Intracellular refractive index (RI) is an essential biophysical parameter, which best represents the mass and the distribution of proteins in the cell interior, including high-density accumulations in membraneless organelles. For RI measurements, a number of sophisticated techniques have been developed; however most of the new approaches are either insufficiently sensitive to intracellular variations of proteins distribution or are not compatible with live cell studies. Here, we outline the fluorescence lifetime imaging (FLIM) strategy for high resolution mapping of subcellular RI. We provide an example of our recent studies in which we utilize FLIM for measurements and monitoring of local RI in the major membraneless organelles within live cultured cells.

中文翻译：

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通过荧光寿命成像对亚细胞折光指数进行高分辨率定位：定量细胞科学的下一个前沿？

细胞内折射率（RI）是必不可少的生物物理参数，最能代表细胞内部蛋白质的质量和分布，包括无膜细胞器中的高密度积累。对于RI测量，已经开发了许多复杂的技术。然而，大多数新方法要么对蛋白质分布的细胞内变化不够敏感，要么与活细胞研究不兼容。在这里，我们概述了亚细胞RI的高分辨率映射的荧光寿命成像（FLIM）策略。我们提供了一个近期研究的例子，其中我们利用FLIM来测量和监测活培养细胞内主要无膜细胞器中的局部RI。