How nanotubes, nanoparticles and antibodies are used to detect tiny amounts of fentanyl

A research team at Pitt led by Alexander Star, a chemistry professor in the Kenneth P. Dietrich School of Arts and Sciences, has developed a fentanyl sensor that is six orders of magnitude more sensitive than any electrochemical sensor for the drug reported in the past five years. The portable sensor can also tell the difference between fentanyl and other opioids.

Their work was published in the journal Small.

Fentanyl is a synthetic opioid and one of the main drivers in overdose deaths in the United States, Star said. It’s often mixed with other drugs, but because of its potency, it’s often present in such small amounts that it can be hard to detect.

Star’s sensor uses carbon nanotubes and gold nanoparticles to tell fentanyl apart from other opioids. The key to its groundbreaking sensitivity, however, is the incorporation of fentanyl antibodies. “We’re using nature’s invention, so to speak,” Star said. “That’s how we can reach these ultralow levels of detection.”

The sensor is a modified version of a COVID-19 sensor developed by Star’s research group in 2020. The COVID sensor is itself an adaptation of a THC breath test — similar to a Breathalyzer, but for marijuana — he developed in 2019.

At the core of each of these sensors is a chip with carbon nanotubes attached. Each tube is like a tiny wire that’s 100,000 times smaller than a human hair and great at conducting electricity.  Attached to the nanotubes are gold nanoparticles, each about 43 nanometers tall.

In practice, molecules of fentanyl bound to the nanoparticles, triggering a current that flowed through the nanotubes. Different substances created different currents; using machine learning, the sensor was able to identify a fentanyl molecule. It also had a 91% success rate when it came to telling fentanyl from other opioids, which is helpful when trying to determine if another drug has been tainted with fentanyl.