Fluorescence studies of double-emitting carbon dots and application in detection of H2O in ethanol and differentiation of cancer cell and normal cell

Herein, phenylalanine-bound carbon dots (CDs) with dual fluorescence emission peak behavior were reported, one of which was excitation-dependent and the other was not. The amino and carboxyl groups on the surface of CDs had a certain influence on their fluorescence. When the amino and carboxyl groups on the surface of CDs were removed, their fluorescence was significantly   weakened. The prepared CDs had solvent effect, and the emission peak of CDs shifted according to the change of the polarity of the solvent. Based on this, a method was developed for detecting water content in ethanol using CDs as a ratio probe. The change in the ratio of the intensity of the two emission peaks corresponded to the change of water content in ethanol. The detection linearity was good. In addition, the resulting CDs had good biocompatibility and could be enormously transported into cancer cells by the amino acid transporter on the surface of cancer cells, while normal cells only had a small amount of CDs   through   endocytosis, which laid the base for the distinguishing cancer cells from normal cells. The unique fluorescence properties of the prepared CDs achieved their applications in both water detection and cell differentiation.