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

Abstract

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 H 2 O 2 ) 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.

Prussian Blue Nanozymes with Enhanced Catalytic Activity: Size Tuning and Application in ELISA-like Immunoassay

“…Nanozymes should propose significant advantages compared to enzymes, because commercial enzyme-based assays possess excellent analytical characteristics, and are technologically mature and well optimized. Issues of high-throughput synthesis and hydrolysis stability of ‘artificial peroxidase’ nanozymes despite being partially addressed [ 72 , 73 ], however still to be completely resolved. Further improvement of catalytic activity via defect engineering [ 74 ] or active site microenvironment [ 75 ] is also necessary.…”

Prussian blue nanozymes with enhanced catalytic activity: size tuning and application in ELISA-like immunoassay

“…Nanozymes should propose significant advantages compared to enzymes, because commercial enzyme-based assays possess excellent analytical characteristics, and are technologically mature and well optimized. Issues of high-throughput synthesis and hydrolysis stability of 'artificial peroxidase' nanozymes despite being partially addressed [77,83], however still to be completely resolved. Further improvement of catalytic activity via defect engineering [84] or active sites microenvironment [85] is also necessary.…”

“…The mechanism of hydrolysis is the attack of Fe II -CN-Fe III bonds by hydroxyl ions [73]. This limitation forces researchers to develop various methods of improving the storage stability of prussian blue nanoparticles, such as storage in highly acidic conditions [9] or protection by nickel hexacyanoferrate [76,77]. Despite that, some authors report successful functionalization [12] or storage [31,78] of prussian blue nanoparticles in neutral and even alkaline mediums.…”

Core-Shell Iron-Nickel Hexacyanoferrate Nanoparticle-Based Sensors for Hydrogen Peroxide Scavenging Activity

“…Stabilized Prussian Blue (PB-NiHCF) nanoparticles were produced as described in [39]. Nanoparticles size distribution was estimated by dynamic light scattering using Malvern Zetasizer Nano ZS (Malvern Instruments Ltd., Malvern, UK).…”

“…PB nanoparticles can be prepared by chemical [34] or electrochemical [35] means and used to create improved sensors [36] and biosensors [37,38], whose performance characteristics are better compared to sensors based on Prussian Blue films. The only disadvantage of PB nanoparticles-low operational stability-was overcome in 2021 by performing catalytic synthesis on core-shell nanoparticles based on a PB core stabilized with a nickel hexacyanoferrate (NiHCF) shell [39].…”