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的荧光探针的开发，这些探针可以到达细胞内靶标并以高特异性标记它们。已经报道了优良的荧光罗丹明染料，但它们通常需要长且低产率的合成，并且在光谱上仅限于可见光范围。在这里，我们提出了一种使用分子内闭环方法将聚甲嘧啶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、开启的聚甲辛染料来说明这种方法的通用性，其发射范围遍及可见光和近红外光谱。这些探针与自标记蛋白和小分子靶向配体兼容，可与基于罗丹明的染料结合使用，用于多色和荧光寿命多重成像。这种策略提供了明亮的荧光染料，与现有的罗丹明基染料相比，这些染料的发射波长更加红移。