Carbon dots based turn-on fluorescent probes for oxytetracycline hydrochloride sensing

In this paper, we have presented a facile, economic and green one-step hydrothermal synthesis route using tannic acid as carbon source to prepare water-soluble fluorescent carbon dots (CDs). The as-prepared CDs contain distinctive catechol groups on their surfaces, which have a special response toward Fe3+ ions. So the fluorescence emission of CDs gradually decreased with increasing Fe3+ ions. Such fluorescence responses can be used for well quantifying Fe3+ ions in the range of 0-5 mu M with the detection limit of 24.4 nM. Most importantly, quenched fluorescence of CDs-Fe3+ could be recovered with the addition of oxytetracycline hydrochloride based on a competition mechanism, which provides a turn-on sensing strategy for oxytetracycline hydrochloride assay. The proposed sensing system has been successfully used for the assay of oxytetracycline hydrochloride in milk samples, indicating the practical potential.