The influence of cholesterol (CHO) on the phase behavior of 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) planar supported lipid bilayers (PSLBs) was investigated by sum-frequency vibrational spectroscopy (SFVS). The intrinsic symmetry constraints of SFVS were exploited to measure the asymmetric distribution of phase segregated phospholipid domains in the proximal and distal layers of DSPC + CHO binary mixtures as a function of CHO content and temperature. The SFVS results suggest that cholesterol significantly affects the phase segregation and domain distribution in PSLBs of DSPC in a concentration dependent manner, similar to that found in bulk suspensions. The SFVS spectroscopic measurements of phase segregation and structure change in the binary mixture indicate that membrane asymmetry must be present in order for the changes in SFVS signal to be observed. These results therefore provide important evidence for the delocalization and segregation of different phase domain structures in PSLBs due to the interaction of cholesterol and phospholipids.

中文翻译：

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通过和频振动光谱检测由胆固醇和 1,2-二硬脂酰-sn-甘油-3-磷酸胆碱组成的平面支撑脂质膜的相行为

通过和频振动光谱 (SFVS) 研究了胆固醇 (CHO) 对 1,2-二硬脂酰-sn-甘油-3-磷酸胆碱 (DSPC) 平面支撑脂质双层 (PSLB) 相行为的影响。利用 SFVS 的内在对称约束来测量作为 CHO 含量和温度的函数的 DSPC + CHO 二元混合物近端和远端层中相分离磷脂域的不对称分布。SFVS 结果表明，胆固醇以浓度依赖性方式显着影响 DSPC 的 PSLB 中的相分离和结构域分布，类似于散装悬浮液中的情况。二元混合物中相分离和结构变化的 SFVS 光谱测量表明必须存在膜不对称性才能观察到 SFVS 信号的变化。因此，由于胆固醇和磷脂的相互作用，这些结果为 PSLB 中不同相域结构的离域和分离提供了重要证据。