Scientists in the US have made a system that rapidly detects both explosives and nerve agents, providing a simple yes-no response. The technique could replace two time-consuming tests that are currently used to assess these threats.

Joseph Wang and colleagues from the University of California, San Diego, combined their expertise in threat detection and electrochemical biosensors with the biocomputing experience of Evgeny Katz from Clarkson University, Potsdam, NY. The team produced an enzyme-based logic gate with the ability to simultaneously detect both nitroaromatic explosives and organophosphate nerve agents. 

The team fed 2,4,6-trinitrotoluene (TNT) and the nerve agent paraoxon into the system, in which a series of reactions catalysed by four enzymes takes place. The products of these reactions deplete hydrogen peroxide, which is used to indicate the presence of one or both threats. H₂O₂  levels exceeding a selected threshold indicate 'safe' situations, while  levels below the threshold value signify a 'hazardous' situation. 

Escalating threats of terrorist activity have led to urgent demands for innovative devices to provide on-site detection of chemical and biological agents, as well as explosive materials. The pressure is therefore on scientists to develop faster, more reliable and portable sensing technology to detect as many threats as possible and to alert the operator when a hazard has been encountered. 

'The ability to simultaneously measure different types of threats holds considerable promise for diverse security screening and surveillance applications,' says Wang. 'The new system is still at an early stage, but the goal is to provide an early and rapid warning for a potential threat and to follow this with identification of the specific hazard.' 

'This study shows that the interface of biology and computing delivers a new class of simple, low cost and reliable analytical devices,' says Lars Angenent, an expert in bioelectrochemical systems at Cornell University in the US. 'This is exciting innovative work and I'm looking forward to seeing other important applications for this technology,' he concludes. 

Emma Shiells 

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