A series of novel near-infrared (NIR) xanthene-chalcone fluorophores were constructed through a modular synthesis with the electron-donating xanthene moiety and the electron-withdrawing chalcone moiety. These fluorophores are convenient for fluorescence imaging in living cells, benefiting from their NIR emissions (650–710 nm), large Stokes shifts (>100 nm), moderate quantum yields and low cytotoxicity. The substituted hydroxyl group of the xanthene-chalcone fluorophore HCA-E facilitates the development of multifunctional fluorescent probes. As an example, a highly sensitive and selective probe N-HCA-E for glutathione (GSH) detection was developed based on the fluorophore HCA-E. A 4-nitrobenzenesulfonyl (4-Ns) group was introduced to cage the hydroxyl group of HCA-E, which was used as a selective recognition site for the thiol of GSH and an effective fluorescence quencher. Probe N-HCA-E revealed NIR “turn-on” fluorescence (709 nm) for endogenous and exogenous GSH detection in lysosomes with a large Stokes shift (129 nm) and high anti-interference ability.

中文翻译：

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开发具有大斯托克斯位移的近红外呫吨-查尔酮荧光团用于荧光成像

通过与供电子呫吨部分和吸电子查尔酮部分的模块化合成，构建了一系列新型近红外（NIR）呫吨-查耳酮荧光团。这些荧光团受益于其近红外发射（650-710 nm）、大斯托克斯位移（>100 nm）、中等量子产率和低细胞毒性，可方便地在活细胞中进行荧光成像。呫吨查耳酮荧光团HCA-E的取代羟基有利于多功能荧光探针的开发。例如，基于荧光团HCA-E开发了用于谷胱甘肽 (GSH) 检测的高灵敏度和选择性探针N-HCA-E。引入4-硝基苯磺酰基（4-Ns）来笼罩HCA-E的羟基，将其用作GSH硫醇的选择性识别位点和有效的荧光猝灭剂。探针N-HCA-E显示近红外“开启”荧光（709 nm），用于溶酶体中内源和外源 GSH 检测，具有大斯托克斯位移（129 nm）和高抗干扰能力。