Fig. 4: Enhanced catalytic activity of Fer in the presence of SnF₂.

a Change in the absorption of TMB (chromogenic substrate) at 652 nm in different conditions. Inset: Photographs of TMB incubated with various reagents (left: SnF₂ alone, middle: Fer alone, and right: Fer + SnF₂) 10 min after H₂O₂ addition (n = 3 independent experiments). b UV–visible absorption spectra of TMB in the presence of SnF₂, Fer, or Fer + SnF₂ at the times indicated. c Peroxidase-like activity of Fer and Fer + SnF₂ at three pH values (4.5, 5.5, and 6.5) as determined by the colorimetric TMB assay (n = 3 independent experiments). d Change in the absorption of OPD at 450 nm in different conditions (n = 4 independent experiments). The increase in absorption at 450 nm shows ROS production. e Comparison of change in PL intensities of DCF at 520 nm at various conditions (n = 5 independent experiments). The increase in PL intensity at 520 nm depicts ROS production. f The change in PL intensity of 7-hydroxycoumarin at 452 nm as a function of time in the presence of Fer with or without SnF₂ (n = 5 independent experiments). The increase in the PL intensity at 452 shows the generation of •OH. Effect of NaF (g), BaF₂ (h), and SnCl₂ (i) on the catalytic activity of Fer in 0.1 M sodium acetate buffer (pH 4.5) (n = 3 independent experiments). The data are presented as mean ± standard deviation. ***p < 0.001; ns nonsignificant; one-way ANOVA followed by Tukey test. Source data are provided as a Source Data file.