By Stephen Beech via SWNS
Lung cancer can be detected early using a potentially lifesaving new "ultrasensitive" breath test.
Chinese researchers have developed tiny sensors that in small-scale tests distinguished a key change in the chemistry of the breath of people with the disease.
They explained that exhaled breath contains chemical clues to what's going on inside the body - including diseases.
Devising ways to sense those compounds could help doctors provide early diagnoses - and improve patients' survival chances.
Study co-leader Professor Pingwei Liu, of Zhejiang University, said: "People breathe out many gases, such as water vapor and carbon dioxide, as well as other airborne compounds.
"Researchers have determined that declines in one exhaled chemical - isoprene - can indicate the presence of lung cancer.
"However, to detect such small shifts, a sensor would need to be highly sensitive, capable of detecting isoprene levels in the parts-per-billion (ppb) range.
"It would also need to differentiate isoprene from other volatile chemicals and withstand breath's natural humidity."
Previous attempts to engineer gas sensors with such characteristics have focused on metal oxides, including one particularly promising compound made with indium oxide.
The Chinese team set out to refine indium oxide-based sensors to detect isoprene at the level at which it naturally occurs in breath.
They developed a series of indium(III) oxide (In2O3)-based nanoflake sensors.
In experiments, they found one type - which they called Pt@InNiOx for the platinum (Pt), indium (In) and nickel (Ni) it contains - performed best.
The sensors were able to detect isoprene levels as low as 2 ppb, a sensitivity that far exceeded earlier prototypes.
They also responded to isoprene more than other volatile compounds commonly found in breath, according to findings published in the journal ACS Sensors.
The researchers' analysis of the nanoflakes' structure and electrochemical properties revealed that Pt nanoclusters uniformly anchored on the nanoflakes catalyzed the activation of isoprene sensing, leading to ultrasensitive performance.
To showcase the potential medical use of the sensors, the researchers incorporated the Pt@InNiOx nanoflakes into a portable sensing device.
They introduced into the device breath collected earlier from 13 people, five of whom had lung cancer.
The sensor detected isoprene levels lower than 40 ppb in samples from participants with cancer and more than 60 ppb from cancer-free participants.
Liu added: "This sensing technology could provide a breakthrough in non-invasive lung cancer screening and has the potential to improve outcomes and even save lives."