Dual-Emission Fluorescent Carbon Dots Grafted by Rhodamine-B for Selective Detection of Iron Ion and Bioimaging in Cell

Rhodamine-B grafted carbon dots (RhB-CDs) with double emission fluorescence are developed , one of which has excitation dependence, while the other have not. The prepared RhB-CDs have good dispersibility, uniform spherical shape, and excellent water solubility. They could be used to specifically detect Fe³⁺ ions in an aqueous solution with the detection limit of 1.1 × 10⁻⁶ m and with good anti-interference ability, because Fe³⁺ ions are easier to combine with hydroxyl groups on the surface of RhB-CDs to form aggregates (such as ferric hydroxide) than other metal ions, which lead to the fluorescence quenching of RhB-CDs. Fe³⁺ ions not only quench the fluorescence intensity of both double emission peaks of RhB-CDs, but also change the relative fluorescence intensity of these two fluorescence emission peaks. Therefore, two different fluorescence analysis methods are used to specifically identify iron ions and the results are consistent with each other. At the same time, the double emission fluorescent RhB-CDs have low hemolysis rate and cytotoxicity, indicating that RhB-CDs do little harm to cells and are further used to detect Fe³⁺ ions in cells through fluorescence bioimaging. All of the above indicates that the prepared RhB-CDs would have potential application value in detecting iron ions in blood and cells.