Super-sensitive spray-on explosive detector makes great television

May 23, 2008

US scientists have designed a new spray-on explosive detector sensitive enough to detect just a billionth of a gram of explosive. After treatment the explosive glows blue under UV light, making it perfect for use in the field – or on CSI: Miami.

William Trogler and his team at the University of California, San Diego, made a silafluorene-fluorene copolymer to identify nitrogen-containing explosives. It is the first of its kind to act as a switchable sensor with picogram (10-15g) detection limits, and is reported in the Royal Society of Chemistry’s Journal of Materials Chemistry.

Trogler's polymer can detect explosives at much lower levels than existing systems because it detects particles instead of explosive vapours. In the team’s new method one can simply spray the polymer solution over the test area, let it dry, and shine UV light on it. Spots of explosive quench the fluorescent polymer and turn blue – this makes it quick and visually exciting enough to be featured on the hit US TV programme CSI: Miami.

The polymer is able to show the difference between nitrate esters, such as trinitroglycerin, and nitroaromatic explosives, such as TNT.

Initially, polymer-treated spots of both compounds appear blue under UV light, but after further exposure the trinitroglycerin spot fluoresces green-yellow whilst the TNT spot remains blue. This colour change is thought to be due to photooxidation of the fluorenyl groups of the polymer.

Trogler was surprised to find that adding a spirofluorene co-monomer gave the polymer a 100 per cent efficient conversion of UV light into fluorescence, describing this increase as dramatic. 'From a technology perspective, the most surprising thing was the ability to use photochemistry to attain a reasonably chemospecific turn-on sensor,' he says.

The technology is now being commercially produced by RedXDefense, a security company based in the US.

The team are currently working on a similar system to detect peroxide-based explosives and say they hope to be able to investigate perchlorates and organic nitrates too.

Original article: Sanchez and Trogler, J. Mater. Chem., 2008, DOI: 10.1039/b802623h

Source: Royal Society of Chemistry

Explore further: Engineer develops real-time listeria biosensor prototype

Related Stories

Ultra-sensitive polymer detects explosive devices

Jun 05, 2013

(Phys.org) —A chemical that's often the key ingredient in improvised explosive devices (IEDs) can be quickly and safely detected in trace amounts by a new polymer created by a team of Cornell chemists.

Recommended for you

Nearly indestructible virus yields tool to treat diseases

25 minutes ago

By unlocking the secrets of a bizarre virus that survives in nearly boiling acid, scientists at the University of Virginia School of Medicine have found a blueprint for battling human disease using DNA clad ...

DNA mutations get harder to hide

3 hours ago

Rice University researchers have developed a method to detect rare DNA mutations with an approach hundreds of times more powerful than current methods.

Use your smartphone for biosensing

5 hours ago

An Australian research team has shown that smartphones can be reconfigured as cost-effective, portable bioanalytical devices, with details reported in the latest edition of the Open Access Journal 'Sensors'.

Faster, portable microbial analysis in the field

May 25, 2015

Until recently, it took hours – sometimes days – to analyze biological samples after they were frozen in the field and brought back to the laboratory. But now there is a faster, cheaper and smaller way ...

User comments : 2

Adjust slider to filter visible comments by rank

Display comments: newest first

Pogsquog
not rated yet May 23, 2008
Sounds like a brilliant way to get false positives.
dirk_bruere
not rated yet May 23, 2008
So how does it react to ammonia in urine?

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.