Core–Shell Nanozymes “Artificial Peroxidase”: Stability with Superior Catalytic Properties

We report on the nanoparticles composed of the catalytically synthesized Prussian Blue (PB) core stabilized with the nickel hexacyanoferrate (NiHCF) shell. Catalyzing hydrogen peroxide reduction, the resulting nanozymes (ø = 66 nm) display catalytic rate constants, which for pyrogallol or ferrocyanide are, respectively, 25 and 35 times higher than those for peroxidase enzyme. After more than half a year of storage at a room temperature, the core–shell PB-NiHCF nanozymes retain both their size and physicochemical properties; such stability is unreachable for the enzymes. Being immobilized, core–shell PB-NiHCF nanozymes (ø = 45 nm) result in a hydrogen peroxide sensor with a sensitivity similar to that of the sensor based on sole PB nanoparticles. However, whereas the latter response in hard inactivating conditions (25 min in 1 mM H2O2) drops down to 7.5%, the PB-NiHCF nanozymes-based sensor retains >75% of initial sensitivity. Application of the core–shell PB-NiHCF nanozymes "artificial peroxidase" would obviously open new horizons in elaboration of anti-inflammatory drugs and (bio)sensors.