Detection of immuno-complex formation via surface plasmon resonance on gold-coated diffraction gratings.

The sensitivity of surface plasmon resonance techniques to changes in local interfacial refractive index has been exploited to detect immuno-complex formation in two model biochemical systems. A gold-coated diffraction grating has been used to excite surface plasmons at the gold/solution interface to which either human immunoglobulin G or the immunoglobulin fraction of sheep antiserum to human serum albumin was physically adsorbed. The complementary proteins, either affinity purified goat anti-human-IgG IgG or human serum albumin was subsequently specifically bound by immuno-complex formation. The binding reactions could be followed with respect to time.