In vitro magnetic hyperthermia using polyphenol-coated Fe3O4@γFe2O3 nanoparticles from Cinnamomun verum and Vanilla planifolia: the concert of green synthesis and therapeutic possibilities

We report on a new, environment-friendly synthesis route to produce Fe3O4 magnetic nanoparticles (MNPs) from extracts of the plants Vanilla planifolia and Cinnamomun verum. These aqueous plant extracts have the double function of reducing agents due to their phenolic groups, and also capping materials through the -OH bonding over the MNPs surface. The resulting MNPs have average sizes approximate to 10-14 nm with a core-shell Fe3O4-gamma Fe2O3 structure due to surface oxidation driven by the phenolic groups through OH-covalent bonding. Saturation magnetization values of M-s = 70.84 emu g(-1) (C. verum) and M-s = 59.45 emu g(-1) (V. planifolia) are among the largest reported so far from biosynthetic samples. Electron microscopy and infrared spectroscopy data showed a thin organic layer coating the Fe3O4 @gamma Fe2O3 MNPs, composed by the phenolic groups from the starting extracts of both C. verum and V. planifolia. A proof of concept for these MNPs as heating agents in magnetic hyperthermia experiments (570 kHz, 23.9 kA m(-1)) was performed in-vitro, showing their efficacy to induce cell death on BV2 microglial cells after 30 min at a target temperature T = 46 degrees C.