Biotinylated antibodies bound to streptavidin beads: a versatile solid matrix for immunoassays.

Streptavidin was covalently bound to commercially available polyacrylamide beads (3-10 microns diameter) by peptide bond formation between the carboxyl groups on the solid matrix and the amino groups of the soluble protein. Biotinylated antibody or lectin was linked to the polyacrylamide beads via the streptavidin molecules. Immunoassays for human IgA1, IgA2, IgE, and vitronectin were developed utilizing the antibody or lectin as a capture ligand. The protein being assayed was quantitated colorimetrically at 492 nm via horseradish peroxidase-conjugated antibodies.