The Raman analysis of films cast from dissolved feather keratin

Raman spectroscopy was used to characterize films cast from dissolved feather keratin. Spectra obtained from the films were found to be very similar to those of the feather components from which they were derived. The protein structure of the films was dominated by β-sheet conformation with possibly more disordered protein content and slightly less disulfide cross-linking compared to the feather. Study of the solubilized keratin protein that the films were made from revealed that the protein conformation was more disordered and that the disulfide cross-links were largely cleaved. During the film formation process these bonds were largely reformed and the intra-chain order of the proteins increased even though the films themselves remained isotropic. The results of a polarization study revealed that upon mechanical stretching of the film, the protein chains tended to orientate towards the draw axis. The extent of orientation was found to vary randomly along the length of the stretched film suggesting domains with different properties may exist within the “as-prepared” film.