A chemiluminescent sensor could be used to detect sarin with a glow response, say US scientists.

Eric Anslyn at the University of Texas at Austin, and colleagues have designed a chemiluminescent system that can detect an analogue of the nerve gas sarin, giving off a blue glow in its presence.  The analogue, diisopropyl fluorophosphonate or DFP, is in the same class of compounds as sarin, but is less toxic. The blue glow can be seen with the naked eye, which, Anslyn explained, is an advantage over established methods that require an external light source to view the results. 

Anslyn's system is based the chemiluminescence of oxalate esters.  This is a well-known and well-understood phenomenon, where oxalate esters produce chemiluminescence - luminescence as a result of a chemical reaction - in the presence of fluorescent dyes such as diphenylanthracene.

Anslyn's team modified this system by adding a super-nucleophile called an oximate.  This molecule reacts with the oxalate ester in the system, blocking the chemiluminescence reaction.  But when the sarin analogue DFP is present the oximate prefers to react with the phosphorous in the toxic molecule instead. This leaves the oxalate esters free to trigger the luminescence.

Work is underway to hone the system for practical use. 'The use of chemiluminescence is fascinating and has many possibilities, and we are just venturing into this area,' said Anslyn. 

Jon Silversides