The Study On The Application Of Self-assembly Of Gold Nanoparticles And Surface-Enhanced Raman Spectroscopy (SERS) In Labeled Immunoassay

Surface-Enhanced Raman Spectroscopy(SERS)has been extensively applied into various microanalysis on molecular level because of its high sensitivity and it will have great practical potential in Labeled Immunoassay especially when NIR FT-Raman Spectrometer is used as detector. In this article SERS labeled immunogold is made out for immunoassay:The relationship between FT-SERS intensity and the size of spheroid gold nanoparticles is firstly discussed with thiophenol as probe molecule. Perfect SERS signal was obtained from NIR FT-Raman Spectrometer when 50nm Au nanoparticles were prepared by Hydroxylamine Seeding, while no SERS can be obtained on 30nm Au nanoparticles. It is also found that the size growth of self-assembled Au nanoparticles can also increase SERS intensity.The above 50nm Au sol was then made into SERS Reporter-thiophenol labeled immunogold. The amount of the reporter molecule, the reaction time between thiophenol and gold and the combination of thiophenol labeled gold with goat anti-rat IgG are discussed.SERS labelled immunogold was then used as probe to detect the interaction between the Goat anti-rat IgG and silver substrate (which we will use it as the substrate for solid antibody). It is found from experiment that SERS labelled immunogold can be non-specifically adsorbed onto silver surface uniformly because of the strong interaction between the protein molecule and silver. Strong SERS signal of thiophenol was also observed after the silver was treated with thiophenol labelled immunogold. BSA was used to eliminate the non-specific adsorption.