The superoxide anion (O₂^•–) and hydroxyl radical (^•OH) are important reactive oxygen species (ROS) used as biomarkers in physiological and pathological processes. ROS generation is closely related to the development of a variety of inflammatory diseases. However, the changes of ROS are difficult to ascertain with in situ tracing of the inflammation process by real-time monitoring, owing to the short half-lives of ROS and high tissue autofluorescence in vivo. Here we developed a new near-infrared (NIR) ratiometric fluorescence imaging approach by using a Förster resonance energy transfer (FRET)-based ratiometric fluorescent nanoprobe for real-time monitoring of O₂^•– and ^•OH generation and also by using in situ tracing of the inflammation process in vivo. The proposed nanoprobe was composed of PEG functionalized GQDs as the energy donor connecting to hydroIR783, serving as both the O₂^•–/^•OH recognizing ligand and the energy acceptor. The nanoprobe not only exhibited a fast response to O₂^•– and ^•OH but also presented good biocomapatibility as well as a high photostability and signal-to-noise ratio. We have demonstrated that the proposed NIR ratiometric fluorescent nanoprobe can monitor the changes of O₂^•– and ^•OH in living RAW 264.7 cells via a drug mediating inflammation model and further realized visual monitoring of the change of O₂^•– and ^•OH in mice for in situ tracing of the inflammation process. Our design may provide a new paradigm for long-term and real-time imaging applications for in vivo tracing of the pathological process related to the inflammatory diseases.

中文翻译：

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一种新的近红外比率荧光纳米探针的设计，用于实时成像活细胞中的超氧阴离子和羟基自由基以及体内炎症过程的原位追踪

超氧阴离子（O ₂ ^•–）和羟基自由基（^• OH）是重要的活性氧（ROS），在生理学和病理学过程中用作生物标记。ROS的产生与多种炎性疾病的发展密切相关。然而，由于ROS的半衰期短和体内体内高组织自发荧光，很难通过实时监测通过炎症过程的原位追踪来确定ROS的变化。在这里，我们使用基于Förster共振能量转移（FRET）的比率荧光纳米探针开发了一种新的近红外（NIR）比率荧光成像方法，用于实时监测O ₂ ^•和^•OH的产生以及体内炎症过程的原位追踪。拟议的纳米探针由PEG官能化的GQD组成，作为连接到hydroIR783的能量供体，既充当O ₂ ^•– / ^• OH识别配体，又充当能量受体。纳米探针不仅表现出对O ₂ ^•–和^• OH的快速响应，而且还表现出良好的生物相容性以及高光稳定性和信噪比。我们已经证明，提出的NIR比例荧光纳米探针可以监测O ₂ ^•–和^•的变化。通过药物介导的炎症模型，可以在活的RAW 264.7细胞中产生OH，并进一步实现了视觉监测小鼠中O ₂ ^•–和^• OH的变化，以原位追踪炎症过程。我们的设计可能为长期和实时成像应用提供新的范例，以便在体内追踪与炎症性疾病相关的病理过程。