Breath detector

University of Michigan researchers have devised a chemical method of detecting nitric oxide in exhaled breath.

As elevated concentrations of nitric oxide in breath are a tell-tale sign of many diseases, including lung cancer and tuberculosis, the development could prove useful in diagnosing illness and monitoring the effects of treatment.

To create their chemical detector, Anne McNeil, an assistant professor of chemistry, and Jing Chen, a graduate student, manufactured a material whose solubility changes in the presence of nitric oxide and oxygen.

'We took the approach of designing a molecule that has a shape that won't pack together with other, identical molecules very well, but will change into a more stackable shape on exposure to nitric oxide,' McNeil said. When the molecules stack together, gelation occurs.

As it is easy to see when the material stops flowing and turns into a gel, this method of nitric oxide detection is simpler and less subject to interpretation than other detection methods such as colourimetry and spectroscopy.

'I like the simplicity of not needing an instrument and just being able to flip the sample vial over and see if a gel has formed,' added McNeil.

At this point, the technique is not sensitive enough for clinical use, but McNeil and Chen are working to improve its sensitivity. They are also extending the approach to develop chemicals that could detect hazardous materials, such as explosives.

McNeil and Chen reported earlier stages of their work in a paper published in the Journal of the American Chemical Society in November 2008.