Based on in vivo 4T1 tumor‐bearing mice model, the intravenous administration of CaO2‐Fe3O4@HA nanoparticles achieved 69.08% tumor‐suppression rate (Figure 2e,f), much higher as compared to either Fe3O4@HA nanoparticles (19.44%) and CaO2@HA nanoparticles (29.39%).[58] Similarly, transferrin‐modified MgO2 nanosheets were constructed for H2O2 self‐supplying and Fenton reaction based oxidative therapy.[62] The initial reaction of MgO2 with H2O produced H2O2, which damaged the transferrin structure to release the trapped Fe3+. Here, TF is linked to neoplasm.