Bright hydrophilic and organophilic fluorescence carbon dots: One-pot fabrication and multi-functional applications at visualized Au3+ detection in cell and white light-emitting devices

Hydrophilic and organophilic carbon dots (HCDs and OCDs) have been synthesized simultaneously by simple one-pot solvothermal carbonization of methylene blue and sulfuric acid using ethanol as the solvent. The synthesized HCDs and OCDs show evidently different properties, which can be respectively dissolved in distilled water and ethanol, exhibiting bright white and blue fluorescence under an UV illumination of 365 nm, and their fluorescence quantum yield reach up to 16.5% and 21.1%, respectively. The different functional groups on the surface are responsible for the distinction in fluorescence and solubility of these two kinds of carbon dots. Especially, HCDs can not only be used in visualizing detection of Au3+ in PC12 cells, but also fabricating the white-light-emitting diodes, implying their potential in exploiting low-cost CDs as replacements of phosphors for light-emitting devices.