Handheld Sensor Could Put Biothreat Detection Capability in First Responders' HandsApril 2012
Topics: Emergency Preparedness and Response, Sensor Technology
Processing incoming mail at a busy office, a worker slices open an ordinary-looking envelope. He removes a folded sheet of paper and with it a dusting of coarse tan-colored powder. The letter's handwritten message reads, "You cannot stop us. We have this anthrax. Are you afraid?"
Is it real—or a hoax? Skin exposure to Bacillus anthracis, the agent that causes anthrax, can result in lesions. Inhaled anthrax spores travel through the body's lymphatic system and can trigger internal bleeding, severe damage to major organs, and often, death.
Identifying the bacteria is expensive, time consuming, and potentially dangerous. However, a portable detection system called BioFlow, under development in MITRE's Bio-Nano Lab, could help an emergency response team identify the bacteria on site—saving time, money, and possibly lives.
"These portable detectors could become as common as automated external defibrillators among first responders' tool kits," says MITRE's Russell Graef, a senior artificial intelligence engineer who has led the project under MITRE's independent research program. He has demonstrated the concept of BioFlow for several MITRE government sponsors, including the Departments of Defense and Homeland Security, which have expressed interest in learning more.
Laboratory-Quality Results in the Field
BioFlow combines existing technology and sampling techniques to identify a variety of targets—from bacteria and viruses to clinical markers such as thyroid stimulating hormone (TSH). It could identify them in a range of samples, including water, soil, blood, or urine. The goal of Graef's continued research is development of a detector—a self-contained, reusable device that is easy to operate, quickly delivers accurate and reproducible results, and costs substantially less than a more sophisticated lab-based system.
The BioFlow process relies on antibody-coated magnetic microspheres to extract and identify specific targets, such as bacteria that cause illness or hormones present during a heart attack. Currently, a sample needs to be tested in a lab, where a technician exposes the target sample to these microspheres, each smaller than the width of a human hair. Each antibody has a unique partner—specific bacteria, hormones, or viruses, for example—with which it will couple. In the presence of that specific partner, coupling takes place. A device in the lab then conveys the microspheres one by one through a laser reader that identifies which spheres have reacted with the sample.
This process, called "flow cytometry," has been used since the 1950s to count small particles—cells, microspheres, even chromosomes. In its research, MITRE uses a type of flow cytometry technology that the Luminex Corporation of Austin, Texas, developed about 15 years ago specifically for pairing antibody-coated microspheres. The equipment remains so sensitive that moving it—even within the laboratory itself—can cause a malfunction. The testing sample also must travel intact from the field to the lab, which can cost valuable time.
Reusable, Affordable, and Fast
Graef, a molecular biologist, envisioned a process that brings the sensor to the sample. "We know our sponsors have specific challenges, such as on-site bio-threat analysis, and we're helping to address that."
At a sponsor meeting with Graef and others in 2010, members of bio-weapon treaty verification teams working outside the United States expressed a similar need. Their job is to gather samples of soil and other media from the world's trouble spots for testing, but then they must pack the samples and ship them to U.S. labs for analysis. "They told me, 'We don't want to have to bring stuff back,'" he says.
Graef had been conducting research on commercially available sensors on his own and realized that each had significant limitations. At about the same time, Graef attended a presentation at MITRE's McLean campus in which Peter Kiesel, principal scientist, and Noble Johnson, manager of the optoelectronics group at the Palo Alto (Calif.) Research Center (PARC), described technology they were developing, including an affordable hand-held sensor for use in resource limited settings, such as developing countries. Since then, Graef and the PARC team have been collaborating in the effort.
"It became apparent we could extend the technology from a basic 'swipe and scan' test to something that would be much more useful from a technology standpoint," Graef says. The project's goal is to marry the extraction process with the PARC sensor design to develop a rugged, deployable device—about the size of a brick—as sensitive as the lab-based system.
Ultimately, anyone with basic training—from a first responder or medical technician to a field scientist—could use the device, whether identifying toxins in soil or E. coli in spinach, regardless of the contamination source. "It could be intentional or accidental contamination," Graef says.
The MITRE-PARC team is also working to make this sophisticated technology affordable. "The real cost savings will be in the re-use of the system and the number of samples a customer runs using it," Graef says. "It's not going to do a high through-put level of screening, as a lab would do, but it could process two or three samples in 10 to 20 minutes for near real-time screening, and in that case it could be very affordable to use. The cost savings is in the fast turnaround time—being able to perform the analysis on site, rather than shipping the sample to a lab and awaiting results."
Currently, the BioFlow team is developing a multi-target assay—or microsphere set—that will test for agents including anthrax, influenza A, staphylococcal enterotoxin B (SEB), and TSH. Microsphere sets themselves would be in cartridges, following the same concept used for ink in office printers. BioFlow users would switch out the microsphere sets depending on the target assay, to replace used microspheres, or to update assays as new antibodies become available.
Helping Those Who Help Themselves
This system has its limitations, Graef notes. "You have to know what you want to test for. The system cannot identify a true unknown, only what the microspheres are designed to detect. For example, a microsphere set designed to detect clinical markers—such as the hormones that indicate heart attack—won't identify bio-threat toxins such as SEB."
The team is also studying how factors such as heat or moisture could affect samples that the BioFlow tests and whether the device would be sensitive enough to detect samples that had degraded.
While it remains in development, Graef says sponsors want to know more. "We've been positively received. People want to know how soon we'll have a prototype."
—by Molly Manchenton