Eco-friendly synthesis of nitrogen-doped carbon nanodots from wool for multicolor cell imaging, patterning, and biosensing

We report an eco-friendly strategy for fabrication of nitrogen-doped carbon nanodots (N-CDs) and demonstrate their applications for multicolor cell imaging, patterning, and biosensing. N-CDs have been synthesized using wool as raw material via pyrolysis and microwave treatment, providing a green way for the production of N-CDs without the use of toxic/expensive solvents and starting materials. The prepared N-CDs exhibit exceptional advantages including high fluorescent quantum yield (22.5%), excellent biocompatibility, low toxicity, and satisfactory chemical stability. Depending on these superior properties, the N-CDs have been applied in multicolor bioimaging, patterning, and biosensing. Imaging of living cells has been observed with high resolution using N-CDs as a probe, which validates their use in imaging applications and their multicolor property in the living cell system. Additionally, the obtained N-CDs have been used as fluorescent inks for drawing luminescent patterns, showing favorable application in anti-counterfeit and optoelectronic dimensions. Most strikingly, the as-prepared N-CDs could visualize Fe 3+ fluctuations in living cells with negligible autofluorescence based on their high sensitivity and selectivity detection for Fe 3+ ions with a linear range of 0.1–10   μM and a detection limit of 10   nM.