Hydrothermal growth of nitrogen-rich carbon dots as a precise multifunctional probe for both Fe3+ detection and cellular bio-imaging

A precise probe that can be applied in a variety of situations, such as both environmental sensor and in vitro imaging, is very attractive and promising. Here, we firstly reported a kind of nitrogen-rich carbon dots (N-CDots) growing during hydrothermal treatment, which emit bright and colorful fluorescence can be utilized as a reliable probe for Ferric ions (Fe3+) detection and bio-imaging. The nitrogen/carbon molar ratio (N/C) in N-CDots is as high as 39.9%. It is the high nitrogen content which provides N-CDots high quantum yield (at excitation wavelength of 365 nm, 400 nm, 440 nm: 34.8%, 27.6%, 22.3%) and thus high sensitivity and bright imaging when detecting Fe3+ and labeling cells, respectively. Regards to Fe3+ detection, the N-CDots show really low detection limit (7.6 nM), high selectivity when 16 kinds of other cationic ions are present and high accuracy to determine the concentration of Fe3+ in tap water. Regards to bio-imaging, the N-CDots showing low toxicity, are successfully loaded into cells and emit colorful florescence in cytoplasm and cytoderm. Furthermore, the N-CDots possess good water dispersibility, excellent photochemical stability and excitation dependent behavior, revealing the big potential for practical applications.