22 September 2009

Portable "breathalyzer" for early diagnosis of lung cancer

Lung cancer is one of the most common oncological diseases, which is often diagnosed at late stages, which are practically untreatable due to metastases that have spread throughout the body. At the same time, lung cancer detected in time is treated successfully enough by removing the affected segment or the entire diseased lung. Scientists at the Israeli University of Technology in Haifa are working on creating a so-called "electronic nose", with unprecedented sensitivity detecting compounds contained in the air exhaled by lung cancer patients.

Earlier attempts to create such sensors looked promising enough, but the content of metabolic products specific to cancer cells in the exhaled air is so small that for the adequate operation of most similar sensors, their developers had to resort to various ways to increase the concentration of biomarkers.

In addition, the "breathalyzers" ("breathalyzer", from the English breath+analyzer) used for conducting similar tests are based on expensive methods for registering volatile compounds, such as the use of optical and acoustic detectors and mass spectrometry. Such systems are often quite large and untransportable.

The new sensor, created by Hossam Haick and his colleagues, is based on a matrix of gold nanoparticles that captures volatile organic compounds in their initial concentration at a humidity level characteristic of human respiration. Detectors based on gold nanoparticles promise to be small and inexpensive. The only point that caused difficulties was the search for an approach that would ensure the interaction of volatile compounds with gold nanoparticles.

To date, the authors are waiting for a patent for their invention and prefer not to disclose the details of its device. (The pictures shown here do not contain commercial secrets: on the left is an experimental sample of the device, on the right is a chemiresistor that changes electrical resistance when exposed to certain gases. "Breathalyzer" contains 9 such chemoresistors for detecting biomarkers of lung cancer in the exhaled air.)

Using their sensors, the authors analyzed the composition of exhaled air samples obtained from 40 healthy volunteers and 56 patients diagnosed with lung cancer, and developed a panel of biomarkers that allows us to reliably talk about the diagnosis of lung cancer. Repeated testing of the sensor after its adjustment to identify this complex of biomarkers showed its ability to distinguish the breathing of a healthy person from the breathing of a sick person with a high degree of reliability. Currently, the developers are testing their brainchild on a larger group of lung cancer patients at different stages of the disease. They believe that in 2-3 years they will be able to start conducting clinical trials of their breathalyzer.

The results of preliminary testing indicate that sensors based on gold nanoparticles allow not only differential diagnosis of various stages of lung cancer, but also to identify biomarker complexes characteristic of other diseases, such as liver failure. The developers even tested the device on colonies of cancer cells cultured in the laboratory. As a result, they identified a number of previously unknown volatile organic compounds associated with lung cancer. Currently, Haik is studying the metabolism of these compounds in the hope of obtaining new data that will improve the effectiveness of treatment of this fairly common disease.

The results of the work were published on August 30 in the online version of the journal Nature Nanotechnology.

Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of Technology Review: A More Sensitive Cancer Breathalyzer.


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