Prussian blue modified ferritin as peroxidase mimetics and its applications in biological detection.

Ferritins are natural nanoscale structures composed with 24 subunits endowed with similar three-dimensional structures. The iron is stored in the form of ferrihydrite phosphate in the hollow spherical ferritin shells. Prussian blue nanoparticles (PBNPs) have been certified a kind of mimetic enzyme with the advantages of stability, high catalytic activity and low prices. In this context, we designed a strategy to synthesize PBNPs of small size using ferritin as template and meanwhile retain the biological properties of ferritin. Our results show the resulting nanostructures (Prussian blue modified ferritin nanoparticles, PB-Ft NPs) got very small size and relatively high catalytic activity, furthermore, PB-Ft NPs successfully combined the intrinsic enzyme mimetic activity of PBNPs and the specificity of ferritin. Peroxidase-like activity which fits well the Michaelis-Menten kinetics was found strongly depending on pH, temperature and the concentration of PB-Ft NPs. Then a sensitive method for glucose detection was developed using glucose oxidase (GOx) and PB-Ft NPs. The consequence of Enzyme-linked immunosorbent assay (ELISA) shows PB-Ft NPs possess both specificity and peroxidase-like activity, which suggests that PB-Ft NPs can be served as a useful reagent in some biological detections.