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Published on: January 27, 2023
D-band strain underestimates fibril strain for twisted collagen fibrils at low strains
Matthew P Leighton1, Andrew D Rutenberg2, Laurent Kreplak2
1Department of Physics and Atmospheric Science, Dalhousie University, Halifax, B3H 4R2, Nova Scotia, Canada; Department of Physics, Simon Fraser University, Burnaby, V5A 1S6, British Columbia, Canada.
Abstract:
Collagen fibrils are the main structural component of load-bearing tissues such as tendons, ligaments, skin, the cornea of the eye, and the heart. The D-band of collagen fibrils is an axial periodic density modulation that can be easily characterized by tissue-level X-ray scattering. During mechanical testing, D-band strain is often used as a proxy for fibril strain. However, this approach ignores the coupling between strain and molecular tilt. We examine the validity of this approximation using an elastomeric collagen fibril model that includes both the D-band and a molecular tilt field. In the low strain regime, we show that the D-band strain substantially underestimates fibril strain for strongly twisted collagen fibrils - such as fibrils from skin or corneal tissue.
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