State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, People's Republic of China.
Langmuir. 2012 Apr 10;28(14):5927-33. doi: 10.1021/la2048773. Epub 2012 Mar 28.
Using molecular dynamics simulation, we performed theoretical calculations on the curvature constant and edge energy of bilayers of salt-free, zero-charged, cationic and anionic (catanionic) surfactant vesicles composed of alkylammonium cations (C(m)(+)) and fatty acid anions (C(n)(-)). Both the minimum size and edge energy of vesicles were calculated to examine the relation between the length of the surfactant molecules and the mechanical properties of the catanionic bilayers. Our simulation results clearly demonstrate that, when the chain lengths of the cationic and anionic surfactants are equal, both the edge energy and the rigidity of the catanionic bilayers increase dramatically, changing from around 0.36 to 2.77 kBT·nm(-1) and around 0.86 to 6.51 kBT·nm(-1), respectively. For the smallest catanionic vesicles, the curvature is not uniform and the surfactant molecules adopt a multicurvature arrangement in the vesicle bilayers. We suspect that the multicurvature bending of bilayers of catanionic vesicles is a common phenomenon in rigid bilayer systems, which could aid understanding of ion transport through bilayer membranes.
我们使用分子动力学模拟，对由烷基铵阳离子（C(m)(+)）和脂肪酸阴离子（C(n)(-）组成的无盐、零电荷、阳离子和阴离子（两性离子）表面活性剂双层的曲率常数和边缘能进行了理论计算。我们计算了双层囊泡的最小尺寸和边缘能，以考察表面活性剂分子的长度与两性离子双层的力学性能之间的关系。我们的模拟结果清楚地表明，当阳离子和阴离子表面活性剂的链长相同时，两性离子双层的边缘能和刚性都显著增加，分别从约 0.36 到 2.77 kBT·nm(-1)和从约 0.86 到 6.51 kBT·nm(-1)。对于最小的两性离子囊泡，曲率不均匀，并且囊泡双层中的表面活性剂分子采用多曲率排列。我们怀疑两性离子囊泡双层的多曲率弯曲是刚性双层系统中的一种常见现象，这有助于理解离子通过双层膜的运输。
