Superparamagnetic Iron Oxide-Gold Core-Shell Nanoparticles for Biomedical Applications
G. Saini, D. Shenoy, D.K. Nagesha, R. Kautz, S. Sridhar and M. Amiji
Northeastern University, US
iron oxide-gold, nanoparticles, biomedical
Iron oxide nanoparticles (NPs) in the form of maghemite and magnetite have been used for targeted drug delivery, magnetic cell sorting, magnetic resonance imaging (MRI) contrast agents and immunoassays. Surface modification of these NPs is one approach to enhance their biomedical applications. We have prepared a Fe2O3 NPs with a thin coating of gold to form a core/shell system. The Fe2O3 core was prepared by oxidizing Fe3O4 NPs formed by the co-precipitation of Fe(II) and Fe(III) salts in alkaline medium. The gold shell was formed by the reduction of Au3+ on iron oxide surface by the iterative hydroxylamine method. The NPs were characterized by UV-Vis absorption spectroscopy and transmission electron microscopy (TEM). SQUID magnetometry revealed that the superparamagnetic property of the NPs was not affected by the presence of Au shell. The potential use of these NPs as MRI contrast agents was investigated by monitoring the T2 relaxation time of the NPs at various concentrations. The preliminary results show a linear dependency of T2 relaxation time with concentration. Cytotoxicity of these NPs was studied by monitoring cell viability and proliferation in the presence of NPs. The bioconjugation protocols used for gold can be extended to these Fe oxide/Au shell NPs. These initial results and presence of gold coatings opens the door for a variety of applications for the Fe oxide/Au core-shell NPs.
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Nanotech 2005 Conference Program Abstract