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 (H 2 O 2 ) and glucose, which utilized the synergistically enhanced effects of Ce 3+ and Fe 2+ on copper nanoclusters (CuNCs) and coumarin. In the CuNCs-Ce 3+ /Fe 2+ -coumarin system, Ce 3+ triggered the aggregation-induced emission phenomenon of CuNCs, and Fe 2+ catalyzed the Fenton reaction to efficiently yield hydroxyl radical (•OH). In the presence of H 2 O 2 , the 625-nm red fluorescence of CuNCs was sharply quenched owing to the oxidation of CuNCs to Cu(II) by •OH, but the 460-nm blue fluorescence of 7-hydroxycoumarin from the oxidation of coumarin by •OH dramatically increased. Based on the reversible changes in two fluorescence signals, a satisfactorily ratiometric probe was constructed for H 2 O 2 assay with a detection limit (LOD) of 0.6 μM accompanied by a visual color variation from red to blue. For glucose assay, this ratiometric probe gave a linear range of 3.2–160 μM and LOD of 0.96 μM owing to the oxidization of glucose to yield H 2 O 2 in the presence of glucose oxidase and O 2 . Overall, the newly developed ratiometric probe shows a great prospect in real applications for visual assay of H 2 O 2 and glucose by our naked eyes.