Glowing films reveal traces of explosives

May 23, 2008

New spray-on films developed by UC San Diego chemists will be the basis of portable devices that can quickly reveal trace amounts of nitrogen-based explosives.

Contaminated fingerprints leave dark shadows on the films, which glow blue under ultraviolet light. One of the films can distinguish between different classes of explosive chemicals, a property that could provide evidence to help solve a crime, or prevent one.

A recent episode of CSI: Miami featured the technology, which linked fingerprints left on a video camera to a bomb used in a bank heist, revealing the motive for the robbery. In real life, the security systems company RedXDefense has developed a portable kit based on the technology that security officers could use with minimal training.

Detection relies on fluorescent polymers developed at UCSD by chemistry and biochemistry professor William Trogler and graduate student Jason Sanchez. “It’s a very intuitive detection method that doesn’t require a scientist to run,” Trogler said.

Sanchez and Trogler describe the synthesis and properties of their polymers in a forthcoming issue of the Journal of Materials Chemistry.

The polymers emit blue light when excited by ultraviolet radiation. Nitrogen-based explosive chemicals such as TNT quench that glow by soaking up electrons.

Because the polymers fluoresce brightly, no special instruments are needed to read the results. Only a very thin film sprayed on a suspect surface is needed to reveal the presence of a dangerous chemical. A single layer of the polymer, about one thousandth of a gram, is enough to detect minute amounts of some explosives, as little as a few trillionths of a gram (picograms) on a surface a half-foot in diameter. Handling explosives can leave 1,000 times that quantity or more stuck to fingers or vehicles.

The films also adhere directly to potentially contaminated surfaces, making them more sensitive than previous methods, which rely on capturing molecules that escape into the air.

Detection can be fast, revealing incriminating fingerprints as soon as the solvents dry, within 30 seconds. Exposure to ultraviolet light for an minute or two alters one of the films so that traces a nitrate esters, a class chemicals that includes the highly explosive PTEN, begin to glow green. Traces of other classes of explosives, such as nitroaromatics like TNT, stay dark.

Trogler’s group is currently developing similar systems to detect explosives based on peroxides.

Source: University of California - San Diego

Explore further: The origins of handedness in life

add to favorites email to friend print save as pdf

Related Stories

Laser as sniffer dog for explosives

Nov 08, 2013

A new compact sensor system based on an LED pumped polymer laser detects explosive vapors quickly and sensitively. This is a promising approach for the detection of hazards, for instance in humanitarian land ...

Glass has potential to be stronger, researchers say

Sep 21, 2012

(Phys.org)—Glass is strong enough for so much: windshields, buildings and many other things that need to handle high stress without breaking. But scientists who look at the structure of glass strictly by ...

Recommended for you

The origins of handedness in life

14 hours ago

Handedness is a complicated business. To simply say life is left-handed doesn't even begin to capture the blooming hierarchy of binary refinements it continues to evolve. Over the years there have been numerous ...

Have our bodies held the key to new antibiotics all along?

17 hours ago

As the threat of antibiotic resistance grows, scientists are turning to the human body and the trillion or so bacteria that have colonized us—collectively called our microbiota—for new clues to fighting microbial infections. ...

Characterizing an important reactive intermediate

22 hours ago

An international group of researchers led by Dr. Warren E. Piers (University of Calgary) and Dr. Heikki M. Tuononen (University of Jyväskylä) has been able to isolate and characterize an important chemical ...

Surfaces that communicate in bio-chemical Braille

22 hours ago

A Braille-like method that enables medical implants to communicate with a patient's cells could help reduce biomedical and prosthetic device failure rates, according to University of Sydney researchers.

User comments : 0