Development of a Sensor for Direct Detection of Proteins Based on Reverse Micelle Electro-extraction

生物和食品样品中蛋白质的快速和简单检测的电化学传感器是可取的。在这项研究中，我们开发了一种直接的蛋白质传感器，它检测蛋白质作为其在油/水界面上转移的电流信号。作为基础研究，我们研究了几种蛋白质在阴离子表面活性剂存在下，在极化的油/水界面上的伏安行为。当水相为中性(pH为7)时，证实了在界面形成的反胶束可以将蛋白质输送到油相。然而，在这些条件下，我们没有观察到任何由于蛋白质转移而产生的伏安波，除了一种小蛋白质，即鱼精蛋白。然而，当水相是酸性的(例如，pH 3.5)时，所有研究的蛋白质都给出了一个发育良好的伏安波。然后，利用控制电位电解法对反应机理进行了详细的研究。研究发现，在酸性条件下，含蛋白质的反胶束在油相中不稳定存在，蛋白质-表面活性剂络合物吸附在油/水界面，产生伏安波。当表面活性剂浓度足够高时，伏安波的峰电流应与蛋白质浓度成正比。出现伏安波的电位在不同蛋白质之间是不同的。因此，目前的电化学反应使我们能够对蛋白质进行定量和定性的分析，并建立了一种新的、直接的蛋白质传感器的原理。此外，我们还制作了一种采用全极化油水界面电解槽的在线蛋白质传感器样机，并对其基本性能进行了测试。

Electrochemical sensors for rapid and simple detection of proteins in biological and food samples are desirable. In this study, we have developed a direct protein sensor, which detects proteins as the current signal for their transfer at the oil/water interface. As the fundamental study, we have investigated the voltammetric behaviors of several proteins at the polarized oil/water interface in the presence of anionic surfactants. When the water phase was neutral (pH 7), it was confirmed that reverse micelles formed at the interface could transport proteins into the oil phase. Under these conditions, however, we could not observe any voltammetric wave due to the transfer of proteins other than a small protein, i.e. protamine. When the water phase was acidic (e.g., pH 3.5), however, all the proteins studied gave a well-developed voltammetric wave. Then, the reaction mechanism has been studied in detail, with the help of controlled potential electrolysis. It has been found that under the acidic conditions, protein-containing reverse micelles do not stably exist in the oil phase, and in turn the protein-surfactant complexes are adsorbed at the oil/water interface, giving the voltammetric wave. When the surfactant concentration is high enough, the peak current of the voltammetric wave should be proportional to the protein concentration. The potential, where the voltammetric wave appears, is different between proteins. It has thus been confirmed that the present electrochemical reaction enables us to carry out quantitative and qualitative analyses of proteins and to establish the principle of a new, direct protein sensor. Furthermore, we have made a prototype of an on-line protein sensor using a whole electrolytic cell with a polarized oil/water interface and have examined the basic performance.