Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Department of Mechanical Engineering, University of Hawaii at Manoa, Honolulu, Hawaii 96822, USA.
Soft Matter. 2020 Oct 7;16(38):8904-8911. doi: 10.1039/d0sm01027h.
Lipid vesicles have received considerable interest because of their applications to in vitro reductionist cell membrane models as well as therapeutic delivery vehicles. In these contexts, the mechanical response of vesicles in nonequilibrium environments plays a key role in determining the corresponding dynamics. A common understanding of the response of lipid vesicles upon exposure to a hypotonic solution is a characteristic pulsatile behavior. Recent experiments, however, have shown vesicles exploding under an osmotic shock generated by photo-reactions, yet the explanatory mechanism is unknown. Here we present a generalized biophysical model incorporating a stochastic account of membrane rupture to describe both swell-burst-reseal cycling and exploding dynamics. This model agrees well with experimental observations, and it unravels that the sudden osmotic shock strains the vesicle at an extreme rate, driving the vesicle into buckling instabilities responsible for membrane fragmentation, i.e. explosion. Our work not only advances the fundamental framework for non-equilibrium vesicle dynamics under osmotic stress, but also offers design guidelines for programmable vesicle-encapsulated substance release in therapeutic carriers.
脂质体因其在体外简化细胞膜模型以及治疗性药物输送载体中的应用而受到广泛关注。在这些情况下，脂质体在非平衡环境中的力学响应在决定相应动力学中起着关键作用。当脂质体暴露于低渗溶液时，人们对其响应的一个常见理解是特征性的脉动行为。然而，最近的实验表明，在光反应产生的渗透压冲击下，脂质体发生了爆炸，但解释机制尚不清楚。在这里，我们提出了一个包含膜破裂随机描述的广义生物物理模型，以描述肿胀-破裂-再密封循环和爆炸动力学。该模型与实验观察结果吻合较好，并且表明突然的渗透压冲击以极端的速率使囊泡变形，导致囊泡发生弯曲不稳定性，从而导致膜的破裂，即爆炸。我们的工作不仅推进了渗透压应激下非平衡囊泡动力学的基本框架，而且为治疗性载体中可编程囊泡包裹物质释放提供了设计准则。
