Can coffee grounds help with brainwave detection?

At work in the morning, there's nothing like a steaming glass of American style to start your day refreshed. Today, we have one more reason to love this drink. Recently, researchers reported a method of making coffee grounds into an environmentally friendly electrode coating and using it for neurochemical measurements, a material that could help scientists better control brain activity as well as detect trace amounts of neurotransmitters.

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The last "brilliance" of coffee grounds was still used to make porous carbon supercapacitors for energy storage. This time, coffee grounds play a role in biology. Ashley Ross' team, the study's principal investigator, demonstrated that carbon-coated electrodes in coffee grounds can detect trace amounts of biomolecules in vitro, which Ross believes is the first example of repurposing residual coffee grounds for biosensing applications.

Ross said: "I saw some papers on the use of waste coffee grounds to make porous carbon to store energy, and thought maybe we could use this conductive material in neurochemical detection work." It would also be a great excuse to buy plenty of coffee for the lab! Dr. Ross of the University of Cincinnati and several members of her team claim coffee lovers.

The traditional microelectrodes used by neuroscientists are typically made of carbon fibers tied together by thin and strong carbon chains, and the manufacturing process is arduous and expensive, involving multiple steps and overly irritating chemicals. Ultimately, Ross wanted to make the entire electrode out of carbon from coffee grounds because it was inexpensive and environmentally friendly. As a first step toward achieving this goal, the researchers used material from coffee grounds as a coating for traditional electrodes.

Carbon fibers and multi-empty carbon nanofibers under electron microscopes | References [2]

This initial challenge was initiated by Kamya Lapsley, then a summer student in Ross Lab and now an undergraduate at Kent State University. She and other members of the lab roast the used coffee grounds and heat them in a tube stove at temperatures of about 1300 degrees Fahrenheit. Next, they added the material to a potassium hydroxide solution to activate the carbon and open holes in its structure. The researchers then reheated the mixture under nitrogen to remove any unwanted by-products. What remains is a pitch-black slurry filled with particles of porous carbon. Finally, after diluting the resulting slurry with water, the researchers immersed a carbon fiber electrode in it to coat it with a layer of porous carbon that was 100 times thinner than the diameter of a human hair.

The researchers compared the performance of the coated and uncoated electrodes in sensing small amounts of the neurotransmitter dopamine using the rapid scanning cyclic voltammetry (FSCV). FSCV allows them to apply rapidly varying voltages to the electrodes to alternately oxidize and reduce dopamine. The technology can quickly detect the release of subsecond neurotransmitters as they occur in the brain. The researchers found that in the presence of dopamine, electrodes coated with porous carbon achieved oxidation current levels more than three times higher than bare carbon fibers, indicating that electrodes coated with porous carbon had a more sensitive surface for detecting dopamine. Ross said the porous structure not only allows more dopamine molecules to participate in the reaction due to the large surface area of the coating, but also temporarily traps dopamine molecules between the cracks in the electrode. These properties improve sensitivity and enable researchers to make faster measurements. The team is currently exploring how these porous coatings affect the time resolution of this technology.

Next, the team will use the porous carbon in the coffee grounds to make a carbon fiber electrode from scratch, which will give the entire electrode a uniform porosity, rather than just acting on the electrode surface. Ross predicts that this will further improve the neurochemical detection capabilities of the electrodes because more of the electrode's total surface area will be used to adsorb dopamine molecules. Ross also plans to test existing coated electrodes in the brains of live mice.

Ross also said there is no shortage of project materials in the lab because members of the lab love to drink coffee.

bibliography

[1] Society, A. C. (n.d.). Waste coffee grounds could someday help detect brain waves. Retrieved March 21, 2022, from https://phys.org/news/2022-03-coffee-grounds-brain.html

[2] Ostertag, B. J., Cryan, M. T., Serrano, J. M., Liu, G., & Ross, A. E. (2022). Porous Carbon Nanofiber-Modified Carbon Fiber Microelectrodes for Dopamine Detection. ACS Applied Nano Materials, 5(2), 2241–2249. https://doi.org/10.1021/acsanm.1c03933

Compiler: Zhang Mingyu

Edit: Crispy fish

Typography: Yin Ningliu

Image source: Pixabay

Research team

Corresponding author Ashley E. Ross, PhD: Assistant Professor, Department of Chemistry, University of Cincinnati, USA

First author Blaise J. Ostertag: PhD student in the Department of Chemistry, University of Cincinnati, USA

Thesis information

Published the journal ACS, an academic journal of the American Chemical Society

Published January 21, 2022

The paper is titled Poous Carbon Nanofiber-Modified Carbon Fiber Microelectrodesfor Dopamine Detection

(DOI:https://doi.org/10.1021/acsanm.1c03933)