持独立氧化还原反应的耦合和使用荧光成像来探索在各种电化学几何形状中实现的各种空间变化的电化学现象。
Electrochemical reactions occurring at the opposite ends of bipolar electrodes (BPEs) are necessarily coupled, enabling electron transfer events at one end to be read out optically, for example, by coupling to fluorogenic reactions at the other end. To explore the potential of this technique for studying multiple redox events, arrays of parallel BPE interdigitated electrode arrays (IDEAs) were fabricated and integrated with separate analytical and reporter microfluidic channels, respectively, in a closed BPE configuration. The apparatus was initially evaluated employing Fe(CN)63/4− in the analytical channel coupled to weakly emissive resazurin and strongly emissive resorufin as the fluorogenic redox reporter pair. The device was then used to investigate a proton-coupled electron transfer reaction, hydroquinone (QH2) oxidation, in structures with an integrated pH modulation electrode (PME). A pH-sensitive dye, fluorescein, was co-introduced into the analytical channel to monitor PME modulation of solution pH, and its coupling to QH2 oxidation, thereby permitting changes in solution pH, and consequently QH2 oxidation rate, to be monitored directly in the analytical channel and compared to the fluorescence in the reporter channel. In addition, diffusion of OH− generated at the PME produced a spatial pH profile that was visualized via fluorescein emission, and, because the oxidation of QH2 at each BPE is strongly dependent on the local pH, via the coupled fluorogenic reaction at the opposite pole of the corresponding BPE digit in the reporter channel. Thus, BPE IDEAs support the coupling of independent redox reactions and the use of fluorescence imaging to explore a diverse set of spatially varying electrochemical phenomena realized in a variety of electrochemical geometries.