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  • Dr. You Qiang from Univ. of Idaho gave a colloquium on Core-shell nanoclusters: synthesis, magnetism and biomedical application on September 28, 2005.

     

Dr. You Qiang, a assistant professor at Physics Department at University of Idaho, gave audiences of Physics Department of UTA a colloquium. The talk is titled "Core-shell nanoclusters: synthesis, magnetism and biomedical application". The abstract of the seminar is as follows: 

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 low specific magnetic moments of about 30 emu/g and polydispersive. In my talk, I will report a new approach based on magnetic metal nanoparticles passivated by an oxide coating. Specifically we prepared passivated or coated monodispersed magnetic nanoclusters in sizes between 1-100 nm. We attached proteins, including antibodies, to these magnetic nanoparticles. The magnetic properties of nanoparticles have be investigated by superconducting quantum interference device (SQUID) magnetometry and related tools such as HRTEM, AFM and XPS.

The cluster beam deposition apparatus developed recently in our laboratory is mainly composed of three parts: a cluster source, an e-beam evaporation chamber and a deposition chamber. The mean size of clusters, from 1 nm to 100 nm, is easily varied by adjusting the aggregation distance, the sputter power, the pressure in the aggregation tube, and the ratio of He to Ar gas flow rate. A major advantage of this type of system is that the clusters have much smaller size dispersion than grains obtained in any typical pro. A typical size distribution is less than 10%. Applying a pulsed-field mass selector to nanoclusters reduces it to about 3%.

We have synthesized monodispersive core-shell nanostructured iron clusters. 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 at the size larger than 80 nm. This moment is almost 10 times higher than commercial products. The use of high magnetic moment and monodispersive nanoparticles can 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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