The sample with an unknown amount of antigen is immobilized on a solid support (usually a polystyrene microtiter plate) either non-specifically (via adsorption to the surface) or specifically (via capture by another antibody specific to the same antigen, in a 'sandwich' ELISA). Performing an ELISA involves at least one antibody with specificity for a particular antigen.
If there was binding, the subsequent reaction produces a detectable signal, most commonly a color change. In the final step, a substance containing the enzyme's substrate is added. This antibody is linked to an enzyme and then any unbound antibodies are removed. Then, a matching antibody is applied over the surface so it can bind the antigen. In the most simple form of an ELISA, antigens from the sample to be tested are attached to a surface. ELISA has been used as a diagnostic tool in medicine, plant pathology, and biotechnology, as well as a quality control check in various industries.
The assay uses a solid-phase type of enzyme immunoassay (EIA) to detect the presence of a ligand (commonly a protein) in a liquid sample using antibodies directed against the protein to be measured. The enzyme-linked immunosorbent assay ( ELISA) ( / ɪ ˈ l aɪ z ə/, / ˌ iː ˈ l aɪ z ə/) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971.
