Microwave-assisted facile synthesis of yellow fluorescent carbon dots from o-phenylenediamine for cell imaging and sensitive detection of Fe3+ and H2O2

Strongly yellow fluorescent carbon dots (CDs) have been directly synthesized from o-phenylenediamine (o-PD) through a facile microwave-assisted method. The as-prepared o-CDs exhibit excitation-dependent photoluminescent behavior and excellent water-solubility due to some amino or hydroxy functional groups on the surface. An emission peak appears at 573 nm when the o-CDs solution is excited at 400 nm, and the quantum yield (QY) is 38.5%. Owing to their low toxicity and water solubility the as-prepared o-CDs can be directly used for cell imaging. More importantly, the as-prepared o-CDs solution also shows sensitivity for H2O2. The limits of detection (LOD) for Fe3+ and H2O2 are 16.1 nM and 28.1 nM, respectively, which is much lower than what's reported in previous studies. The fluorescence intensity also shows a dependence on pH and the strongest fluorescence intensity appears at pH 9. In addition, we also find that the fluorescent properties of CDs prepared from m-phenylenediamine (m-PDs) and p-phenylenediamine (p-PDs) are quite different from those of o-CDs.