Zn Magnetite nanoparticles for hyperthermia treatment

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

Campinas

Encuentro; 21ª Reunião Anual de Usuários do LNLS; 2011

Laboratorio Nacinal de Luz Sincrotron, Campinas-SP

It has been demonstrated that ferrofluids can be used for localized hyperthermiatreatment due to magnetic relaxation heating effects in the presence of a radiofrequency(RF) magnetic field[1]. Magnetic nanoparticles (MNP) relaxation can increase tumortemperature above 43 ºC and selectively kill tumor cells. One important feature of MNPfor hyperthermia therapy is their specific loss power (SLP), which determines the heatingrate 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 werecharacterized with several techniques to determine their structural, microstructural andmagnetical properties and correlate them with their SLP performance.ZnxFe(3-x)O4 nanoparticles were prepared by coprecipitation from FeSO4/ZnSO4precursors in basic pH and studied by Mössbauer Spectroscopy, TEM, DRX, SAXS,XAFS, magnetic thermogravimetry, VSM and RF-SLP. The nanoparticles have cubic-typeshape with mean sizes of about 50 to 100 nm, decreasing with Zn concentration. It wasobserved that Zn2+ replaces Fe3+ at tetrahedric sites of the spinel structure increasing theFe3+/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)