New Delhi: A steaming cup of joe is something many people consume to give their morning a quick boost. Now, researchers have found yet another reason to love coffee.
Scientists from the American Chemical Society (ACS) recently reported the first application of used coffee grounds in electrochemistry and neuroscience. Coffee grounds can be used as environmentally friendly electrode coatings for sensitive neurochemistry measurements, and could help scientists better understand brain activity and detect minute levels of neurotransmitters, according to the researchers from ACS. They will present their findings at the spring meeting of the ACS.
How Have The Researchers Used Coffee Waste?
Waste coffee grounds have also been used to make porous carbon supercapacitors for energy storage. A supercapacitor, like a battery, is a means to store and release energy. As part of the new research, scientists have taken recycled coffee waste in a more biological direction, a statement issued by ACS said. They have demonstrated that electrodes coated with carbon from coffee waste can detect trace levels of biomolecules in vitro (outside the living body). This is the first example of residual coffee grounds being repurposed for biosensing applications, according to Ashley Ross, principal investigator of the study. Biosensing is a detection of target molecules based on the principles used by a living system such as an immune system.
Quoting Ross, the statement said that she saw papers about using spent grounds to produce porous carbon for energy storage, and thought of the possibility of using the conductive material in neurochemistry detection work.
Neuroscientists use traditional microelectrodes which are made from carbon fibre. Fine, solid carbon strands bundled together form carbon fibre. The process of making carbon fibres is tedious and expensive, and involves several steps and harsh chemicals.
Ross’ aim is to fabricate electrodes with carbon from coffee grounds, the statement said. This is because this would be an inexpensive and environmentally friendly approach. The team, as a first step toward realising the goal, used coffee ground as a coating for conventional electrodes.
Coating Electrodes With Coffee Grounds
One of the researchers dried used coffee grounds and heated them in a tube furnace at about 1,300 degrees Fahrenheit. After that, they added the coffee grounds to a potassium hydroxide solution to activate the carbon and open up holes in the structure.
In order to remove undesired byproducts, the team heated the mixture under nitrogen gas. An inky slurry full of flecks of porous carbon was left. The researchers subsequently diluted the sludge with water, and dipped the carbon fibre electrodes into it to coat with a layer of porous carbon nearly a hundred times thinner than the diameter of a human hair.
Coating Electrodes With Coffee Enables Faster Detection Of Neurotransmitters
The scientists compared the performance of coated and uncoated electrodes for sensing small quantities of dopamine, a neurotransmitter, with fast-scan cyclic voltammetry, a electrochemical measurement technique used to measure changing concentrations of dopamine. It is fast enough to detect sub second neurotransmitter release, similar to what happens in the brain.
Using the fast-scan cyclic voltammetry technique, the researchers applied a rapidly varying voltage to the electrode to alternatively oxidise and reduce dopamine.
The scientists observed that electrodes coated with porous carbon reached oxidative current levels over three times higher than bare carbon fibres in the presence of dopamine. This indicated that the coated electrode offered a more sensitive surface for dopamine detection, according to ACS.
Due to the coating’s large surface area, the porous structure allows more dopamine molecules to participate in the reaction. Ross said that the structure also momentarily traps dopamine molecules in the crevices of the electrode.
The sensitivity of the electrochemical process is increased due to these properties. Also, the researchers could carry out faster measurements.
What Do The Researchers Aim To Do Next?
The team now aims to make carbon fibre electrodes from scratch with porous carbon from waste coffee grounds because this would give the electrodes uniform porosity not just on the surface, but also within.
According to Ross, this could boost their neurochemical detection abilities because an even larger total surface area of the electrode will be exposed to adsorb the dopamine molecules.
Ross also intends to put the current coffee-coated electrodes to the test in the brains of live rats.