The activity of neurotransmitters — chemical messengers that nerve cells use to communicate — in the bodies of living animals might be measured using NeuroString, a soft, flexible sensor.
This new sensor was detailed in the publication “A tissue-like neurotransmitter sensor for the brain and stomach,” which was published in Nature. It could be useful in Parkinson’s disease research. Nerve cells emit neurotransmitters, which are substances that send signals to other nerves and sections of the body. These molecules are important in both health and sickness. Parkinson’s disease, for example, is caused by the loss and malfunctioning of cells in the brain that produce the neurotransmitter dopamine.
NeuroString is a “soft electronic” developed to detect dopamine and serotonin, two neurotransmitters. “My group has been making soft electronics for quite some time,” said Zhenan Bao, PhD, a professor at Stanford and the paper’s senior author. The new sensor is constructed of graphene, an extraordinarily thin type of carbon. The team used a laser to engrave a “hairy entangled network” of graphene onto a plastic with nanoparticles to improve the detection of neurotransmitters. Finally, a rubber matrix is used to embed the network.
“Graphene itself is not very stretchable but if it is entangled as a mesh and embedded in a rubber, then it becomes stretchable,” said Dr Jinxing Li, the study’s first author. NeuroString may be placed in the body of a living animal without causing significant tissue damage since it is soft and flexible — even when the surrounding tissue is moving.
To test the sensor, the researchers ran a series of proof-of-concept experiments. The device may be put in the brain or stomach of mice without affecting their behaviour or bowel movements, according to the findings. In a series of experiments, the sensor was able to precisely detect variations in dopamine and serotonin levels in the stomachs and brains of mice and pigs. Giving chocolate to mice, for example, resulted in higher dopamine levels in the brain and serotonin levels in the gut, as expected.
“We now have the tool to allow real-time monitoring of the impact of those drugs on serotonin fluctuation in both the brain and gut in mouse models,” said study co-author Xiaoke Chen, PhD, a professor at Stanford. “Now that we’ve shown that the probe works, there’s a very long list of biological questions we want to tackle.”