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

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