Ionic liquids as precursors for highly luminescent, surface-different nitrogen-doped carbon dots used for label-free detection of Cu2+/Fe3+ and cell imaging

•Surface-different carbon dots (C-Dots) were synthesized by using different ionic liquids (ILs).•The as-prepared surface-different C-Dots show different selectivity to metal ions (Cu2+/Fe3+).•The detection limits for Cu2+ and Fe3+ are 5 nM and 20 nM, respectively.

Carbon nanodots (C-Dots) have attracted much attention in recent years due to their low cost, ready scalability, excellent chemical stability, biocompatibility and multicolor luminescence. Here, we report a facile strategy for producing highly luminescent, surface-different nitrogen-doped carbon dots (C-Dots) by using different ionic liquids (ILs). Intriguingly, the surface-different C-Dots show different selectivity for Cu2+ and Fe3+. To the best of our knowledge, this is the first example which shows that ILs are excellent precursors for producing luminescent nanomaterial used for detection of different metal ions. The resultant nitrogen-doped C-Dots are highly photoluminescent and can be used for multicolor bioimaging. Most notable, by taking different ILs as precursors, we obtain surface-different C-Dots, which can be directly used for selective detection of Cu2+ and Fe3+ without any modification. These C-Dots based sensors exhibit high sensitivity and selectivity and the sensing process can be easily accomplished with one-step rapid operation. More importantly, compared with other method using QDs, organic dyes and organic solvent, this strategy is much more eco-friendly. This work may offer a new approach for developing low cost and sensitive C-Dots-based sensors for biological and environmental applications.

Graphical abstractHere, we report a facile strategy for producing highly luminescent, surface-different nitrogen-doped carbon dots (C-Dots) by using different ionic liquids (ILs). Intriguingly, the surface-different C-Dots show different selectivity for Cu2+ and Fe3+.Figure optionsDownload full-size imageDownload as PowerPoint slide