A colorimetric and fluorometric dual-mode carbon dots probe derived from phenanthroline precursor for the selective detection of Fe and Fe.

Iron's metabolism is heavily involved in the regulation of redox balance for cell functions, however, the simultaneous monitoring of Fe concentration is still a great challenge due to their transitional nature in biological systems. A novel type of carbon dots (CDs) was synthesized by solvothermal treatment with 5-amino-1,10-phenanthroline (Aphen) and salicylic acid as precursors, and the resulting targeted CDs (T-CDs) were used to simultaneously detect Fe and Fe. Comprehensive experimental characterizations revealed that the strong binding affinity of Aphen moiety to Fe leads to the formation of rigid T-CDs aggregates, which causes a substantial enhancement of fluorescence intensity, whereas Fe could cause the fluorescence quenching of T-CDs due to the oxidation-reduction induced electron transfer. These different fluorescence responses allow T-CDs to sensitively differentiate Fe from Fe, and give the limit of detection (LOD) of 1.78 and 2.78 μM for Fe and Fe, respectively. Furthermore, the Aphen dominated structure endows the T-CDs with a colorimetric response to Fe with a LOD of 0.13 μM, which is very different from Fe. Thus, the dynamic changes of Fe and Fe in solution can be accurately monitored by T-CDs within the total iron concentration of 50 μM, which is probably the most sensitive dual-mode probe reported so far. In addition, this probe is successfully applied to detect the Fe concentration in cells, demonstrating a huge application potential in the sensing of the dynamic equilibrium of these important transition metals during the cell metabolism or stimulated process. The dynamic changes of Fe and Fe in solution can be accurately monitored by carbon dots based on the colorimetric and fluorometric dual-mode.

© 2022. The Author(s), under exclusive licence to The Japan Society for Analytical Chemistry.