Fig. 1.

Characterization of catalytic properties and bioactivity of ferumoxytol. a Schematic depiction of the pH-dependent catalytic activity of ferumoxytol. Insets: negative stain TEM of ferumoxytol (Scale bar: 50 nm and 10 nm for close up image) and hydrodynamic diameter measurements. b Peroxidase-like activity of ferumoxytol at different pH values as determined by a colorimetric assay using 3,3’,5,5′-tetramethylbenzidine (TMB) and Michaelis–Menten kinetics plotting (inset). The catalytic reaction of TMB (which serves as a peroxidase substrate) in the presence of H₂O₂ produces a blue color. c Peroxidase-like activity of ferumoxytol at different concentrations at pH 4.5 and pH 6.5. d The amount of intact ferumoxytol and released free irons at pH 4.5 and their respective catalytic activities (e). The data are presented as the mean ± s.d. from three independent experiments (n = 6). The quantitative data were subjected to Student’s t test for a pairwise comparison. ^**P < 0.01, ^***P < 0.001