Simple and green approach for photoluminescent carbon dots prepared from faba bean seeds as a luminescent probe for determination of Hg ions and cell imaging.

In this research, for the first time, a dedicated sensor was designed to detect Hg ions using photoluminescent carbon dots (CDs). Due to the preferred green synthesis of CDs from bio-resources, carbohydrate-rich faba bean seeds as a potential carbon precursor were applied to the synthesis of CDs. The CDs were prepared from the faba bean seeds using the hydrothermal method in an aqueous solution in the absence of substances such as an acid or base and any other additives. The synthesized CDs exhibited maximum emission intensity at 387 nm when excited at 310 nm and their luminescence quantum yield was calculated to be ~5.94%. Then, the fluorescence emission of CDs was examined in the presence of different metal ions. Results revealed that the CDs had good selectivity towards the Hg ions, so the fluorescence emission was significantly changed in the presence of these ions with a limit of detection (LOD) as low as 0.35 μM. Furthermore, because of their very low cytotoxicity, these CDs can be applied for cell imaging.