In situ surface protein conjugation of small molecules for SPR immunoassays.

Solution based protein conjugation of small molecules involves multiple steps of chemical syntheses, bio-conjugation and purifications which are labor intensive and time-consuming. Since many small molecules have limited water solubility, conjugation to a protein is also a relatively low efficiency process in aqueous solutions. In this study, a model in situ protein conjugation of small molecules was achieved onto SPR surfaces, using progesterone and ovalbumin as a model small-molecule-protein system. The in situ protein conjugation not only eliminated the requirement for wet chemistry, but also provided an easy way to optimize the assay performance and screen various molecular linkers.