A new study, conducted by researchers at the Brown University now finds that multilayer graphene can provide a two-fold defence against mosquito bites acting as a mosquito repellent. Clothes that have been lined with graphene could offer protection from mosquitoes and help prevent the spread of deadly mosquito-borne diseases like dengue, malaria and chikungunya.
The findings were published in the journal Proceedings of the National Academy of Sciences.
Notably, the ultra-thin yet strong material acts as a physical barrier that mosquitoes cannot bite through.
The research further found that graphene blocks chemical signals in sweat that mosquitoes use to sense that a blood
meal is near and thus blunts their urge to bite, in the first place.
The findings thus suggest that clothing that has a graphene lining added to it would be an effective barrier against mosquitoes, which spread the deadly malaria bug among other diseases.
Study authors revealed that half the world's population is at risk of malaria transmission with an estimated 445,000 deaths in 2016.
Speaking about the same, Robert Hurt, a professor in Brown's School of Engineering and senior author of the paper said that mosquitoes are important vectors for disease all over the world, and "there's a lot of interest in non-chemical mosquito bite protection," adding that they had been working on fabrics that incorporate graphene as a barrier against toxic chemicals, and they started thinking about what else the approach might be good for.
"We thought maybe graphene could provide mosquito bite protection as well," he went on to add.
To test the material, they had participants placed their arms in a mosquito-filled enclosure so that only a small patch of their skin was available to the mosquitoes for biting.
Notably, the researchers then compared the number of bites participants received on their bare skin, on skin covered in cheesecloth and on skin covered by graphene oxide (GO) films sheathed in cheesecloth.
They were surprised to find that the mosquitoes completely changed their behaviour in the presence of the graphene-covered arm.
Researchers found that when the skin was covered by dry GO films, participants did not get a single bite, while bare and cheesecloth skin saw a lot of bites.
The study's lead author Cintia Castilho commented, "With the graphene, the mosquitoes weren't even landing on the skin patch - they just didn't seem to care."
While researchers had thought that graphene would act as a physical barrier to biting, but the experiments showed that there was a chemical barrier as well. Researchers then dabbed some human sweat outside of a graphene barrier and this caused mosquitoes to flock to the patch as they would flock to bare skin. Tests showed GO was puncture-resistant to mosquito bites but only when dry.
Notably, the second form of GO with reduced oxygen content called rGO was shown to provide a bite barrier when both wet and dry. However, that is not breathable and researchers are now trying to find a way of stabilising the GO so that it is tougher when wet. They are trying to create a material that gives the full benefit of breathability and bite protection.
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