Stretching Single Collagen Fibrils Reveals Nonlinear Mechanical Behavior.
Emilie Gachon1, Patrick Mesquida1
1Department of Physics, King's College London, Strand, London, United Kingdom.
Biophysical Journal
|February 20, 2020
Summary
Type I collagen fibrils exhibit unique mechanical properties, including strain stiffening and softening, due to molecular changes. Understanding these collagen fibril mechanics is crucial for cell-matrix interactions and disease research.
Area of Science:
- Biophysics
- Materials Science
- Biochemistry
Background:
- Collagen fibrils are key components of the extracellular matrix, influencing cell behavior.
- Their mechanical properties are intrinsically linked to their molecular structure and cross-linking.
- Understanding collagen mechanics is vital for comprehending tissue function and disease pathogenesis.
Purpose of the Study:
- To investigate the nonlinear mechanical behavior of type I collagen fibrils.
- To elucidate the molecular mechanisms underlying strain stiffening and softening in collagen.
- To explore the impact of cross-linking on collagen fibril mechanics.
Main Methods:
- A novel combination of uniaxial, longitudinal straining and radial nanoindentation was employed.
- Mechanical responses were analyzed across different strain levels (0-25%).
- Comparison between native and artificially cross-linked (glutaraldehyde) fibrils was performed.
Main Results:
- Type I collagen fibrils demonstrated significant strain stiffening (0-15% strain) followed by strain softening (15-25% strain).
- This nonlinear behavior is attributed to the unfolding of disordered domains and breaking of native cross-links.
- Artificial cross-linking abolished this phenomenon, and nanoindentation differentiated mechanics of overlap and gap regions.
Conclusions:
- The observed mechanical behavior of collagen fibrils is explained by distinct molecular events occurring at different strain levels.
- Findings offer insights into matrix mechanics and the role of glycation in age-related diseases like diabetes.
- The developed straining method is simple, requires no specialized equipment, and has potential applications in nanometer-scale biophysics.
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