Electromechanical Properties and Deformation of Biomembranes

哺乳动物、鸟类和爬行动物的细胞外缘有一层薄薄的细胞膜，由脂肪分子(脂类)组成。电池的内部和外部的带电分子浓度不同，导致跨膜的电场改变了它的机械性能。细胞膜的机械性能对细胞的功能有着深远的影响。这项研究将通过实验确定细胞膜的机械性能如何因暴露在电场中而发生变化。实验结果将用‘壳理论’的工程方法来模拟，该理论可以模拟薄材料的曲率对其机械性能的影响。质膜上的电势差对所有活细胞都是常见的，对于生理功能，如产生细胞间通讯的动作电位是必不可少的。虽然细胞电活动的基础已经很好地建立了(例如，动作电位的Hodgkin-Huxley模型)，但电压和膜变形之间的耦合受到的关注有限。为了填补这一空白，我们将对外加电场下的仿生膜进行理论和实验相结合的研究。具体地说，这项研究试图确定膜电压、膜特性(如弯曲刚度、张力和自发曲率)和膜形状之间的关系。本课题采用理论和实验相结合的方法，分析了在外加电场作用下的小的热驱动双层起伏和大的类屈曲变形。该项目的革命性影响在于它对生物膜形状和电压之间的动态耦合进行了开创性的研究；我们的发现将揭示与涉及可兴奋细胞的广泛生理过程相关的新物理。

The cells of mammals, birds and reptiles have as their outer edge a thin layer, a cell membrane, that is composed of fatty molecules (lipids). The inside of the cell has a different concentration of charged molecules from the outside of the cell, resulting in an electric field across the membrane that changes its mechanical properties. The mechanical properties of the cell membrane have a profound effect upon how the cell functions. The research will determine by experiment how the mechanical properties of a cell membrane change as the result of exposure to electrical fields. The results of the experiments will be modeled using the engineering methods of 'shell theory' which can model the effects of the curvature of a thin material on its mechanical properties.An electric potential difference across the plasma membrane is common to all living cells and is essential to physiological functions such as generation of action potentials for cell-to-cell communication. While the basics of cell electrical activity are well established (e.g. the Hodgkin-Huxley model of the action potential), the coupling between voltage and membrane deformation has received limited attention. To fill this void, a combined theoretical and experimental study of biomimetic membranes in externally applied electric fields will be studied. Specifically, the research seeks to determine the relation between membrane voltage, membrane properties such as bending rigidity, tension, and spontaneous curvature, and membrane shape. The project integrates theory and experiment to analyze both the small thermally-driven bilayer undulations and the large buckling-like deformations in an applied electric field. The transformative impact of the project lies in its pioneering research of the dynamic coupling between shape and voltage of biomembranes; our findings will uncover new physics relevant to a broad range of physiological processes involving excitable cells.