Peroxidase-like activity of MexFe(3-x)O4 Magnetic Nanoparticles with potential application in Magnetic Hyperthermia

ANA CAROLINA MORENO MALDONADO; ENIO LIMA JR; ELIN WINKLER; CARLOS A RAMOS; MARIANA RANIERI; HORACIO E. TROIANI; MARY LUZ MOJICA PISCIOTTI; LUIS RODRIGUEZ; ROBERTO D. ZYSLER

Bariloche

Simposio; XXIII Latin American Symposium on Solid State Physics; 2018

Magnetic nanoparticles (NPs) are widely used in medicine as contrast agents for MRI, controlled drug release, oncology hyperthermia (MFH) therapy, and otherapplications. Due to their high magnetization, chemical stability and low toxicity, ferrite nanoparticles, especially magnetite Fe3O4, are intensively studied in this context and even applied clinically. In 2007, Gao it et al [1] found that this material is capable of catalyzing the production of free radicals (FR) in the Fenton reaction because they possess peroxidase catalytic activity. Fenton reactions are oxidative reactions of hydrogen peroxide (H2O2) decomposition catalyzed by transition metals. FR are highly unstable, with paramagnetic behavior, that occur naturally in the body as a result of processes such as cellular respiration. In small amounts they are used as messengers incellular signaling processes, but in high concentrations they can induce oxidative stress, concluding with the death of the cells. Determining the peroxidase-like catalytic activity of magnetic nanoparticles in different media is of vital importance, due to the increasing demand for NPs in clinical applications. In this work we present a study of the FR formation catalyzed by magnetic nanoparticles in the presence of H2O2. The FR were quantified by the Electronic Paramagnetic Resonance Spectroscopy (EPR) using DMPO as spin trapping, which reacts with the short half-live FR producing a more stable radical with a longer half-life that can be measured. Three nanoparticle systems were used: Fe3O4, MnFe2O4 and NiFe2O4 prepared by the thermal decomposition of iron acetylacetonate at high temperature in the presence of surfactants. The nanoparticles were characterized morphologically by TEM microscopy, chemically by FTIR, and magnetically by magnetization measurements as function of applied field and temperature. The EPR spectra were taken at 293 K, 313 K and 318 K. The areas of the lines were adjusted, taking into account the hyperfine interactions of each radical bound to the DMPO. The quantification of the formed radicals was performed comparing the EPR spectra with a standard sample of Mn2+: MgO. The spectra reveal the formation of hydroxyl (·OH) and superoxide (·OOH) radicals from the H2O2 decomposition together with the methyl radical (·CH3) from the DMSO in which the DMPO was dissolved. The temporal evolution for the three systems was measured and and showed an expected progression.