New analytical technique for detecting liquid explosives

Published 16 October 2006

ASU professor set out to develop a more sensitive enzymatic detector for better management of diabetics, and realized that the technology may be used for quick and accurate detection of liquid explosives; and a good thing, too, as terrorists show a greater tendency to move away from commercial explosives toward home-made ones

The would-be London terrorists had a brilliant idea: Smuggle innocuous chemicals on board a plane, and then mix them while in flight into a potent explosive. They were thwarted this time around, but will security officers be able to thwart another group of terrorists next time? Science comes to the rescue, again. Professor Joe Wang, director of the Center for Biosensors and Bioelectronics at the Biodesign Institute at Arizona State University (ASU), has developed a highly sensitive technology which rapidly — that is, in about fifteen seconds — detects liquid peroxide explosives. The results are published in this week’s edition of The Analyst.

Wang, who serves as a faculty member with joint appointments in the Departments of Chemical Engineering in the Ira A. Fulton School of Engineering and Chemistry and Biochemistry in the College of Liberal Arts and Sciences, says that “Previously, there have been no effective sensing technologies that can detect these compounds in a rapid and sensitive manner, so this is an important first step in trying to stay ahead of the terrorists who are becoming increasingly sophisticated in their methods.” We had better stay one step ahead of the terrorists because, in the past few years, they have turned from high-grade commercial explosives toward improvised, homemade explosives which can be made from off-the-shelf products. Yes, U.K. security forces prevented the terrorists from using such devices in the travel plot of two months ago, but such devices were employed in the Madrid and London train bombings of 2004 and 2005, respectively.

Wang reached his explosive-detection idea by doing research on diabetes management. Wang has devoted more than twenty years to design tiny sensors for commercial products to aid diabetics. The diabetics detection technology he developed relies on an enzymatic test in which blood glucose is converted to a hydrogen peroxide byproduct and measured by an electrochemical sensor. His team of researchers was looking to make something like a hand-held glucose meter, but realized that they could apply their efforts toward the screening and detection of peroxide explosives.

For the more scientifically inclined: The sensitive assay Wang has developed can rapidly detect the two more common peroxide-based explosives, triacetone triperoxide (TATP) and hexamethylene triperoxide diamine (HMTD), in trace amounts down to the part per billion level. The approach irradiates these explosives with ultraviolet light, converting the TATP and HMTD into hydrogen peroxide. A UV lamp system provides results in five minutes, but the higher intensity laser irradiation greatly reduces the time down to about fifteen seconds. The key to the technical innovation was employing what Wang describes as an “artificial peroxidase” system, that is, a novel electrocatalyst that accelerates the electrochemical reaction of the liberated hydrogen peroxide.

Wang is now actively working with the Arizona Technology Enterprises (AzTE), the commercialization arm of ASU, to engage government and commercial partners to further develop the technology.

-read more in Donglai Lu, Avi Cagan, Rodrigo A. A. Munoz, Tanin Tangkuaram, and Joseph Wang, “Highly Sensitive Electrochemical Detection of Trace Liquid Peroxide Explosives at a Prussian-blue Artificial-Peroxidase Modified Electrode,” The Analyst , 12 October 2006 (sub. req.)