Carbon dots (CDs) have gained great attention as multifunctional materials because of their interesting properties and general applicability. However, there are some reports for the preparation of highly luminescent green-emitting CDs (G-CDs), although these reports seem not to be extensible. Herein, new G-CDs (quantum yield: 27.2%) were synthesized from a facile hydrothermal treatment of p-aminosalicylic acid and ethylene glycol dimethacrylate as both carbon and nitrogen source and cross-linking agent, respectively. The chemical composition and optical properties of the as-prepared G-CDs were successfully investigated using transmission electron microscopy, atomic force microscopy, dynamic light scattering, X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy and fluorescence and UV-vis spectroscopies. Interestingly, the fluorescence intensity of G-CDs was selectivity quenched by Fe3+ in the range of 0.05-10.0 µmol L-1, with a detection limit of 13.7 nmol L-1. Meanwhile, ascorbic acid found to reduce Fe3+ to Fe2+, thereby causing restoration of the fluorescence of G-CDs. The detection limit for ascorbic acid detection was estimated as 82.0 nmol L-1 over a linear range from 0.2 to 11.0 µmol L-1. Furthermore, the designed sensing platform was successfully utilized to the detection of Fe3+ and ascorbic acid in water and urine samples and to intracellular imaging without surface modification.
Keywords: Ascorbic acid; Fe(3+) ion; Green-emitting carbon dots; Intracellular imaging; Synthesis and characterization.
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