Surface-Enhanced Raman Spectroscopy of Phe and Gly-Gly Adsorbed on Colloidal Silver

Surface-Enhanced Raman scattering (SERS) are potentially important tools in the characterization of biomolecules such as amino acids, complicated peptides and proteins, and even tissues or living cells. Amino acids and small peptides contain different functional groups. Therefore, they are suitable for the investigations of the competitive-interactions of these functional groups with colloidal silver surfaces. SERS spectra of Phe and Gly-Gly are measured in colloidal silver solutions in this paper. Orientation of the samples, as well as specific-competitive interactions of their functional groups with the colloidal silver surface, were predicted by detailed spectral analysis of the obtained SERS spectra. In addition, using SERS measurement obtained in different time we discuss an existing controversy regarding the adsorption mechanism of Gly-Gly on the silver surface.