Reminder - PhD Defense, Chris Earhart

Chris Earhart cearhart at stanford.edu
Tue Jul 27 10:43:04 PDT 2010


A Ph.D. Defense Announcement

"Magnetic Sifter and Nanoparticles for Cell and Protein Separation"

PhD Candidate: Chris Earhart
Department of Materials Science and Engineering

Advisor: Professor Shan X. Wang

Date: Wednesday, July 28, 2010
Time: 9:30 am (refreshments at 9:15 am)
Place: CIS-X Auditorium (Rm 101)

Abstract:
Nanoscience and nanotechnology have been applied in recent years to
cancer research, with the goal of making a revolutionary change in the
ways in which cancer is diagnosed and treated.  Magnetic
nanotechnologies, in particular, have shown significant potential in
several areas such as imaging, therapeutics, and early detection.  The
topic of this presentation is a novel magnetic separation device, the
magnetic sifter, and physically fabricated magnetic nanoparticles for
applications in cell and protein separation.

The magnetic sifter is a microfabricated planar die containing a dense
array of pores (~200-5000/mm2) in a magnetically soft membrane.  When
magnetized by an external field, the sifter pores generate large
magnetic field gradients near the pore edges, which capture nanoscale
magnetic carriers during flow with high efficiency and throughput.
The magnetic sifter is a microfluidic device, in the sense that it
contains microfabricated, micron-scale pores for fluid flow.  It is
also a macrofluidic device, in that high-volume throughput is achieved
by parallel flow through the large number of pores.
When paired with magnetic carriers functionalized with recognition
moieties, the magnetic sifter can be used in both cell and protein
enrichment schemes.  Separations of magnetically labeled tumor cells
and individual magnetic nanoparticles using the sifter will be
discussed.  With its planar structure and presentation of captured
cells, the sifter can also be used as a cell imaging platform.  The
use of the sifter to capture and quantify low concentrations (~100/mL)
of tumor cells in whole blood samples has been demonstrated.

Lastly, a method for high-throughput fabrication of novel magnetic
carriers, synthetic antiferromagnetic (SAF) nanoparticles, will be
presented.  The method has enabled production of large quantities of
SAF nanoparticles, which have desirable properties for applications in
magnetic separation.  The capture and release of SAF nanoparticles
with the magnetic sifter has been shown.  High capture efficiencies
are achieved at flow rates 10-20x higher than what was previously
possible with commercially available magnetic carriers.



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