Peptides adsorption on TiO2 and Au: Molecular organization investigated by NEXAFS, XPS and IR

We present a spectroscopic study of the structure of two peptides deposited on Au and TiO2:- PeptA, (EAK16-RGD) bringing the adhesive RGD sequence linked to EAK16;- PeptB, having RGD linked to a “scrambled” sequence of the EAK16 peptide.Previously reported NEXAFS investigations on thin films of the self-assembling peptide EAK16 deposited on Au and TiO2, revealed molecular order and orientation for both substrates.IR spectra show a β-sheet conformation for PeptA and a random structure for PeptB. Angular-dependent NEXAFS measurements reveal an ordered structure with preferential molecular orientation only for PeptA. XPS analysis indicates that PeptA is adsorbed on TiO2 in a larger amount than PeptB.