Stress-strain experiments on individual collagen fibrils
Stress-strain experiments on individual collagen fibrils
复制标题
DOI：
10.1529/biophysj.107.124602
复制
发表时间：
2008-10-15
影响因子：
3.4
通讯作者：
Eppell, Steven J.
中科院分区：
文献类型：
--
作者：
Shen, Zhilei L.;Dodge, Mohammad Reza;Eppell, Steven J.
胶原蛋白是一种由三个编织的蛋白质螺旋组成的分子，是许多生物组织（包括骨、肌腱、软骨和皮肤）的主要构建块。胶原蛋白分子的交错阵列形成原纤维，其排列成更高级的结构，如纤维和纤维束。由于胶原蛋白在决定这些组织的机械性能方面起着至关重要的作用，因此重要的理论研究是针对开发胶原蛋白分子和原纤维的刚度、强度和韧性的模型。然而，指导这些模型开发的实验数据很少，并且仅限于小应变响应。使用微机电系统平台测试部分水合胶原纤维在单轴拉伸下，我们获得了定量的，可重复的机械测量的应力-应变曲线的I型胶原纤维，直径范围从150-470 nm。原纤维显示出0.86 +/-0.45GPa的小应变（ε < 0.09）模量。在高达100%的应变下测试的原纤维表现出应变软化（σ（屈服）= 0.22 +/- 0.14 GPa; σ（屈服）= 0.21 +/- 0.13）和应变硬化、时间依赖性可恢复残余应变、脱水诱导脆化和对循环疲劳的敏感性。结果表明，胶原纤维的应力-应变行为是由全局特征尺寸以及内部结构决定的。
Collagen, a molecule consisting of three braided protein helices, is the primary building block of many biological tissues including bone, tendon, cartilage, and skin. Staggered arrays of collagen molecules form fibrils, which arrange into higher-ordered structures such as fibers and fascicles. Because collagen plays a crucial role in determining the mechanical properties of these tissues, significant theoretical research is directed toward developing models of the stiffness, strength, and toughness of collagen molecules and fibrils. Experimental data to guide the development of these models, however, are sparse and limited to small strain response. Using a microelectromechanical systems platform to test partially hydrated collagen fibrils under uniaxial tension, we obtained quantitative, reproducible mechanical measurements of the stress-strain curve of type I collagen fibrils, with diameters ranging from 150-470 nm. The fibrils showed a small strain (epsilon < 0.09) modulus of 0.86 +/- 0.45 GPa. Fibrils tested to strains as high as 100% demonstrated strain softening (sigma(yield) = 0.22 +/- 0.14 GPa; epsilon(yield) = 0.21 +/- 0.13) and strain hardening, time-dependent recoverable residual strain, dehydration-induced embrittlement, and susceptibility to cyclic fatigue. The results suggest that the stress-strain behavior of collagen fibrils is dictated by global characteristic dimensions as well as internal structure.