Mimicking Horseradish Peroxidase and NADH Peroxidase by Heterogeneous Cu 2+ -Modified Graphene Oxide Nanoparticles.

Cu2+ -ion-modified graphene oxide nanoparticles, Cu2+ -GO NPs, act as a heterogeneous catalyst mimicking functions of horseradish peroxidase, HRP, and of NADH peroxidase. The Cu2+ -GO NPs catalyze the oxidation of dopamine to aminochrome by H2 O2 and catalyze the generation of chemiluminescence in the presence of luminol and H2 O2 . The Cu2+ -GO NPs provide an active material for the chemiluminescence detection of H2 O2 and allow the probing of the activity of H2 O2 -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 Cu2+ -GO NP-stimulated chemiluminescence intensity generated by the H2 O2 product. Similarly, the Cu2+ -GO NPs catalyze the H2 O2 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 Cu2+ -GO NPs-catalyzed regeneration of NAD+ .