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Microchip Dialysis of Protein Samples Using Laser-polymerized Nanoporous Membranes
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Funding: DOE
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Complex samples (e.g., cell extract) often require extensive cleanup or
pretreatment before introduction to analysis channels in a
miniaturized device. These pretreatment steps are often performed
off-chip using large volumes of sample and other reagents, and
hence often add substantially to the total analysis time and cost.
Dialysis, or size-based separation of species via selective
diffusion through a semipermeable membrane, is a widely used
technique for cleanup of biological samples. We have
developed a technique for fabricating thin (4-14 micron)
nanoporous polymer dialysis membranes within the channels of
a glass microchip. UV laser-initiated polymerization is
used for controlled placement of the dialysis membrane
in a chip for cleanup of complex or dirty samples; this
technique is rapid and inexpensive and increases the
potential functionality of integrated microfluidic
devices. The semipermeable membrane and fabrication
technique can be used to control cell positioning and to extract a small
molecular weight analyte of interest from a complex matrix, facilitating
chemical analysis in general and
cellular analysis in particular.
Our work in this area includes development of patterned dialysis membranes patterned
in-situ within microchips, their use for counterflow mass exchange, their use for protein
concentration, and their use for positioning and lysing cells.
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Publications and Presentations on Microchip Dialysis
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Song S, Mela P, van den Berg A,
Kirby BJ
"Microfluidic architectures for integrated cell lysis,
lysate dialysis and cell stimulus," in MicroTAS 2004, Kluwer Academic Publishers (2004).
pdf
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Song S, Singh AK,
Kirby BJ
"Electrophoretic
Concentration of Proteins at Laser-Patterned Porous
Membranes," Analytical Chemistry 76:4589-4592 (2004).
doi
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Song S, Singh AK, Shepodd TJ,
Kirby BJ
"Fabrication and characterization of photopatterned polymer
membranes for protein concentration and dialysis in microchips," in Hilton Head MEMS Workshop 2004 (2004).
pdf
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Song S, Singh AK, Shepodd TJ,
Kirby BJ
"Microchip dialysis of proteins using in situ
photopatterned nanoporous polymer membranes", Analytical
Chemistry 76:2367-2373 (2004).
doi
pdf
text
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Song S, Shepodd TJ, Singh AK,
Kirby BJ
"Microchip-based dialysis of protein
samples using photopatterned nanoporous membranes," in MicroTAS 2003, Kluwer Academic Publishers (2003).
pdf
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Fintschenko Y,
Kirby BJ,
Hasselbrink, Jr. EF,
Singh AK, Shepodd TJ
"Monolithic Materials: Miniature
and Microchip Technologies," in Monolithic Materials:
Preparation, Properties, and Applications Elsevier,
Amsterdam (2003).
pdf
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Kirby BJ,
Singh AK
"In-situ Fabrication of
Dialysis Membranes in Glass Microchannels Using Laser-induced
Phase-separation Polymerization," in MicroTAS 2002,
Kluwer Academic Publishers, pp. 742-744 (2002).
pdf
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We use laser-microfabrication to make microscale polymer elements within
etched microchannels, for use for
microfluidic control
or
dialysis.
A frequency-tripled Nd:YAG laser is used to photopolymerize a liquid-phase solution
of monomers, solvents, and photoinitiators. The structural, tribological, and chemical
properties of the resulting solid polymer structure are controlled by the material
precursors.
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A nanoporous membrane (~20 microns thick)
patterned at the intersection of two glass microchannels, which can be used for
sample dialysis or protein concentration.
A frequency-tripled Nd:YAG laser is used to
photopolymerize
a zwitterionic polyacrylate
from a primarily aqueous solvent mixture. The resulting membrane passes salts and other
low-molecular weight species but does not allow protein transport.
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