Carbon quantum dots as a turn-on fluorescent probe for the sensitive detection of Cd 2+

In this study, fluorescent carbon dots were synthesized for the first time using ammonium citrate and glutamic acid as precursors via a one -pot hydrothermal method. The synthesized carbon dots emit blue fluorescence at 436 nm (excited at 320 nm) and demonstrate excellent photobleaching resistance and fluorescence stability in high salt environments. Within the range of 1 -25 mu M, the fluorescence of CDs gradually increases with the increasing concentration of Cd 2 + , reaching a limit of detection as low as 13 nM. This phenomenon could be ascribed to the chelation-enhanced fluorescence, a result of Cd 2 + forming complexes with the abundant surface functional groups such as CN -, -COOH, -OH, -NH 2 in CDs. Furthermore, this turn -on fluorescent probe has been successfully used for the detection of Cd 2 + in tap water and lake water, providing an efficient and sensitive method for the analysis of environmental metals.