Photonics Spectra - September 2009

NEWS
TECH
Baking powder or anthrax?
Ask the Ceeker

CHRISTCHURCH, New Zealand – These days, anyone who comes across a strange white powder might like to know – as quickly and as accurately as possible – whether it is benign baking powder or deadly anthrax.

The Ceeker can help.

Pronounced “seeker,” the handheld gadget was created by Veritide Ltd., which develops biological identification and detection devices. It analyzes a suspicious sample and, within minutes, can reveal whether it contains bacterial spores. First responders such as police and firefighters, HazMat personnel, airport security, postal workers and military units would benefit most from the tool because they are more likely than the general populace to encounter hazardous materials on the job.

“At the very beginning, when we came up with the technology … it was very clear to us … it was something that would help a lot of people,” said Lou Reinisch, professor of physics and head of the physical and Earth sciences department at Jacksonville State University in Alabama. Reinisch is the inventor of the technology behind the device.

Drs. Andrew Rudge (left), CEO of Veritide Ltd., and Lou Reinisch (right), inventor of the Ceeker’s optical technology with the device.

With a push of a button, Veritide Ltd.’s Ceeker can accurately analyze a sample in 10 minutes. Traditional methods involve sending the sample to a laboratory, where it takes two to three days before scientists can determine whether the substance is anthrax or not. Images courtesy of Veritide Ltd.

Singling out spores

With just a push of a button, operators can identify a substance. The equipment uses fluorescence – ultraviolet light near 350 nm – to measure instances of dipicol-inic acid (DPA), a chemical compound that makes up 5 to 15 percent of the dry weight of bacterial spores. “This particular compound is unique to all bacterial spores,” Reinisch said.

Both DPA and calcium-DPA (CaDPA) complex, which constitutes about 80 percent of DPA, can be identified with the UV light. However, both composites are weakly fluorescing, and photochemistry must be applied to verify the presence of hazardous matter. Because of this, a shorter wavelength of light, near 250 nm, is used to illuminate the sample, prompting photodissociation of a slight amount of DPA and CaDPA. The exposure causes the DPA to lose a carboxylic group and to

convert into picolinic acid – a more fluorescing fluorophore.

Another fluorescence test then is carried out at 350 nm. This time, the Ceeker’s software looks at and compares both results to determine whether DPA and picolinic acid are present. “This gives the absolute certainty that DPA was detected and indicates that bacterial spores are present,” Reinisch said.

Because there is no wet chemistry involved in the process, and no heat or ultrasound testing, the sample avoids damage, and examination can continue. The equipment also can be tested for additional substances without delay. Each result is stored for future reference, along with the equipment’s operational factors during testing. “All information is archived in the device and can be downloaded at a later date,” he said.

After a brief 10-minute analysis, a yes or no answer is displayed on an LCD screen positioned at the top of the device. Current methods involve sending the sample to a laboratory, which can take up to a few days for scientists to confirm the presence of toxins. The delay can negatively affect a business because it must be shut down during the investigation.

Nowhere to hide

During a two-week independent test run at Midwest Research Institute in Palm

Bay, Fla., the detector accurately identified 100 percent of bacterial spores and 95 percent of hoax substances. Veritide said that a sample size of only 3000 spores is required for an accurate readout, while other detectors require at least 10,000 to 10 million spores for a valid result.

“Our detection level is well below the estimated 10,000 spores (LD50) [lethal dose 50 percent] it takes to infect someone,” Reinisch said. Furthermore, the Ceeker can identify bacterial spores in wet or dry samples, even if the substance is mixed with contaminants such as dust or dirt.

He noted that anthrax threats or “white powder incidents” occur in the US at least 20,000 times a year – or about 55 per day. The Ceeker’s reliability and meticulousness may help to alleviate the threat in many of these situations by immediately informing first responders as to whether a substance is anthrax or not.

Veritide is working on incorporating the same technology to identify both Ricin toxin, a white powder or liquid protein extracted from castor beans, and Botulinum toxin, produced by the bacterium Clostridium botulinum. The two also are frequently used as biological weapons.