Could graphene-lined clothing help prevent mosquito bites?

Graphene, a nanomaterial, has been the focus of attention for its potential uses in everything from solar cells to tennis rackets. But a new study by researchers at Brown University discovered a surprising new use of the material: prevention of mosquito bites.

In an article published in Proceedings of the National Academy of Sciences, researchers have shown that multilayer graphene can be a double defense against mosquito bites. The ultra-thin but strong material acts as a barrier that mosquitoes can not bite. At the same time, experiments have shown that graphene also blocks the chemical signals used by mosquitoes to detect the presence of a blood meal, thus lessening their urge to bite. The researchers said the results suggest that graphene-lined garments could be an effective barrier against mosquitoes.

"Mosquitoes are vectors of important diseases around the world, and protection against the bites of non-chemical mosquitoes is attracting a lot of interest," said Robert Hurt, a professor at the Brown's School of Engineering and author of the newspaper. "We had been working on fabrics that incorporated graphene as a barrier against toxic chemicals, and we started to think about how such an approach might be good, and we thought that graphene might also protect mosquito bites. "

To find out if this would work, the researchers recruited brave participants willing to do some mosquito bites in the name of science. The participants placed their arms in an enclosure filled with mosquitoes, so that the mosquitoes have access to only a small part of their skin to be able to be bitten. The mosquitoes were bred in the laboratory so that we can confirm that they are disease free.

The researchers compared the number of bites received by participants on their bare skin, covered with cheese skin and covered with graphene oxide (GO) film covered with cotton cloth. GO is a derivative of graphene that can be made into films large enough for large scale applications.

The researchers found that graphene was an effective deterrent. When dry GO films covered the skin, participants did not take a single bite, while bare skin covered with a cheese cloth was easily feasted. The researchers said that what was surprising was that the mosquitoes completely changed their behavior in the presence of the graphene-coated arm.

"With graphene, the mosquitoes did not even land on the skin patch – they just did not seem to care about it," said Cintia Castilho, Ph.D. student at Brown and the lead author of the study. "We had assumed that graphene would be a physical barrier to sting, thanks to the resistance to puncture, but when we saw these experiences, we started to think that it was also a problem. a chemical barrier preventing mosquitoes from detecting the presence of someone. "

To confirm the idea of ​​a chemical barrier, the researchers buffered some human sweat on the outside of a graphene barrier. Chemicals on the other side of the graphene, the mosquitoes flocked to the patch in the same way that they gathered to the bare skin.

Other experiments have shown that GO can also provide resistance to puncture, but not all the time. By using a small needle to replace the mosquito's proboscis, as well as computer simulations of the bite process, researchers have shown that mosquitoes simply can not generate enough strength to punch GO. But this only applied when the GO was dry. The simulations showed that GO would be vulnerable to perforation when it was saturated with water. And of course, experiments have shown that mosquitoes can sting through the wet GO. However, another form of oxygen-reduced GO (called rGO) has proven to be a wet and dry bite barrier.

The next step in the search would be to find a way to stabilize the GO so that it is harder when it gets wet, Hurt explains. Indeed, GO has a distinct advantage over rGO in wearable technology.

"GO is breathable, which means you can sweat through it, while rGO is not," said Hurt. "So, our favorite embodiment of this technology would be to find a way to stabilize GO GO so that it stays solid when it's wet. This next step would give us all the benefits of breathability and protection against bites. "

According to the researchers, the study suggests that well-designed graphene liners could be used for making protective clothing against mosquitoes.

Dong Li, Liu Muchun, Yue Liu and Huajian Gao also participated in the study.