title: Self-repair of a biological fiber guided by an ordered elastic framework.
abstract: Incorporating sacrificial cross-links into polymers represents an exciting new avenue for the development of self-healing materials, but it is unclear to what extent their spatial arrangement is important for this functionality. In this respect, self-healing biological materials, such as mussel byssal threads, can provide important chemical and structural insights. In this study, we employ in situ small-angle X-ray scattering (SAXS) measurements during mechanical deformation to show that byssal threads consist of a partially crystalline protein framework capable of large reversible deformations via unfolding of tightly folded protein domains. The long-range structural order is destroyed by stretching the fiber but reappears rapidly after removal of load. Full mechanical recovery, however, proceeds more slowly, suggesting the presence of strong and slowly reversible sacrificial cross-links. One likely role of the highly ordered elastic framework is to bring sacrificial binding sites back into register upon stress release, facilitating bond reformation and self-repair.
authors.affiliation: Department of Biomaterials, Max Planck Institute of Colloids and Interfaces, 14424 Potsdam, Germany.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Krauss
authors.forename: Till Hartmut
authors.initials: TH
authors.lastname: Metzger
authors.forename: Peter
authors.initials: P
authors.lastname: Fratzl
authors.forename: Matthew James
authors.initials: MJ
authors.lastname: Harrington
mesh_terms: D000818:Animals; D020285:Cryoelectron Microscopy; D004548:Elasticity; D049878:Mytilus / Q000737:chemistry* / Q000648:ultrastructure; D011506:Proteins / Q000737:chemistry* / Q000648:ultrastructure; D012038:Regeneration; D053838:Scattering, Small Angle; D013314:Stress, Mechanical; D013718:Tensile Strength; D014961:X-Ray Diffraction
chemical_list: D011506:Proteins