Carbon dots prepared by solid state method via citric acid and 1,10-phenanthroline for selective and sensing detection of Fe2+ and Fe3+

A new kind of convenient, low-cost, environmentally friendly, and simple one step synthetic route for the preparation of C-dots-based CDs (CA + Phen) fluorescent turn-off probe for Fe2+ and Fe3+ from 1,10-phenanthroline (Phen) using anhydrous citric acid (CA) as the sole precursor without any solvents by solid state method. Only the Fe2+ and Fe3+ can readily quench the fluorescence of the CDs (CA + Phen), indicating a remarkably high selectivity towards Fe2+ and Fe3+ over other metals with a detection limit as low as 20 nM and 35 nM. The CDs (CA + Phen) exhibited a low cytotoxicity and could label the HK-2 cells. Additionally, this CDs (CA + Phen) has been successfully applied for the determination of Fe in real sample of milk. Endowed with relatively high sensitivity and selectivity, the present sensor holds the potential to be applied for the detection of Fe2+ and Fe3+ in aqueous media.