Department of Applied Physics, Chalmers University of Technology, S-412 96 Göteborg, Sweden.
Langmuir. 2010 Apr 20;26(8):5706-14. doi: 10.1021/la903814k.
Supported lipid bilayers (SLBs) containing different types of bilayer-associated molecules (membrane-bound molecules) where one part of the molecule resides inside the lipid bilayer and another part of the molecule sticks out of the bilayer (e.g., membrane proteins) are important biophysical model systems. SLBs are commonly formed via lipid vesicle adsorption on certain surfaces (e.g., SiO(2)). However, vesicles doped with different types of (bio)molecules often do not form an SLB on the surface, and the reasons for this are not clear. Using a newly developed model of a lipid bilayer, simulations were performed to clarify the influence of the bilayer-associated molecules on vesicle adsorption and rupture. It is shown that by increasing the concentration of membrane-bound molecules in the vesicles the tendency for vesicle rupture decreases markedly and for a certain concentration rupture does not happen. The reason for this is that vesicles containing significant concentrations of such molecules tend to deform less on the surface (lower vesicle strain), especially for a significantly corrugated bilayer-surface potential. After vesicle rupture, membrane-bound molecules face either the surface or the solution in the resulting bilayer patch on the surface, depending on whether the molecules point outward or inward in the original vesicle, respectively. Vesicle surface diffusion is also studied for weak and strong surface corrugation, where vesicles are found to be almost immobile in the latter case.
含有不同类型的双层相关分子（膜结合分子）的支撑脂质双层（SLBs），其中分子的一部分位于脂质双层内部，另一部分分子突出双层（例如，膜蛋白），是重要的生物物理模型系统。SLBs 通常通过脂质囊泡在某些表面上的吸附形成（例如，SiO2）。然而，掺杂有不同类型的（生物）分子的囊泡通常不会在表面上形成 SLB，其原因尚不清楚。使用新开发的脂质双层模型，进行了模拟以阐明双层相关分子对囊泡吸附和破裂的影响。结果表明，通过增加囊泡中膜结合分子的浓度，囊泡破裂的趋势显著降低，并且在一定浓度下不会发生破裂。原因是含有此类分子的囊泡在表面上的变形较小（较低的囊泡应变），尤其是对于明显波纹状的双层-表面电势。在囊泡破裂后，根据分子在原始囊泡中指向外向还是内向，膜结合分子在表面上的双层补丁中面对表面或溶液。还研究了弱和强表面波纹对囊泡表面扩散的影响，发现囊泡在后者情况下几乎处于静止状态。
