Synthesis of multi-functional green fluorescence carbon dots and their applications as a fluorescent probe for Hg2+ detection and zebrafish imaging

Heteroatom doped carbon dots, due to their excellent fluorescence properties and potential applications in the biological and photo-electronic industry, have attracted great attention recently. In this work, we reported a single-step synthesis of nitrogen carbon dots (N-CDs) using a simple and straightforward hydrothermal method. The luminescence properties of the synthesized N-CDs were correlated with the precursor ratio (aniline and ethylenediamine ratio of (1:5) in CDs). To further investigate the fluorescence properties and related mechanisms of N-CDs, different characterization techniques were applied, including fluorescence spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). In addition, the as-prepared N-CDs exhibit strong emission at 510 nm when excited at 410 nm, and emit bright green fluorescence under 365 nm UV radiation. N-CDs exhibited a strong selectivity for Hg2+ in the range of 0-70 M, and can be used for the rapid detection of Hg2+ in biomedical applications. The sample of N-CDs as a probe was used for fluorescence bioimaging of zebrafish, validating the potential of N-CDs as a probe in bioimaging applications.