Highly fluorescent carbon polymer dots prepared at room temperature, and their application as a fluorescent probe for determination and intracellular imaging of ferric ion

Carbon polymer dots (CPDs) were prepared by a one-pot aqueous synthetic route from ascorbic acid and diethylenetriamine at room-temperature. The CPDs under 350-nm excitation exhibit blue fluorescence peaking at 430 nm with a quantum yield of 47%. Other features include an average diameter of 5 nm, a fluorescence that is independent of the excitation wavelength, good water dispersibility and photostability, and excellent biocompatibility. The CPDs are shown to be viable fluorescent probes for ferric ion which acts as a strong quencher. The response to Fe(III) is linear in the 0.2 to 10 mu M concentration range, and the detection limit is 0.1 mu M. The probe was applied to the determination of Fe(III) in environmental waters and to intracellular imaging of ferric ions in HeLa cells.