MSRH, Department of Chemistry, Imperial College London, Wood Lane, London W12 0BZ, U.K.
Anal Chem. 2023 Aug 15;95(32):12006-12014. doi: 10.1021/acs.analchem.3c01747. Epub 2023 Aug 1.
Lipid membranes are crucial for cellular integrity and regulation, and tight control of their structural and mechanical properties is vital to ensure that they function properly. Fluorescent probes sensitive to the membrane's microenvironment are useful for investigating lipid membrane properties; however, there is currently a lack of quantitative correlation between the exact parameters of lipid organization and a readout from these dyes. Here, we investigate this relationship for "molecular rotors", or microviscosity sensors, by simultaneously measuring their fluorescence lifetime to determine the membrane viscosity, while using X-ray diffraction to determine the membrane's structural properties. Our results reveal a phase-dependent correlation between the membrane's structural parameters and mechanical properties measured by a BODIPY-based molecular rotor, giving excellent predictive power for the structural descriptors of the lipid bilayer. We also demonstrate that differences in membrane thickness between different lipid phases are not a prerequisite for the formation of lipid microdomains and that this requirement can be disrupted by the presence of line-active molecules. Our results underpin the use of membrane-sensitive dyes as reporters of the structure of lipid membranes.
脂质膜对于细胞的完整性和调节至关重要，对其结构和机械性能的严格控制对于确保其正常功能至关重要。对膜微环境敏感的荧光探针可用于研究脂质膜性质；然而，目前脂质组织的精确参数与这些染料的读出值之间缺乏定量相关性。在这里，我们通过同时测量其荧光寿命来研究“分子转子”（或微粘度传感器）的这种关系，以确定膜的粘度，同时使用 X 射线衍射来确定膜的结构特性。我们的结果揭示了基于 BODIPY 的分子转子测量的膜的结构参数和机械性能之间的与相相关的相关性，为脂质双层的结构描述符提供了极好的预测能力。我们还表明，不同脂质相之间的膜厚度差异不是形成脂质微区的前提条件，并且线活性分子的存在可以破坏这种要求。我们的结果为膜敏感染料作为脂质膜结构报告者的使用提供了依据。
