Thin films of a self-assembling peptide on TiO2 and Au studied by NEXAFS, XPS and IR spectroscopies

EAK16 is a 16 amino acid peptide consisting of an alternation of polar and non-polar pending groups and of positively and negatively charged residues, that makes this material capable of self-assembling, producing an extended ordered structure. Thin films of EAK16 were prepared on TiO2 and Au surfaces and investigated by surface-sensitive techniques such as XPS (X-ray photoelectron spectroscopy), NEXAFS (near edge X-ray absorption fine structure) and IR spectroscopies. XPS analysis allowed to check the chemical structure of the samples and to determine the film thickness. IR experiments yielded evidence of the h-sheet conformation of the peptide backbone. Polarization dependent NEXAFS measurements allowed estimating the angle between the axis of the peptide backbone and the sample surface.