PULS Group, Institute for Theoretical Physics and the Interdisciplinary Center for Nanostructured Films, Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany; Group for Computational Life Sciences, Division of Physical Chemistry, Institut Ruđer Bošković, Zagreb, Croatia.
PULS Group, Institute for Theoretical Physics and the Interdisciplinary Center for Nanostructured Films, Friedrich Alexander University Erlangen-Nürnberg, Erlangen, Germany; II. Institut für Theoretische Physik, Universität Stuttgart, Stuttgart, Germany.
Biophys J. 2019 Aug 6;117(3):542-552. doi: 10.1016/j.bpj.2019.06.036. Epub 2019 Jul 9.
In biological settings, membranes typically interact locally with other membranes: the extracellular matrix in the exterior or internal cellular structures such as the cytoskeleton, locally pinning the membrane. Characterizing the dynamical properties of such interactions presents a difficult task. Significant progress has been achieved through simulations and experiments, yet analytical progress in modeling pinned membranes has been impeded by the complexity of governing equations. Here, we circumvent these difficulties by calculating analytically the time-dependent Green's function of the operator governing the dynamics of an elastically pinned membrane in a hydrodynamic surrounding and subject to external forces. This enables us to calculate the equilibrium power spectral density for an overdamped membrane pinned by an elastic, permanently attached spring subject to thermal excitations. By considering the effects of the finite experimental resolution on the measured spectra, we show that the elasticity of the pinning can be extracted from the experimentally measured spectrum. Membrane fluctuations can thus be used as a tool to probe mechanical properties of the underlying structures. Such a tool may be particularly relevant in the context of cell mechanics, in which the elasticity of the membrane's attachment to the cytoskeleton could be measured.
在生物环境中，膜通常与其他膜局部相互作用：细胞外基质在外部或细胞内结构（如细胞骨架）内部局部固定膜。描述这种相互作用的动力学特性是一项艰巨的任务。通过模拟和实验已经取得了重大进展，但由于控制方程的复杂性，在受固定膜的建模方面的分析进展受到了阻碍。在这里，我们通过计算在流体环境中受弹性固定的膜的动力学的控制算子的随时间变化的格林函数，从而避免了这些困难，并且该膜还受到外部力的作用。这使我们能够计算在热激发下由弹性、永久附着的弹簧固定的过阻尼膜的平衡功率谱密度。通过考虑有限实验分辨率对测量谱的影响，我们表明可以从实验测量的谱中提取固定的弹性。因此，膜波动可以用作探测基础结构机械特性的工具。在细胞力学的背景下，这种工具可能特别相关，因为可以测量膜与细胞骨架的附着的弹性。
