Steacie Institute for Molecular Sciences, National Research Council of Canada, 100 Sussex Drive, Ottawa, ON, Canada K1A 0R6.
Langmuir. 2010 Jun 1;26(11):8525-33. doi: 10.1021/la904532s.
Supported membranes prepared from binary mixtures of DOPC and the bolalipid C(20)BAS have been examined by atomic force microscopy (AFM). The supported membranes are phase separated to give a thicker DOPC-rich phase and a thinner bolalipid-rich phase for a range of lipid compositions. These results confirm an earlier prediction from mean field theory that phase separation is the thermodynamically stable state for membranes containing approximately equimolar C(20)BAS and double chain monopolar lipids with chain lengths exceeding 15 carbons. Hydrophobic mismatch between the monopolar lipid hydrocarbon chains and the membrane spanning bolalipid chains was suggested to provide the driving force for phase separation. The AFM results also show that the morphology of the mixed POPC:C(20)BAS supported membranes varies significantly with the conditions used to prepare the vesicles and supported membrane samples. The complex membrane morphologies observed are attributed to the interplay of several factors, including a compositionally heterogeneous vesicle population, exchange of lipid between the vesicle solution and solid substrate during formation of the supported membrane, and slow equilibration of domains due to pinning of the lipids to the solid support.
由 DOPC 和 bolalipid C(20)BAS 的二元混合物制备的支撑膜已经通过原子力显微镜 (AFM) 进行了研究。对于一系列脂质组成，支撑膜发生相分离，形成较厚的富含 DOPC 的相和较薄的富含 bolalipid 的相。这些结果证实了早期平均场理论的预测，即对于含有大约等摩尔 C(20)BAS 和链长超过 15 个碳原子的双链单极脂质的膜，相分离是热力学稳定状态。单极脂质烃链和膜贯穿 bolalipid 链之间的疏水失配被认为是相分离的驱动力。AFM 结果还表明，混合 POPC：C(20)BAS 支撑膜的形态随制备囊泡和支撑膜样品的条件显著变化。观察到的复杂膜形态归因于几个因素的相互作用，包括组成不均匀的囊泡群体、囊泡溶液和固体基底之间在支撑膜形成过程中脂质的交换、以及由于脂质固定在固体支撑物上而导致的域缓慢平衡。
