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The Hierarchical Response of Human Corneal Collagen to Load

DOI: 10.1016/j.actbio.2017.11.015 DOI Help

Authors: J. S. Bell (Cardiff University) , Sally Hayes (Cardiff University) , C. Whitford (University of Liverpool) , J. Sanchez-weatherby (Diamond Light Source) , O. Shebanova (Diamond Light Source) , C. Vergari (University of Exeter) , C. P. Winlove (University of Exeter) , N. Terrill (Diamond Light Source) , T. Sorensen (Diamond Light Source) , A. Elsheikh (University of Liverpool) , K. M. Meek (Cardiff University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Acta Biomaterialia

State: Published (Approved)
Published: November 2017
Diamond Proposal Number(s): 12810 , 11316

Abstract: Fibrillar collagen in the human cornea is integral to its function as a transparent lens of precise curvature, and its arrangement is now well-characterised in the literature. While there has been considerable effort to incorporate fibrillar architecture into mechanical models of the cornea, the mechanical response of corneal collagen to small applied loads is not well understood. In this study the fibrillar and molecular response to tensile load was quantified using small and wide angle X-ray scattering (SAXS/WAXS), and digital image correlation (DIC) photography was used to calculate the local strain field that gave rise to the hierarchical changes. A molecular scattering model was used to calculate the tropocollagen tilt relative to the fibril axis and changes associated with applied strain. Changes were measured in the D-period, molecular tilt and the orientation and spacing of the fibrillar and molecular networks. These measurements were summarised into hierarchical deformation mechanisms, which were found to contribute at varying strains. The change in molecular tilt is indicative of a sub-fibrillar “spring-like” deformation mechanism, which was found to account for most of the applied strain under physiological and near-physiological loads. This deformation mechanism may play an important functional role in tissues rich in fibrils of high helical tilt, such as skin and cartilage.

Journal Keywords: Collagen; Cornea; X-ray scattering; Biomechanics; Microstructure

Subject Areas: Biology and Bio-materials, Medicine


Instruments: I02-Macromolecular Crystallography , I22-Small angle scattering & Diffraction