C-X-C趋化因子受体类型4（CXCR4）是一种趋化因子受体，已发现能促进各种癌细胞类型的癌症进展和转移。为了研究该受体的药理学，并进一步阐明其在癌症中的作用，新型化学工具是必不可少的。在本研究中，采用经典的药物化学方法，基于先前报道的小分子拮抗剂，设计并合成了基于小分子的荧光探针。我们在此报告发展出三种不同化学类的荧光探针，这些探针在新型荧光基纳米BRET结合测定（pKD范围为6.6-7.1）中显示出特异性与CXCR4受体结合。由于它们在CXCR4中保持亲和性，我们进一步报告它们在竞争结合实验和共聚焦显微镜中的应用，以研究该受体的药理学和细胞分布。

The C-X-C chemokine receptor type 4, or CXCR4, is a chemokine receptor found to promote cancer progression and metastasis of various cancer cell types. To investigate the pharmacology of this receptor, and to further elucidate its role in cancer, novel chemical tools are a necessity. In the present study, using classic medicinal chemistry approaches, small-molecule-based fluorescent probes were designed and synthesized based on previously reported small-molecule antagonists. Here, we report the development of three distinct chemical classes of fluorescent probes that show specific binding to the CXCR4 receptor in a novel fluorescence-based NanoBRET binding assay (pKD ranging 6.6-7.1). Due to their retained affinity at CXCR4, we furthermore report their use in competition binding experiments and confocal microscopy to investigate the pharmacology and cellular distribution of this receptor.