There is nothing like a steaming cup of Joe to give your morning a quick boost. Now there’s another reason to love the drink. Today, researchers report the first use of coffee grounds as environmentally friendly electrode coatings for sensitive neurochemical measurements. The material could eventually help scientists gain a better grasp on brain activity and detect minute levels of neurotransmitters.
The researchers will present their findings at the Spring Meeting of the American Chemical Society (ACS). ACS Spring 2022 is a hybrid meeting that takes place virtually and in person March 20-24, with on-demand access available March 21 – April 8.
Consumed coffee grounds were previously used to make porous carbon supercapacitors for energy storage. But now, new research led by Chief Investigator Ashley Ross, Ph.D., has taken recycled coffee waste in a different, more biological direction. They and their team have proven that electrodes coated with carbon from this waste can detect trace levels of biomolecules in vitro. According to Ross, this is the first example of residual coffee grounds being implemented for biosensing applications.
I have seen papers on the use of spent land to produce porous carbon for energy storage, and I thought we could use this conductive material in our neurochemistry detection work. And I also thought this would be a good excuse to buy a lot of coffee for the lab! “
Ashley Ross, Ph.D., Chief Investigator
Ross is at the University of Cincinnati, and several members of her team are self-professed coffee lovers.
The traditional microelectrodes that neuroscientists use are commonly made from carbon fiber -; fine, solid carbon strands bundled together. Doing so is typically a laborious and expensive process, involving many steps and heavy chemicals. Finally, Ross wants to manufacture whole electrodes with carbon for coffee reasons, because this kind of approach would be inexpensive and environmentally friendly. As a first step towards achieving this goal, the researchers adapted the material from the field as a coating for conventional electrodes.
Kamya Lapsley, who was a summer student at Ross’s lab and is currently a bachelor’s student at Kent State University, accepted this initial challenge. They and other members of the lab dried used coffee grounds and heated them in a raw furnace at about 1300 F. Besides, they added the material to a potassium iodide solution to activate the carbon and open holes in the structure. Then the researchers reheated the mixture under nitrogen gas to remove any unwanted by-products. What was left was an inkwell full of porous carbon stains. As a final step, the researchers diluted the mud with water, in which they tapped the carbon fiber electrodes to coat them with a layer of porous carbon almost a hundred times thinner than the diameter of a human hair.
The researchers compared the performance of coated and uncoated electrodes to sense small quantities of dopamine, a neurotransmitter, with fast-scanning cyclic voltammetry. Using this technique, they applied a rapidly varying voltage to the electrode to oxidize and reduce alternative dopamine. The technique is fast enough to detect a subsecond neurotransmitter release, just like happens in the brain. The researchers found that electrodes coated with porous carbon reached oxidative current levels about three times higher than blue carbon fiber in the presence of dopamine, proving that the coated electrode provides a more sensitive surface for dopamine detection. Not only does the porous structure allow more dopamine molecules to participate in the reaction due to the large surface area of the coating, it also currently traps dopamine molecules in the gaps of the electrode, Ross says. These properties increase sensitivity and allow researchers to perform faster measurements. The group is now exploring how these porous coatings affect the temporary dissolution of the technique.
Next, the team will make carbon fiber electrodes from zero with porous carbon from waste coffee grounds, giving the electrodes uniform porosity not only on the surface, but also through and through. Ross predicts that this will strengthen their neurochemical detection capabilities, as an even larger total surface area of the electrode will be exposed to adsorb the dopamine molecules. At the same time, Ross plans to test the current coffee-coated electrodes in the brains of live rats.
In the meantime, there is no shortage of start-up materials to carry out the next stages of the project, as the whole lab seems to love their brew. “Degree students have provided quite a lot of coffee grounds -; more than we’ll ever need,” Ross says. “My whole lab really likes this project.”
Source:
American Chemical Society
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