Red Emission B, N, S-co-Doped Carbon Dots for Colorimetric and Fluorescent Dual Mode Detection of Fe3+ Ions in Complex Biological Fluids and Living Cells

Colorimetric and fluorescent dual mode detection methods have gained much attention in recent years; however, it is still desirable to develop new colorimetric and fluorescent dual mode nanosensors with more simple preparation procedures, low cost, and excellent biocompatibility. Herein, a colorimetric and fluorescent nanosensor based on B, N, S-co-doped carbon dots (BNS-CDs) was synthesized by one-step hydrothermal treatment of 2,5-diaminobenzenesulfonic acid and 4-aminophenylboronic acid hydrochloride. Using this nanosensor, a highly sensitive assay of Fe³⁺ in the range of 0.3-546 μM with a detection limit of 90 nM was provided by quenching the red emission fluorescence. It is more attractive that Fe³⁺ can also be visualized by this nanosensor via evident color changes of the solution (from red to blue) under sunlight without the aid of an ultraviolet (UV) lamp. Furthermore, the designed nanosensor can be applied for efficient detection of intracellular Fe³⁺ with excellent biocompatibility and cellular imaging capability, and it holds great promise in biomedical applications.