Osmotically driven tensile stress in collagen-based mineralized tissues
Osmotically driven tensile stress in collagen-based mineralized tissues
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DOI：
10.1016/j.jmbbm.2015.03.010
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发表时间：
2015-12-01
影响因子：
3.9
通讯作者：
Fratzl, Peter
中科院分区：
文献类型：
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作者：
Bertinetti, Luca;Masic, Admir;Fratzl, Peter
胶原蛋白是哺乳动物中最丰富的蛋白质，其主要作用是在许多细胞外基质如骨、肌腱、皮肤或血管中充当机械支撑。水是胶原蛋白结构的组成部分，但其作用仍然知之甚少，尽管众所周知胶原蛋白的机械性质取决于水合作用。最近，研究表明，胶原蛋白三螺旋的构象在水去除后发生变化，导致分子以相当大的力收缩。在这里，我们调查的矿化对这种效果的影响，通过研究骨和火鸡腿肌腱（TLT）作为模型系统。事实上，TLT部分矿化，因此在同一肌腱中可以发现具有各种矿物质含量的良好排列的胶原蛋白。我们表明，水的去除导致胶原蛋白收缩，在所有情况下产生拉伸应力高达80 MPa。此外，胶原蛋白的这种收缩使矿物质颗粒受到压缩，导致约1%的应变，这意味着矿物质中的局部压缩载荷高达800 MPa。这表明矿化时胶原蛋白脱水是骨矿物质中常见的压缩预应变的起源。（C）2015 Elsevier Ltd.保留所有权利。
Collagen is the most abundant protein in mammals and its primary role is to serve as mechanical support in many extracellular matrices such as those of bones, tendons, skin or blood vessels. Water is an integral part of the collagen structure, but its role is still poorly understood, though it is well-known that the mechanical properties of collagen depend on hydration. Recently, it was shown that the conformation of the collagen triple helix changes upon water removal, leading to a contraction of the molecule with considerable forces. Here we investigate the influence of mineralization on this effect by studying bone and turkey leg tendon (TLT) as model systems. Indeed, TLT partially mineralizes so that well-aligned collagen with various mineral contents can be found in the same tendon. We show that water removal leads to collagen contraction in all cases generating tensile stresses up to 80 MPa. Moreover, this contraction of collagen puts mineral particles under compression leading to strains of around 1%, which implies localized compressive loads in mineral of up to 800 MPa. This suggests that collagen dehydration upon mineralization is at the origin of the compressive pre-strains commonly observed in bone mineral. (C) 2015 Elsevier Ltd. All rights reserved.