Mimicking Peroxidase Activities with Prussian Blue Nanoparticles and Their Cyanometalate Structural Analogues

Nanoparticles composed of Prussian Blue, PB, and the cyanometalate structural analogues, CuFe, FeCoFe, and FeCo, are examined as inorganic clusters that mimic the functions of peroxidases. PB acts as a superior catalyst for the oxidation of dopamine to aminochrome by H₂O₂. The oxidation of dopamine by H₂O₂ in the presence of PB is 6-fold faster than in the presence of CuFe. The cluster FeCo does not catalyze the oxidation of dopamine to aminochrome. The most efficient catalyst for the generation of chemiluminescence by the oxidation of luminol by H₂O₂ is, however, FeCo, and PB lacks any catalytic activity toward the generation of chemiluminescence. The order of catalyzed chemiluminescence generation is FeCo ≫ CuFe > FeCoFe. The clusters PB, CuFe, FeCoFe, and FeCo mimic the functions of NADH peroxidase. The catalyzed oxidation of NADH by H₂O₂ to form NAD⁺ follows the order PB ≫ CuFe ∼ FeCoFe, FeCo. The efficient generation of chemiluminescence by the FeCo-catalyzed oxidation of luminol by H₂O₂ is used to develop a glucose sensor. The aerobic oxidation of glucose in the presence of glucose oxidase, GOx, yields gluconic acid and H₂O₂. The chemiluminescence intensities formed by the GOx-generated H₂O₂ relate to the concentration of glucose, thus providing a quantitative readout signal for the concentrations of glucose.