Small molecule therapeutic drugs must reach their intended cellular targets (pharmacokinetics) and engage them to modulate therapeutic effects (pharmacodynamics). These processes are often difficult to measure in vivo due to their complexities and occurrence within single cells. It has been particularly difficult to directly measure cellular drug target binding. Fluorescence polarization is commonly used in pharmacological screening assays to measure drug-protein or protein-protein interactions. We hypothesized that fluorescence polarization imaging could be adapted and used with fluorescently labeled drugs to measure drug target engagement in vivo . Here, we summarize recent results using two photon fluorescence anisotropy microscopy. Our imaging technique offers quantitative pharmacological binding information of diverse molecular interactions at the microscopic level, differentiating between bound, and unbound states. Used in combination with other recent advances in the development of novel fluorescently labeled drugs, we expect that the described imaging modality will provide a window into the distribution and efficacy of drugs in real time and in vivo at the cellular and subcellular level.

中文翻译：

---

用于成像和直接测量细胞内药物靶标的双光子荧光各向异性显微镜

小分子治疗药物必须达到其预期的细胞靶点（药代动力学）并使它们参与调节治疗效果（药效学）。由于这些过程的复杂性和在单个细胞中的发生，这些过程通常难以在体内测量。直接测量细胞药物靶标结合特别困难。荧光偏振常用于药理学筛选试验，以测量药物-蛋白质或蛋白质-蛋白质相互作用。我们假设荧光偏振成像可以适应并与荧光标记药物一起使用，以测量体内药物靶标的参与。在这里，我们使用两个光子荧光各向异性显微镜总结了最近的结果。我们的成像技术在微观水平上提供多种分子相互作用的定量药理学结合信息，区分结合和未结合状态。结合新型荧光标记药物开发的其他最新进展，我们预计所描述的成像方式将为实时和体内细胞和亚细胞水平的药物分布和功效提供一个窗口。