Electromechanical Properties and Deformation of Biomembranes

Brown University, Providence RI

Investigators

Abstract

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.