Blood-sucking insects like mosquitoes are among the most dangerous disease transmitters in the world. Vector-borne diseases, which include malaria, dengue fever, yellow fever and others, cause more than 700,000 deaths worldwide each year, accounting for more than 17% of all infectious disease globally.1
According to the World Health Organization, malaria alone, which is transmitted by the Anopheles mosquito, kills 400,000 people annually, most of them children under 5.2 In the U.S., mosquito bites can transmit viruses like West Nile, St. Louis encephalitis and La Crosse encephalitis, which in rare cases can be severe or deadly.3
Even in the best-case scenario — a mosquito bites you but no disease is transmitted — the bite can be painful and itchy, causing varying levels of annoyance depending on the severity of itching and the number of bites.
Mosquito bite prevention is therefore a key topic among researchers, and a nanomaterial known as graphene is emerging as a potential new player. However, as with most new technological innovations, there are risks involved.
What Is Graphene?
Graphene is a carbon-based nanomaterial that exhibits extraordinary properties.4 It’s made of two-dimensional carbon lattices, which are invisible to the naked eye. Yet, graphene is incredibly strong — showing about 10 times greater strength than steel sheets when it comes to penetration energy. Researchers confirmed graphene has “exceptional strength and stiffness” in response to miniaturized ballistic tests.5
Graphene, often described as a “wonder material,” is also an efficient conductor of heat and electricity and has antibacterial properties.6 David Bradley, writing in Materials Today, explained:7
“Graphene has become the focus of much research since, in 2004, Andre Geim and Konstantin Novoselov of the University of Manchester, England, found they could tear a strip off using nothing more sophisticated than sticky tape, a glass slide, and a pencil.
The material exists as standalone atomic monolayers of carbon arranged in the familiar hexagonal pattern of graphite that resembles chicken wire fencing, providing many a useful metaphor for a science media keen to discuss the substance. Graphene is transparent, flexible, very strong, and has already been used to create fast transistors.”
Graphene has been pegged for usage in a wide range of applications, including electronics (particularly in creating thin, flexible displays), improved energy storage (such as batteries), creating stronger and more conductive materials and as a new antibacterial agent for medical uses.8
But this is only the beginning. As noted in Nanoethics, “Whereas these applications are extraordinary enough, there are also expectations of even more revolutionary innovations not yet conceptualized but waiting for discovery in the future.”9 One of these may involve an innovative method of warding off mosquitoes.
Graphene May Help Prevent Mosquito Bites
Researchers from Brown University tested whether graphene could act as a nonchemical mosquito repellant. They had participants reach into a mosquito-filled box for five minutes, with their skin uncovered, covered only in cheesecloth (a penetrable fabric) or covered with graphene and then cheesecloth.
When the skin was uncovered or covered only in cheesecloth, the participants were bitten multiple times, ranging from five to 20 bites during the five-minute sessions. When graphene was used, however, no mosquito bites were received.
Initially, the researchers suspected that graphene would act as a mechanical barrier, preventing mosquitoes from penetrating the skin. But it turned out that mosquitoes also tended to avoid graphene-coated skin altogether, and if they did land on it, they didn’t stay long and didn’t attempt to bite.10 Lead study author Cintia Castillho, a Ph.D. student at Brown, said in a news release:11
“With the graphene, the mosquitoes weren’t even landing on the skin patch — they just didn’t seem to care. We had assumed that graphene would be a physical barrier to biting, through puncture resistance, but when we saw these experiments we started to think that it was also a chemical barrier that prevents mosquitoes from sensing that someone is there.”
Indeed, when the researchers put human sweat onto the outside of a graphene barrier, mosquitoes were drawn to the patch, which suggests the graphene acts as a sort of chemical barrier. Meanwhile, it also acts as a physical barrier, as mosquitoes can’t generate enough force to puncture the material.
One major caveat: this is only true when the graphene is dry. When the graphene barrier was wet, simulations of the mosquito bite process suggest the insects would be able to get through it. One form of graphene — graphene with reduced oxygen content, or rGO — however, was impenetrable whether dry or wet.12 The problem with rGO is that it’s not breathable, making it a less-than-desirable choice for use in clothing.
“GO [graphene] is breathable, meaning you can sweat through it, while rGO isn’t,” senior study author Robert Hurt said in a news release. “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.”13
Graphene Is Already Being Used in Clothing
While graphene-coated clothing has yet to reach the masses, in large part because it’s expensive, Vollebak released a graphene jacket in 2018. The experimental prototype — dubbed The Graphene Jacket 1 — sold out in five days, even with a $ 695 price tag. The “bionic clothing” was described as going where clothing has never gone before. According to Vollebak:14
“As physicists at the Max Planck Institute discovered, graphene challenges the fundamental laws of heat conduction, which means your jacket will not only conduct the heat from your body around itself to equalize your skin temperature and increase it, but the jacket can also theoretically store an unlimited amount of heat, which means it can work like a radiator.
