Materials science: A tissue-like sensor for the brain and gut

A tissue-mimicking sensor that can be used for real-time monitoring of neurotransmitter molecules in both the brain and gut is described in a paper published in Nature. The power of this sensor is illustrated by studying brain–gut communication in mice. The device may have the potential to perform biomolecular sensing in other soft organs across the body.

Neurotransmitters play essential roles in various processes and systems in the human body, and monitoring the dynamics of neurotransmitters is important for understanding the communications between neurons and their targets. But the tools for studying biochemical signalling in living animals and human bodies remain limited and underdeveloped. Current probes are usually rigid and brittle, leading to early device failure or severe inflammatory response, especially in organs that are constantly moving like the brain and gut.

To address this challenge, Zhenan Bao, Xiaoke Chen and colleagues designed a soft and stretchable graphene-based electrochemical sensor, termed “‘NeuroString’”, which can simultaneously and selectively sense multiple neurotransmitters in the brain and gut in real-time. The authors found that NeuroString can detect neurotransmitter signals for up to 16 weeks in mice, demonstrating exceptional stability for long-term neurochemical sensing. In a proof-of-principle experiment, the authors used the NeuroString sensors to measure changes in neurotransmitter concentrations in the brain and gut of a mouse after feeding it chocolate. Catecholamine and 5-HT (serotonin) are both important neurotransmitters involved in regulation of cognitive processes and gut function. They detected release of catecholamine in the brain after intake of chocolate within seconds, and an increase of 5-HT in the colon was observed after around 30–60 minutes, which is consistent with the typical transit time of food through the gastrointestinal tract. The result showed the potential of using NeuroString for understanding neurotransmitter dynamics and their roles in the brain–gut axis.

Further development is planned to enable NeuroString to detect different molecules with better selectivity. Combining its excellent biological compatibility and sensitivity, the NeuroString platform could be a powerful tool for studying the dynamics of various signalling biomolecules and electrophysiological signals throughout the body in primates, the authors conclude.