Ce3+ and Fe2+ Co-Enhanced Ratiometric Fluorescence Probe Utilizing Copper Nanoclusters and Coumarin for Sensitive Assay of Hydrogen Peroxide and Glucose

A novel ratiometric fluorescent probe was constructed for sensitive assay of hydrogen peroxide (H2O2) and glucose, which utilized the synergistically enhanced effects of Ce3+ and Fe2+ on copper nanoclusters (CuNCs) and coumarin. In the CuNCs-Ce3+/Fe2+-coumarin system, Ce3+ triggered the aggregation-induced emission phe-nomenon of CuNCs, and Fe2+ catalyzed the Fenton reaction to efficiently yield hydroxyl radical (center dot OH). In the presence of H2O2, the 625-nm red fluorescence of CuNCs was sharply quenched owing to the oxidation of CuNCs to Cu(II) by center dot OH, but the 460-nm blue fluorescence of 7-hydroxycoumarin from the oxidation of coumarin by center dot OH dramatically increased. Based on the reversible changes in two fluorescence signals, a satisfactorily ratio -metric probe was constructed for H2O2 assay with a detection limit (LOD) of 0.6 mu M accompanied by a visual color variation from red to blue. For glucose assay, this ratiometric probe gave a linear range of 3.2-160 mu M and LOD of 0.96 mu M owing to the oxidization of glucose to yield H2O2 in the presence of glucose oxidase and O2. Overall, the newly developed ratiometric probe shows a great prospect in real applications for visual assay of H2O2 and glucose by our naked eyes.