Coffee ground waste may soon be used to detect brain activity, according to a new study from the American Chemical Society. The experts have demonstrated that spent coffee grounds can be transformed into environmentally friendly electrode coatings for accessing sensitive neurochemistry measurements.
According to the researchers, coffee ground waste may ultimately help to detect minute levels of neurotransmitters in the brain.
Coffee grounds have previously been used to make supercapacitors for energy storage. Dr. Ashley Ross of the University of Cincinnati led the new study, which she says is the first example of residual coffee grounds being repurposed for biosensing applications.
“I saw papers about using spent grounds to produce porous carbon for energy storage, and I thought maybe we could use this conductive material in our neurochemistry detection work,” said Dr. Ross. “And I also thought this would be a good excuse to buy lots of coffee for the lab!”
Traditional microelectrodes are made from carbon fiber in a process that involves multiple steps and harsh chemicals. The goal of the ACS study is to fabricate entire electrodes with carbon from coffee grounds, which would be less expensive and much more energy efficient and eco-friendly.
“Neurotransmitters are chemical messengers released from nerve terminals between neuronal synapses to regulate brain function. Although very important, neurotransmission occurs in extremely low molar concentrations and are quite difficult to detect in-vivo. Fast-scan cyclic voltammetry (FSCV) is an electrochemical technique which enables real-time detection of neurotransmitters at carbon fiber microelectrodes in the brain,” wrote the researchers.
“Despite its utility, sensitive detection of low molar fluctuations in the brain remains difficult. Here, we are developing a carbon fiber modification method which uses porous carbon material made from waste coffee grounds for sensitive dopamine detection.”
The researchers heated used, dried coffee grounds in a tube furnace at about 1,300 degrees Fahrenheit. Next, they added the material to a potassium hydroxide solution to activate the carbon and open up holes in the structure. This mixture was heated again under nitrogen gas to remove any undesired byproducts.
“A solution containing 2 mg/mL porous carbon material was dissolved in water and dip coated onto the carbon fiber. The oxidative current was compared before and after electrode modification,” wrote the study authors.
“Overall, we demonstrate the use and synthesis of porous carbon material from waste coffee grounds to improve the sensitivity, limits of detection, and electron transfer rate for catecholamine detection with FSCV.”
According to the experts, the electrodes coated with the material reached oxidative current levels that were more than three times higher than carbon fibers in the presence of dopamine. The technique is fast enough to detect neurotransmitter release as quickly as it happens in the brain.
Dr. Ross predicts that making carbon fiber electrodes from scratch with porous carbon from coffee grounds will boost their neurochemical detection abilities because an even larger total surface area of the electrode will be exposed to adsorb the dopamine molecules.
The research will be presented at the spring meeting of the American Chemical Society (ACS). ACS Spring 2022.