Separation-free electrochemical immunosensor strategies

The simplification of the assay strategy is an essential development for th e commercial success of immunosensors. The problems associated with assay s implification stem from the fact that immune recognition is not accompanied by an easily detectable event. Direct methods such as those based on optic al systems have circumvented such problems by measuring mass changes. Howev er, such devices are not so amenable to instrumental simplification. Electr ochemical methods have so far offered the best prospects for commercial bio sensors. Success has only occurred with enzyme-based biosensors measuring s imple biochemical molecules such as glucose, lactate and creatinine. The us e of antibody-based assay strategies requires the introduction of electroch emical labels. Introduction of such species results in greater complexity, accompanied by a series of assay steps. This extension in assay complexity is in direct opposition to the concept of the biosensor: simplicity. Severa l strategies have been taken to remove these assay steps and reduce the com plexity of the immunoassay. Such strategies may contribute to the applicati on of Immunosensors as a serious commercial proposition.