Research Team's Findings on Carbon Nanotubes Could Offer New Diabetes Test

Research from the University of Pittsburgh, led by Professor Alexander Star, suggests the possibility of a diabetes breathalyzer that could be used in place of blood testing.

The research, published in the May 21, 2013, edition of Journal of the American Chemical Society, used specially created carbon nanotubes to detect and quantify breath acetone and give an indication of blood glucose level.

“Our technology is based on a semiconducting material called ‘carbon nanotubes,’ which are coated with a material called ‘titania,’” Uri Green, PhD, a postdoctoral researcher working on the sensors, said in an e-mail to Pharmacy Times. “These hybrid tubes are very ‘sensitive’ to the extent that when you breathe on the device, it can sense how many acetone molecules are in your breath, which could give an indication of the glucose level in the blood.”

According to Dr. Green, the researchers take a baseline measurement of the device’s electrical conductance before introducing acetone. Once introduced, the acetone molecules interact with the sensors, changing the electrical conductivity. The change can be quantified, and is linearly proportional to the acetone concentration, Dr. Green said.

Titanium dioxide’s ability to detect acetone has been reported in other studies, he added. The hybrid nanotube design, created by study authors Dr. Mengning Ding and Dr. Alexander Star, was a particular achievement, Dr. Green noted.

Prior research with carbon nanotubes required higher concentration of acetone in order to detect it on the breath, the research stated. The hybrid tubes with titanium dioxide allowed for a greater interaction between the acetone and the sensors, lowering the amount needed to register acetone presence.

The researchers also performed cross-sensitivity tests with the gases typically present in human breath (oxygen, carbon dioxide, water vapor, and ethanol), as well as other breath biomarkers (ammonia, carbon monoxide, and nitrogen monoxide).

Most of the tests did not have a significant effect on the device. Researchers noted sensitivity to oxygen and water vapor; however, the sensor successfully detected 20 ppm of acetone vapor when air and high humidity were present.

The sensor showed a different response to breath acetone when ethanol vapors were also present, which could indicate a false-positive reading if a patient has consumed alcohol, the researchers noted.

The research hinges on established principles regarding breath and disease. Acetone odor on the breath and its correspondence with blood glucose is among the most well-known associations.

“The ‘smell’ of breath has been used in Eastern medicine for more than 3000 years,” Dr. Green said. “With the advancement of measuring technologies in sensitivity and selectivity, more specific breath gas species have been identified and established as biomarkers of a particular disease.

“Due to the difficulty of determining the concentration of acetone in breath quickly, precisely, and at low cost, only now is the technology catching up with the dream. The hybrid carbon nanotube technology is particularly suited to each of those factors,” Dr. Green added. He estimated the cost of creating the devices used in the research at approximately 30 cents per device. The researchers are currently investigating the device lifespan.

“Nanotube technology has applications in industry, biotechnology, energy, [and] medicine, just to name a few fields,” Dr. Green said. “Regarding the diabetes breath sensor specifically, we envision it becoming incorporated in smartphones or home kits with the hope that one day this will replace invasive blood testing.”