The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
Biophys J. 2012 Sep 5;103(5):918-29. doi: 10.1016/j.bpj.2012.07.010.
Biomembranes are thin capacitors with the unique feature of displaying phase transitions in a physiologically relevant regime. We investigate the voltage and lateral pressure dependence of their capacitance close to their chain melting transition. Because the gel and the fluid membrane have different area and thickness, the capacitance of the two membrane phases is different. In the presence of external fields, charges exert forces that can influence the state of the membrane, thereby influencing the transition temperature. This phenomenon is called "electrostriction". We show that this effect allows us to introduce a capacitive susceptibility that assumes a maximum in the melting transition with an associated excess charge. As a consequence, voltage regimes exist in which a small change in voltage can lead to a large uptake of charge and a large capacitive current. Furthermore, we consider electromechanical behavior such as pressure-induced changes in capacitance, and the application of such concepts in biology.
生物膜是具有独特特性的薄电容器，能够在生理相关范围内显示相变。我们研究了接近其链熔转变时电压和侧向压力对其电容的影响。由于凝胶和流体膜的面积和厚度不同，两种膜相的电容也不同。在外部场的存在下，电荷会产生力，从而影响膜的状态，进而影响转变温度。这种现象称为“电致伸缩”。我们表明，这种效应使我们能够引入一个电容率，在熔化转变中具有一个与过剩电荷相关的最大值。因此，存在一些电压范围，在这些范围内，电压的微小变化会导致电荷的大量吸收和较大的电容电流。此外，我们还考虑了诸如电容随压力变化的机电行为，以及这些概念在生物学中的应用。
