00 September 2009 The Hindu
Nanosensor Breathalyser for Diagnosing Lung Cancer
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 using a breath analyser containing gold nanoparticles.
A paper published online in the journal Nature Nanotechnology shows how easy it is to diagnose lung cancer. Lung cancer accounts for 28 per cent (1.3 million) of cancer-related deaths in the world.
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.
40 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 the samples.
The air from the bags was then 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. “There was no overlap [of the detectable compounds] of the lung cancer and healthy patterns,” the paper notes.
The gold-silicon sensors, when used in an array, were able to detect many volatile compounds. The team used conventional methods like gas chromatography/mass spectrometry to detect 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 optimise the sensors, demonstrating good agreement between patient and simulated breath samples,” the authors note in their paper. The gold circuits are much better than Dr. Haick’s carbon nanotubes used for diagnosing lung cancer.
The nanotubes have a major drawback — adequate pre-treatment of simulated breath samples is required.
The team realised something very important after they finished their paper. With this sensor patients were not required to avoid alcohol, coffee, tobacco, or food before tests, all of which had confounded previous devices.
The authors have already started a large-scale study to thoroughly probe if the sensors are able to pick up cancer in patients irrespective of diet and alcohol consumption, metabolic state and genetics. “The experiments are under way…and will be published elsewhere,” they note.
The authors are confident that their portable sensors that are inexpensive would be the best tool to diagnose lung cancer non-invasively. The sensors can also be reused.
“The potential exists for using the proposed technology to diagnose other conditions and diseases, which could mean additional cost reductions and enhanced opportunities to save lives,” the paper notes.
Source: The Hindu /...
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