Hydrothermal synthesis of dual emission carbon dots with yellow fluorescence for ratio detection of Al3+

Dual-emission carbon dots with strong yellow fluorescence (Y-CDs) were prepared by one-step hydrothermal method from p-aminophenol and ethylenediamine. Two emission centres appeared at 380 nm and 520 nm under excitation of 270 nm. After adding Al3+, the fluorescence at 520 nm decreased due to static quenching, while the fluorescence at 380 nm gradually increased. Therefore, it could be used for ratiometric detection of Al3+. In addition, the synthesized Y-CDs were concentration dependent, and the occurrence of dual emission peaks was considerably related to the concentration. When the concentration of Y-CDs decreased, the intensity of its emission peak at 380 nm gradually increased. There was an excellent linear relationship between the concentration of synthesized Y-CDs and the ratio of two emission peaks after adding Al3+, which had been used for the detection of Al3+ in actual water samples. Moreover, the synthesized Y-CDs were successfully applied to A549 cell imaging.