Iron oxide nanoparticles as a drug delivery vehicle for MRI monitored magnetic targeting of brain tumors

This study explored the possibility of utilizing iron oxide nanoparticles as a drug delivery vehicle for minimally invasive, MRI-monitored magnetic targeting of brain tumors. In vitro determined hydrodynamic diameter of similar to 100nm, saturation magnetization of 94 emu/g Fe and T-2 relaxivity of 43 s(-1) mM(-1) of the nanoparticles suggested their applicability for this purpose. In vivo effect of magnetic targeting on the extent and selectivity of nanoparticle accumulation in tumors of rats harboring orthotopic 9L-gliosarcomas was quantified with MRI. Animals were intravenously injected with nanoparticles (12mg Fe/kg) under a magnetic field density of 0T (control) or 0.4 T (experimental) applied for 30 min. MR images were acquired prior to administration of nanoparticles and immediately after magnetic targeting at I It intervals for 4h. Image analysis revealed that magnetic targeting induced a 5-fold increase in the total glioma exposure to magnetic nanoparticles over non-targeted tumors (p = 0.005) and a 3.6-fold enhancement in the target selectivity index of nanoparticle accumulation in glioma over the normal brain (p = 0.025). In conclusion, accumulation of iron oxide nanoparticles in gliosarcomas can be significantly enhanced by magnetic targeting and successfully quantified by MR imaging. Hence, these nanoparticles appear to be a promising vehicle for glioma-targeted drug delivery. (c) 2007 Elsevier Ltd. All rights reserved.