However, many studies showed opposite results; researchers found that Fe3O4 nanoparticles (Fe3O4 NPs), did not show any sign of POD‐like activity, causing negligible cytotoxicity to cancer cells.[10] In some cases, Fe3O4 nanozymes even showed catalase‐like (CAT‐like) activity, which led to the clearance of intracellular ROS.[8, 11]. Here, CAT is linked to cancer.