Noninvasive fluorescence (FL) imaging and high-performance photocatalytic therapy (PCT) are opposing optical properties that are difficult to combine in a single material system. Herein, a facile approach to introducing oxygen-related defects in carbon dots (CDs) via post-oxidation with 2-iodoxybenzoic acid is reported, in which some nitrogen atoms are substituted by oxygen atoms. Unpaired electrons in these oxygen-related defects rearrange the electronic structure of the oxidized CDs (ox-CDs), resulting in an emerging near-infrared (NIR) absorption band. These defects not only contribute to enhanced NIR bandgap emission but also act as trappers for photoexcited electrons to promote efficient charge separation on the surface, leading to abundant photo-generated holes on the ox-CDs surface under visible-light irradiation. Under white LED torch irradiation, the photo-generated holes oxidize hydroxide to hydroxyl radicals in the acidification of the aqueous solution. In contrast, no hydroxyl radicals are detected in the ox-CDs aqueous solution under 730 nm laser irradiation, indicating noninvasive NIR FL imaging potential. Utilizing the Janus optical properties of the ox-CDs, the in vivo NIR FL imaging of sentinel lymph nodes around tumors and efficient photothermal enhanced tumor PCT are demonstrated.

中文翻译：

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构建具有 Janus 光学特性的碳纳米点中与氧相关的缺陷：无创近红外荧光成像和有效的光催化治疗

无创荧光（FL）成像和高性能光催化疗法（PCT）具有相反的光学特性，很难在单一材料系统中结合起来。本文报道了一种通过用 2-碘氧基苯甲酸进行后氧化在碳点（CD）中引入与氧相关的缺陷的简便方法，其中一些氮原子被氧原子取代。这些与氧相关的缺陷中的不成对电子会重新排列氧化CD（ox-CD）的电子结构，从而产生新的近红外（NIR）吸收带。这些缺陷不仅有助于增强近红外带隙发射，而且还可以作为光激发电子的捕获剂，促进表面有效的电荷分离，从而在可见光照射下在ox-CDs表面产生丰富的光生空穴。在白光 LED 灯照射下，光生空穴在水溶液酸化过程中将氢氧化物氧化为羟基自由基。相比之下，在 730 nm 激光照射下，ox-CDs 水溶液中没有检测到羟基自由基，表明其具有非侵入性 NIR FL 成像潜力。利用 ox-CD 的 Janus 光学特性，证明了肿瘤周围前哨淋巴结的体内 NIR FL 成像和有效的光热增强肿瘤 PCT。