title: Effect of mechanical deformation on the structure of regenerated Bombyx mori silk fibroin films as revealed using Raman and infrared spectroscopy.
abstract: To better understand the effect of mechanical stress during the spinning of silk, the protein orientation and conformation of Bombyx mori regenerated silk fibroin (RSF) films have been studied as a function of deformation in a static mode or in real time by tensile-Raman experiments and polarization modulation infrared linear dichroism (PM-IRLD), respectively. The data show that either for step-by-step or continuous stretching, elongation induces the progressive formation of β-sheets that align along the drawing axis, in particular above a draw ratio of ~2. The formation of β-sheets begins before their alignment during a continuous drawing. Unordered chains were, however, never found to be oriented, which explains the very low level of orientation of the amorphous phase of the natural fiber. Stress-perturbed unordered chains readily convert into β-sheets, the strain-induced transformation following a two-state process. The final level of orientation and β-sheet content are lower than those found in the native fiber, indicating that various parameters have to be optimized in order to implement a spinning process as efficient as the natural one. Finally, during the stress relaxation period in a step-by-step drawing, there is essentially no change of the content and orientation of the β-sheets, suggesting that only unordered structures tend to reorganize.
authors.affiliation: Department of Chemistry, Centre de recherche sur les matériaux avancés, Centre québécois sur les matériaux fonctionnels, Regroupement québécois de recherche sur la fonction, la structure et l'ingénierie des protéines, Université Laval, Québec, QC, Canada G1V 0A6.
authors.forename: Alexandrine
authors.initials: A
authors.lastname: Huot
authors.forename: Thierry
authors.initials: T
authors.lastname: Lefèvre
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Rioux-Dubé
authors.forename: François
authors.initials: F
authors.lastname: Paquet-Mercier
authors.forename: Anne-Philipe
authors.initials: AP
authors.lastname: Nault
authors.forename: Michèle
authors.initials: M
authors.lastname: Auger
authors.forename: Michel
authors.initials: M
authors.lastname: Pézolet
mesh_terms: D000818:Animals; D012831:Bombyx / Q000737:chemistry*; D005349:Fibroins / Q000032:analysis* / Q000737:chemistry*; D011487:Protein Conformation; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman
chemical_list: D005349:Fibroins