title: An electrochemical amplification immunoassay using bi-electrode signal transduction system.
abstract: An electrochemical immunoassay technique has been developed based on the sensitive detection of the enzyme-generated product with a bi-electrode signal transduction system. The system uses two separate electrodes, an immunoelectrode and a detection electrode to form a galvanic cell to implement the redox reactions on two different electrodes, that is the enzyme-generated reductant in the anode region is electrochemically oxidized by an oxidant (silver ions) in the cathode apartment. Based on a sandwich procedure, after immunoelectrode with antibody immobilized on its surface bound with the corresponding antigen and alkaline phosphatase conjugated antibody successively, the immunoelectrode was placed in enzyme reaction solution and wired to the detection electrode which was immerged into a silver deposition solution. These two solutions are connected with a salt bridge. Thus a bi-electrode signal transduction system device is constructed in which the immunoelectrode acts as anode and the detection electrode serves as cathode. The enzyme bound on the anode surface initiates the hydrolysis of ascorbic acid 2-phosphate to produce ascorbic acid in the anode region. The ascorbic acid produced in the anodic apartment is electrochemically oxidized by silver ions coupled with the deposition of silver metal on the cathode. Via a period of 30min deposition, silver will deposited on the detection electrode in an amount corresponding to the quantity of ascorbic acid produced, leading to a great enhancement in the electrochemical stripping signal due to the accumulation of metallic silver by enzyme-generated product. Compared with the method using chemical deposition of silver, the electrochemical deposition of silver on a separate detection electrode apartment avoids the possible influence of silver deposition on the enzyme activity.
authors.affiliation: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.
authors.forename: Zhao-Peng
authors.initials: ZP
authors.lastname: Chen
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Jiang
authors.forename: Xiao-Bing
authors.initials: XB
authors.lastname: Zhang
authors.forename: Guo-Li
authors.initials: GL
authors.lastname: Shen
authors.forename: Ru-Qin
authors.initials: RQ
authors.lastname: Yu