NIR SERS DETECTION OF IMMUNE-REACTION ON GOLD COLLOID PARTICLES WITHOUT BOUND FREE ANTIGEN SEPARATION/

This paper reports the near-infrared (NIR) surface-enhanced Raman scat tering (SERS) detection of immune reaction on gold colloid particles w ithout bound/free (B/F) antigen separation, A SERS spectrum was measur ed for anti-mouse IgG at 2.2 x 10(-8) M adsorbed on gold colloid parti cles. The spectrum showed a number of Raman bands assignable to amide groups and aromatic amino acid residues of anti-mouse IgG, A SERS spec trum of the same system at 1.9 x 10(-10) M did not yield any Raman ban d. However, Raman bands again appeared after the reaction of anti-mous e 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 pa ttern 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 c omplex 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 spectrosc opy without any B/F antigen separation, (C) 1998 John Wiley & Sons Ltd .