An enzyme-linked immunosorbent assay (ELISA) is a specific type of enzyme immunoassay (EIA) that allows for the quantitation of a molecule of interest using antibodies. Antibodies are used to specifically identify the analyte (eg, peptides, proteins, antibodies, small molecules). An enzyme, such as horseradish peroxidase (HRP), is either directly or indirectly coupled to the antibody in order to provide the detection method and possible signal amplification.
An ELISA differs from other immunoassays in that this technique amplifies signals while using a sample in solution.
ELISAs deliver a simple, robust, and cost-effective method to analyze and quantify one or more antigens from a variety of sample types, such as cell lysate, tissue lysate, or serum.
ELISA is a popular technique for research and diagnostic samples and can be used as both a single sample test or high throughput method for screening.
There are several experimental set-ups depending on the type of ELISA carried out.
All these set-ups are typically performed in a micro-well plate to which either the antigen or capture antibody is adsorbed. They rely on the amplification of signal from the antibody enzyme conjugate, which will bind to the antigen of interest.
The added enzymatic substrate will produce either a change in color, fluorescence, or luminescence and be detected and then quantified.
The success of the experiment and reliability of the results are predicated upon highly specific binding of the chosen antibodies to the antigen of interest. Along with specificity, the chosen antibodies should have high affinity and avidity for the antigen.
ELISA is considered a gold standard for quantitative analysis of biologic samples due to the specificity of antibody reagents and simplicity of the assay.
ELISAs can be broadly used in multiple research areas as well as diagnostic screening. Cell Signaling Technology offers ELISA solutions for research areas such as:
ELISA cannot be used when spatial resolution is required to analyze results.
In contrast to western blots, ELISA provides a more accurate quantitation and considers molecules in their nondenatured form.