Raman and XPS study on the interaction of taurine with silver nanoparticles

This is the first report on the surface-enhanced Raman scattering (SERS) and X-ray photoelectron spectroscopic (XPS) studies of taurine adsorbed on the surface of silver nanoparticles. Taurine, the sulphonic acid analogue of beta-alanine participates in numerous biological and physiological functions in the human body and is a potent antioxidant. The interpretation of the SERS spectrum based on the surface selection rules, XPS studies and DFT calculations has clearly indicated that the gauche tautomer of taurine is predominant on the silver nanoparticle surface. Taurine is directly bound to the silver surface through the sulphonate group along with interactions from the NH2 group that lies in close proximity to the metal surface. The binding of taurine through the oxygen atoms of the sulphonate group is confirmed by the XPS studies which show the presence of 71% Ag-O in taurine functionalized silver nanoparticles.