title: Structural hierarchy governs fibrin gel mechanics.
abstract: Fibrin gels are responsible for the mechanical strength of blood clots, which are among the most resilient protein materials in nature. Here we investigate the physical origin of this mechanical behavior by performing rheology measurements on reconstituted fibrin gels. We find that increasing levels of shear strain induce a succession of distinct elastic responses that reflect stretching processes on different length scales. We present a theoretical model that explains these observations in terms of the unique hierarchical architecture of the fibers. The fibers are bundles of semiflexible protofibrils that are loosely connected by flexible linker chains. This architecture makes the fibers 100-fold more flexible to bending than anticipated based on their large diameter. Moreover, in contrast with other biopolymers, fibrin fibers intrinsically stiffen when stretched. The resulting hierarchy of elastic regimes explains the incredible resilience of fibrin clots against large deformations.
authors.affiliation: Biological Soft Matter Group, Foundation for Fundamental Research on Matter, Institute for Atomic and Molecular Physics, Amsterdam, The Netherlands.
authors.forename: Izabela K
authors.initials: IK
authors.lastname: Piechocka
authors.forename: Rommel G
authors.initials: RG
authors.lastname: Bacabac
authors.forename: Max
authors.initials: M
authors.lastname: Potters
authors.forename: Fred C
authors.initials: FC
authors.lastname: Mackintosh
authors.forename: Gijsje H
authors.initials: GH
authors.lastname: Koenderink
mesh_terms: D001696:Biomechanical Phenomena; D004548:Elasticity / Q000502:physiology*; D005337:Fibrin / Q000737:chemistry*; D005782:Gels / Q000737:chemistry*; D008422:Materials Testing; D019563:Mechanics; D008958:Models, Molecular; D012212:Rheology; D033081:Shear Strength / Q000502:physiology*; D013718:Tensile Strength / Q000502:physiology
chemical_list: D005782:Gels; D005337:Fibrin