A Fluorescent “Turn-off” Probe for the Determination of Curcumin Using Upconvert Luminescent Carbon Dots

This work established a novel and simple method for quantitative determination of curcumin by developing a “turn-off” fluorescence probe based on upconvert luminescent carbon dots (p-CDs). The carbon dots were synthesized with p-aminobenzoic acid (PABA) and ethanol by solvothermal method and had specific up-conversion luminescence properties which could be applied in other sensing fields. The sensing mechanism of this fluorescent probe was based on the inter filter effect (IFE) between p-CDs and curcumin. As the concentration of curcumin increased, the fluorescence of p-CDs could be selectively quenched. Under the optimal conditions, the fluorescence quenching intensity of p-CDs had a good linear relationship with curcumin in the range of 0.4–45 µΜ and the detection limit was 0.133 µM. In addition, the fluorescent “turn-off” probe constructed with p-CDs exhibited high accuracy and recovery in the analysis of real sample curry powder, indicating that the fluorescence “turn-off” probe had potential application for the detection of curcumin in the complex matrixes.