Preparation of fluorescent carbon dots from peatfor Fe3+sensing andcellular imaging

Novel fluorescent carbon dots (CDs) were fabricated using the hydrothermal carbonisation method by peat, which is a very abundant and low-cost natural material in the world. The transmission electron microscopy images revealed that the peat-derived CDs (PCDs) are well-crystalline with an average size of 4 nm. Fourier transform infrared and X-ray photoelectron spectra suggested large amounts of oxygenous functionality which made the synthesised PCDs water-soluble. The optical characterisations turned out that PCDs showed a stable and excellent excitation-dependent photoluminescence (PL), while the quantum yield was calculated to be 18.3%. As the PL of the PCDs could be efficiently quenched by ferric ions with a low-detection limit of 20 nM, the as-prepared PCDs could be employed as a highly fluorescent probe for ferric ions. Furthermore, the obtained PCDs have been successfully used for fluorescent imaging and Fe3+ detecting at cell level.