Immunoassays are based on the molecular recognition occurring between an antigen and its
antibody. They can be set up in a variety of formats (sandwich or competitive assays). The main
differences between them are the immobilised species (antibody or target analyte), the number of
experimental steps involved, and in which order the different reagents are exposed to the surface. The
choice of the format depends on the molecular size of the analyte, the availability of reagents and the
cost. Radioimmunoassays (RIA), fluorescence immunoassays (FIA) and enzyme immunoassays (EIA)
are well established in clinical diagnostics. For the development of hand held devices which can be used
for point of care measurements, electrochemical immunoassays are optimal alternative to existing
immunochemical tests.
In this chapter, the current status of research in electrochemical immunoassays is considered. Primary
attention was focused on label-free and enzyme-labelled immunosensors, and the analytical
performance of these devices are discussed. Moreover, the use of magnetic beads as new materials for
immunoassays coupled with electrochemical transduction is also described. Examples of such devices
used for the detection of some biomarkers in clinical analysis are reported.
Keywords: Antibodies, Immunoelectrochemical Sensors, Biomarkers
