A ‘on-off-on’ fluorescent probe for sensitive detection of Fe3+ and ascorbic acid by cross-linking agent protected carbon dots

Abstract

ABSTRACT Carbon dots (CDs) have gained great attention as multifunctional materials because of their interesting properties and general applicability. Herein, new CDs were synthesised from a facile hydrothermal treatment of cysteine and ethylene glycol dimethacrylate as both carbon and nitrogen source and cross-linking agent with high quantum yield (47.2%), respectively. The as prepared CDs were used to detect Fe3+ and ascorbic acid. The fluorescence intensity of CDs was selectivity quenched by Fe3+ in the range of 0.03–15.0 µM, with a detection limit of 10.2 nM. Meanwhile, ascorbic acid was found to reduce Fe3+ to Fe2+, thereby causing restoration of the fluorescence of CDs. The detection limit for ascorbic acid detection was estimated as 54.3 nM over a linear range from 0.1 to 25.0 µM. Furthermore, the designed sensing platform was successfully utilised to the detection of Fe3+ and ascorbic acid in water and fruits samples.