Fluctuations and instability of a biological membrane induced by interaction with macromolecules
Fluctuations and instability of a biological membrane induced by interaction with macromolecules
复制标题
DOI：
10.1103/physreve.72.041901
复制
发表时间：
2005-10-01
影响因子：
2.4
通讯作者：
Misbah, C
中科院分区：
文献类型：
--
作者：
Divet, F;Danker, G;Misbah, C
本文研究了磷脂膜在具有吸附和解吸能力的外来分子（如聚合物、蛋白质等）的扩散场存在下的动力学和波动。我们开发了一个模型，除流体动力学外，还包括周围流体中的分子扩散和横向扩散（即沿膜扩散）以及附着和脱离膜的动力学。此模型用于整体处于平衡状态的自由膜的情况，而非平衡部分将在将来介绍。我们表明，如果膜和分子之间的耦合足够强，平面膜可以遭受形态不稳定。在非线性状态下的数值计算显示出萌芽和自发囊泡发射的初始阶段。当满足稳定条件时，我们展示了动力学波动如何导致表达主要耗散机制的丰富多样的动力学行为。我们表明，在与起作用的物理机制相关的分离良好的长度尺度的极限下，膜波动的宽度w表现出具有普遍标度指数的各种动态标度。结果表明，在不同的时间和长度尺度上，与t（1/3）相似的时间w的通常行为发生了变化。例如，我们发现w类似于t(1/4)， w类似于t(1/2)， w类似于[t ln(t)](1/2)，这取决于哪种物理机制限制了膜在考虑的时间尺度上的波动。波动谱的实验研究可以看作是一种宝贵的工具，以获得潜在的微观物理机制。
This paper studies the dynamics and fluctuations of a phospholipidic membrane in the presence of a diffusion field of foreign molecules, such as polymers, proteins, etc., which have the ability to adsorb on, and to desorb from, the membrane. We develop a model that includes, besides hydrodynamics, molecular diffusion in the surrounding fluid and lateral diffusion (i.e., diffusion along the membrane) as well as the kinetics of attachment and detachment to and from the membrane. This model is exploited here for the case of a free membrane which is globally at equilibrium while the nonequilibrium part will be presented in the future. We show that if the coupling between the membrane and the molecules is strong enough, the flat membrane can suffer a morphological instability. The numerical calculation in the nonlinear regime reveals budding, and an initial stage of spontaneous vesicle emission. When the condition of stability is satisfied we show how kinetic fluctuations lead to a rich variety of dynamical behaviors expressing the dominant dissipation mechanisms. We show that in the limit of well separated length scales related to the physical mechanisms that enter into play, the width w of the membrane fluctuations exhibits various dynamical scalings with universal scaling exponents. It is shown that the usual behavior with time w similar to t(1/3) is altered in various time and length scales of interest. For example, we find that w similar to t(1/4), w similar to t(1/2), and w similar to[t ln(t)](1/2), depending on which physical mechanism limits the membrane fluctuations on the time scale under consideration. The experimental study of the fluctuation spectrum can be viewed as a precious tool in order to have access to the underlying microscopic physical mechanisms.