Scientists have developed highly sensitive nanosensors that detect subtle changes in breath chemistry. They specifically target a decrease in isoprene levels, a potential biomarker for lung cancer. By accurately measuring these changes, these sensors could lead to earlier diagnosis and improved treatment outcomes for lung cancer patients. The study was published in the journal ACS Sensors.
Image Credit: Yurchanka Siarhei/Shutterstock.com
Exhaled breath carries chemical indicators of internal bodily processes, including markers of diseases like lung cancer. Developing methods to detect these compounds could aid doctors in making early diagnoses and enhancing patient outcomes. Researchers created ultrasensitive nanoscale sensors that, in small-scale tests, identified a distinct chemical change in the breath of individuals with lung cancer. November is recognized as Lung Cancer Awareness Month.
Humans exhale various gases, including water vapor, carbon dioxide, and other airborne compounds. Researchers have found that reduced levels of one particular exhaled compound, isoprene, can signal lung cancer. Detecting such subtle changes requires a highly sensitive sensor capable of identifying isoprene concentrations at parts-per-billion (ppb) levels, distinguishing it from other volatile chemicals, and tolerating the natural humidity of breath.
Previous efforts to design gas sensors with these capabilities have often used metal oxides, including a promising compound made from indium oxide. A team led by Pingwei Liu and Qingyue Wang aimed to optimize indium oxide-based sensors to detect naturally occurring isoprene levels in the breath.
The researchers created a series of indium(III) oxide (In₂O₃)-based nanoflake sensors. In their experiments, they identified one type—named Pt@InNiOx, for its platinum (Pt), indium (In), and nickel (Ni) components—that demonstrated the best performance. These Pt@InNiOx sensors:
- Detected isoprene concentrations as low as 2 ppb, achieving a sensitivity significantly higher than previous sensors.
- Showed a stronger response to isoprene over other common volatile compounds in breath.
- Maintained consistent performance across nine simulated uses.
Importantly, the authors’ real-time analysis of the nanoflakes’ structure and electrochemical properties showed that Pt nanoclusters, uniformly anchored on the nanoflakes, catalyzed isoprene activation, resulting in the sensor’s ultrasensitive performance.
To demonstrate the potential medical application of these sensors, the researchers integrated the Pt@InNiOx nanoflakes into a portable device. Using this device, they analyzed breath samples collected earlier from 13 individuals, including five with lung cancer.
The device detected isoprene levels below 40 ppb in samples from participants with cancer, compared to over 60 ppb in those without cancer. According to the researchers, this technology could significantly advance non-invasive lung cancer screening, potentially improving outcomes and saving lives.
The study was funded by the National Natural Science Foundation of China, China’s State Key Laboratory of Chemical Engineering, the State Key Laboratory of Electrical Insulation and Power Equipment, the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering, the National Key Research and Development Program of China-Young Scientists, the Research Funds of the Institute of Zhejiang University-Quzhou, and the Science and Technology Program of the Institute of Zhejiang University-Quzhou.
Journal Reference:
Cheng, Y., et al. (2024) Ultrasensitive In2O3-Based Nanoflakes for Lung Cancer Diagnosis and the Sensing Mechanism Investigated by Operando Spectroscopy. ACS Sensors. doi.org/10.1021/acssensors.4c01298.