Biomechanics of fibrous proteins of the extracellular matrix studied by Brillouin scattering
Biomechanics of fibrous proteins of the extracellular matrix studied by Brillouin scattering
复制标题
DOI：
10.1098/rsif.2014.0739
复制
发表时间：
2014-12-06
影响因子：
3.9
通讯作者：
Fioretto, Daniele
中科院分区：
文献类型：
--
作者：
Palombo, Francesca;Winlove, C. Peter;Fioretto, Daniele
布里渊光散射（BLS）光谱是一种能够探测材料中热激发声子的技术。这些声子的传播速度可以从入射光和散射光之间的布里渊频移的幅度来确定，从而提供了在千兆赫范围内测量材料机械性能的方法。生物组织的细胞外基质及其组成生物聚合物的机械性质对于正常组织功能是重要的，并且这些性质的干扰广泛地与疾病有关。BLS提供了在活组织中微观尺度上测量力学性质的前景，从而提供了在正常和病理条件下结构-功能关系的见解。在这项研究中，我们研究了胶原蛋白和弹性蛋白-细胞外基质（ECM）的纤维蛋白中的BLS。对大鼠尾腱中的I型胶原、关节软骨中的II型胶原和项韧带弹性蛋白进行了测定。在背散射几何中，使用反射基板的BLS光谱对纤维取向的依赖性进行了研究。两个峰，体模式所产生的声子传播沿着准径向方向的纤维轴和模式平行于表面，这取决于样品相对于纤维轴的取向，可以区分。后一个峰值被拟合到通过六边形对称弹性固体的波传播模型，并且弹性张量的五个分量被组合以给出纤维的轴向和横向杨氏模量、剪切模量和体积模量。脱水的I型胶原蛋白和弹性蛋白的压力分别为10.2、8.3、3.2和10.9 GPa，以及6.1、5.3、1.9和8 GPa。前者的值接近以前报告的值。还应用微聚焦BLS方法，提供单纤维的选择。胶原蛋白和弹性蛋白的模量远高于在较低频率下使用宏观应变测量的模量，并且它们之间的差异小得多。因此，我们相信，像以前的研究人员一样，分子尺度的粘弹性效应是纤维生物力学的频率依赖性的原因。因此，在未来，将BLS与大规模的机械测试方法相结合，将提供一种跟踪ECM中复杂结构形成过程中机械性能演变的方法。
Brillouin light scattering (BLS) spectroscopy is a technique that is able to detect thermally excited phononswithin a material. The speed of propagation of these phonons can be determined fromthe magnitude of the Brillouin frequency shift between incident and scattered light, thereby providing a measure of the mechanical properties of the material in the gigahertz range. The mechanical properties of the extracellular matrices of biological tissues and their constituent biopolymers are important for normal tissue function and disturbances in these properties arewidely implicated in disease. BLS offers the prospect ofmeasuring mechanical properties on a microscopic scale in living tissues, thereby providing insights into structure-function relationships under normal and pathological conditions. In this study, we investigated BLS in collagen and elastin-the fibrous proteins of the extracellular matrix (ECM). Measurements were made on type I collagen in rat tail tendon, type II collagen in articular cartilage and nuchal ligament elastin. The dependence of the BLS spectrum on fibre orientation was investigated in a backscattering geometry using a reflective substrate. Two peaks, a bulk mode arising from phonon propagation along a quasi-radial direction to the fibre axis and a mode parallel to the surface, depending on sample orientation relative to the fibre axis, could be distinguished. The latter peak was fitted to a model of wave propagation through a hexagonally symmetric elastic solid, and the five components of the elasticity tensor were combined to give axial and transverse Young's, shear and bulk moduli of the fibres. These were 10.2, 8.3, 3.2 and 10.9 GPa, and 6.1, 5.3, 1.9 and 8 GPa for dehydrated type I collagen and elastin, respectively. The former values are close to those previously reported. A microfocused BLS approach was also applied providing selection of single fibres. The moduli of collagen and elastin are much higher than those measured at lower frequency using macroscopic strains, and the difference between themismuch less. We therefore believe, like previous investigators, that molecular-scale viscoelastic effects are responsible for the frequency dependence of the fibre biomechanics. Combining BLS with larger-scale mechanical testing methods therefore should, in the future, provide a means of following the evolution of mechanical properties in the formation of the complex structures found in the ECM.