基于双极电极的电化学阻抗成像分析

Bipolar electrodes possess advantages of wireless, easy to be operated and processed to an array. As a hot topic in electrochemistry, bipolar electrodes have wide applications in many fields, especially in biosensor. Since optical probes must be used to obtain electrochemical information on bipolar electrodes, bipolar electrochemistry is limited to potential scan or potential step. At present there is no report on bipolar electrodes combined with electrochemical impedance. Recently the applicant utilized a new electrochemical imaging technique to achieve interfacial potential imaging on bipolar electrode without optical probe (Angew. Chem.,2017). This result provides theoretical foundation for electrochemical impedance analysis based on bipolar electrodes. Based on the result, this project will systematically study the effect of outer electric field and bipolar electrode structure on interfacial potential and capacitance distribution. A new electrochemical sensing theory of bipolar electrodes based on non-faradic impedance will be proposed. The effect of interfacial potential distribution on interaction between interfacial bio-molecules will be further studied and this will promote the application of bipolar electrodes for array detection of bio-molecules without any label. The above research will achieve electrochemical impedance imaging analysis based on bipolar electrode array for the first time. Also they will rich theoretical knowledge of interfacial electrochemistry and promote development of novel methods for high throughput analysis.

双极电极具有无线、易于阵列化及操作简便等优点，在生物传感等领域获得了广泛的应用，已成为电化学的一个新的研究热点。由于需借助光学探针获取电化学信息，目前只能在电势扫描或电势阶跃模式下开展双极电化学研究，尚未能实现其与电化学阻抗这一重要电化学技术联用。申请人最近利用一种无需光学探针的电化学成像新技术，实现了双极电极上界面电势的直接成像(Angew. Chem.,2017)，为基于双极电极的电化学阻抗分析奠定了理论基础。本项目拟在此项成果基础上，系统探索外部电场和电极结构对双极电极电势和电容分布的影响规律，提出和完善基于非法拉第阻抗的双极电化学传感分析新理论；深入研究双极电极特殊的电势分布对界面生物分子相互作用的影响，推动这一分析新原理在生物分子免标记、阵列化检测中的应用。此研究将首次实现基于双极电极阵列的电化学阻抗成像分析，对于丰富和完善界面电化学基础理论，发展新型高通量分析方法具有重要意义。

双极电极具有无线、易于阵列化及操作简便等优点，在生物传感等领域获得了广泛的应用，已成为电化学的一个新的研究热点。由于需借助光学探针获取电化学信息，目前只能在电势扫描或电势阶跃模式下开展双极电化学研究，尚未能实现其与电化学阻抗这一重要电化学技术联用。本项目利用电化学结合表面等离子共振成像（SPRM）技术，研究不同形状双极电极界面电势分布，得到和理论相一致的电势分布结果，进一步分析非法拉第条件下的零电势线，结果表明中心对称图形的零电势线和几何平分线重合，而非中心对称图形中，由于电荷向尖角聚集，靠近尖角处往往具有高的电势。法拉第反应能引起零极化电势线的移动，移动距离和双极电极形状及活性物质氧化还原电位有关。将双极电极的尺寸进一步缩小至纳米级别，制备了金纳米棒，测定了单个金纳米颗粒的非法拉第电化学阻抗谱，将传统双极电极和单颗粒电化学研究从电势扫描模式推进到高频交流调制模式，为拓展基于双极电极的电化学阻抗谱成像方法应用奠定了基础。