The mosquito is the world’s most important vector for transmission of infectious diseases, and chemical agents currently used for bite prevention can have environmental or human health side effects.

However, now graphene-based materials are being developed for a variety of wearable technologies to provide advanced functions that include sensing; temperature regulation; chemical, mechanical, or radiative protection; or energy storage. It has been suggested that graphene films now may also offer an additional unanticipated function: mosquito bite protection for light, fiber-based fabrics. Currently being investigated is the fundamental interactions between graphene-based films and the globally important mosquito species, Aedes aegypti (yellow fever mosquito), through a combination of live mosquito experiments, needle penetration force measurements, and mathematical modeling of mechanical puncture phenomena.

The current results show that graphene or graphene oxide nanosheet films in the dry state are highly effective at suppressing mosquito biting behavior on live human skin. Surprisingly, behavioral assays indicate that the primary mechanism is not mechanical puncture resistance, but rather interference with host chemosensing. This interference is proposed to be a molecular barrier effect that prevents Aedes from detecting skin-associated molecular attractants trapped beneath the graphene films and thus prevents the initiation of biting behavior.

The molecular barrier effect can be circumvented by placing water or human sweat as molecular attractants on the top (external) film surface. In this scenario, pristine graphene films continue to protect through puncture resistance—a mechanical barrier effect—while graphene oxide films absorb the water and convert to mechanically soft hydrogels that become nonprotective.

You can read this study further at https://www.pnas.org/content/116/37/18304

Sourced: View ORCID Profile Cintia J. Castilho, Dong Li, Muchun Liu, Yue Liu,  View ORCID Profile Huajian Gao, and Robert H. Hurt
PNAS September 10, 2019 116 (37) 18304-18309; first published August 26, 2019 https://doi.org/10.1073/pnas.1906612116

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