An "on-off" ratio photoluminescence sensor based on catalytically induced PET effect by Fe3O4 NPs for the determination of coumarin.

• Construct a coumarin ratio fluorescence sensor with artificial nano enzymes firstly. • Fe 3 O 4 NPs used to conveniently control the catalytic reaction and purification system. • The method for analysis of complex samples with great selectivity and sensitivity. Herein, using Fe 3 O 4 nanoparticles (Fe 3 O 4 NPs) as a magnetic artificial peroxidase, an "on–off" ratiometric photoluminescence sensor with high-sensitivity and high-selectivity for coumarin was constructed based on photoinduced electron transfer (PET) between 7-hydroxycoumarin and rhodamine B (RB). The results showed that Fe 3 O 4 NPs catalyzed H 2 O 2 to generate nucleophilic group ·OH, which attacked the active site of coumarin and produced strong fluorescent 7-hydroxycoumarin molecules. Then, the fluorescence of RB was quenched with 7-hydroxycoumarin through the PET effect. The ratio signal generated in the above process was used for the quantitative detection of coumarin. Under optimized conditions, the linear range 0.5–25 mg/L was acquired for coumarin with the detection limit of 0.016 mg/L. This method had excellent selectivity and the recovery rate was 81.8%−106.8% with the relative standard deviation less than 5.6%, so it can be used for the quantitative analysis of coumarin in complex matrix samples. [ABSTRACT FROM AUTHOR]