Mastodon Scientific Frontline: New sensors allow the exact measurement of the messenger substance dopamine

Friday, May 27, 2022

New sensors allow the exact measurement of the messenger substance dopamine

Sebastian Kruss (right) and Björn Hill belong to the team that was able to measure the messenger substance dopamine directly.
Credit: RUB, Kramer

Carbon nanotubes shine brighter in the presence of the messenger. In this way, signals between nerve cells can be measured easily and precisely.

Dopamine is an important signaling molecule for nerve cells. So far, its concentration could not be determined spatially and temporally. Thanks to a new process, this is now possible: A research team from Bochum, Göttingen and Duisburg used modified carbon nanotubes that glow brighter in the presence of the messenger substance dopamine. With these sensors, the release of dopamine from nerve cells with a resolution that has not yet been achieved has been made visible. The researchers around Prof. Dr. Sebastian Kruss from the Physical Chemistry of the Ruhr University Bochum (RUB) and Dr. James Daniel and Prof. Dr. Nils Brose from the Max Planck Institute for Multidisciplinary Natural Sciences in Göttingen reports on this in the journal PNAS.

Fluorescence changes in the presence of dopamine

The messenger substance dopamine controls, among other things, the reward center of the brain. If this signal transmission no longer works, diseases such as Parkinson's can occur. In addition, the chemical signals are changed by drugs such as cocaine and play a role in addiction. "However, there was previously no method with which the dopamine signals could be made visible at the same time with high spatial and temporal resolution," explains Sebastian Kruss, head of the functional interfaces and biosystems group at the RUB and member of the Ruhr Explores Solvation Cluster of Excellence, in short RESOLV, and the Research Training Group International Graduate School of Neuroscience (IGSN).

This is where the new sensors come into play. They are based on very thin tubes made of carbon, about 10,000 times thinner than human hair. If you irradiate them with visible light, they then shine in the near infrared range with wavelengths of 1,000 nanometers and more. "This area of light is not visible to humans, but can penetrate deeper into tissue and thus provide better and sharper images than visible light," says Kruss. In addition, there are significantly fewer background signals in this area that can falsify the result.

"We have systematically modified this property by binding various short nucleic acid sequences to the carbon nanotubes in such a way that they change their fluorescence when they come into contact with defined molecules," explains Sebastian Kruss. His working group has succeeded in making carbon nanotubes tiny nanosensors, which, for example, bind specifically to dopamine and fluoresce more or less depending on the dopamine concentration. "It was immediately clear to us that such sensors would be interesting for neurobiology," says Kruss.

Paint healthy nerve cells with a sensor layer

To do this, however, the sensors must be brought close to functional neural networks. Dr. Sofia Elizarova and James Daniel from the Max Planck Institute for Multidisciplinary Natural Sciences in Göttingen developed cell culture conditions in which the nerve cells remain healthy and can be painted with an extremely thin layer of sensors. This enabled the researchers to make individual dopamine release events along the neuronal structures visible for the first time and to gain insights into the mechanisms of dopamine release.

Kruss, Elizarova and Daniel and are convinced of the potential of the new sensors: "They enable new insights into the plasticity and regulation of dopamine signals," says Sofia Eizarova. “In the long term, they could also make progress in treating diseases like Parkinson's possible. “In addition, other sensors are currently being developed with which other signal molecules can be made visible - right up to the identification of pathogens.

Source/Credit: Ruhr University Bochum

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