Covalent coupling of immunoglobulin G to self-assembled monolayers as a method for immobilizing the interfacial-recognition layer of a surface plasmon resonance immunosensor

Protocols have been developed for the random and site-directed covalent cou pling of immunoglobulin G [anti-hIgG] [IgG] to silver surfaces modified wit h a self-assembled monolayer [SAM] of thioctic acid, mercaptopropionic acid [MPA], L-cysteine or 4-aminothiophenol [PATP]. A surface plasmon resonance [SPR] immunosensor fabricated with a more ordered and hydrophilic IgG-SAM- silver interfacial layer, demonstrates an increased ability for performing sensitive and selective assay of human immunoglobulin G [hIgG] compared wit h a device fabricated with a physically-adsorbed IgG-silver interfacial-lay er due to reduced levels of non-specific binding. Detection limits [D-L] fo r hIgG from serum down to 6 mu g/ml (40nM ) and assay sensitivities up to 0 .24 ng hIgG/mm(2)/nM are reported. (C) 1998 Elsevier Science S.A. All right s reserved.