title: Osmotically driven tensile stress in collagen-based mineralized tissues.
abstract: Collagen is the most abundant protein in mammals and its primary role is to serve as mechanical support in many extracellular matrices such as those of bones, tendons, skin or blood vessels. Water is an integral part of the collagen structure, but its role is still poorly understood, though it is well-known that the mechanical properties of collagen depend on hydration. Recently, it was shown that the conformation of the collagen triple helix changes upon water removal, leading to a contraction of the molecule with considerable forces. Here we investigate the influence of mineralization on this effect by studying bone and turkey leg tendon (TLT) as model systems. Indeed, TLT partially mineralizes so that well-aligned collagen with various mineral contents can be found in the same tendon. We show that water removal leads to collagen contraction in all cases generating tensile stresses up to 80MPa. Moreover, this contraction of collagen puts mineral particles under compression leading to strains of around 1%, which implies localized compressive loads in mineral of up to 800MPa. This suggests that collagen dehydration upon mineralization is at the origin of the compressive pre-strains commonly observed in bone mineral.
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany.
authors: Luca
authors: L
authors: Bertinetti
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany.
authors: Admir
authors: A
authors: Masic
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany.
authors: Roman
authors: R
authors: Schuetz
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany; Laboratoire International Associé "Recycling" CNRS/MPIKG, France; Institut de Chimie Séparative de Marcoule, UMR5257, CEA/CNRS/UM2/ENSCM, 30207 Bagnols-sur-Cèze, France.
authors: Aurelio
authors: A
authors: Barbetta
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany.
authors: Britta
authors: B
authors: Seidt
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany.
authors: Wolfgang
authors: W
authors: Wagermaier
authors: Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Research Campus Golm, 14424 Potsdam, Germany. Electronic address: fratzl@mpikg.mpg.de.
authors: Peter
authors: P
authors: Fratzl
mesh_terms: D000388:Air; D000818:Animals; D002113:Calcification, Physiologic; D002417:Cattle; D003094:Collagen / Q000737:chemistry / Q000378:metabolism*; D019245:Compressive Strength; D008297:Male; D008903:Minerals / Q000378:metabolism*; D009997:Osmotic Pressure; D011092:Polyethylene Glycols / Q000737:chemistry; D013314:Stress, Mechanical; D013710:Tendons / Q000378:metabolism; D013718:Tensile Strength; D014422:Turkeys; D014867:Water / Q000737:chemistry / Q000378:metabolism
chemical_list: D008903:Minerals; D014867:Water; D011092:Polyethylene Glycols; D003094:Collagen
keywords: Collagen; Contraction; In-situ tensile testing; Mechanical properties; Synchrotron X-ray diffraction; Water