Surface Enhanced Raman and 2D-Fluorescence spectroscopy for the investigation of amino acids and egg proteins

Fluorescence excitation-emission spectroscopy and Surface-Enhanced Raman Spectroscopy (SERS) are applied in the analysis of model proteinaceous compounds with the aim to develop versatile methodologies so as to aid analytical investigations of organic and bio-organic archaeological residue materials. A compact mobile Raman spectrometer was employed and SER spectra were collected from thin film samples of natural amino acids (L-Trp, L-Tyr, L-Cys) and egg white, properly mixed with silver colloidal nanoparticles. In parallel the fluorescence behavior of egg white, egg yolk and milk films was investigated on a laboratory spectrofluorimeter. Comparison of 2D-fluorescence excitation-emission maps collected from fresh and aged films, revealed the formation of new fluorophores, indicative of chemical alteration and degradation process of the proteins taking place during aging.