FLOW-THROUGH AMPEROMETRIC IMMUNOSENSOR - FAST SANDWICH SCHEME IMMUNOASSAY

A flow-through immunosensor based on a high-surface-area carbon immuno electrode has been developed. Dispersed carbon material serves as a ca rrier for immobilized antibodies and at the same time as an electrode material. The 'sandwich' scheme of immunoassay has been used. Iodine f ormed as a result of the enzymatic oxidation of iodide by a peroxidase label has been detected amperometrically. The immunosensor consists o f a disposable sensing element (immunocolumn) containing dispersed car bon material with immobilized antibodies which also acts as a working electrode. A current collector connects the working electrode to the m easuring device. The electrochemical detection time of the peroxidase- labeled immune-complex does not exceed several minutes. The overall ti me of analysis including flowing of analyte, flowing of antigen, washi ng and detection stages is as low as 22min. This technique allows fast determination of rabbit IgG (used as a model analyte) with a low dete ction limit in the picomolar range and also the determination of human IgM in blood plasma with a low detection limit in the nanomolar range . (C) 1997 Elsevier Science Limited.