Faculty of Chemistry , University of Warsaw , Pasteura 1 , 02-093 Warsaw , Poland.
Anal Chem. 2019 Dec 17;91(24):15525-15531. doi: 10.1021/acs.analchem.9b03405. Epub 2019 Dec 3.
Bipolar electrodes working in a self-powered mode are a basis for the development of easy to use electrochemical-optical sensors, these systems are very promising due to their simplicity and no need of external polarization. However, the self-powered mode can be used only in cases when the redox potential difference of reactions occurring at opposite poles of the electrode is sufficiently high. To overcome this limitation, we propose the development of a system working spontaneously, but involving two bipolar electrodes, forming a cascade system. One of electrodes ("driving" electrode) works in self-powered mode and triggers charge transfer processes in the second ("sensing") bipolar electrode. For the sensing electrode, an electrochemical process of an analyte occurs at one pole, accompanied by a complementary process at the second pole, inducing an optical (fluorimetric) analytical signal. This concept was successfully tested on a model system of a sensing bipolar electrode with a platinum electrode participating in oxidation of an analyte, l-ascorbic acid, connected with electrode coated by poly(3-octylthiophene), where reduction of the polymer results in formation of fluorimetrically active neutral form. As the driving system, bipolar electrodes with zinc wire as one pole, characterized by a low redox potential, were used.
双极电极在自供电模式下工作是开发易于使用的电化学-光学传感器的基础，由于其简单性和无需外部极化，这些系统非常有前途。然而，自供电模式只能在电极相反极上发生的反应的氧化还原电位差足够高的情况下使用。为了克服这一限制，我们提出开发一种自发工作的系统，但涉及两个双极电极，形成级联系统。一个电极（“驱动”电极）在自供电模式下工作，并在第二个“感应”双极电极中触发电荷转移过程。对于感应电极，在一个极上发生分析物的电化学过程，同时在第二个极上发生互补过程，诱导光学（荧光）分析信号。该概念在一个具有参与分析物氧化的铂电极的感应双极电极的模型系统上得到了成功测试，分析物为抗坏血酸，与涂覆有聚（3-辛基噻吩）的电极相连，聚合物的还原导致形成荧光活性的中性形式。作为驱动系统，使用了具有低氧化还原电位的锌丝作为一个电极的双极电极。
