CINDECA   05422
CENTRO DE INVESTIGACION Y DESARROLLO EN CIENCIAS APLICADAS "DR. JORGE J. RONCO"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
SYNTHESIS AND CHARACTERIZATION OF SUPERPARAMAGNETIC IRON OXIDE NANOPARTICLES FOR BIO-MEDICAL APPLICATIONS
Autor/es:
L.A. CANO, M.V. CAGNOLI, S.J. STEWART, E.D. CABANILLAS, E.L. ROMERO, AND S.G. MARCHETTI
Lugar:
La Plata, Argentina
Reunión:
Conferencia; 11th Latin American Conference On Applications Of The Mössbauer Effect; 2008
Institución organizadora:
Instituto de Física La Plata
Resumen:
<!-- /* Font Definitions */ @font-face {font-family:CMR10; panose-1:0 0 0 0 0 0 0 0 0 0; mso-font-charset:0; mso-generic-font-family:auto; mso-font-format:other; mso-font-pitch:auto; mso-font-signature:3 0 0 0 1 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 3.0cm 70.85pt 3.0cm; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> Magnetic nanoparticles offer exciting new opportunities toward developing effective drug delivery systems, since it is feasible to produce, and specifically tailor their functional properties for these applications. An external localized magnetic field gradient may be applied to a chosen site to attract drug-loaded magnetic nanoparticles from blood circulation. Drug targeting to tumors is desirable since anticancer agents demonstrate non-specific toxicities that significantly limit their therapeutic potentials [1]. The synthesis of magnetite nanoparticles has been carried out using standard airless procedures and commercially available reagents [2]. Fe(acac)3, 1-2 hexadecanediol, oleic acid, oleylamine and phenyl ether were mixed and magnetically stirred under a nitrogen flow and heated to reflux. The obtained nanoparticles, coated with oleic acid, were redispersed into hexane. The solids were characterized by TEM, XRD, magnetization measurements, and M¨ossbauer Spectroscopy at different temperatures. Through TEM a narrow distribution of spherical nanoparticles of 3 nm of diameter were observed. The diffractogram shows a very broad peaks (corresponding to particles of about 3 nm). They are coincident with Fe3O4 and/or gamma- Fe2O3. The M¨ossbauer spectra show some interesting aspects. Thus, at room temperature it was not possible to detect any signal. However, when the spectrum was obtained at 281K (below the oleic acid fusion temperature) a central signal begins to appear. Maybe, the extremely small size of the particles inhibit to obtain a free recoil-less factor to produce M¨ossbauer effect when the temperature is above the oleic acid fusion point and the sample behaviour is similar to a liquid. From the M¨ossbauer spectrum at 25K the existence of Fe3O4 was determined. This spectrum shows a curved background indicating that the magnetic ordering is still not complete and coexists with the superparamagnetic relaxation. The presence of gamma- Fe2O3 can not be discarded. By the M-H loops measurements a saturation magnetization of Ms= 89 emu/g at T=2K was estimated, which is similar to that reported for Fe3O4 bulk (85 emu/g). This result would indicate that the spin disorder at the surface layer is very small or that the presence of oleic acid on the surface would increase the Ms value. Besides, the curves are reversible down to 5K. Decreasing the temperature to 2K, a hysteretic behaviour is observed with Hc= 106 Oe.