Negative normal stress in semiflexible biopolymer gels
Negative normal stress in semiflexible biopolymer gels
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DOI：
10.1038/nmat1810
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发表时间：
2007-01-01
期刊：
影响因子：
41.2
通讯作者：
Mackintosh, Fred C.
中科院分区：
文献类型：
--
作者：
Janmey, Paul A.;Mccormick, Margaret E.;Mackintosh, Fred C.
当受到应力或外部载荷时，大多数材料都能抵抗变形。例如，任何稳定的材料都能抵抗压缩--即使是液体。固体还可以抵抗简单的剪切变形，从而保持体积。然而，在剪切作用下，大多数材料也有在垂直于所施加的剪切应力的方向上膨胀的趋势，这种响应被称为正法向应力(1)。例如，湿沙在剪切时往往会膨胀，因此当我们在海滩上行走时，湿沙会在我们的脚周围变干。在简单固体的情况下，弹性棒或线在受到扭转时往往会伸长。在这里，我们展示了半柔性生物聚合物网络，如那些组成细胞细胞骨架和细胞外基质的网络显示出相反的趋势：当在两个平板之间剪切时，它们往往会将平板拉在一起。我们证明了这些负法向应力可以和剪切应力一样大，并且这种特性与生物聚合物凝胶的非线性应变硬化行为直接相关(3)。
When subject to stress or external loads, most materials resist deformation. Any stable material, for instance, resists compression - even liquids. Solids also resist simple shear deformations that conserve volume. Under shear, however, most materials also have a tendency to expand in the direction perpendicular to the applied shear stress, a response that is known as positive normal stress(1). For example, wet sand tends to dilate when sheared, and therefore dries around our feet when we walk on the beach. In the case of simple solids, elastic rods or wires tend to elongate when subject to torsion(2). Here, we show that networks of semiflexible biopolymers such as those that make up both the cytoskeleton of cells and the extracellular matrix exhibit the opposite tendency: when sheared between two plates, they tend to pull the plates together. We show that these negative normal stresses can be as large as the shear stress and that this property is directly related to the nonlinear strain-stiffening behaviour of biopolymer gels(3).