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A ratiometric fluorescence platform based on carbon dots for visual and rapid detection of copper(II) and
Xue Gao1, Minjun Sun1, Xiuying Liu1
1College of Food Science and Technology, National & Local Joint Engineering Research Center of Storage, Processing and Safety Control Technology for Fresh Agricultural and Aquatic Products, Food Safety Key Lab of Liaoning Province, The Fresh Food Storage and Processing Technology Research Institute of Liaoning Provincial Universities, Bohai University, Jinzhou, 121013, Liaoning, China.
Abstract:
A simple smartphone-integrated ratiometric fluorescent sensing system for visual determination of copper ions (Cu2+) and fluoroquinolones (FQs) was developed based on carbon dots (CDs) which were synthesized through the high-temperature pyrolysis of citric acid. In this system, with the fluorescence resonance energy transfer effect between CDs and 2,3-diaminophenazine (oxOPD), the detection of Cu2+ and ciprofloxacin (CIP, an example for FQs) was realized. Cu2+ catalyzes the oxidation of OPD to form oxOPD with yellow fluorescence, resulting in the quenching of CDs. In addition, CIP can inhibit the catalytic activity of Cu2+ and induce the recovery of CDs fluorescence. Under the excitation of 400 nm, the changes of CDs fluorescence at 472 nm and oxOPD fluorescence at 556 nm were monitored. The detection results showed that the sensing system exhibited good selectivity and sensitivity to Cu2+ and CIP with the limit of detection of 2.32 × 10-8 mol L-1 and 0.2 ng mL-1, respectively. In addition, a smartphone was developed as a portable analyzer to capture the change of fluorescence color and quickly analyze the concentration of Cu2+ and CIP. The proposed smartphone-based sensing platform has satisfactory sensitivity, and it has application prospects for detecting Cu2+ and FQs in food safety monitoring.
