Monoclonal antibodies are specific for a single epitope i.e a small region of protein. As a result, they are helpful in reducing cross reactivity and are not generally expected to trigger non-specific signals in a given immunoassay.
They are used in kits as matched pairs or with polyclonal antibodies to amplify the signal or provide a greater chance of capturing antigen from complex solutions.
Monoclonals have an inherent monospecificity for epitopes, which allows fine detection and quantification of small antigenic differences. You can also navigate https://www.bosterbio.com/featured-products to know more about monoclonal and polyclonal antibodies.
Image Source: Google
Polyclonals are often used as capture antibodies to remove as much of the antigen as possible. The monoclonal was then used as a detecting antibody in the sandwich assay to provide better specificity.
Polyclonal antibodies are a group of complex antibodies containing different epitopes of a single antigen. Due to the heterogeneity of the epitope, polyclonal antibodies can be a powerful tool for in-depth antigen detection.
Also, it is rare that they fail to bind due to a blocked single antibody binding site, altered antigen configuration, or incorrect folding. Polyclonals lead to higher nonspecific signals because they tend to share one or more epitopes with closely related proteins. One solution to reduce this problem is to use purified or cross-absorbed polyclonal antibodies.
Sometimes the ELISA detection method is switched from direct detection to indirect detection and thus from monoclonal to polyclonal to increase the sensitivity of the assay due to the higher binding of polyclonal antibodies to the target antigen.
They can be used as capture and detection antibodies. Antibodies from the same polyclonal pool can capture the analyte and subsequently detect it in a biotin-associated format.