MS&E Colloquium - Prof. Tom Healy, University of Melbourne
Date: March 05, 2010 from 2:00 pm to 3:00 pm EST
Location: 214 S. W. Mudd
Contact: For further information regarding this event, please contact Chad Gurley by sending email to .
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The Electrokinetic Properties of Colloidal Magnetic Iron Oxides

Nano-sized magnetic iron oxides, important in information storage-reproduction technologies, are finding increasing use in the preparation and delivery of biomolecular effects. A biomolecule, adsorbed or chemically bound at the magnetic particle-water interface can be reacted chemically and the magnetic particles held or moved by external magnets, then washed, re-suspended and further treated to provide novel properties for use in biosensors and other such platforms.


We have measured the fundamental, underlying electrokinetic properties of the magnetic particle-water interface itself so as to better control the uptake of biomolecular species and fragments for subsequent use, in particular, in novel biosensor platforms. To do this we have developed an electrokinetic streaming potential technique that relies on the ability of an external magnet to hold a bed or plug of particles, collected from a suspension, in a fixed position within the flowing aqueous solution. Our technique clearly idenifies the iso-electric point-point of zero charge of the magnetite and other magnetic oxides. However we observe anomalously low values of the zeta potential and an anomalous dependence on salt concentration. Using both chemical and instrumentation changes we have removed these anomalies. A new conduction path from particle to particle in the magnetic particle bed is indicated.


Thomas W. Healy


Department of Chemical & Biomolecular Engineering

University of Melbourne, Vic. 3010.  Australia