Ratiometric fluorescence (FL) probes are highly desirable for highly sensitive and reliable assays. Dual-emitting carbonized polymer dots (CPDs) have great application prospects in building ratiometric FL sensors. However, dual-emitting CPDs are usually synthesized at high temperatures and high pressures, which not only increases the cost but also complicates the structure of CPDs. Here, we developed a facile strategy for the fabrication of dual-emitting CPDs at room temperature using tetrachlorobenzoquinone and ethylenediamine. The formation of CPDs was induced by Schiff base condensation reaction, enabling the following cross-linking polymerization process. The dual-emitting CPDs demonstrate good photostability and antioxidant capacity. Importantly, the typical dual-emission bands of the as-prepared CPDs are found to have a blue emission band at 445 nm with a maximum excitation of 350 nm and a yellow emission band at 575 nm with a maximum excitation of 440 nm. Based on the dual-emitting property of CPDs, a ratiometric FL nanoprobe is obtained for sensitive determination of vitamin B12 (VB12), as the inner filtering and static quenching effects between VB12 and CPDs allow effective quenching of the blue FL of CPDs, while the yellow FL is maintained. The established assay shows linear detection ranges of 0.25–100 μM with a low limit of detection of 0.14 μM. These findings provide new guidance for the facile preparation of CPDs with excellent dual-emitting optical properties, indicating good prospects in biosensing.

中文翻译：

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室温下合成的双发光碳化聚合物点用于维生素 B12 的比率荧光传感

比率荧光 (FL) 探针对于高度敏感和可靠的测定非常理想。双发射碳化聚合物点 (CPD) 在构建比例 FL 传感器方面具有巨大的应用前景。然而，双发射CPDs通常在高温高压下合成，不仅增加了成本，而且使CPDs的结构复杂化。在这里，我们开发了一种简便的策略，用于在室温下使用四氯苯醌和乙二胺制造双发射 CPD。CPD 的形成是由席夫碱缩合反应诱导的，从而实现了以下交联聚合过程。双发光 CPD 表现出良好的光稳定性和抗氧化能力。重要的，发现所制备的 CPD 的典型双发射带在 445 nm 处具有蓝色发射带，最大激发为 350 nm，在 575 nm 处具有黄色发射带，最大激发为 440 nm。基于 CPDs 的双发射特性，获得了一种用于灵敏测定维生素 B12 (VB12) 的比率 FL 纳米探针，因为 VB12 和 CPDs 之间的内部过滤和静态猝灭效应可以有效猝灭 CPDs 的蓝色 FL，而黄色 FL 保持不变。已建立的测定显示线性检测范围为 0.25–100 μM，检测下限为 0.14 μM。这些发现为轻松制备具有优异双发射光学特性的CPD提供了新的指导，表明了生物传感的良好前景。