ELASTIC AND FLEXOELECTIC ASPECTS OF OUT-OF-PLANE FLUCTUATIONS IN BIOLOGICAL AND MODEL MEMBRANES

Out-of-plane fluctuations of biological membranes are examined. The present article concentrates on the liquid crystal (elastic and flexoelectric) aspects of these fluctuations of membrane curvature. The theoretical basis of curvature elasticity and curvature-induced (flexoelectric) polarization of a membrane is provided by liquid crystal physics. Special attention is paid to experimental and theoretical studies of curvature elasticity and flexoelectricity of a pure lipid bilayer in a liquid crystal state. Optical and electrical (noise) investigations of out-of-plane fluctuations in model and living membrane systems are reviewed.