LabAutomation 2006 - SLAS

MP47
Joohoon Kim
University of Texas at Austin
Austin, Texas
jkim94@mail.utexas.edu
LabAutomation2006
Co-Author(s)
Rahul Dhopeshwarkar
Texas A&M University
Richard M. Crooks
University of Texas at Austin
Sensitive DNA Detection Assay Using Probe-Conjugated Microbeads and a Hydrogel
Microplug in a Microfluidic Device
We report a novel approach for simple and sensitive DNA detection, which relies on the concentration of fluorescein-labeled target DNA
strands and their subsequent capture in a microfluidic device. The device consisted of probe-conjugated microbeads packed in front
of a hydrogel microplug photopolymerized in a microchamber. The microbeads were conjugated with a probe that is complementary
to a desired target. The target DNA strands were electrokinetically transported and concentrated at an interface between the highly
cross-linked hydrogel microplug and buffer solution, and captured by the probe-conjugated microbeads through DNA hybridization. The
probe-conjugated microbeads allowed fast and sequence-specific capture of the targets. The hydrogel microplug allowed the passage of
buffer ions but hindered larger migrating single-stranded target DNA, resulting in concentration of the targets. The concentration of targets,
either by a uncharged or negatively charged hydrogel on its backbone, provided an enhancement in the sensitivity of the DNA detection
assay using probe-conjugated microbeads. This work is important because it enables sensitive detection of trace amounts of DNA as well
as a rapid and simple DNA detection methodology within a simple microfluidic architecture.
MP48
Kapeeleshwar Krishana
Princeton University
Co-Author(s)
David Inglis, John Davis, James Sturm
Robert Austin, Stephen Chou, Edward Cox
Princeton University
David Lawrence
Wadsworth Institute of Public Health
Microfluidic Device for Separation and Analysis of Blood Components
We recently pioneered a microfluidic device known as the “bump” array, in which particles above a critical size are deterministically
“bumped” from obstacle to obstacle to follow a path different from that of small particles. The method does not rely on any particular
particle shape, and is independent of electrical charge. It has been used to fractionate nanoparticles with record resolution, and to quickly
(in seconds) separate blood into streams of red blood cells, white blood cells, and plasma and platelets. We have also succeeded in
separating rare or “desirable” cells from a population by selectively attaching nanoparticles of a material with a high magnetic susceptibility
to a cell based on the chemistry of the cell’s surface and the corresponding co-receptor on the nanoparticle. The cell can then be steered
by magnetic field gradients. White blood cells were tagged with magnetic nanoparticles based on the CD45 antigen. The blood was then
injected into a microfluidic structure with magnetized stripes embedded in the substrate at an angle to the flow. The stripes create a high
magnetic field gradient near the stripes edges, which then trap cells tagged with the nanoparticles. These cells then flow diagonally along
the stripes, and are separated from the main flow of untagged cells which flow vertically over the stripes with no magnetic effects. We will
present an overview of the technology developed at Princeton and discuss the latest advances towards rapid screening of blood based on
the change in deformability of the cells on radiation exposure.
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