State Key Laboratory of Medicinal Chemical Biology, College of Chemistry, Nankai University, Tianjin, 300071, PR China.
Chemistry. 2013 Feb 11;19(7):2276-83. doi: 10.1002/chem.201203641. Epub 2013 Jan 15.
Carbon dots (Cdots) are an important probe for imaging and sensing applications because of their fluorescence property, good biocompatibility, and low toxicity. However, complex procedures and strong acid treatment are often required and Cdots suffer from low photoluminescence (PL) emission. Herein, a facile and general strategy using carbonization of precursors and then extraction with solvents is proposed for the preparation of nitrogen-doped Cdots (N-Cdots) with 3-(3,4-dihydroxyphenyl)-L-alanine (L-DOPA), L-histidine, and L-arginine as precursor models. After they are heated, the precursors become carbonized. Nitrogen-doped Cdots are subsequently extracted into N,N'-dimethylformamide (DMF) from the carbogenic solid. A core-shell structure of Cdots with a carbon core and the oxygen-containing shell was observed. Nitrogen has different forms in N-Cdots and oxidized N-Cdots. The doped nitrogen and low oxidation level in N-Cdots improve their emission significantly. The N-Cdots show an emission with a nitrogen-content-dependent intensity and Cdot-size-dependent emission-peak wavelength. Imaging of HeLa cells, a human cervical cancer cell line, and HepG2 cells, a human hepatocellular liver carcinoma line, was observed with high resolution using N-Cdots as a probe and validates their use in imaging applications and their multicolor property in the living cell system.
碳点（Cdots）由于其荧光特性、良好的生物相容性和低毒性，是成像和传感应用的重要探针。然而，通常需要复杂的程序和强酸处理，并且 Cdots 的光致发光（PL）发射效率较低。在此，提出了一种使用前驱体碳化然后用溶剂萃取的简便通用策略，以 3-(3,4-二羟基苯基）-L-丙氨酸（L-DOPA）、L-组氨酸和 L-精氨酸作为前驱体模型制备氮掺杂碳点（N-Cdots）。加热后，前驱体碳化。氮掺杂碳点随后从碳质固体中萃取到 N,N'-二甲基甲酰胺（DMF）中。观察到 Cdots 的核壳结构，其中碳核和含氧壳。N-Cdots 中存在不同形式的氮和氧化氮-Cdots。掺杂氮和氮-Cdots 中的低氧化水平显著提高了它们的发射。N-Cdots 的发射强度与氮含量有关，发射峰波长与 Cdot 尺寸有关。用 N-Cdots 作为探针观察到 HeLa 细胞（人宫颈癌细胞系）和 HepG2 细胞（人肝癌细胞系）的高分辨率成像，验证了它们在成像应用中的用途及其在活细胞系统中的多色性质。
