Understanding structures of interfacial biological molecules is important for the development of advanced biomedical materials, marine anti-biofouling coatings, new antimicrobial peptides with excellent activity and selectivity, and membranes for biological separations.
Sum frequency generation (SFG) vibrational spectroscopy has been applied to investigate peptides and proteins at solid/liquid interfaces in situ in real time, supplemented by linear optical spectroscopic techniques. Various peptides and proteins, including magainin 2, tachyplesin I, alamethicin, cytochrome b5, fibrinogen, and cecropin have been examined in model cell membranes or on polymer surfaces. This research demonstrates that the combined use of nonlinear and linear optical spectroscopic techniques can elucidate interfacial orientations/structures of various secondary structures such as alpha-helix, 3-10 helix, and beta-sheet, as well as entire proteins.