Lipid Flip-Flop Driven Mechanical and Morphological Changes in Model Membranes

Effects of passive phospholipid flip-flop and asymmetric external fields on bilayer phase equilibria

Compositional asymmetry between the leaflets of bilayer membranes modifies their phase behaviour, and is thought to influence other important features such as mechanical properties and protein activity. We address here how phase behaviour is affected by passive phospholipid \textit{flip-flop}, such that the compositional asymmetry is not fixed. We predict transitions from "pre flip-flop" behaviour to a restricted set of phase equilibria that can persist in the presence of passive flip-flop. Surprisingly, such states are not necessarily symmetric. We further account for external symmetry-breaki…

Molecular dynamics simulation of polymer insertion into lipid bilayers

Relatively short peptides, such as toxins and antimicrobial-peptides, are known to insert themselves into cell membranes. On the basis of simple bead-spring models for the membrane lipids, the peptide, and water, detailed processes of the peptide insertion is investigated by molecular dynamics simulation; our special concern is in the highly cooperative motions of membrane lipids and the peptide. Our model lipid has a head group of three hydrophilic beads and a tail of seven hydrophobic beads, while the model peptide is a block-copolymer made of hydrophilic and hydrophobic blocks, with total l…

活性胶体被巨型脂质囊泡自主吞噬

Autonomous Engulfment of Active Colloids by Giant Lipid Vesicles

本研究设计由葡萄糖和光驱动的Janus胶体，揭示拉型游泳模式与粘附作用使活性粒子能自主触发巨型脂质囊泡的内吞吞噬，为药物递送和纳米医学提供物理原则。

Solvent-free coarse-grained lipid model for large-scale simulations

A coarse-grained molecular model, which consists of a spherical particle and an orientation vector, is proposed to simulate lipid membrane on a large length scale. The solvent is implicitly represented by an effective attractive interaction between particles. A bilayer structure is formed by orientation-dependent (tilt and bending) potentials. In this model, the membrane properties (bending rigidity, line tension of membrane edge, area compression modulus, lateral diffusion coefficient, and flip-flop rate) can be varied over broad ranges. The stability of the bilayer membrane is investigated v…

利用双光子荧光寿命成像显微镜研究液滴界面双层上的界面应力

Interfacial Stresses on Droplet Interface Bilayers Using Two Photon Fluorescence Lifetime Imaging Microscopy

本文提出一种利用双光子荧光寿命成像显微镜和分子翻转器，在液滴界面双层上无创测量界面应力的微型平台，并揭示了双层形成与分离过程中的应力分布及分子翻转器的应力感知机制。

大肠杆菌模型脂质膜中接触诱导的分子重组

Contact-induced molecular reorganization in E. coli model lipid membranes

本研究利用大肠杆菌内膜模型脂质膜，发现膜-基底接触可降低转变温度、减慢相转变动力学并诱导侧向分子重组，验证了物理接触驱动细菌膜脂筏形成的理论，对理解细菌膜功能有重要意义。

Interplay of packing and flip-flop in local bilayer deformation. How phosphatidylglycerol could rescue mitochondrial function in a cardiolipin-deficient yeast mutant

In a previous work, we have shown that a spatially localized transmembrane pH gradient, produced by acid micro-injection near the external side of cardiolipin-containing giant unilamellar vesicles, leads to the formation of tubules that retract after the dissipation of this gradient. These tubules have morphologies similar to mitochondrial cristae. The tubulation effect is due to direct phospholipid packing modification in the outer leaflet that is promoted by protonation of cardiolipin headgroups. Here we compare the case of cardiolipin-containing giant unilamellar vesicles with that of phosp…

使用锚定冻结片段模拟弯曲的脂双分子层

Simulating Curved Lipid Membranes Using Anchored Frozen Patches

本文提出一种通过锚定冻结平衡膜片段引入任意曲率的方法，用于模拟弯曲脂双分子层，验证了该方法在平膜上的有效性，并探讨了曲率与膜不对称性的耦合效应及对膜形态和性质的影响。

Membrane domain formation induced by binding/unbinding of curvature-inducing molecules onto both membrane surfaces

The domain formation of curvature-inducing molecules, such as peripheral or transmembrane proteins and conical surfactants, is studied in thermal equilibrium and nonequilibrium steady states using meshless membrane simulations. These molecules can bind onto both surfaces of a bilayer membrane and also move to the opposite leaflet by a flip-flop. In symmetric conditions for the two leaflets, the membrane domains form checkerboard patterns in addition to stripe and spot patterns. The unbound membrane stabilizes the vertices of the checkerboard. In asymmetric conditions, the domains form kagome-l…

Solvent free model for self-assembling fluid bilayer membranes: Stabilization of the fluid phase based on broad attractive tail potentials

We present a simple and highly adaptable method for simulating coarse-grained lipid membranes without explicit solvent. Lipids are represented by one head-bead and two tail-beads, with the interaction between tails being of key importance in stabilizing the fluid phase. Two such tail-tail potentials were tested, with the important feature in both cases being a variable range of attraction. We examined phase diagrams of this range versus temperature for both functional forms of the tail-tail attraction and found that a certain threshold attractive width was required to stabilize the fluid phase…