Fluctuations of coupled fluid and solid membranes with application to red blood cells
Fluctuations of coupled fluid and solid membranes with application to red blood cells
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DOI：
10.1103/physreve.76.051910
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发表时间：
2007-11-01
影响因子：
2.4
通讯作者：
Gov, Nir S.
中科院分区：
文献类型：
--
作者：
Auth, Thorsten;Safran, S. A.;Gov, Nir S.
研究了固定平均距离下两个膜的波动光谱和膜间相互作用。每个膜可以是流体膜或固体膜，并且单独地，其波动分别由裸弯曲模量或波矢量相关弯曲模量来描述。膜通过排除体积相互作用进行相互作用；平均距离由外部均匀压力维持。对于强耦合，波动可以通过结合弹性特性的单个有效膜来描述。对于弱耦合，单个非相互作用膜的波动被恢复。由一种流体和一种固体膜组成的复合膜的情况可以作为红细胞质膜和细胞骨架的微观模型。我们发现，尽管真实细胞中双层和细胞骨架的微观结构复杂，但单个聚合膜的波动可以很好地描述波长 lambda 大于或等于 400 nm 的波动（前提是微观结构不存在不均匀性）。该模型应用于盘细胞（“正常”红细胞）、口细胞和棘红细胞的波动数据。从实验中提取了膜的弹性参数和量化活跃的、代谢驱动的波动的有效温度。
The fluctuation spectra and the intermembrane interaction of two membranes at a fixed average distance are investigated. Each membrane can either be a fluid or a solid membrane, and in isolation, its fluctuations are described by a bare or a wave-vector-dependent bending modulus, respectively. The membranes interact via their excluded-volume interaction; the average distance is maintained by an external, homogeneous pressure. For strong coupling, the fluctuations can be described by a single, effective membrane that combines the elastic properties. For weak coupling, the fluctuations of the individual, noninteracting membranes are recovered. The case of a composite membrane consisting of one fluid and one solid membrane can serve as a microscopic model for the plasma membrane and cytoskeleton of the red blood cell. We find that, despite the complex microstructure of bilayers and cytoskeletons in a real cell, the fluctuations with wavelengths lambda greater than or similar to 400 nm are well described by the fluctuations of a single, polymerized membrane (provided that there are no inhomogeneities of the microstructure). The model is applied to the fluctuation data of discocytes ("normal" red blood cells), a stomatocyte, and an echinocyte. The elastic parameters of the membrane and an effective temperature that quantifies active, metabolically driven fluctuations are extracted from the experiments.