Department of Applied Mathematics and Theoretical Physics, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom.
Phys Rev Lett. 2013 Jul 19;111(3):038103. doi: 10.1103/PhysRevLett.111.038103. Epub 2013 Jul 17.
The viscosity of lipid bilayer membranes plays an important role in determining the diffusion constant of embedded proteins and the dynamics of membrane deformations, yet it has historically proven very difficult to measure. Here we introduce a new method based on quantification of the large-scale circulation patterns induced inside vesicles adhered to a solid surface and subjected to simple shear flow in a microfluidic device. Particle image velocimetry based on spinning disk confocal imaging of tracer particles inside and outside of the vesicle and tracking of phase-separated membrane domains are used to reconstruct the full three-dimensional flow pattern induced by the shear. These measurements show excellent agreement with the predictions of a recent theoretical analysis, and allow direct determination of the membrane viscosity.
脂质双层膜的黏度在决定嵌入蛋白的扩散常数和膜变形的动力学方面起着重要作用，但在历史上一直很难测量。在这里，我们介绍了一种新方法，该方法基于对在微流控装置中粘附在固体表面并受到简单剪切流作用的囊泡内部诱导的大尺度循环模式的定量。基于旋转盘共聚焦成像的示踪粒子在囊泡内外的粒子图像测速法和分离膜域的相位跟踪用于重建剪切引起的全三维流动模式。这些测量结果与最近的理论分析的预测非常吻合，并允许直接确定膜黏度。
