Structural effect of Fe3O4 nanoparticles on peroxidase-like activity for cancer therapy

Abstract Ferromagnetic nanoparticles (Fe 3 O 4 NPs) have been proven to have the intrinsic peroxidase-like activity. This property has been used for analyte detection, tumor tissue visualization, and cancer therapy, etc . However, the effect of particle structure and morphology on its peroxidase-like activity has been rarely reported. In this work, we fabricated Fe 3 O 4 nanoparticles with different structures (nanoclusters, nanoflowers, and nanodiamonds) by facilely tuning the pH values in the hydrothermal reaction. Their in vitro peroxidase-like activity was evaluated via chromogenic reaction of 3,3′,5,5′-tetramethylbenzidine (TMB) by the reduction of H 2 O 2 to H 2 O. It was found the nanostructures had a great influence on their peroxidase-like activity, following the order of nanoclusters > nanoflowers > nanodiamonds. With this activity, the peroxidase-like activity of Fe 3 O 4 NPs was used for cancer therapy with the addition of low-concentration H 2 O 2 . The cancer cell-killing activity was due to the intracellular generated reactive oxygen species (ROS) after endocytosis of Fe 3 O 4 NPs into the Hela cells. It was interesting that the cell killing ability of these three kinds of Fe 3 O 4 NPs was not consistent with the in vitro enzyme-like activity. It was deduced that the cell endocytosis of the nanoparticles along with their enzyme-like activity co-determined their cancer cell-killing performance.