Mimicking Horseradish Peroxidase and NADH Peroxidase by Heterogeneous Cu²⁺-Modified Graphene Oxide Nanoparticles

Cu 2+ -ion-modified graphene oxide nanoparticles, Cu 2+ -GO NPs, act as a heterogeneous catalyst mimicking functions of horseradish peroxidase, HRP, and of NADH peroxidase. The Cu 2+ -GO NPs catalyze the oxidation of dopamine to aminochrome by H 2 O 2 and catalyze the generation of chemiluminescence in the presence of luminol and H 2 O 2 . The Cu 2+ -GO NPs provide an active material for the chemiluminescence detection of H 2 O 2 and allow the probing of the activity of H 2 O 2 -generating oxidases and the detection of their substrates. This is exemplified with detecting glucose by the aerobic oxidation of glucose by glucose oxidase and the Cu 2+ -GO NP-stimulated chemiluminescence intensity generated by the H 2 O 2 product. Similarly, the Cu 2+ -GO NPs catalyze the H 2 O 2 oxidation of NADH to the biologically active NAD + cofactor. This catalytic system allows its conjugation to biocatalytic transformations involving NAD + -dependent enzyme, as exemplified for the alcohol dehydrogenase-catalyzed oxidation of benzyl alcohol to benzoic acid through the Cu 2+ -GO NPs-catalyzed regeneration of NAD + .