Assembly of collagen matrices as a phase transition revealed by structural and rheologic studies
Assembly of collagen matrices as a phase transition revealed by structural and rheologic studies
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DOI：
10.1016/s0006-3495(03)74942-x
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发表时间：
2003-02-01
影响因子：
3.4
通讯作者：
Sackmann, E
中科院分区：
文献类型：
--
作者：
Forgacs, G;Newman, SA;Sackmann, E
我们通过相差显微镜和转盘流变仪研究了细胞外基质蛋白型胶原蛋白组装网络的结构和粘弹性特性。组装的初始阶段是胶原单体与随机分布的延伸数微米的分支簇结合的成核过程。最终发生溶胶-凝胶转变，这是由于这些簇的互连。我们用渗流理论分析了这种转变。粘弹性参数（储能模量 G' 和损耗模量 G"）作为时间函数测量了 omega = 0.2 rad/s 至 6.9 rad/s 范围内的五个不同频率。我们发现，在凝胶点，G' 和 G" 均遵循比例定律 G' (omega) alpha G" (omega) alpha omega(Delta)，临界指数 Delta = 0.7 和临界损耗角 delta(tan delta = G" / G') 与渗透理论预测的频率无关。因此，胶原蛋白的凝胶化代表二级相变。
We have studied the structural and viscoelastic properties of assembling networks of the extracellular matrix protein typed collagen by means of phase contrast microscopy and rotating disk rheometry. The initial stage of the assembly is a nucleation process of collagen monomers associating to randomly distributed branched clusters with extensions of several microns. Eventually a sol-gel transition takes place, which is due to the interconnection of these clusters. We analyzed this transition in terms of percolation theory. The viscoelastic parameters (storage modulus G' and loss modulus G") were measured as a function of time for five different frequencies ranging from omega = 0.2 rad/s to 6.9 rad/s. We found that at the gel point both G' and G" obey a scaling law G' (omega) alpha G" (omega) alpha omega(Delta), with the critical exponent Delta = 0.7 and a critical loss angle delta(tan delta = G" / G') being independent of frequency as predicted by percolation theory. Gelation of collagen thus represents a second order phase transition.