Phosphorous-doped green-emission fluorescent carbon dots sensing for pH, lemon yellow and the antioxidant application

    In this paper, we reported green-emission carbon dots (CDs) using a single step hydrothermal carbonization. The CDs were prepared by m-phenylenediamine, tris, phosphoric acid, and pure water by heating for 8 h at 180 ℃. The CDs exhibited green-emission fluorescence, were sensitive to pH, and was successfully used analysed the pH of real water samples. Besides, the CDs could detect of food additive lemon yellow, with the limit of detection as low as 0.13 μM. More importantly, the CDs could be used as an antioxidant to remove superoxide anions (O2 - ) and hydroxyl radicals (–OH). The linear range of CDs concentrations for superoxide anion and hydroxyl radicals were 0 - 300 mg/mL and 0 - 14 mg/mL, respectively. In addition, the CDs could be a fluorescnet reagent in bioimaging of beer yeast, mould and onion skins. The favorable pH, optical properties, antioxidant ability, and bioimaging ability ensure the CDs can be exploited in food analysis and other fields.