How does sandwich ELISA work?

In a sandwich ELISA, an immobilized capture antibody binds the target antigen, and a detection antibody binds to a different epitope on the same antigen. This antibody-antigen-antibody “sandwich” enables highly specific detection and quantitative measurement.

Sandwich ELISA is commonly selected when sensitivity and specificity are important. Depending on the assay design, the detection antibody may be enzyme-conjugated directly or detected using an additional enzyme-linked secondary antibody.