Carbon dots/Ag nanoclusters-based fluorescent probe for ratiometric and visual detection of Cu2+

A fluorescent probe, N-doped carbon dots/Ag nanoclusters (N-CDs/AgNCs), was designed and synthesized successfully based on fluorescence inner filler effect (IFE) for the ratiometric and visual detection of Cu2+. Due to the IFE, the as-prepared probe exhibited a weak blue emission at 455 nm and a strong red emission and 665 nm. After adding Cu2+, the red fluorescence can be quenched because of the strong chelating interaction between GSH and Cu2+, whereas the blue fluorescence could be recovered because of the weakening of the IFE, accompanying by a remarkable fluorescence color change from pink to blue under a UV light. Under optimized experimental conditions, the N-CDs/AgNCs probe showed excellent selectivity to Cu2+ and a good linear relationship between the fluorescence intensity proportion (I665/I455) and Cu2+ concentration in the range of 0–60 μM with a detection limit of 0.13 µM. Further, N-CDs/AgNCs could be used for detecting Cu2+ in tap water and lake water. These results showed that the IFE ratiometric fluorescent probe may provide a new idea for the visualization and semiquantitative detection of Cu2+ and imply that it has great potential to detect Cu2+ in real environment water samples.