Over recent decades, lipid membranes have become standard models for examining the biophysics and biochemistry of cell membranes. Interrogation of lipid domains within biomembranes is generally done with fluorescence microscopy via exogenous chemical probes. However, fluorophores have limited partitioning tunability, with the majority segregating into the liquid-disordered phase, and fluorescence only strictly reports on the small percentage of tagged lipids. We present simple, label-free imaging of domain formation in lipid monolayers, with chemical selectivity in unraveling lipid and cholesterol composition in different domain types. Exploiting conventional vibrational contrast in spontaneous Raman imaging, combined with chemometrics analysis, allows for examination of ternary systems containing saturated lipids, unsaturated lipids, and cholesterol. We confirm features commonly observed by fluorescence microscopy and provide a quantitative thermodynamic analysis of cholesterol distribution at the single-monolayer level.

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模型膜中胆固醇和脂质分布的分子成像

在最近的几十年中，脂质膜已成为检查细胞膜的生物物理学和生物化学的标准模型。通常使用荧光显微镜通过外源化学探针对生物膜内的脂质结构域进行询问。但是，荧光团的分配可调性有限，大多数团聚进入液体无序相，并且荧光仅严格报告了少量标记的脂质。我们目前在脂质单层中形成域的简单，无标签的成像，具有化学选择性，可以揭示不同域类型中的脂质和胆固醇成分。在自发拉曼成像中利用传统的振动对比技术，并结合化学计量学分析，可以检查含有饱和脂质，不饱和脂质的三元体系，和胆固醇。我们确认了通常通过荧光显微镜观察到的特征，并提供了单层胆固醇水平的定量热力学分析。