Physics Department

The University of Texas at Arlington



Candidate for Assistant Professor of Physics

in Nano-Bio Physics



A Novel Approach to Biomagnetic Sensing



Dr. Seok-Hwan Chung


Argonne National Laboratory


Thursday February 23, 2006

4:00 p.m., Room 121 SH




Magnetic nanoparticles fabricated by self-assembly or templating techniques offer great opportunities in nanomagnetism, including applications in spintronics, magnetic logic devices, and magnetic data storage technologies. Most importantly, micron and nanosized magnetic particles coated with biochemical ligands have emerged as a substantial component for enabling many fundamental biological study and medical applications. In particular biomagnetic sensors have received attention due to their potential advantages of simplicity and rapidity. I demonstrate a novel substrate-free approach to biomagnetic sensing which uses the magnetic ac susceptibility of ferromagnetic nanoparticles suspended in a liquid for the signal transduction. The magnetic relaxation of these particles is mainly due to their Brownian rotational diffusion, which can be modified by binding the particles to the target of interest.  This scheme has several advantages: (i) it requires only one binding event for successful sensing; (ii) there is a useful signal both in absence and presence of the target allowing for an inherent check of integrity; and (iii) the signal contains additional information about the size of the target. Moreover, theoretical calculations show that this sensing scheme can tolerate a broad size distribution of the magnetic nanoparticles. In addition to improving and miniaturizing the instrumentation, it is desirable to have biomagnetic nanoparticles with narrow size dispersion with desired biochemical affinity for increased sensitivity. I will also present work on a recent development of bio-functional “magnetic viruses” using an empty virus capsid as a template for the chemical precipitation of magnetic nanoparticles. This newly developed technique offers highly monodisperse size distribution of magnetic nanoparticles with very well defined biochemical selectivity.



Refreshments will be served in the Physics Library at 3:30pm, 108 Science Hall.