Expanding the palette of fluorescent dyes is vital to push the frontier of biological imaging. Although rhodamine dyes remain the premier type of small-molecule fluorophore owing to their bioavailability and brightness, variants excited with far-red or near-infrared light suffer from poor performance due to their propensity to adopt a lipophilic, nonfluorescent form. We report a framework for rationalizing rhodamine behavior in biological environments and a general chemical modification for rhodamines that optimizes long-wavelength variants and enables facile functionalization with different chemical groups. This strategy yields red-shifted ‘Janelia Fluor’ (JF) dyes useful for biological imaging experiments in cells and in vivo.

扩大荧光染料的调色板对于推动生物成像的前沿至关重要。尽管罗丹明染料由于其生物利用度和亮度而仍然是小分子荧光团的主要类型，但用远红光或近红外光激发的变体由于倾向于采用亲脂性、非荧光形式而性能不佳。我们报告了一个使罗丹明在生物环境中的行为合理化的框架，以及对罗丹明进行一般化学修饰，以优化长波长变体并使不同化学基团的功能化变得容易。该策略产生红移“Janelia Fluor”(JF) 染料，可用于细胞和体内的生物成像实验。