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Immunochromatography is a rapid, reliable, and cost effective method of detecting biowarfare agents. The format is
similar to that of an over-the-counter pregnancy test. A sample is applied to one end of a cassette and then a control line,
and possibly a sample line, are visualized at the other end of the cassette. The test is based upon a sandwich assay. For
the control, a line of Protein A is immobilized on the membrane. Gold nanoparticle bound IgG flows through the
membrane and binds the Protein A, creating a visible line on the membrane. For the sample, one epitope is immobilized
on the membrane and another epitope is attached to gold nanoparticles. The sample binds gold bound epitope, travels
through the membrane, and binds membrane bound epitope. The two epitopes are not cross-reactive, therefore a sample
line is only visible if the sample is present. In order to efficiently screen for binders to a sample target, a novel,
Continuous Magnetic Activated Cell Sorter (CMACS) has been developed on a disposable, microfluidic platform. The
CMACS chip quickly sorts E. coli peptide libraries for target binders with high affinity. Peptide libraries, are composed
of approximately ten million bacteria, each displaying a different peptide on their surface. The target of interest is
conjugated to a micrometer sized magnetic particle. After the library and the target are incubated together to allow
binding, the mixture is applied to the CMACS chip. In the presence of patterned nickel and an external magnet,
separation occurs of the bead-bound bacteria from the bulk material. The bead fraction is added to bacterial growth
media where any attached E. coli grow and divide. These cells are cloned, sequenced, and the peptides are assayed for
target binding affinity. As a proof-of-principle, assays were developed for human C-reactive protein. More defense
relevant targets are currently being pursued.
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