Fig. 1.

Physical and chemical characterizations of Pt NPs. (A) TEM image of Pt NPs. (B) The size distribution of Pt NPs. The insert was zeta potential of Pt NPs. (C) CAT-like activity: time-dependent UV–visible absorption at 240 nm of H₂O₂ solution after incubating with Pt NPs. H₂O₂ alone was considered as control. (D) POD-like activity: time-dependent UV–visible absorption at 652 nm of the solution after incubating with Pt NPs. TMB alone (black) and TMB mixing with H₂O₂ (cyan) as control. (E) SOD-like activity: concentration-dependent SOD activity of Pt NPs at increased concentrations. (F) No Fenton-reaction-like activity of Pt NPs: H₂O₂ mixing with SA, FeSO₄ or without FeSO₄ was used as control, respectively. The mixture of H₂O₂, SA and various concentrations of Pt NPs (blue) was used for testing. The Pt NPs were pre-incubation wiht PBS (pH 6–7) or acetate buffer (pH 3–4).