Facile synthesis of nitrogen-doped carbon dots for Fe(3+) sensing and cellular imaging.

A fast and facile approach to synthesize highly nitrogen (N)-doped carbon dots (N-CDs) by microwave-assisted pyrolysis of chitosan, acetic acid and 1,2-ethylenediamine as the carbon source, condensation agent and N-dopant, respectively, is reported. The obtained N-CDs are fully characterized by elemental analysis, transmission electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, X-ray diffraction pattern, X-ray photoelectron spectroscopy, UV-vis absorption, and photoluminescence spectroscopy. Doping N heteroatoms benefits the generation of N-CDs with stronger fluorescence emission. As the emission of N-CDs is efficiently quenched by Fe(3+), the as-prepared N-CDs are employed as a highly sensitive and selective probe for Fe(3+) detection. The detection limit can reach as low as 10 ppb, and the linear range is 0.010-1.8 ppm Fe(3+). The as-synthesized N-CDs have been successfully applied for cell imaging and detecting Fe(3+) in biosystem.