Green and facile synthesis of nitrogen-doped carbon nanodots for multicolor cellular imaging and Co2+ sensing in living cells

We report a facile and eco-friendly strategy for the fabrication of highly fluorescent nitrogen-doped carbon nanodots (N-CDs) and demonstrate their applications for multicolor cellular imaging and Co 2+ sensing in living cells. One-pot hydrothermal method using pigskin as the precursor yields bright green-emitting N-CDs, providing an easy way for the production of N-CDs without a tedious synthetic methodology or the toxic/expensive solvents and starting materials. Doping N heteroatoms benefits the generation of N-CDs with stronger fluorescence emission. As-prepared N-CDs exhibit exceptional advantages including high fluorescent quantum yield (24.1%), excellent biocompatibility, low-toxicity, and satisfactory chemical stability. Depending on these superior properties, as-synthesized N-CDs have been successfully used for multicolor cellular imaging. More strikingly, as-synthesized N-CDs generates strong response to Co 2+ ions and gives rise to the fluorescence quenching and further application is extended to precise and quantitative detection of Co 2+ ions in living cells.