. Scientific Frontline: Nanotubes as an optical stopwatch for the detection of messenger substances

Wednesday, April 12, 2023

Nanotubes as an optical stopwatch for the detection of messenger substances

Bochum research team: Linda Sistemich and Sebastian Kruß
Photo Credit: © RUB, Kramer

Carbon nanotubes not only lighten in the presence of dopamine, but also longer. The lighting duration can serve as a new measurement for the detection of messenger substances.

An interdisciplinary research team from Bochum and Duisburg has found a new way to detect the important messenger substance dopamine in the brain. The researchers used carbon nanotubes for this. In previous studies, the team led by Prof. Dr. Sebastian Kruß has already shown that the tubes light up in the presence of dopamine. Now the interdisciplinary group showed that the duration of the lighting also changes. "It is the first time that an important messenger like dopamine has been detected in this way," says Sebastian Kruß. “We are convinced that this will open up a new platform that will also enable better detection of other human messenger substances such as serotonin. "The work was a cooperation between Kruß’ two working groups in physical chemistry at the Ruhr University Bochum and the Fraunhofer Institute for Microelectronic Circuits and Systems (IMS).

The results are described by a team led by Linda Sistemich and Sebastian Kruß from the Ruhr University Bochum together with colleagues from the IMS and the University of Duisburg-Essen in the journal Angewandte Chemie - International Edition, published online on 9. March 2023.

With dopamine, the nanotubes not only shine brighter, but also longer

The sensors used are tubes made of carbon, which are 100,000 times thinner than human hair. If they are irradiated with visible light, they can emit light themselves in the near-infrared range, i.e. with a wavelength of 1,000 nanometers that is not visible to humans.

Previous studies led by Sebastian Kruß had shown that certain carbon nanotubes modified with biopolymers glow brighter when they come into contact with dopamine. In the new study, the researchers looked at how long it took for the nanotubes to send out this light in near infrared. For this, the scientists viewed the emitted light as individual light particles. With a stopwatch, they recorded the time it took the light particles from the time the nanotubes were irradiated until the light particles were emitted from the nanotubes. "To measure such a period of time, we need special stopwatches, because the emission of light is 100 million times faster than the blinking of a person," illustrates Linda Sistemich.

This so-called lifetime of light is characteristic of different substances and represents a more robust signal compared to brightness. While the brightness depends on how many layers of cells the light has to penetrate until it can be measured, the lifetime of the light remains unaffected. Because each individual light particle contains information about the lifetime, each measured particle is an increase in information, regardless of how many particles are measured. "Above all, this is advantageous, if you, like us, not only measures in simple aqueous solutions, but also in complicated environments such as in cell culture or in the organism itself”, explains Sebastian Kruß, who heads the functional interfaces and biosystems group at the Ruhr University and is a member of the Ruhr Explores Solvation Cluster of Excellence, short RESOLV, as well as in the Research Training Group International Graduate School of Neuroscience.

In the present work, the dopamine release of individual cells was recorded. The method would also be applicable to networks of cells or organisms.

Dopamine is a central messenger in the brain

The proven dopamine is an important messenger in the human brain through which the cells communicate with each other. Dopamine not only controls the reward center, but is also the driving force for movement, coordination, concentration and mental performance. If too little dopamine is released, there may be movement disorders and decreasing memory - symptoms that occur, for example, with Parkinson's disease.

Funding: The work was funded by the DFG, the RESOLV Cluster of Excellence and the Fraunhofer Attract program.

Published in journalAngewandte Chemie International Edition

Source/CreditRuhr University Bochum

Reference Number: chm041223_02

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