ELISA Kits / ELISA Assays

Enzyme-linked immunosorbent assay (ELISA) kits make it easier to use ELISAs for detecting molecules or performing ligand-binding assays successfully. Many ELISA kits use the detection enzymes horseradish peroxidase (HRP) or alkaline phosphatase (AP), along with chromogenic, fluorescent, or chemiluminescent substrates. Alternative detection strategies, such as fluorescent tags or other detectable probes, are also accepted under the umbrella term of ELISAs if they are plate-based methods, regardless of whether they use reporter enzymes or antibodies for detection. There are several ELISA formats, including the “sandwich,” competitive, direct and indirect detection assays. In the robust sandwich assay, the target is adsorbed to the assay plate, then bound by two primary antibodies. The competitive assay is often used for smaller targets that may have only one binding site. In direct detection, a labeled primary antibody binds to the target. In indirect detection, the most common protocol for ELISAs, the target is bound by the primary antibody, and detected when a labeled secondary antibody binds to the primary antibody.