Surface-enhanced resonance Raman spectroscopy of heme proteins on a gold grid electrode.

The combination of surface-enhanced resonance Raman spectroscopy (SERRS) and electrochemistry is an ideal tool to study the redox process of the heme proteins and is often performed on silver electrodes. In this manuscript, we present an approach using a microstructured gold surface that serves as the electrochemical working electrode, and at the same time, acts as SERS active substrate. The cell requires a micromolar concentration of sample at the electrode surface. Even if the performance of the gold grid as SERS substrate exhibited a smaller enhancement factor than expected for silver, oxidized and reduced spectra of proteins (Сyt c, Hb and Mb) monolayers could be obtained and the characteristic redox dependent shifts of the marker bands ν19, ν4 and ν10 were seen. The easy modification protocol and the higher stability of the gold electrode towards oxidative currents are the advantages of the present spectroeletrochemical cell. Finally, FDTD simulations confirm that the roughness of the gold grid has an effect on the Raman enhancement of the adsorbed proteins.