Zn doped magnetite nanoparticles for hyperthermia therapy

SANCHEZ, F.H.; P. MENDOZA ZÉLIS; G.A. PASQUEVICH; M.B. FERNÁNDEZ VAN RAAP; S J STEWART; I J BRUVERA; C. LABORDE; B PIANCIOLA; S. JACOBO; J. APHESTEGUY

Campinas

Encuentro; 21. RAU: Annual meeting of the LNLS users; 2011

It has been demonstrated that ferro°uids can be used for localized hyperthermia treatment due to magnetic relaxation heating e®ects in the presence of a radiofre- quency (RF) magnetic ¯eld[1]. Magnetic nanoparticles (MNP) relaxation can in- crease tumor temperature above 43±C and selectively kill tumor cells. One important feature of MNP for hyperthermia therapy is their speci¯c loss power or speci¯c ab- sorption rate (SLP/SAR), which determines the heating rate during treatments. In this work Znx Fe3¡x O4 (0 · x · 0:5) MNP in the form of powder and chit- tosan/aqueous ferro°uids were prepared. Mean sizes (> 40 nm) and compositions were envisaged to produce high SLP e®ects. To this end, Zn concentration was var- ied to optimize the saturation magnetization Ms. Materials were characterized with several techniques to determine their structural, microstructural and magnetic prop- erties and correlate them with their SLP performance. Znx Fe3¡x O4 nanoparticles were prepared by coprecipitation from FeSO4/ZnSO4 precursors in basic pH and studied by MÄossbauer Spectroscopy, TEM, DRX, SAXS, XAFS, magnetic thermo- gravimetry, 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 of about 105 emu/g) instead of at x = 0.4 (bulk). The measured SLP values were in the range of 100 - 400 W/g.