title: Nanoscale Swelling Heterogeneities in Type I Collagen Fibrils.
abstract: The distribution of water within the supramolecular structure of collagen fibrils is important for understanding their mechanical properties as well as the biomineralization processes in collagen-based tissues. We study the influence of water on the shape and the mechanical properties of reconstituted fibrils of type I collagen on the nanometer scale. Fibrils adsorbed on a silicon substrate were imaged with multiset point intermittent contact (MUSIC)-mode atomic force microscopy (AFM) in air at 28% relative humidity (RH) and in a hydrated state at 78% RH. Our data reveal the differences in the water uptake between the gap and overlap regions during swelling. This provides direct evidence for different amounts of bound and free water within the gap and overlap regions. In the dry state, the characteristic D-band pattern visible in AFM images is due to height corrugations along a fibril's axis. In the hydrated state, the fibril's surface is smooth and the D-band pattern reflects the different mechanical properties of the gap and overlap regions.
authors.affiliation: †Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors.forename: Eike-Christian
authors.initials: EC
authors.lastname: Spitzner
authors.affiliation: †Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Röper
authors.affiliation: †Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Zerson
authors.affiliation: ‡Orthopädie und Traumatologie, Universitätsklinikum Freiburg, D-79095 Freiburg, Germany.
authors.forename: Anke
authors.initials: A
authors.lastname: Bernstein
authors.affiliation: †Fakultät für Naturwissenschaften, Technische Universität Chemnitz, D-09107 Chemnitz, Germany.
authors.forename: Robert
authors.initials: R
authors.lastname: Magerle
mesh_terms: D000818:Animals; D002417:Cattle; D024042:Collagen Type I / Q000737:chemistry* / Q000302:isolation & purification; D006813:Humidity; D018625:Microscopy, Atomic Force; D036103:Nanotechnology; D014867:Water / Q000737:chemistry
chemical_list: D024042:Collagen Type I; D014867:Water
keywords: collagen; dynamic atomic force microscopy; hydration; mechanical properties; swelling; water