Fig. 4: Characterization of the ferritin iron core and phosphate-doped ferrihydrite.

a HRTEM images of ferritin iron core with different P/Fe ratios of three independent experiments with similar results. b FTIR spectra of 2-line ferrihydrite doped with gradient phosphate. c XRD spectra of 2-line ferrihydrite doped with gradient phosphate. d HRTEM and SAED images of 2-line ferrihydrite doped with gradient phosphate of three independent experiments with similar results; inset figures represented partially enlarged images; the scale bar in HRTEM images referred to 5 nm; the inset scale bar referred to 2 nm. e SOD-like activity of the phosphate-doped 2-line ferrihydrite; the data are mean ± SD (n = 3 independent experiments); the significant difference was evaluated by the Two-way ANOVA with post-hoc Tukey HSD test; ns: not significant, p > 0.05. Source data are provided as a Source Data file.