Craig N C, Bryant G J, Levin I W
Biochemistry. 1987 May 5;26(9):2449-58. doi: 10.1021/bi00383a008.
Raman spectroscopy has been used to monitor the concentration of halothane (1-bromo-1-chloro-2,2,2-trifluoroethane) in 20% aqueous dispersions of dipalmitoylphosphatidylcholine (DPPC) as well as to follow changes in the acyl chain order within the hydrocarbon interior of the liposomes. Temperature profiles for the gel to liquid-crystalline phase transitions for the liposomes were constructed from changes in peak height intensity ratios in the C-H stretching mode and C-C stretching mode regions. Halothane present at the clinical level produces a change of -0.5 degrees C in the phase transition temperature. A limiting transition temperature of about 21 degrees C and saturation of the gel phase occur when the molar ratio of halothane to DPPC reaches about 1.25. At molar ratios above 2.1, the liquid-crystalline phase is also saturated with halothane. Calculations of the distribution of halothane between the various phases in the system are presented and used to interpret literature data as well as the present experiments. Ideal solution theory accounts rather well for the depression in the transition temperature over most of the mole ratio range, an outcome which implies that halothane is excluded from the hydrocarbon interior but not the head-group region in the gel phase. The role of halothane in the head-group region is discussed.
拉曼光谱已被用于监测二棕榈酰磷脂酰胆碱（DPPC）20%水分散体中氟烷（1-溴-1-氯-2,2,2-三氟乙烷）的浓度，以及跟踪脂质体烃类内部酰基链有序性的变化。根据C-H伸缩模式和C-C伸缩模式区域中峰高强度比的变化，构建了脂质体从凝胶相向液晶相转变的温度曲线。临床水平的氟烷会使相变温度变化-0.5摄氏度。当氟烷与DPPC的摩尔比达到约1.25时，会出现约21摄氏度的极限转变温度和凝胶相的饱和。当摩尔比高于2.1时，液晶相也会被氟烷饱和。文中给出了系统中各相之间氟烷分布的计算结果，并用于解释文献数据和当前实验。理想溶液理论在大多数摩尔比范围内对转变温度的降低解释得相当好，这一结果意味着氟烷被排除在烃类内部，但在凝胶相中不被排除在头基区域。文中讨论了氟烷在头基区域中的作用。
