Development of a flow-through immunoassay system

A semi-automated flow-through immunoassay system consisting of an amperometric immunosensor and reagent flow arrangements has been developed. The amperometric immunosensor is based on a high-surface-area carbon immunoelectrode. The novel principle of flow immunoelectrode based on highly dispersed carbon material which acts as both an immunosorbent and an immunoelectrode was employed. The immunoelectrode is designed to be a disposable sensing element. The ‘sandwich’ scheme of immunoassay has been used and iodine formed as a result of the enzymatic oxidation of iodide by peroxidase-label has been detected amperometrically. The overall time of analysis including flowing of analyte, flowing of antigen, washing and detecting stages is as low as 17 min. The developed system allows fast determination of rabbit IgG (used as a model analyte) with a low detection limit in the 10 −11 M range and may easily be adapted for detection of various other analyses. The immunoassay system has the potential for miniaturization and complete automation allowing its use in laboratory setting as well as in field conditions.