2007 NSTI Nanotechnology Conference and Trade Show - Nanotech 2007 - 10th Annual

Synthesis, Properties and Biomedical Applications of Novel Core-Shell Iron Magnetic Nanoparticles

Y. Qiang, J. Antony, A. Sharma, D. Meyer, M. Faheem and M. Campanell
University of Idaho, US

Keywords:
magnetic nanoparticles, core-shell structure, cancer cell

Abstract:
Nanoparticles have gained increased attention recently for biomedical and environmental applications. Biocompatible magnetic nanoparticles (MNPs) have been found promising in several biomedical applications for tagging, imaging, drug delivery, sensing and separation in recent years. Most magnetic particles or beads currently used in biomedical applications are based on iron oxides with very low specific magnetic moments of ~30 emu/g. In this presentation, we report room-temperature synthesis of novel iron-iron oxide core-shell nanoclusters using a newly developed nanocluster source. Monodispersive iron nanoclusters with size of diameters from 2 nm to 100 nm are produced in a source chamber and then transmitted into the reaction chamber where a small partial pressure of O2 is present so that the nanoclusters are coated with uniform iron oxide shell. These shells act as passivation layers preventing further oxidation of the cores upon subsequent or continued exposure to air. The size of the iron-iron oxide core-shell nanoclusters varies with the He:Ar ratio, chamber pressure, and growth distance through the aggregation tube. The clusters were characterized by XPS, XRD and HRTEM. The bcc-Fe core with magnetite shells was observed by XRD and HRTEM. The core-shell nanoclusters are superparamagnetic at room temperature for sizes less than 15 nm, and then become ferromagnetic when the cluster size increases. The specific magnetic moment of core-shell MNPs is size dependent, and increases rapidly from about 80 emu/g at the cluster size of around 3 nm to over 200 emu/g up to the size of 100 nm. The use of high magnetic moment nanoclusters for biomedical applications could dramatically enhance the contrast for MRI, reduce the concentration of magnetic particle needs for cell separation, or make drug delivery possible with much lower magnetic field gradients. These MNPs were incubated and successfully untaken by lung cancer cells for the toxicity. *Research supported by DOE, DOE-PNNL and NSF-EPSCoR.

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