Acoustic micromixing increases antibody-antigen binding in immunoassays

Sound wave-assisted acoustic micromixing has been shown to increase the binding of molecules in small volumes (10-100 mu L) where effective mixing is difficult to achieve through conventional techniques. The aim of this work is to study whether acoustic micromixing can increase the binding efficiency of antibodies to their antigens, a reaction that forms the basis of immunoassays, including enzyme-linked immunosorbent assay (ELISA). Using a procedure from a general ELISA and immobilizing an antigen on wells of 96-well plates, it was found that acoustic micromixing at 125-150 Hz increased the initial rate of antibody-antigen binding by over 80 % and the total binding at the end point (i.e., 45 min) by over 50 %. As a result, acoustic micromixing achieved a binding level in 9 min that would otherwise take 45 min on a standard platform rocking mixer. Therefore acoustic micromixing has the potential to increase the detection sensitivity of ELISA as well as shorten the antigen-antibody binding times from typically 45-60 min to 15 min.