Perylene diimide-functionalized CeO₂ nanocomposite as a peroxidase mimic for colorimetric determination of hydrogen...

A novel perylene diimide (PDI) functionalized CeO₂ nanocomposite (NC) was successfully fabricated via one-pot hydrothermal method. Compared with pure CeO₂ nanoparticles (CeO₂ NPs), the NC catalyst presents more Ce³⁺ and active oxygen species and exhibits a higher peroxidase mimicking activity towards the oxidation 3,3',5,5'-tetramethylbenzidine by H₂O₂ to form a blue product with an absorption maximum at 652 nm. The composite catalyst shows high sensitivity and selectivity toward H₂O₂ determination in the range of 20 to 80 μM with a limit of detection (LOD) of 2.59 μM. Based on the colorimetric method, a sensitive method for detecting the reduced glutathione (GSH) was also established over arrange of 1~4 μM with a LOD of 0.92 μM. Electron spin resonance (ESR) experiments suggest that the active radicals during the catalytic processes are •OH and •O₂^-. A possible synergistic catalytic mechanism is discussed. Graphical abstract Schematic presentation of the possible catalytic mechanism for colorimetric determination of hydrogen peroxide and glutathione based on the peroxidase-like activity perylene-diimide (PDI) functionalized CeO₂ nanocomposite.