Lipid bilayer fracture under uniaxial stretch [dataset]

Most studies on pore formation in lipid membranes focus on lipid vesicles under isotropic tension. These models however fail to replicate the anisotropic stresses encountered by living cells and the complex rheological properties of the cell membrane arising from its interactions with the underlying cytoskeleton. Here, we employ a custom-built device to impose uniaxial stretch on PDMS-supported lipid membranes. We show that in contrast to the circular pores in vesicles, supported membranes under uniaxial loading open elliptical pores that are aligned perpendicularly to the direction of stretch. We discuss the constraints on tension diffusion in supported membranes, and how tension distribution determines the density and the shape of the membrane pores in relation to the applied strain rate and strain magnitude. Our paper shows for the first time that lipid membranes can exhibit a fracture behavior similar to the fracture of soft gels under tensile loading.

目前针对脂质膜孔道形成机制的研究，多聚焦于各向同性张力作用下的脂质囊泡体系。然而此类模型无法复现活细胞所承受的各向异性应力，以及细胞膜与下方细胞骨架相互作用所催生的复杂流变特性。本研究采用定制化实验装置，对聚二甲基硅氧烷（PDMS）支撑的脂质膜施加单轴拉伸载荷。研究结果表明，与脂质囊泡中的圆形孔道不同，单轴加载下的支撑脂质膜会形成与拉伸方向垂直对齐的椭圆形孔道。我们还探讨了支撑膜内张力扩散的约束条件，以及张力分布如何依据施加的应变率与应变幅值，调控膜孔的密度与形态。本研究首次证实，脂质膜在拉伸加载条件下可展现出与软凝胶断裂行为相似的力学断裂特性。