Surface plasmon studies of specific recognition reactions at self-assembled monolayers on gold

Abstract Specific recognition reactions of proteins at functionalized interfaces were observed with plasmon surface polariton (PSP) spectroscopy. This optical method offers a vertical resolution of about 0.2 nm in aqueous media. Different types of receptor surfaces were prepared, either by self-assembly of biotinylated alkane thiols or by specific adsorption of streptavidin monolayers. The corresponding substrates were streptavidin and a biotinylated monoclonal antibody. Their binding properties are inversely related to the packing density of the receptors. A good accessibility is only given in the case of a “diluted” presentation of the receptors at the interface. Both binding site and diffusion limited adsorption have been observed.