Long Stokes shift dyes that minimize cross-talk between the excitation source and fluorescent emission to improve the signal-to-background ratio are highly desired for fluorescence imaging. However, simple small molecular dyes with large Stokes shift (more than 120 nanometers) and near-infrared (NIR) emissions have been rarely reported so far. Here, inspired by the chromophore chemical structure of fluorescent proteins, we designed and synthesized a series of styrene oxazolone dyes (SODs) with simple synthetic methods, which show NIR emissions (>650 nanometers) with long Stokes shift (ranged from 136 to 198 nanometers) and small molecular weight (<450 daltons). The most promising SOD9 shows rapid renal excretion and blood-brain barrier passing properties. After functioning with the mitochondrial-targeted triphenylphosphonium (TPP) group, the resulting SOD9-TPP can be engineered for head-neck tumor imaging, fluorescence image–guided surgery, brain neuroimaging, and on-site pathologic analysis. In summary, our findings add an essential small molecular dye category to the classical dyes.

中文翻译：

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仿生大斯托克斯位移小分子染料用于生物医学荧光成像

荧光成像非常需要能够最大限度地减少激发源和荧光发射之间的串扰以提高信背景比的长斯托克斯位移染料。然而，迄今为止很少报道具有大斯托克斯位移（超过 120 纳米）和近红外 (NIR) 发射的简单小分子染料。在这里，受荧光蛋白发色团化学结构的启发，我们采用简单的合成方法设计并合成了一系列苯乙烯恶唑酮染料（SODs），其近红外发射（>650 纳米）具有长斯托克斯位移（范围从 136 到 198 纳米） ) 和小分子量 (<450 道尔顿)。最有希望的 SOD9 显示出快速的肾脏排泄和血脑屏障通过特性。在与线粒体靶向三苯基鏻 (TPP) 组一起发挥作用后，由此产生的 SOD9-TPP 可用于头颈部肿瘤成像、荧光图像引导手术、脑神经成像和现场病理分析。总之，我们的研究结果为经典染料增加了一个重要的小分子染料类别。