Claessens M M A E, Leermakers F A M, Hoekstra F A, Stuart M A Cohen
Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Wageningen, the Netherlands.
J Phys Chem B. 2007 Jun 28;111(25):7127-32. doi: 10.1021/jp070066h. Epub 2007 May 27.
We correlate the molecularly realistic self-consistent field predictions for the mean bending modulus kc of charged lipid vesicles with experimental observations of the size R of corresponding vesicles that are produced by the freeze-thaw method. We elaborate on the Ansatz that the bending modulus is related to the membrane persistence length and that this length scale sets the radius of the vesicles. Alkali cations have a remarkable effect on the mean bending modulus and thus on the equilibrium radius of negatively charged entropically stabilized dioleoylphosphatidylglycerol (DOPG) vesicles. Where cation hydration typically results in thicker and thus stiffer membranes, specific adsorption to the bilayer surface results in a decrease of the surface charge density and the thickness of the membrane-associated electric double layer. As a result of these opposing effects on kc and R, the largest DOPG vesicles are found in the presence of K+, which combines an intermediate hydration enthalpy and PG-binding affinity.
我们将带电脂质囊泡平均弯曲模量(kc)的分子层面逼真的自洽场预测结果，与通过冻融法制备的相应囊泡大小(R)的实验观测结果进行关联。我们详细阐述了这样一种假设：弯曲模量与膜持久长度相关，且这个长度尺度决定了囊泡的半径。碱金属阳离子对平均弯曲模量有显著影响，进而对带负电的熵稳定型二油酰磷脂酰甘油（DOPG）囊泡的平衡半径产生影响。阳离子水合作用通常会导致膜更厚从而更硬，而阳离子在双层表面的特异性吸附会导致表面电荷密度以及与膜相关的双电层厚度降低。由于这些对(kc)和(R)的相反影响，在存在(K^+)的情况下发现了最大的DOPG囊泡，(K^+)兼具中等的水合焓和PG结合亲和力。
