It is not just alcohol that can be detected using a breath analyser. Scientists from the Technion-Israel Institute of Technology in Haifa have found a way to diagnose lung cancer from a person’s breath.

A paper published online in the journal Nature Nanotechnology shows how easy it is to diagnose lung cancer.

According to a news item in the journal Nature, the researchers led by Hossam Haick used gold nanopartciles coated with a thin layer of organic material to diagnose lung cancer.

Forty patients who had confirmed lung cancer and 56 healthy individuals were recruited for the trial. All the individuals were first asked to breathe deeply through a filter that purified the lungs. They were then asked to breathe into a bag. The air in the plastic bags served as samples.

The air from the bags was blown into the gold-silicon circuit. “The electrical resistance of the gold nanoparticles rose or fell depending on the presence or absence of certain compounds,” notes Nature.

Many studies have shown that several volatile organic compounds that are present in human breath can be used to detect lung cancer. While these volatile compounds are present in lower concentrations (1-20 parts per billion (ppb)) in the breath of healthy people, it tends to be present in elevated levels (10 to 100 ppb) in those with lung cancer.

The gold-silicon sensors when used in an array were able to detect many volatile compounds. In combination with conventional methods like microextraction and gas chromatography/mass spectrometry, the team detected 42 compounds that were found at elevated levels in lung cancer patients. The team finally zeroed in on four compounds.

“Four of these [compounds] were used to train and optimize the sensors, demonstrating good agreement between patient and simulated breath samples,” the authors note in their paper.

According to Nature, the gold circuits are much better than Dr. Haick’s carbon nanotubes used for diagnosing lung cancer. The nanotubes have a major drawback — it is too sensitive to water vapour, a major component in human breath.

The team realised something very important after they finished their paper. “Haick's team discovered a bonus: With gold, patients don't have to avoid alcohol, coffee, tobacco, or food before tests, all of which had confounded previous devices,” notes Nature.

The authors are confident that their sensors would be an inexpensive and non-invasive diagnostic tool to diagnose lung cancer. The sensors can also be reused.

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