Encoded Metallic Nanowires Reveal Bioweapons

August 10, 2006

When dangerous infectious diseases or biological weapons are suspected, fast help is required. The first step is a reliable, sensitive, and unambiguous, yet also fast and simple, identification of the pathogen; preferably, this test should be carried out on the spot, not in a laboratory.

Portable miniature biodetection systems that can detect multiple pathogens simultaneously would be ideal for this task.

American researchers from Lawrence Livermore National Laboratory led by Jeffrey Tok, in collaboration with groups at Stanford University, University of California at Davis, and Oxonica Inc. (formerly Nanoplex Technologies Inc) have now developed a new basis for such a multiplex device: they are using silver and gold “striped” nanowires as supports for simultaneous immunological tests for various pathogens. Individual patterns of stripes act in the role of “barcodes”.

These “nanobarcoded” particles are manufactured by Oxonica Inc using template-assisted electrochemical deposition of metals within the tiny cylindrical pores of alumina membranes. When deposited gold and silver are alternated in a defined way, nanowires with different characteristic stripe patterns are produced. The pattern of optical reflections from each sequence of stripes can later be unambiguously recognized—just like a barcode.

Antibodies aimed at specific pathogens can be attached to these wires. For their test runs, Tok and his colleagues selected harmless model substances to stand in for anthrax spores, smallpox virus, and protein toxins such as ricin and botulinum toxin. If a simultaneous test for all of these is desired, the anthrax antibody would be attached to stripe pattern 1, the smallpox antibodies to stripe pattern 2, and the toxin antibodies to stripe pattern 3, for example.

If the corresponding model pathogen is present in a sample, it is “recognized” and bound by its antibodies. At this point, free antibodies that have been tagged with a fluorescent dye are added to the sample. These also dock onto the pathogen so that it is surrounded like the filling in a sandwich; giving the technique its name, “sandwich immunoassay”. Measurement of the fluorescence now gives information about the pathogen concentration. Analysis of the reflection pattern allows the “barcode” of the fluorescing nanowires to be read.

If only wires with stripe pattern 1 fluoresce, for example, then the sample contains anthrax spores. One particular advantage of nanowires over other antibody supports is that the tests do not take place at a surface but instead in a suspension, which makes them run much faster and more accurately. If nickel stripes are also added to the ends of the wires, they can then be magnetically separated out during the required washing steps—a prerequisite for a portable microbiodetector.

Citation: Jeffrey B.-H. Tok, et al., Metallic Striped Nanowires as Multiplexed Immunoassay Platforms for Pathogen Detection, Angewandte Chemie International Edition, doi: 10.1002/anie.200601104

Source: Angewandte Chemie

Explore further: Scientists perfect new nanowire technique

Related Stories

Scientists perfect new nanowire technique

October 14, 2010

Scientists at the University of Leeds have perfected a new technique that allows them to make molecular nanowires out of thin strips of ring-shaped molecules known as discotic liquid crystals (DLCs).

Measurements from the edge: magnetic properties of thin films

September 28, 2007

Materials researchers at the National Institute of Standards and Technology, together with colleagues from IBM and the Massachusetts Institute of Technology, have pushed the measurement of thin films to the edge—literally—to ...

Scientists Create Nano-Patterned Superconducting Thin Films

June 14, 2010

(PhysOrg.com) -- A team of scientists from Bar-Ilan University, Israel, and the Brookhaven National Laboratory has fabricated thin films patterned with large arrays of nanowires and loops that are superconducting -- able ...

Recommended for you

Solving mazes with single-molecule DNA navigators

November 16, 2018

The field of intelligent nanorobotics is based on the great promise of molecular devices with information processing capabilities. In a new study that supports the trend of DNA-based information carriers, scientists have ...

A way to make batteries almost any shape desired

November 16, 2018

A team of researchers from Korea Advanced Institute of Science and Technology, Harvard University and Korea Research Institute of Chemical Technology has developed a way to make batteries in almost any shape that can be imagined. ...

Graphene flickers at 400Hz in 2500ppi displays

November 16, 2018

With virtual reality (VR) sizzling in every electronic fair, there is a need for displays with higher resolution, frame rates and power efficiency. Now, a joint collaboration of researchers from SCALE Nanotech, Graphenea ...

'Smart skin' simplifies spotting strain in structures

November 15, 2018

Thanks to one peculiar characteristic of carbon nanotubes, engineers will soon be able to measure the accumulated strain in an airplane, a bridge or a pipeline – or just about anything – over the entire surface or down ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.