Key Laboratory of Coastal Zone Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS) , Shandong Provincial Key Laboratory of Coastal Zone Environmental Processes, YICCAS, Yantai, Shandong 264003, P. R. China.
ACS Appl Mater Interfaces. 2013 Oct 9;5(19):9488-93. doi: 10.1021/am402245f. Epub 2013 Sep 24.
Pulsed galvanostatic control of ion fluxes across polymeric membrane ion-selective electrodes (ISEs) is an emerging field for potentiometric sensing. Herein we report a novel potentiometric enzyme immunoassay based on current-controlled release of an enzyme substrate, which eliminates the addition of marker ions in the sample solution. In this method, the carboxylated poly(vinyl chloride) matrix at the outer layer of the ISE membrane is employed to attach a primary antibody. A sandwich immunoassay with an alkaline phosphatase labeled antibody (ALP-Ab) as the reporter is used for the determination of human IgG (as a model protein). The large difference between the lipophilicity of the substrate ion and that of the product ion allows p-nitrophenyl phosphate to be used as the enzyme substrate for potentiometric immunosensors. After the immunoreactions, the captured ALP-Ab catalyzes the hydrolysis of the substrate ions released at the sample-membrane interface by using the pulsed galvanostatic technique. This process can be potentiometrically determined by measuring the open circuit potential of the ISE. Under optimal conditions, the potential response of the proposed immunosensor is proportional to the concentration of human IgG in the range of 50-1000 ng/mL with a detection limit of 30 ng/mL (3σ). Owing to simplicity and independence of sample volume and sample turbidity, the proposed potentiometric immunoassay offers a viable alternative to those based on optical absorbance.
聚离子选择性电极（ISE）中离子流的脉冲恒电流控制是一种新兴的电位传感领域。在此，我们报告了一种基于酶底物电流控制释放的新型电位酶免疫分析方法，该方法消除了在样品溶液中添加标记离子。在该方法中，ISE 膜外层的羧基化聚（氯乙烯）基质用于附着抗体。夹心免疫测定法使用碱性磷酸酶标记的抗体（ALP-Ab）作为报告分子，用于测定人 IgG（作为模型蛋白）。底物离子和产物离子的亲脂性差异很大，允许使用对硝基苯磷酸作为电位免疫传感器的酶底物。免疫反应后，捕获的 ALP-Ab 通过使用脉冲恒电流技术催化在样品-膜界面释放的底物离子的水解。通过测量 ISE 的开路电位可以对该过程进行电位测定。在最佳条件下，所提出的免疫传感器的电位响应与人 IgG 的浓度在 50-1000ng/mL 范围内呈正比，检测限为 30ng/mL（3σ）。由于该电位免疫分析具有简单性以及对样品体积和浊度的不依赖性，因此为基于光学吸收的方法提供了一种可行的替代方法。
