Zn-Magnetite nanoparticles for hyperthermia treatment

P. MENDOZA ZÉLIS, G. PASQUEVICH, B. PIANCIOLA, M. FERNANDEZ VAN RAAP, S. STEWART, J. APHESTEGUY, A. FOSSATI, S. JACOBO, F. H. SÁNCHEZ

Manizales

Workshop; Latin American Workshop on Magnetism and Magnetic Materials; 2010

Universidad Nacional de Colombia

It has been demonstrated that ferrofluids can be used for localized hyperthermia treatment due to magnetic relaxation heating effects in the presence of a radiofrequency (RF) magnetic field[1]. Magnetic Nanoparticles (MNP) relaxation can increase tumor temperature above 43 ºC and selectively kill tumor cells. One important feature of MNP for hyperthermia therapy is their specific loss power (SLP), which determines the heating rate during treatments. In this work ZnxFe(3-x)O4 (0 ≤ x ≤ 0.5) MNP and aqueous ferrofluids were prepared. Mean sizes (> 40 nm) and compositions were envisaged to produce high SLP. To this end, Zn concentration was varied to optimize the saturation magnetization Ms. Materials were characterized with several techniques to determine their structural, microstructural and magnetical properties and correlate them with their SLP performance. ZnxFe(3-x)O4 nanoparticles were prepared by coprecipitation from FeSO4/ZnSO4 precursors in basic pH and studied by Mössbauer Spectroscopy, TEM, DRX, SAXS, XAFS, magnetic thermogravimetry, VSM and RF-SLP. The nanoparticles have cubic-type shape with mean sizes of about 50 to 100 nm, decreasing with Zn concentration. It was observed that Zn2+ replaces Fe3+ at tetrahedric sites of the spinel structure increasing the Fe3+/Fe2+ ratio at the octahedric sites, similarly to what was reported for the bulk material; however, the highest Ms occurs at x = 0.1 – 0.2 (Ms ∼ 105 emu/g) instead of at x = 0.4 (bulk). The measured SLP in x=0 sample was 145 W/g. [1] Q. A. Pankhurst, N.K.T. Thanh, S.K. Jones and J. Dobson, J. Phys. D: Appl. Phys. 42 (2009) 224001 (15pp)