Fluorescence imaging is an invaluable tool to study biological processes and further progress depends on the development of advanced fluorogenic probes that reach intracellular targets and label them with high specificity. Excellent fluorogenic rhodamine dyes have been reported, but they often require long and low-yielding syntheses, and are spectrally limited to the visible range. Here we present a general strategy to transform polymethine compounds into fluorogenic dyes using an intramolecular ring-closure approach. We illustrate the generality of this method by creating both spontaneously blinking and no-wash, turn-on polymethine dyes with emissions across the visible and near-infrared spectrum. These probes are compatible with self-labelling proteins and small-molecule targeting ligands, and can be combined with rhodamine-based dyes for multicolour and fluorescence lifetime multiplexing imaging. This strategy provides access to bright, fluorogenic dyes that emit at wavelengths that are more red-shifted compared with those of existing rhodamine-based dyes.

荧光成像是研究生物过程的宝贵工具，进一步的进展取决于先进荧光探针的开发，这些探针能够到达细胞内目标并以高特异性标记它们。已经报道了优异的荧光罗丹明染料，但它们通常需要长时间且低产量的合成，并且光谱仅限于可见光范围。在这里，我们提出了使用分子内闭环方法将聚次甲基化合物转化为荧光染料的一般策略。我们通过创建自发闪烁和免洗的开启聚次甲基染料来说明该方法的普遍性，该染料在可见光和近红外光谱范围内发射。这些探针与自标记蛋白和小分子靶向配体兼容，并且可以与基于罗丹明的染料结合用于多色和荧光寿命多重成像。该策略提供了获得明亮的荧光染料的机会，这些染料的发射波长比现有的罗丹明基染料更红移。