Stress-strain experiments on individual collagen fibrils
Zhilei L Shen1, Mohammad Reza Dodge, Harold Kahn
1Department of Biomedical Engineering and Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, USA.
Biophysical Journal
|July 22, 2008
Summary
This study quantifies the mechanical properties of collagen fibrils, revealing their complex stress-strain behavior under tension. Findings provide crucial data for understanding tissue mechanics and developing biomaterials.
Area of Science:
- Biomaterials Science
- Biophysics
- Tissue Engineering
Background:
- Collagen is a key structural protein in biological tissues, crucial for mechanical properties.
- Existing models of collagen mechanics lack comprehensive experimental data, especially at large strains.
- Understanding collagen fibril mechanics is vital for tissue engineering and biomaterial development.
Purpose of the Study:
- To quantitatively measure the mechanical stress-strain behavior of type I collagen fibrils.
- To investigate large strain responses, including strain softening, strain hardening, and recoverable strain.
- To identify factors influencing collagen fibril mechanical properties.
Main Methods:
- Utilized a microelectromechanical systems (MEMS) platform for uniaxial tension testing.
- Tested partially hydrated collagen fibrils with diameters ranging from 150-470 nm.
- Obtained reproducible stress-strain curves up to 100% strain.
Main Results:
- Small strain modulus: 0.86 ± 0.45 GPa.
- Yield stress (σyield) = 0.22 ± 0.14 GPa at yield strain (εyield) = 0.21 ± 0.13.
- Observed strain softening, strain hardening, time-dependent recoverable residual strain, dehydration-induced embrittlement, and cyclic fatigue susceptibility.
Conclusions:
- Collagen fibril mechanics are complex, influenced by both overall dimensions and internal structure.
- Experimental data reveal critical mechanical behaviors beyond small strain limits.
- Results inform theoretical models and biomaterial design for collagen-based tissues.
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