Abstract
Biocompatible magnetic nanoparticles have been found promising in several biomedical applications for tagging, imaging, sensing and separation in recent years. Most magnetic particles or beads currently used in biomedical applications are based on ferromagnetic iron oxides with very low specific magnetic moments of about 20–30 emu/g. Here we report a new approach to synthesize monodispersed core-shell nanostructured clusters with high specific magnetic moments above 200 emu/g. Iron nanoclusters with monodispersive size of diameters from 2 nm to 100 nm are produced by our newly developed nanocluster source and go to a deposition chamber, where a chemical reaction starts, and the nanoclusters are coated with iron oxides. HRTEM Images show the coatings are very uniform and stable. 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 nanoclusters 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
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Acknowledgements
Financial support from the NSF-EPSCoR, NIH-INBRE and the University Research Office of the University of Idaho for the purchase of a SQUID instrument (MPMS XL-7, Quantum Design, Ins) is gratefully acknowledged. TEM data was collected at EMSL, a user facility sponsored by the DOE and operated by Battelle. Dr. Chongmin Wang at PNNL is thanked for highly valuable TEM assistance.
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Qiang, Y., Antony, J., Sharma, A. et al. Iron/iron oxide core-shell nanoclusters for biomedical applications. J Nanopart Res 8, 489–496 (2006). https://doi.org/10.1007/s11051-005-9011-3
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DOI: https://doi.org/10.1007/s11051-005-9011-3