Nano Detector Hunts Down Anthrax

Friday, July 8, 2011 @ 01:07 PM gHale

An automatic and portable detector that takes fifteen minutes to analyze a sample suspected of contamination with anthrax is now under development.

The technology amplifies any anthrax DNA present in the sample and can reveal the presence of just 40 microscopic cells of the deadly bacteria Bacillus anthracis.

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B. anthracis, commonly known as anthrax, is a potentially lethal microbe that could infect victims through contamination of food and water supplies, aerosolized particles, or even dried powders, such as those used in bioterrorist attacks in the USA. Detection is crucial to preventing widespread fatalities in the event of an anthrax attack.

However, the complexity of the microbe’s biology makes it difficult to build a portable system for use in the field. There are several systems available that use PCR to amplify a particular component of the genetic material present in anthrax and then to flag this amplified signal. These systems are fast and sensitive but do not integrate sample preparation so they are not as convenient as a single detector unit would be.

Nanofabricated fluidic cartridges that can carry out detection of anthrax are put together, said Nathaniel Cady of the College of Nanoscale Science and Engineering (CNSE) of the University at Albany and colleagues there and at Cornell University, New York. The unit is a “lab-on-a-chip” device, or more properly a 3D microfluidic network that contains nanofabricated pillar structures.

The device has fluidic inputs for adding sample and reagents, removing waste, for carrying out DNA purification, and critically an integrated chamber for amplifying only the target DNA in the sample using the polymerase chain reaction (PCR) system. The chip also contains a wave guide for the fluorescence-based identification of the amplified DNA and thus the target microbe. The system works without manual intervention other than loading a droplet of sample into the detector.

“The average time required for DNA purification during these experiments was approximately 15 min, and when combined with real-time PCR analysis, this resulted in an average time to detection of 60 min,” Cady said. The system can detect as few as 40 B. anthracis cells. “Due to its small size and low power requirements, this system can be further developed as a truly portable, hand-held device,” the researcher said.

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