Magnetic field induced particle clustering and its application in viscosity measurement

COLL 174

Rui Hong, rhong1@partners.org, Center for Molecular Imaging Research, Harvard Medical School/ Massachusetts General Hospital, 149-5404, 13th street, Charlestown, MA 02129, Michael J. Cima, Massachusetts Institute of Technology, Ralph Weissleder, Center for Molecular Imaging Research, Massachusetts General Hospital, Harvard Medical School, 149 13th St. Rm 5404, Charlestown, MA 02129, and Lee Josephson, Center for Molecular Imaging Research, Harvard Medical School, 13th Street, Bldg. 149, Room 5406, Charlestown, MA 02129.
Several types of superparamagnetic particles with sizes above a few hundred nanometers exhibit unique characteristics when exposed to homogeneous magnetic fields. Particle clustering was observed when placed in fields, which was readily reversed upon removal from the field. Associated with the reversible particle aggregation and dispersion were the increase and decrease of water spin-spin relaxation times (T2) of the particle solution. The magnetic coupling of the particles, which exceeds their thermal fluctuation thermodynamically, was the driving force for the cluster formation. In addition, medium viscosity was found to influence the rate of aggregation and T2 change dramatically. Based on this concept, a viscosity measurement method was developed. The method may be of particular interest for viscosity measurement of biological fluids such as serum, in that size, number and biohazardous nature of the samples are of major concerns.
 

Fundamental Research in Colloid and Surface Chemistry
6:00 PM-8:00 PM, Monday, August 20, 2007 BCEC -- East Registration, Poster

Division of Colloid & Surface Chemistry

The 234th ACS National Meeting, Boston, MA, August 19-23, 2007