Nanowire bar codes enable detection of biowarfare agents
A team of researchers from California has introduced metallic-striped nanowires to
aid in detecting biological warfare agents with optical reflectance and fluorescence
As described in the group’s Angewandte
Chemie manuscript published online Aug. 4, the nanowires were structured with
submicron gold, silver and nickel layers and coated with antibodies that bound to
fluorophore-tagged antigens in a solution. In both single and multiplex immunoassays,
the team used three nonpathogenic antigens to represent a variety of biological
warfare agents, from micron-size bacterial spores to nanoscale protein toxins. Each
nanowire had a unique “bar-code-like” pattern that corresponded to its
particular antibody coating.
Gold- and silver-striped
nanowires are coated with antibodies and suspended in a solution. Fluorescence imaging
can reveal which fluorophore-tagged antigens, representing biological warfare agents,
are present in the solution.
Reflectance/fluorescence image pairs
were taken with a Zeiss inverted microscope fitted with bright-field reflectance
and fluorescence filter sets. The reflectance images allowed the researchers to
identify the stripe patterns of each nanowire and to determine which antibodies
coated them. Depending on which nanowires were fluorescently lighted, they could
determine which antigens were present in the solution. The fluorescent intensity
represented the concentration of each antigen.
The researchers, from Lawrence Livermore
National Laboratory, Stanford University, Nanoplex Technologies Inc. of Mountain
View and the University of California, Davis, hope to incorporate the assay onto
a microfluidic device to enable a rapid, portable and affordable multiplex biosensing
system. Because the assay can be completed in a matter of hours, it will allow quick
and accurate detection of infectious biological agents.
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