Graphene-based fabrics could provide an effective new way to protect against mosquitoes according to Robert Hurt and colleagues at Brown University. Using live mosquitoes, the team showed that films of reduced graphene oxide (rGO) are bite-resistant and can block the chemicals that mosquitoes use to detect the presence of skin – even when the material is wet. The group’s insights could provide a basis for new skin coverings that prevent the spread of infectious diseases.
Every year hundreds of millions of people are infected with mosquito-borne diseases such as malaria, dengue and yellow fever – causing about one million deaths worldwide. Preventing mosquito bites therefore plays an important role in public health programmes in many countries.
In recent years, graphene-based materials have been proposed for a wide array of applications, including biomonitoring, sensors, and wearable electronics. Until now, however, protection from mosquito-borne diseases has remained almost entirely unexplored.
Mosquitoes can easily puncture through fabric and skin alike using the bundles of microneedles that comprise their feeding apparatus. They can also actively seek out skin by sensing signals from humans including increased carbon dioxide levels, humidity, temperature, and the chemicals and microbes present in sweat. Currently, techniques to inhibit these mechanisms include chemical repellents and protective clothing. However, none of these methods have yet proved effective in completely preventing mosquitoes from feeding.
Hurt and colleagues reckoned that graphene’s high mechanical strength, and its capabilities as a chemical barrier, make it well-suited for protecting skin against mosquito bites. To test this theory, the researchers exposed protected human skin to live Aedes aegypti mosquitoes in lab conditions. This species is widespread in warmer parts of the world and is known to spread disease.
They measured how biting frequency is reduced when the skin was protected by films of graphene oxide (GO). They also tested rGO, in which oxidized functional groups have been removed. The team also repeated the experiment when the materials were wet, and covered in human sweat. Finally, they supplemented these measurements with microneedle penetration force experiments and mathematical models.
Hurt’s team discovered that when dry, both GO and rGO were highly effective at suppressing biting. The materials blocked chemical signals from the skin from attracting mosquitoes and if the insects tried to bite, the materials were highly resistant against puncturing.
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When wet, however, the GO film transformed into a soft hydrogel that could be easily penetrated, rendering it ineffective when covered in sweat. On the other hand, the rGO film retained its structure when wet, meaning skin remained protected even when mosquitoes were attracted by sweat on the film’s external surface.
With further research, the team’s work could provide a basis for graphene-based wearable technologies with the potential to provide unprecedented degrees of protection against mosquito bites and infectious diseases.
The research is described in the Proceedings of the National Academy of Sciences.