Porterfield and McLamore's sensor exploits conductive carbon nanotubes and is only 2 micrometers in diameter, or about 50 times smaller than the diameter of a human hair. They also use an enzyme, called glutamate oxidase, on the end of the probe that reacts with glutamate to create hydrogen peroxide. The carbon nanotubes enhance the conductivity of the hydrogen peroxide, and a computer can calculate the movement of glutamate relative to the cell surface.
The sensor oscillates and samples the concentration activities of glutamate at various positions relative to the neurons in culture. Those measurements at different distances can tell researchers whether the glutamate is flowing back toward the neurons or dissipating in many directions.
Current sensor technology allows for sensing in vitro, but those probes are large and invasive, Porterfield said, and they don't measure the movement of the chemicals.
McLamore said the sensor also is valuable because it is able to hone in on only glutamate using just one probe and custom software that filters out variations in the signals that are read, which removes signal noise due to other compounds.
"There are many compounds present near the neurons which can potentially create noise, but this sensor should be selective for one compound. We filter out all of the background noise," McLamore said. "It's the same thing modern hearing aids do. They're filtering out ambient noises, and that's the same thing you get when you oscillate a biosensor."
The sensor also could be adapted to measure other chemicals by changing the enzyme used on its tip.
Rickus said the sensor's versatility would be valuable for understanding the effects of therapies for epilepsy, Parkinson's disease, damage caused by chemotherapy, memor
|Contact: Brian Wallheimer|