失水状态下动脉弹性蛋白的力学性能
Mechanical Properties of Arterial Elastin With Water Loss.
作者信息
Wang Yunjie, Hahn Jacob, Zhang Yanhang
机构信息
Department of Mechanical Engineering, Boston University, 110 Cummington Mall, Boston, MA 02215.
Department of Mechanical Engineering, Boston University, , Boston, MA 02215.
出版信息
J Biomech Eng. 2018 Apr 1;140(4):0410121-8. doi: 10.1115/1.4038887.
Elastin is a peculiar elastomer in that it requires water to maintain resilience, and its mechanical properties are closely associated with the immediate aqueous environment. The bulk, extra- and intrafibrillar water plays important roles in both elastic and viscoelastic properties of elastin. In this study, a two-stage liquid-vapor method was developed to investigate the effects of water loss on the mechanical properties of porcine aortic elastin. The tissue samples started in a phosphate-buffered saline (PBS) solution at their fully hydrated condition, with a gravimetric water content of 370±36%. The hydration level was reduced by enclosing the tissue in dialysis tubing and submerging it in polyethylene glycol (PEG) solution at concentrations of 10%, 20%, 30%, and 45% w/v, which reduced the water content of the samples to 258±34%, 224±20%, 109±9%, and 58±3%, respectively. The samples were then transferred to a humidity chamber to maintain the hydration level while the samples underwent equi-biaxial tensile and stress relaxation tests. The concentration of 10% PEG treatment induced insignificant changes in tissue dimensions and stiffness, indicating that the removal of bulk water has less effect on elastin. Significant increases in tangent modulus were observed after 20% and 30% PEG treatment due to the decreased presence of extrafibrillar water. Elastin treated with 45% PEG shows a very rigid behavior as most of the extrafibrillar water is eliminated. These results suggest that extrafibrillar water is crucial for elastin to maintain its elastic behavior. It was also observed that the anisotropy of elastin tends to decrease with water loss. An increase in stress relaxation was observed for elastin treated with 30% PEG, indicating a more viscous behavior of elastin when the amount of extrafibrillar water is significantly reduced. Results from this study shed light on the close association between the bulk, extra- and intrafibrillar water pools and the mechanics of elastin.
弹性蛋白是一种特殊的弹性体，因为它需要水来维持弹性，并且其机械性能与周围的水环境密切相关。弹性蛋白整体、纤维外和纤维内的水在弹性和粘弹性方面都起着重要作用。在本研究中，开发了一种两阶段液-气法来研究水分流失对猪主动脉弹性蛋白机械性能的影响。组织样本在完全水合状态下开始置于磷酸盐缓冲盐水（PBS）溶液中，重量含水量为370±36%。通过将组织封闭在透析管中并将其浸入浓度为10%、20%、30%和45%（w/v）的聚乙二醇（PEG）溶液中来降低水合水平，这分别将样本的含水量降低到258±34%、224±20%、109±9%和58±3%。然后将样本转移到湿度箱中以维持水合水平，同时对样本进行等双轴拉伸和应力松弛测试。10% PEG处理浓度对组织尺寸和硬度的影响不显著，表明去除整体水对弹性蛋白的影响较小。20%和30% PEG处理后，由于纤维外水的减少，切线模量显著增加。用45% PEG处理的弹性蛋白表现出非常刚性的行为，因为大部分纤维外水被去除。这些结果表明，纤维外水对于弹性蛋白维持其弹性行为至关重要。还观察到弹性蛋白的各向异性倾向于随着水分流失而降低。用30% PEG处理的弹性蛋白观察到应力松弛增加，表明当纤维外水的量显著减少时，弹性蛋白的粘性行为更强。本研究结果揭示了整体、纤维外和纤维内水池与弹性蛋白力学之间的密切关系。
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