And when clothing can start conducting heat and electricity all sorts of cool things can start happening. It means that over the next decade your clothing can start to become a platform for other innovations.”
The company later re-released the jacket, stating this would be “the second and final time” the jacket would be available “before we disappear back into R&D for the next 2+ years.”15 But before you rush to purchase your own “part-jacket, part-science experiment,” know there are serious questions about whether or not graphene use is safe.
Is Graphene Safe?
As is often the case with new technologies, graphene applications are advancing before adequate research into risks has been completed. Many uncertainties remain, and that’s part of the problem, but already some research has revealed cause for concern.
In 2011, for instance, researchers published a study expressing the possibility that graphene could be inhaled, posing risks to the respiratory system.16 Again in 2013, in a review of the potential environmental and health risks of graphene, researchers expressed concern, stating:17
“The results from this study indicate that graphene could exert a considerable toxicity and that considerable emission of graphene from electronic devices and composites are possible in the future. It is also suggested that graphene is both persistent and hydrophobic.
Although these results indicate that graphene may cause adverse environmental and health effects, the results foremost show that there are many risk-related knowledge gaps to be filled and that the emissions of graphene, the fate of graphene in the environment, and the toxicity of graphene should be further studied.”
It’s been suggested that graphene may be able to enter cells via “spontaneous membrane penetration,”18 and research is challenging, as not all graphene-based materials are the same. Some may have multiple layers, others only one, for instance, and the ratio of carbon to oxygen atoms may be different depending on the application. The length and width of layers may also differ.
“Depending on the combination of these three parameters, not only do completely different material properties result — the effects on humans and the environment also vary greatly. This makes simple, generally valid statements almost impossible,” Nanowerk News reported.19
Not Enough Is Known About Graphene to Accurately Gauge Risks
The Graphene Flagship of the European Commission, a joint research effort with more than 150 academic and industrial research groups in 23 countries, has a budget of $ 1 billion — aimed at taking graphene “from the realm of academic laboratories into European society in the space of 10 years.”20
In a Work Package Health and Environment report devoted to graphene’s risks to health and environment, it’s noted, “The small size and unique physico-chemical properties of graphene pose potential risks to the health of animals, humans and the environment.”21 The paper’s lead author, Bengt Fadeel, again noted in a news release that the substance’s biological effects vary widely:22
“One of the key messages is that this family of materials has varying properties, thus displaying varying biological effects. It is important to emphasize the need not only for a systematic analysis of well-characterized graphene-based materials, but also the importance of using standardised in vitro or in vivo assays for the safety assessment.”
The assessment reveals a number of potential effects, including “nuclear fragmentation, membrane damage, mitochondrial dysfunction and ROS production” in a cell suspension of a model seed plant23 and initiation of an immune response after being injected into the skin in an animal study.24
Potential reproductive and developmental effects were also noted, with researchers stating, “In addition to direct effects of GBMs [graphene-based materials] on reproductive and developmental systems, the indirect consequences of GBMs on maternal and placental tissues and the release of mediators deserves attention as the creation of a hostile environment in the womb may increase the risk for pregnancy complications and the development of diseases later in life.”25
Overall, the assessment concluded that there’s not enough information to accurately assess whether or not graphene — and its many variations — is safe:26
“The present overview of the literature has shown that while the hazard assessment of GBMs is coming of age, with ever increasing numbers of studies addressing the potential impact of GBMs on living systems, data gaps still remain, and this, therefore, precludes the prediction of toxicity based solely on material properties of GBMs.
Indeed, we have shown that for some selected end-points, one may begin to see a (predictable) pattern of effects … but it is also clear that the chemical space of graphene and its derivatives is yet to be fully explored.”
As is the case with other nanomaterials, the use of graphene presents exciting opportunities in many fields, not the least of which may be to prevent mosquito bites. But extreme caution is warranted in working with such an unprecedented material and attempting to produce it on a large scale before its effects are fully understood.
In the case of mosquitoes, there are other tried-and-true approaches you can use to avoid getting bitten. Wear long sleeves and pants if you know you’ll be outdoors in a mosquito-prone area and use natural insect repellants (not synthetic chemical versions), like cinnamon leaf oil, citronella essential oil or catnip oil, as necessary.
If mosquitoes are bothering you in your backyard, a house fan can keep them away while you’re outdoors, as can the strategic planting of marigolds, which mosquitoes tend to stay away from.