Antibodies bind specifically to the antigens that induce their production. This specificity is an advantage when identifying and quantifying proteins in an unknown sample mixture. This is the basis for immunoassays such Western blots and enzyme linked immunosorbent assays (ELISA). However, in some cases structural similarities between proteins and interference from diluent ingredients can lead to nonspecific binding resulting in high background and false positive signals. This is very common problem with polyclonal antibodies, and in multiplexed assays.
Biotin and streptavidin offer solution for improving specificity and reducing background without disrupting the normal biological function of the proteins. Biotin (Vitamin B7) is a water-soluble vitamin which covalently binds to and stabilizes proteins in a biological system. Due to its small molecular weight and simple chemical structure biotin conjugation does not affect the biological function of bound proteins.