This chapter focuses on the various developments in electrochemical immunoassays and immunosensors after 2002. Electrochemical immunoassay is a solid phase system in which an antibody-antigen reaction takes place but the corresponding electrochemical detection is carried out elsewhere. However, an electrochemical immunosensor is a stand-alone device, with the immunoreaction and electrochemical detection occurring within the same device. There are several strategies for immobilizing a captured antibody on a solid phase, which include covalent attachment, physical adsorption, and electrostatic/physical entrapment in a polymer matrix. The (strept)avidin-biotin interaction technique is used to immobilize various types of biomolecules such as nucleic acids, polysaccharides, and proteins, including the capture antibody in immunoassay/immunosensor systems. Another commonly used affinity-based immobilization technique for capture antibodies in immunoassay systems involves a bacterial antibody-binding protein, the two most common of which are Protein A and Protein G. These proteins bind specifically to antibodies through their nonantigenic (Fc) regions, which allow the antigen binding sites of the immobilized antibody to be oriented away from the solid phase and be available to bind the target analyte. The application of conducting polymers such as polyaniline, polypyrrole, and polythiophene for immobilizing capture antibodies in immunoassay systems is widespread and they may be used in amperometric, potentiometric, and impedimetric immunoassay systems. Self-assembled monolayers (SAMs) are another attractive method for immobilizing the capture antibody in immunoassay systems, which takes advantage of the spontaneous chemisorption of alkanethiols to metals such as gold or silver to assemble highly ordered monolayers. Recently, interdigitated array (IDA) microelectrodes have gained popularity as an alternative transducer in electrochemical immunoassays in which a simple design of an IDA consists of a pair of interdigitated microelectrode fingers.
|Title of host publication||Electrochemical Sensors, Biosensors and their Biomedical Applications|
|Editors||Xueji Zhang, Huangxian Ju, Joseph Wang|
|Place of Publication||Amsterdam, Boston|
|Number of pages||29|
|ISBN (Print)||9780123737380, 0123737389|
|Publication status||Published - 2008|