Figure 4.

Peroxidase-like activity assays of M-HFn nanoparticles.

Notes: M-HFn nanoparticles with different sizes of core catalyzed the oxidation of peroxidase substrates in the presence of H₂O₂. (A) TMB as the substrate to give a deep blue color product. (B) DAB as the substrate to give a deep brown color product. Color intensity changes with (a) HFn cage, (b) M-HFn₁₀₀₀, (c) M-HFn₃₀₀₀, (d) M-HFn₅₀₀₀, and (e) M-HFn₇₀₀₀. (C) The peroxidase-like activity of M-HFn nanoparticle is size dependent; larger M-HFn nanoparticles show higher peroxidase-like activity (TMB as the substrate).

Abbreviations: HFn, H chain ferritin; M-HFn, ferrimagnetic H-ferritin; TMB, 3,3′,5,5′-tetramethylbenzidine; DAB, 3,3′-diaminobenzidine tetrahydrochloride.