Cu 2+ -Modified Metal-Organic Framework Nanoparticles: A Peroxidase-Mimicking Nanoenzyme.

The synthesis and characterization of UiO-type metal-organic framework nanoparticles (NMOFs) composed of Zr4+ ions bridged by 2,2'-bipyridine-5,5'-dicarboxylic acid ligands and the postmodification of the NMOFs with Cu2+ ions are described. The resulting Cu2+ -modified NMOFs, Cu2+ -NMOFs, exhibit peroxidase-like catalytic activities reflected by the catalyzed oxidation of Amplex-Red to the fluorescent Resorufin by H2 O2 , the catalyzed oxidation of dopamine to aminochrome by H2 O2 , and the catalyzed generation of chemiluminescence in the presence of luminol/H2 O2 . Also, the Cu2+ -NMOFs mimic NADH peroxidase functions and catalyze the oxidation of dihydronicotinamide adenine dinucleotide, NADH, to nicotinamide adenine dinucleotide, NAD+ , in the presence of H2 O2 . The Cu2+ -NMOFs-catalyzed generation of chemiluminescence in the presence of luminol/H2 O2 is used to develop a glucose sensor by monitoring the H2 O2 formed by the aerobic oxidation of glucose to gluconic acid in the presence of glucose oxidase. Furthermore, loading the Cu2+ -NMOFs with fluorescein and activating the catalyzed generation of chemiluminescence in the presence of luminol/H2 O2 yield an efficient chemiluminescence resonance energy transfer (CRET) process to the fluorescein reflected by the activation of the fluorescence of the dye (λ = 520 nm, CRET efficiency 35%).