A Fluorescent "Turn-Off" Probe for the Determination of Curcumin Using Upconvert Luminescent Carbon Quantum Dots

Abstract

Curcumin is used as a natural pigment and flavoring agent and food additive in food processing industries. Also, curcumin has a wide range of applications in the medical industry and clinical treatment because of its anti-cancer, anti-oxidation, anti-coagulant, anti-HIV choleretic and hypolipidemic effects. Therefore, it is crucial to properly control the concentration of curcumin in food and medicine. In our work, a new and simple method for quantitative detection of curcumin was established by developing a “turn-off” fluorescence probe based on upconvert luminescent carbon quantum dots (p-CDs). The carbon quantum dots were synthesized with p-aminobenzoic acid (PABA) and ethanol by solvothermal method and have specific up-conversion luminescence properties which could be applied in other sensing field. In this sensor, the sensing mechanism of this fluorescent probe was based on the internal filter effect (IFE) between curcumin and p-CDs, the increasing in the concentration of curcumin causes the selective fluorescence quenching of p-CDs. Under optimum conditions, the fluorescence quenching intensity of p-CDs has a good liner relationship with curcumin in the range of 0.4-45 μΜ and with a detection limit of 0.133 μM. What's more, the fluorescent “turn-off” probe constructed with p-CDs exhibited high accuracy and recovery in the analysis of actual sample curry powder, demonstrating the fluorescence “turn-off” probe has potential application for the detection of curcumin in the complex matrixes.