Silver salts of aromatic thiols applicable as core materials of molecular sensors operating via SERS and fluorescence

We have developed dual-tagging sensors, operating via both Raman and fluorescence spectroscopy, composed of silver aromatic thiolates (AgSRs) modified with fluorescent organic dye for multiplex immunoassays. Owing to the photo-induced production of SERS-active Ag nanoparticles, AgSRs exhibit the surface-enhanced Raman scattering (SERS) spectra of corresponding thiols. The fluorescence dye-modified AgSRs were accordingly fabricated using dye-grafted polyelectrolytes during layer-by-layer deposition of cationic and anionic polyelectrolytes onto AgSRs. In the final stage, the tagging sensors assembled with either specific biotin group or specific antibodies (anti-h-IgG or anti-r-IgG) were employed to detect either streptavidin molecules or target antigens (h-IgG or r-IgG), respectively. Since numerous AgSRs can be used as the core materials, multiple bioassays are expected to be accomplishable using the present methodology. The fluorescence signal may be used as an immediate indicator of molecular recognition, while the SERS signals can be used subsequently as the signature of specific molecular interactions. (C) 2009 Elsevier B.V. All rights reserved.