Department of Chemistry, Guru Nanak Dev University, Amritsar-143005, India.
Phys Chem Chem Phys. 2020 Nov 21;22(43):25255-25263. doi: 10.1039/d0cp04014b. Epub 2020 Nov 2.
We have investigated the impact of increasing concentration of imidazolium-based ionic liquids ([CMIM][Br]) on the structural integrity of large unilamellar vesicles (LUVs) made of pure phosphatidylcholine (PC) and phosphatidylglycerol (PG) lipids. Calcein based dye leakage assays were used to monitor the permeability of LUVs in the presence of ionic liquids. As the ionic liquid concentration approaches the critical micelle value, vesicle fusion occurs resulting in unexpected quenching which is accompanied by rapid dye leakage due to the formation of transiently lived fusion-holes. Vesicle fusion is confirmed using dynamic light scattering based size measurements and fluorescence based lipid mixing assays. H-H NOESY measurements using solid-state NMR spectroscopy were performed to obtain insights into the fusion mechanism. While POPC LUVs are more prone to membrane fusion, the overall extent of fusion is higher in POPG LUVs. Ionic liquid induced splaying of phospholipid chains is crucial for overcoming the hydration barrier between the merging bilayers.
我们研究了咪唑鎓基离子液体([CMIM][Br])浓度的增加对由纯磷脂酰胆碱(PC)和磷脂酰甘油(PG)脂质组成的大单室脂质体(LUV)结构完整性的影响。使用基于钙黄绿素的染料渗漏测定法来监测离子液体存在下 LUV 的通透性。随着离子液体浓度接近临界胶束值，囊泡融合发生，导致意想不到的猝灭，这伴随着由于短暂存在的融合孔的形成而导致的快速染料渗漏。使用基于动态光散射的粒径测量和基于荧光的脂质混合测定法证实了囊泡融合。使用固态 NMR 光谱进行 H-H NOESY 测量以获得融合机制的见解。虽然 POPC LUV 更容易发生膜融合，但在 POPG LUV 中融合的总体程度更高。离子液体诱导的磷脂链展开对于克服合并双层之间的水合障碍至关重要。
