Dynabeads MyOne Immunoassay (Carboxyl) immobilizes small antigens such as peptides, steroids and hormones to the surface of beads. The beads are functionalized with a controlled number of carboxylic acid groups. The antigen of choice can then be coupled to the beads, either directly or via a linker, using carbodiimide mediated amide bond formation. This reduces the need for BSA blocking, which is often used to avoid non-specific binding of serum proteins that would otherwise interfere with the assay.