Chemodynamic therapy (CDT) utilizing Fenton or Fenton-like reactions to generate cytotoxic hydroxyl radicals by metal ions has become a compelling strategy for cancer treatment. Visualizing intratumoral Fenton or Fenton-like reactions especially at a cellular level in real-time can directly monitor the process of CDT, which is not yet feasible. Here, we present a molecule BADA chelating Cu²⁺ to form Cu-BADA nanoparticles, exhibiting fluorescence quenching properties through intermolecular electron transfer. The nanoparticles are lit up owing to glutathione and acid dual activatable Fenton-like reaction and generation of near-infrared-II fluorescent o-quinones. Moreover, fluorescence vanishing correlated with the decreased intratumoral Cu concentration, thus enabling to track the “on–off” process of Fenton-like reaction specifically in the tumor. Compared to 660 nm-excitation, the o-quinones excited at 830 nm offer deeper tissue near-infrared-II fluorescence imaging with higher resolution. Our results demonstrate a fluorescence nanotheranostic agent for CDT capable of monitoring the spatiotemporal dynamics of Fenton-like reaction.

中文翻译：

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一种近红外 II 荧光纳米探针，可实时追踪癌症化学动力学治疗诊断学的 Fenton 样反应


化学动力学疗法 （CDT） 利用 Fenton 或 Fenton 样反应通过金属离子产生细胞毒性羟基自由基，已成为癌症治疗的一种引人注目的策略。实时可视化瘤内 Fenton 或 Fenton 样反应，尤其是在细胞水平上，可以直接监测 CDT 的过程，这尚不可行。在这里，我们提出了一个分子 BADA 螯合 Cu²⁺ 以形成 Cu-BADA 纳米颗粒，通过分子间电子转移表现出荧光猝灭特性。由于谷胱甘肽和酸的双重激活 Fenton 样反应以及近红外 II 荧光 o-醌的产生，纳米颗粒被点亮。此外，荧光消失与肿瘤内 Cu 浓度降低相关，因此能够专门在肿瘤中跟踪 Fenton 样反应的“开-关”过程。与 660 nm 激发波长相比，在 830 nm 激发波长下的邻醌可提供更深的组织近红外 II 荧光成像，分辨率更高。我们的结果表明，一种用于 CDT 的荧光替代剂能够监测 Fenton 样反应的时空动力学。