Peroxynitrite (ONOO^–) is a short-term reactive biological oxidant and plays an important role in cellular signal transduction and homeostatic regulation. However, excess ONOO^– is associated with neurodegenerative and cardiovascular diseases. Therefore, rapid, sensitive, and accurate assays for ONOO^– detection are essential for exploring its physiological and pathological function. In this work, a wavelength-shifted and ratiometric fluorescent sensing platform for ONOO^– is constructed by splitting green fluorescent carbon dots (G-CDs) and aggregating orange fluorescent carbon dots (O-CDs). The mixed G-CDs and O-CDs (M-CDs) show a fast and precise response to ONOO^– in the range of 0–250 μM, with a detection limit of 10 nM. In the linearity range within 3 μM ONOO^–, an obvious wavelength shift of G-CDs from 495 to 475 nm is observed owing to the oxidation and nitration of ONOO^– to the surface-state fluorescence of G-CDs, accompanied by the splitting of G-CDs. In the linearity range of 3–250 μM ONOO^–, the fluorescence of G-CDs remains constant, while the molecular-state fluorescence of O-CDs gradually quenches by the oxidation and nitration of ONOO^– through the fluorescence static process and induces their aggregation. Additionally, M-CDs show favorable intracellular imaging of endogenous and exogenous ONOO^–. This study not only presents a new fluorescence wavelength shift mechanism for ONOO^– sensing but also provides insights into CDs’ fluorescence mechanism by exploring their morphology and structure via reacting with reactive oxygen species (ROS).

中文翻译：

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碳点的分裂和聚集：过氧亚硝酸盐的波长偏移和比率荧光传感


过氧亚硝酸盐 （ONOO^–） 是一种短时程反应性生物氧化剂，在细胞信号转导和稳态调节中起重要作用。然而，过量的 ^ONOO– 与神经退行性疾病和心血管疾病有关。因此，快速、灵敏和准确的 ONOO ^检测检测对于探索其生理和病理功能至关重要。在这项工作中，通过分裂绿色荧光碳点 （G-CDs） 和聚集橙色荧光碳点 （O-CDs） 构建了一个用于 ONOO^– 的波长偏移和比率荧光传感平台。混合 G-CD 和 O-CDs （M-CD） 在 0–250 μM 范围内对 ONOO^– 表现出快速而精确的响应，检测限为 10 nM。在 3 μM ^ONOO– 内的线性范围内，由于 ONOO^– 的氧化和硝化到 G-CDs 的表面态荧光，伴随着 G-CDs 的分裂，观察到 G-CDs 的波长从 495 到 475 nm 的明显偏移。在 3–250 μM ^ONOO– 的线性范围内，G-CDs 的荧光保持恒定，而 O-CDs 的分子状态荧光通过 ONOO^– 通过荧光静态过程的氧化和硝化逐渐猝灭并诱导其聚集。此外，M-CDs 显示出内源性和外源性 ONOO ^– 的良好细胞内成像。本研究不仅提出了一种新的 ONOO 荧光波长偏移机制^，而且还通过与活性氧 （ROS） 反应探索其形态和结构，从而深入了解 CDs 的荧光机制。