论文标题
流体囊泡的曲率波动揭示了双层中的流体动力耗散
Curvature fluctuations of fluid vesicles reveal hydrodynamic dissipation within the bilayer
论文作者
论文摘要
膜的生物学功能与它们的柔软度密切相关，它们通常通过膜的热驱动波动进行研究。分析通常假定纯弯曲变形的弛豫率取决于周围介质中膜弯曲刚度和粘性耗散之间的竞争。在这里，我们重新检查了这种假设，并证明膜内的粘性流占主导地位的非平面膜弯曲波动的动力学，其曲率比Saffman-Delbrück长度小。使用由DPPC制成的巨型囊泡的闪烁光谱：胆固醇混合物和纯二嵌段 - 聚合物膜，我们通过实验检测到曲率波动中膜耗散的特征，并表明膜粘度可以从形状时间越来越短的时间行为中可靠地获得。结果表明，DPPC：胆固醇膜作为牛顿液的表现，而聚合物膜表现出更复杂的流变。我们的研究提供了对生物学和合成膜曲率重塑的时间尺度的物理见解。
The biological function of membranes is closely related to their softness, which is often studied through the membranes' thermally-driven fluctuations. The analysis commonly assumes that the relaxation rate of a pure bending deformation is determined by the competition between membrane bending rigidity and viscous dissipation in the surrounding medium. Here, we reexamine this assumption and demonstrate that viscous flows within the membrane dominate the dynamics of bending fluctuations of non-planar membranes with a radius of curvature smaller than the Saffman-Delbrück length. Using flickering spectroscopy of giant vesicles made of DPPC:Cholesterol mixtures and pure diblock-copolymer membranes, we experimentally detect the signature of membrane dissipation in curvature fluctuations, and show that membrane viscosity can be reliably obtained from the short time behavior of the shape time correlations. The results indicate that the DPPC:Cholesterol membranes behave as a Newtonian fluid, while polymer membranes exhibit more complex rheology. Our study provides physical insights into the time scales of curvature remodeling of biological and synthetic membranes.
