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| Inexpensive DNA-based biosensors may hold the key to stopping future terrorist attacks. |
Sensors often are the first line of defense against a chemical or biological attack, but up until now they've often relied on lasers to detect the minute quantities of substances needed to identify an attack quickly. That's made them expensive to build and difficult to maintain.
Now, researchers at the MITRE Corporation are developing genetically engineered bio-sensors, and while they're still a few years from the marketplace, these sensors promise to be even more accurate than today's detection devices - and they'll cost far less. That's because in the micro and nano-scale realms in which sensors operate, it's a lot easier to replicate and test DNA strands than it is to assemble mechanical or electronic parts. "Mass producing low-cost sensors will allow thousands of them to be deployed in large public areas that are subject to terrorist attack," said John Dileo who leads the MITRE effort in synthetic biology.
Bio-sensors could also be continually replaced with advanced versions designed to spot new threats as they emerge. Just as the human immune system can fine tune itself to detect any number of diseases, biologists working in this area believe that as they better understand how to assemble synthetic strands of DNA, they'll be able to design bio-sensors able to spot far more harmful substances than sensors employed today. Adding yet another protective layer, the sensors can be networked and overseen by intelligent computer algorithms that can quickly pinpoint the source of an attack, while also monitoring and predicting its spread.
MITRE is collaborating with an academic group led by Jean Peccoud, associate professor at the Virginia Bioinformatics Institute at Virginia Tech. They believe genetically engineered cells could function as intelligent threat detection devices - mini computers, if you will. "Cells possess innate abilities that make them ideal for environmental sensing applications," they explain in a paper entitled Co-Design in Synthetic Biology: A System-Level Analysis of the Development of an Environmental Sensing Device to be presented in January 2010 at the Pacific Symposium on Biocomputing. Specifically, cells are inherently able to detect small concentrations (parts per billion) of chemicals (or combinations of chemicals) in their environment and respond to it, usually with an amplified signal."
Genetically tweaked in just the right way, cells can even function in a sequential manner that's akin to how a computer linked to a mechanical sensor might operate. Peccoud's group identified three tasks their synthetic cell would need to perform in order to be an effective threat detector: an input layer, where a dangerous substance was introduced to the cell; the processing layer, where the substance was identified as being dangerous, and an output layer, where the cell was programmed to sound an alarm.
Even finer calibration is possible, Peccoud's group demonstrated, so the synthesized cell only emits a detectable optical signal when two or more suspicious substances are present. " Many substances are benign on their own, but potentially lethal if combined with other substances, " noted James Valdes, a US Army Senior Advisor for Biotechnology based at the Edgewood Chemical and Biological Center. " Mustard gas, for example, is made up of a compound called thiodiglycol, which is employed as a solvent in dyes, and phosphorous trichloride, a chemical often used to make organic phosphorous-containing products. "
Genetically-engineered material within the cell can be calibrated so that it will fail to respond if just one reactant is present but send a chemical message when it detects a pair of chemicals. In a manner similar to the way labs-on-a-chip today perform myriad tests at once, the cells chemical signals can be converted to electrical alarms when they are received then transmitted to a remote computer for analysis. "Just like electrical engineers are used to partition the design of electronic devices between hardware and software implementations, bioengineers need to learn how to partition their designs between hardware, software, and wetware," said Matthew Lux, one of the article's lead authors.
In the future, as terrorist groups become more and more adept at using readily purchasable substances to make WMDs, researchers may react to intelligence agency warnings of the latest potential threats and design bio-detectors ready to spot those threats should they occur. It's a scenario similar to how world health officials today order vaccines to combat the latest flu strains each year, and it may well become just as necessary and commonplace.
Mark Ingebretsen wrote regularly about homeland security issues as a healthcare and biotech columnist for the Online Wall Street Journal. As a regular contributor to IEEE Intelligent Systems magazine, he covers topics such as forensic data mining, pandemic disease detection and emergency response.
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