Analysis of glutathione and immunoglobuline G inside chromatographic beads using surface-enhanced Raman scattering spectroscopy

Gold-containing chromatographic beads were used to record spectra of the tripeptide glutathione and the protein immunoglobulin G (IgG) by surface-enhanced Raman scattering (SERS) spectroscopy. SERS spectra were recorded from glutathione in solution at three different pH values, 2, 6 and 10. It was found that the SERS spectra are strongly dependent on pH, which indicates that the adsorption mode of glutathione changes with the pH value of the solution. Assignment of some of the observed bands and a suggestion for adsorption modes at the different pH were made. A SERS spectrum of human IgG in ethanolamine was also recorded. No complete assignment of the bands in this spectrum was performed, but the results indicate adsorption to the gold nanoparticles by aromatic amino acids and cystine residues.