The adsorption of rifampicin on gold or silver surfaces mediated by 2-mercaptoethanol investigated by surface-enhanced Raman scattering spectroscopy

In this work the adsorption of the antibiotic rifampicin (RP) on the surface of gold (AuNP) or silver nanoparticles (AgNP) was investigated using both surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) spectroscopies. Such spectra were obtained in the absence and presence of the surface modifier 2-mercaptoethanol (ME) using excitations by laser radiations of 532, 632.8 and 1064 nm wavelengths. The use of different conditions under the presence of ME led to changes in the spectral pattern ascribed to the influence of resonance Raman (RR) effect and distinct chemical interactions of RP with the metallic surfaces. The sensibility of the chromophoric moiety, i.e. a <pi>-conjugated orbital, to the adsorption geometries, which can be controlled by surface modifiers, impacts the RR effect. Theoretical models involving RP and metal atoms were obtained from Density Functional Theory (DFT) calculations, and used for supporting the vibrational assignment. © 2016 Elsevier B.V. All rights reserved.