Immunoassay

Abstract

Immunoassay, a diagnostic and measurement method that utilizes antibodies to detect and quantify specific analytes (antigens), is characterized by high analyte specificity, high sensitivity (routinely detecting ng to pg analyte levels), and rapid data output. It is amenable to a variety of formats, from single immunoassays carried out manually, to fully automated instruments capable of performing multiple assays on the same or different analytes. Immunoassay quantification methods are based on immunoprecipitation, such as agglutination assays, or on specific indicator reagents linked to antibody or antigen reagents used in the immunoassay. These include radioisotopes for radioimmunoassay, enzymes for enzyme‐linked immunoassay, fluorophores for fluorescence immunoassay, and chemicals or proteins for chemiluminescent or bioluminescent immunoassay. Immunoassay technology is continuing to evolve and applications have moved beyond traditional clinical settings to industry and the environment. Immunoassays are also serving as the basis for newer measurement technologies including hybrid immunoassay‐nucleic acid probe assays, immunobiosensors, and antibody‐based microarrays.