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Assessing collagen fibrils molecular damage after a single stretch-release cycle
S M Asif Iqbal1, Dylan Deska-Gauthier2, Laurent Kreplak3
1Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Canada. kreplak@dal.ca.
Soft Matter
|July 24, 2019
Summary
Collagen molecular damage occurs in tendons and ligaments during mechanical testing, even without visible damage. This denaturation is strain-dependent and happens without fibril failure.
Area of Science:
- Biomaterials Science
- Biomechanics
- Connective Tissue Research
Background:
- Mechanical testing of connective tissues can cause collagen denaturation.
- Molecular damage occurs in tendons and ligaments under various tensile loading conditions.
- Previous studies show molecular damage in whole tendons and extracted fibrils.
Purpose of the Study:
- To investigate molecular and supramolecular changes in collagen fibrils after tensile stress relaxation.
- To determine if collagen denaturation occurs without fibril failure or visible structural changes.
- To quantify strain-dependent denaturation and associated energy density.
Main Methods:
- Tensile stress relaxation tests on single collagen fibrils from bovine digital extensor tendons.
- Assessment of fibril integrity, D-band spacing, and collagen hybridizing peptide binding.
- Measurement of cross-sectional area changes to estimate volume loss and energy density.
Main Results:
- No broken fibrils or significant changes in D-band spacing were observed.
- Significant, strain-dependent binding of a fluorescent collagen hybridizing peptide indicated denaturation.
- Peptide binding correlated with decreased fibril cross-sectional area, estimating dry volume loss and mechanical energy density (25-110 MJ m⁻³).
Conclusions:
- Collagen molecular damage (denaturation) can occur in connective tissues without macroscale damage or fibril failure.
- Denaturation is strain-dependent and occurs within specific relaxation timeframes.
- Visible supramolecular structure remains unchanged despite molecular-level damage.
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