发表机构
University of California San Diego（加州大学圣迭戈分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过连续介质模拟揭示渗透压驱动脂质囊泡经历屈曲、平滑和折叠三阶段演化，并预测了屈曲与折叠时间标度，阐明了膜塌缩与内陷的物理机制。
AI 中文摘要
我们利用可渗透、面积不可压缩且具有弯曲弹性和表面粘性的流体膜的连续介质模拟，研究了受到渗透压冲击的球形脂质囊泡的动力学。该动力学由单一无量纲参数 $\varGamma$ 控制，该参数衡量渗透压与弯曲力的相对强度。渗透压驱动引发三阶段演化，包括快速屈曲和塌缩、随后皱纹和脊的平滑，以及最终缓慢折叠成内陷形态，这种形态类似于实验观察到的囊泡内囊泡结构的前驱体。线性稳定性分析预测了初始屈曲不稳定性的波长和增长率，并表明无量纲屈曲时间按 $\varGamma^{-2}$ 标度，与模拟定量一致。在更长时间尺度上，能量收支揭示了弹性能量传递的逆转：屈曲期间积累的弯曲能量在松弛过程中释放，并被膜粘性耗散。对折叠动力学的标度分析预测无量纲折叠时间按 $\varGamma^{-2/3}$ 标度，再次与模拟结果高度吻合。这些结果为控制渗透驱动膜塌缩和内陷的机制及广泛分离的时间尺度提供了连续介质描述。
英文摘要
We investigate the dynamics of spherical lipid vesicles subjected to an osmotic shock using continuum simulations of a permeable, area-incompressible fluid membrane with bending elasticity and surface viscosity. The dynamics are governed by a single dimensionless parameter $\varGamma$, which measures the relative strength of osmotic pressure and bending forces. Osmotic forcing drives a three-stage evolution comprising rapid buckling and collapse, smoothing of the resulting wrinkles and ridges, and slow folding into an invaginated morphology resembling the precursor to experimentally observed vesicle-in-vesicle structures. Linear stability analysis predicts the wavelength and growth rate of the initial buckling instability and shows that the dimensionless buckling time scales as $\varGamma^{-2}$, in quantitative agreement with simulations. At longer times, the energy budget reveals a reversal in elastic energy transfer: bending energy accumulated during buckling is released during relaxation and dissipated by membrane viscosity. A scaling analysis of the folding dynamics predicts that the dimensionless folding time scales as $\varGamma^{-2/3}$, again in excellent agreement with simulations. These results provide a continuum description of the mechanisms and widely separated timescales governing osmotically driven membrane collapse and invagination.
Comments9 pages, 5 figures
