Dynabeads M-270 Immunoassay (Carboxyl) immobilizes antigens such as proteins, peptides, steroids and hormones for in vitro diagnostic (IVD) magnetic bead-based immunoassay applications. The antigens are coupled directly or via a cross-linker to carboxylic acid groups on 2.8 micron Dynabeads. The hydrophilic surface of the beads ensures low non-specific binding of serum proteins that would otherwise interfere with the assay. The beads disperse well, are easily handled in a variety of buffers and do not inhibit enzymatic activity. They can also be included directly in downstream analysis of the bead-bound target molecule.