NIR SERS Detection of Immune Reaction on Gold Colloid Particles Without Bound/Free Antigen Separation

Abstract

This paper reports the near-infrared (NIR) surface-enhanced Raman scattering (SERS) detection of immune reaction on gold colloid particles without bound/free (B/F) antigen separation. A SERS spectrum was measured for anti-mouse IgG at 2.2 x 10-8 M adsorbed on gold colloid particles. The spectrum showed a number of Raman bands assignable to amide groups and aromatic amino acid residues of anti-mouse IgG. A SERS spectrum of the same system at 1.9 x 10-10 M did not yield any Raman band. However, Raman bands again appeared after the reaction of anti-mouse IgG at 10-10 M with the antigen on the gold colloid particles. The band intensity of the spectrum obtained was weak, but the spectral pattern was very similar to that of anti-mouse IgG at 10-8 M adsorbed on the gold colloid particles. Probably, the formation of the immune complex on the gold colloid particles changed the configuration of anti-mouse IgG, enhancing the SERS signals. In this way, one could detect the immune complex on the gold colloid particles by NIR SERS spectroscopy without any B/F antigen separation. © 1998 John Wiley & Sons Ltd.