The hierarchical response of human corneal collagen to load.
The hierarchical response of human corneal collagen to load.
复制标题
DOI：
10.1016/j.actbio.2017.11.015
复制
发表时间：
2018-01
影响因子：
9.7
通讯作者：
Meek KM
中科院分区：
文献类型：
--
作者：
Bell JS;Hayes S;Whitford C;Sanchez-Weatherby J;Shebanova O;Vergari C;Winlove CP;Terrill N;Sorensen T;Elsheikh A;Meek KM
人角膜中的原纤维胶原是其作为具有精确曲率的透明透镜的功能不可或缺的，并且其排列现在在文献中被充分表征。虽然已经有相当大的努力，将纤维状结构纳入角膜的机械模型，角膜胶原蛋白的机械响应，以小的应用负载没有得到很好的理解。在这项研究中，纤维和分子的拉伸负荷的反应进行了量化，使用小和广角X射线散射（SAXS/WAXS），和数字图像相关（DIC）摄影被用来计算局部应变场，引起的层次变化。使用分子散射模型来计算原胶原相对于原纤维轴的倾斜度以及与施加的应变相关的变化。在D-周期，分子倾斜和纤维和分子网络的取向和间距的变化进行了测量。这些测量结果被总结为分层变形机制，这被发现有助于在不同的应变。分子倾斜的变化表明亚原纤“弹簧样”变形机制，发现其占生理和近生理负荷下施加的大部分应变。这种变形机制可能在富含高螺旋倾斜原纤维的组织中发挥重要的功能作用，例如皮肤和软骨。胶原蛋白是软组织生物力学的主要介质，其层次结构的变化传达了器官正常运作所需的不同数量的结构支撑。在这里，我们已经检查了角膜胶原蛋白的结构响应拉伸负荷使用X射线探测层次从分子到纤维。我们发现了一种以前未报道的变形机制，即相对于其原纤维轴螺旋排列的分子，其倾斜度的变化类似于弹簧拉伸的方式。这种“弹簧状”机制在低应变（<3%）下占所施加变形的很大一部分。这些发现将为正在开发的胶原基人工角膜的未来设计提供信息，以解决全球角膜供体组织短缺的问题。
Fibrillar collagen in the human cornea is integral to its function as a transparent lens of precise curvature, and its arrangement is now well-characterised in the literature. While there has been considerable effort to incorporate fibrillar architecture into mechanical models of the cornea, the mechanical response of corneal collagen to small applied loads is not well understood. In this study the fibrillar and molecular response to tensile load was quantified using small and wide angle X-ray scattering (SAXS/WAXS), and digital image correlation (DIC) photography was used to calculate the local strain field that gave rise to the hierarchical changes. A molecular scattering model was used to calculate the tropocollagen tilt relative to the fibril axis and changes associated with applied strain. Changes were measured in the D-period, molecular tilt and the orientation and spacing of the fibrillar and molecular networks. These measurements were summarised into hierarchical deformation mechanisms, which were found to contribute at varying strains. The change in molecular tilt is indicative of a sub-fibrillar “spring-like” deformation mechanism, which was found to account for most of the applied strain under physiological and near-physiological loads. This deformation mechanism may play an important functional role in tissues rich in fibrils of high helical tilt, such as skin and cartilage. Collagen is the primary mediator of soft tissue biomechanics, and variations in its hierarchical structure convey the varying amounts of structural support necessary for organs to function normally. Here we have examined the structural response of corneal collagen to tensile load using X-rays to probe hierarchies ranging from molecular to fibrillar. We found a previously unreported deformation mechanism whereby molecules, which are helically arranged relative to the axis of their fibril, change in tilt akin to the manner in which a spring stretches. This “spring-like” mechanism accounts for a significant portion of the applied deformation at low strains (<3%). These findings will inform the future design of collagen-based artificial corneas being developed to address world-wide shortages of corneal donor tissue.
登录
查看更多内容
DOI：
10.1186/s40662-015-0029-z
发表时间：
2015
期刊：
Eye and vision (London, England)
影响因子：
--
作者：
Elsheikh A;McMonnies CW;Whitford C;Boneham GC
通讯作者：
Boneham GC
影响因子：
5.7
作者：
Aghamohammadzadeh, H;Newton, RH;Meek, KM
通讯作者：
Meek, KM
影响因子：
3.9
作者：
Hayes, Sally;White, Tomas;Meek, Keith M.
通讯作者：
Meek, Keith M.
影响因子：
2.8
作者：
Borasio, Edmondo;Mehta, Jodhbir S.;Maurino, Vincenzo
通讯作者：
Maurino, Vincenzo
影响因子：
3.4
作者：
Lewis PN;White TL;Young RD;Bell JS;Winlove CP;Meek KM
通讯作者：
Meek KM