Scientists have found the carbon-based material graphene extremely useful in applications ranging from 3D printing to electronic devices to the creation of new materials. Now a team at Brown University has explored a rather novel use of the two-dimensional material—to help prevent someone from getting bitten by mosquitoes.
A team led by Robert Hurt, a professor in Brown’s School of Engineering, has developed fabrics that use graphene to repel mosquitoes in two distinct ways, researchers said.
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One is by acting as a barrier the pesky insects are unable to bite through, they said. The textile’s use of graphene also has proven in experiments to block chemical signals the pesky insects use to sense blood, which dims their urge to bite someone in the first place, researchers said.
Mosquitoes carry serious and sometimes-fatal diseases such as malaria and dengue fever in many parts of the world where medical care is limited, and can infect humans with their bite. This is why there is “a lot of interest in non-chemical mosquito bite protection,” Hurt said in a press statement.
His team already had been working on fabrics that integrate graphene as a barrier against toxic chemicals, which inspired them to explore new uses for the material in textiles, he said. “We thought maybe graphene could provide mosquito bite protection as well,” Hurt said in the statement.
Permission to Bite
To test if graphene could indeed repel mosquitoes, researchers recruited some brave test subjects who were willing to put their arms in a mosquito-filled enclosure with a small patch of skin exposed to disease-free mosquitoes for biting.
The team compared the number of bites participants received on their bare skin, on skin covered in cheesecloth, and on skin covered by a graphene oxide (GO) films sheathed in cheesecloth. GO is a derivative of graphene that can be made into films.
The mosquitoes all but ignored the graphene patch, leading researchers to believe that the material might not just have a physical, but also a chemical component to blocking the insects, they said.
Indeed, the skin covered by dry GO films didn’t get a single bite; participants wearing the cheesecloth and those without protection were not so lucky, sustaining multiple bites.
The Chemical Connection
After this initial test, researchers set out to see if their idea that there is a chemical barrier to mosquitoes in graphene was correct. They dabbed some human sweat onto the outside of a graphene barrier that had previously blocked the mosquitoes. This time, the insects showed as much interest in the area as they did to bare skin, researchers said.
Further tests confirmed that the graphene oxide could provide puncture resistance to the proboscis of mosquitoes that do the biting. However, it worked only when the material was dry; graphene saturated with water would offer little resistance, researchers found.
A workaround for this would be to use GO with a reduced oxygen content called rGO, which proved to be a barrier in both wet and dry conditions, they said.
The team published a paper on their findings in the journal Proceedings of the National Academy of Sciences.
Researchers next want to try to find a way to make GO water resistant as well by stabilizing it, as it has a key advantage over rGO when designing and developing mosquito-resistant clothing, which is the team’s ultimate aim, Hurt said.
“GO is breathable, meaning you can sweat through it, while rGO isn’t,” he said in the statement. “So our preferred embodiment of this technology would be to find a way to stabilize GO mechanically so that is remains strong when wet. This next step would give us the full benefits of breathability and bite protection.”
Elizabeth Montalbano is a freelance writer who has written about technology and culture for more than 20 years. She has lived and worked as a professional journalist in Phoenix, San Francisco and New York City. In her free time she enjoys surfing, traveling, music, yoga and cooking. She currently resides in a village on the southwest coast of Portugal.
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