Aggregation‐induced emission luminogens (AIEgens) that undergo excited‐state intramolecular proton transfer (ESIPT) have many applications in bioimaging since they have high quantum efficiency in the aggregated state and a low background signal in aqueous solutions because of their large Stokes shift. One disadvantage of many of the AIEgens with ESIPT that has been described so far is that they require time‐consuming synthesis and the use of toxic reagents. Another disadvantage with most of these materials is that they are only used for bioimaging in cells and are unsuitable for in vivo bioimaging. Herein, a new AIEgen with ESIPT, quercetin (QC) is described, which is easily prepared from Sophora japonica. AIE is attributed to crystallization‐promoted keto emission. The fluorescence is temperature dependent and shows strong resistance to photobleaching. QC AIEgen with ESIPT is shown to have excellent biocompatibility and is successfully used for bioimaging both in cellular cytoplasm and in vivo.

中文翻译：

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新型槲皮素聚集诱导的发光光原（AIEgen）和激发态分子内质子转移用于体内生物成像

经历激发态分子内质子转移（ESIPT）的聚集诱导发射发光剂（AIEgens）在生物成像中具有许多应用，因为它们在聚集态下具有高量子效率，并且由于其较大的斯托克斯位移而在水溶液中具有低背景信号。迄今为止已经描述了许多带有ESIPT的AIEgen的缺点之一是它们需要耗时的合成和使用有毒的试剂。这些材料中的大多数的另一个缺点是它们仅用于细胞中的生物成像而不适用于体内生物成像。在这里，描述了一种新的具有ESIPT的槲皮素（QC）的AIEgen，可以轻松地从槐花中制备。AIE归因于结晶促进的酮释放。荧光是温度依赖性的，并且显示出对光漂白的强抵抗力。具有ESIPT的QC AIEgen被证明具有出色的生物相容性，已成功用于细胞质和体内的生物成像。