Han Yunlong, Lin Hao, Ding Mingming, Li Rui, Shi Tongfei
State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, P. R. China.
Soft Matter. 2019 Apr 17;15(16):3307-3314. doi: 10.1039/c9sm00116f.
We use finite element method to investigate the flow-induced translocation of vesicles through a narrow pore from a dynamic point of view. In order to complete the coupling between fluid flow and the vesicle membranes, we employ the fluid-structure interactions with the arbitrary Lagrangian-Eulerian method. Our results demonstrate that the vesicle shows similar shape change from bullet-like to dumbbell-like, dumbbell-like to bulb-like, and bulb-like to parachute-like if it is pushed by flow field to pass through a narrow pore smaller than its size. We further find that the strain energy exhibits a higher peak and a lower peak in the whole translocation process, where the higher peak corresponds to the dumbbell-like shape and the lower peak corresponds to the parachute-like shape due to more stretching of the membrane for the dumbbell-like shape than that of the parachute-like shape. The translocation time of the vesicle from one side to the other side of the narrow pore decreases with the increase of inlet velocity, but the strain energy exhibits an increase, which implies that the vesicle needs more time to complete the translocation with the lower inlet velocity, but the requirement for the mechanical properties of the membrane is lower. Our work answers the mapping between the positions of the vesicles and deformed states with the stress distribution and change of strain energy, which can provide helpful information on the utilization of vesicles in pharmaceutical, chemical, and physiological processes.
我们从动力学角度使用有限元方法研究了囊泡在狭窄孔隙中因流动诱导的转运。为了实现流体流动与囊泡膜之间的耦合，我们采用任意拉格朗日 - 欧拉方法进行流固耦合。我们的结果表明，如果囊泡被流场推动通过小于其尺寸的狭窄孔隙，它会呈现出类似的形状变化，从子弹状变为哑铃状，从哑铃状变为球茎状，再从球茎状变为降落伞状。我们进一步发现，在整个转运过程中，应变能呈现出一个较高的峰值和一个较低的峰值，其中较高的峰值对应哑铃状形状，较低的峰值对应降落伞状形状，这是因为哑铃状形状的膜比降落伞状形状的膜拉伸程度更大。囊泡从狭窄孔隙一侧转运到另一侧的时间随着入口速度的增加而减少，但应变能却增加，这意味着入口速度较低时囊泡完成转运需要更多时间，但对膜力学性能的要求较低。我们的工作揭示了囊泡位置与变形状态之间以及应力分布和应变能变化之间的对应关系，这可为囊泡在制药、化学和生理过程中的应用提供有用信息。
