Fig. 5. (A) BMPO trapped EPR spectra over Mn₃O₄ microspheres after 1 min of reaction. (V = 100 μL, pH = 4.5, Mn₃O₄ = 100 μg mL⁻¹, BMPO = 10 mM). (B) BMPO trapped EPR spectra over GSH reducing the colored TMBox to colorless TMB after 1 min of reaction. (V = 1 mL, pH = 4.5, Mn₃O₄ = 10.0 μg mL⁻¹, TMB = 0.416 mM, GSH = 60 μM, BMPO = 10 mM). (C) Effect of HO˙ scavenger (hypotaurine, 10%) and H₂O₂ scavenger (CAT, 15 μg mL⁻¹) on the oxidase-like activity of Mn₃O₄. (D) Effect of O₂ concentration on the oxidase-like activity of Mn₃O₄.