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研究了一种微生物脂肽——表面活性素与二肉豆蔻酰磷脂酰胆碱(DMPC)在气/液界面形成的混合单分子膜性质。测定了混合单分子膜的表面压-分子面积(π-A)曲线,根据π-A曲线获得了不同表面压下混合单分子膜的过剩面积(Aex)和混合过剩自由能(ΔGmex)与混合单分子膜中表面活性素摩尔分数的关系。Aex和ΔGemx的计算结果均表明,表面活性素与DMPC在纯水亚相上形成的混合单分子膜中不相容,二者之间的相互作用主要是排斥力。通过原子力显微镜观察了在表面压15mN/m下的混合单分子膜的LB膜,发现表面活性素与DMPC发生了微相分离,说明二者在混合膜中的烷基链取向不同,这可能是二者发生排斥作用的主要原因之一。此外,还研究了亚相pH对混合单分子膜相容性的影响,发现表面活性素与DMPC在混合单分子膜中的相容性在碱性环境下增强,这可能与二者极性头基之间的相互作用有关。
A mixed monolayer film was synthesized at the air / liquid interface of microbial lipopeptide-surfactant and dimyristoylphosphatidylcholine (DMPC). The surface pressure-molecular area (π-A) curve of the mixed monolayer was measured. The excess area (Aex) and excess free energy (ΔGmex) of mixed monolayer under different surface pressures were obtained according to π-A curve. Relationship Between Molar Fraction of Surfactant in Monolayer. The calculated results of Aex and ΔGemx indicate that the interaction between surfactant and DMPC is not compatible in the mixed monolayer formed on pure water and the interaction between them is mainly repulsive. The LB films of mixed monolayers at a surface pressure of 15 mN / m were observed by atomic force microscopy. It was found that there was a microphase separation of surfactant and DMPC, indicating that the orientation of the alkyl chains in the hybrid membranes was different One of the main reasons for the exclusion of the two. In addition, the influence of the pH of the subphase on the compatibility of the mixed monolayers was also studied. It was found that the compatibility of the surfactant with the DMPC in the mixed monolayer enhanced under alkaline conditions, which may be related to the polarity of both Basis of the interaction between.