Wu Fu-Gen, Yang Pei, Zhang Chi, Li Bolin, Han Xiaofeng, Song Minghu, Chen Zhan
State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University , Nanjing 210096, China.
Langmuir. 2014 Jul 22;30(28):8491-9. doi: 10.1021/la501718n. Epub 2014 Jul 10.
Sum frequency generation (SFG) vibrational spectroscopy was applied to study molecular interactions between amantadine and substrate supported lipid bilayers serving as model cell membranes. Both isotopically asymmetric and symmetric lipid bilayers were used in the research. SFG results elucidated how the water-soluble drug, amantadine, influenced the packing state of each leaflet of a lipid bilayer and how the drugs affected the lipid flip-flop process. It is difficult to achieve such detailed molecular-level information using other analytical techniques. Especially, from the flip-flop rate change of isotopically asymmetric lipid bilayer induced by amantadine, important information on the drug-membrane interaction mechanism can be derived. The results show that amantadine can be associated with zwitterionic PC bilayers but has a negligible influence on the flip-flop behavior of PC molecules unless at high concentrations. Different effects of amantadine on the lipid bilayer were observed for the negatively charged DPPG bilayer; low concentration amantadine (e.g., 0.20 mM) in the subphase could immediately disturb the outer lipid leaflet and then the lipid associated amantadine molecules gradually reorganize to cause the outer leaflet to return to the original orderly packed state. Higher concentration amantadine (e.g., 5.0 mM) immediately disordered the packing state of the outer lipid leaflet. For both the high and low concentration cases, amantadine molecules only bind to the outer PG leaflet and cannot translocate to the inner layer. The presence of amantadine within the negatively charged lipid layers has certain implications for using liposomes as drug delivery carriers for amantadine. Besides, by using PC or PG bilayers with both leaflets deuterated, we were able to examine how amantadine is distributed and/or oriented within the lipid bilayer. The present work demonstrates that SFG results can provide an in-depth understanding of the molecular mechanisms of interactions between water-soluble drugs and model cell membranes.
利用和频振动光谱（SFG）研究了金刚烷胺与用作模型细胞膜的底物支撑脂质双层之间的分子相互作用。研究中使用了同位素不对称和对称脂质双层。SFG结果阐明了水溶性药物金刚烷胺如何影响脂质双层各小叶的堆积状态，以及药物如何影响脂质翻转过程。使用其他分析技术很难获得如此详细的分子水平信息。特别是，从金刚烷胺诱导的同位素不对称脂质双层的翻转速率变化中，可以得出有关药物-膜相互作用机制的重要信息。结果表明，金刚烷胺可与两性离子PC双层结合，但除非在高浓度下，对PC分子的翻转行为影响可忽略不计。对于带负电荷的DPPG双层，观察到金刚烷胺对脂质双层有不同影响；亚相中低浓度的金刚烷胺（例如0.20 mM）可立即扰乱外层脂质小叶，然后与脂质结合的金刚烷胺分子逐渐重新组织，使外层小叶恢复到原来的有序堆积状态。较高浓度的金刚烷胺（例如5.0 mM）会立即扰乱外层脂质小叶的堆积状态。对于高浓度和低浓度情况，金刚烷胺分子仅与外层PG小叶结合，无法转运到内层。带负电荷的脂质层中存在金刚烷胺对于将脂质体用作金刚烷胺的药物递送载体具有一定意义。此外，通过使用两侧小叶均氘代的PC或PG双层，我们能够研究金刚烷胺在脂质双层中的分布和/或取向。目前的工作表明，SFG结果可以深入了解水溶性药物与模型细胞膜之间相互作用的分子机制。
