Double emission CDs modified with rhodamine B for ratiometric sensing detection and bioimaging

In this paper, rhodamine B (RhB) was modified on carbon dots (CDs) by hydrothermal method, and a double emission ratiometric fluorescent probe (RhB-CDs) with red luminescence was successfully constructed. The synthesized RhB-CDs had exceptional optical properties and exhibit two emission peaks (480 nm and 590 nm) at 350 nm excitation. It could be used for ratiometric detection of MnO4− and Cr2O72−, and the fluorescent color would also change (red to orange) when the pH changed from 6 to 7, showing great application potential in the field of sensing and detection. Moreover, the ratio of the emission peak fluorescence intensity had a linear relationship with the water content of alcohols, which was successfully used to detect actual water samples. In addition, the synthesized RhB-CDs had low cytotoxicity and were successfully used for multicolor cell imaging.