Science

Natural treatment could make you almost invisible to mosquito bites

View 5 Images
The cellulose nano crystals could be applied as a transparent spray or gel to act as a "chemical camouflage"
The cellulose nano crystals could be applied as a transparent spray or gel to act as a "chemical camouflage"
Mosquitos are the deadliest animal on the planet
This illustration shows how the CNC gel blocks signals that attract bloodthirsty female mosquitoes
Daniel Voignac et al/PNAS Nexus
Hand testing setup and percentage of blood-fed females in cage with CNC–glycerol on hand and without CNC–glycerol on hand
Daniel Voignac et al/PNAS Nexus
The self-assembling nanocrystals form an incredibly sturdy barrier
Daniel Voignac et al/PNAS Nexus
View gallery - 5 images

Mosquitoes are responsible for around 350 million human illnesses every year, with the number sure to increase as climate change bolsters the disease-carrying insect's numbers. A recent study even showed how another human impact, light pollution, may be responsible for extending the mosquito blood-drawing season.

New research into bite-protection has taken a readily available natural molecule, cellulose, and manipulated it to produce a product that saw an 80% reduction in mosquito feeds on human skin.

Cellulose, which is cheaply and abundantly sourced from the likes of wood industry waste, plus local food and paper waste, assembles into nanocrystals when treated with sulfuric acid. These cellulose nanocrystals (CNCs) assemble as a strong but transparent barrier film.

Scientists found that when mixed with water and a small amount of glycerol, these CNCs could be applied to the skin in a spray or gel and block the mosquito’s ability to bite through it to draw blood.

The self-assembling nanocrystals form an incredibly sturdy barrier
Daniel Voignac et al/PNAS Nexus

Adult female mosquitoes need blood from humans or animals to produce eggs, so a large reduction in this food source, particularly in highly populated areas, could have a positive impact on controlling the insect’s numbers.

CNCs and the efficient barrier they form have been in development for a wide range of ‘green’ uses, such as in soundproofing, removing dye from textiles and making strong binders like superglue and composite materials as tough as bone.

In trials with live Aedes aegypti mosquitoes, lead researcher Daniel Voignac from The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem and colleagues tested CNC-treated and non-treated hands, exposing skin for 10 minutes inside an enclosed cage of mosquitoes that contained an average of 15 females.

The result was the thin film of CNC gel acting like a chemical camouflage, with a drop of 80% in bites compared to a hand exposed to the insects without the biomaterial barrier.

This illustration shows how the CNC gel blocks signals that attract bloodthirsty female mosquitoes
Daniel Voignac et al/PNAS Nexus

Further studies showed that the CNC coat also blocked the passage of ammonium hydroxide vapor – a common mosquito attractant – when it was applied to filter paper and exposed to the insects.

The widespread Ae. Aegypti and Ae. Albopictus species are vectors for more than 22 serious arboviruses, including dengue, chikungunya, Zika, Japanese encephalitis, Rift Valley fever, yellow fever and West Nile viruses.

While in a preliminary stage, the research shows promise for the development of cheap, transparent natural compounds that could block the emission of the skin's chemicals that alert female mosquitoes to a blood feast. Green, inexpensive and scalable, it has the potential to push back against the worldwide problem of mosquito-borne illness.

The research is published in the journal PNAS Nexus.

Source: The Hebrew University of Jerusalem

View gallery - 5 images
  • Facebook
  • Twitter
  • Flipboard
  • LinkedIn
8 comments
michael_dowling
If it doesn't smell like DEET,I am onboard with trying it!
Don Rathburn
Just use super glue or clear fingernail polish. The little devils won't be able to bite through those.
TechGazer
Maybe it is effective at blocking the volatile chemicals that attract the mosquitoes. However, applying it and sticking the arm in a case is not a fair test of how it works when you are active outdoors. How effective is it after an hour, or several hours, of normal outdoor activity?
Karmudjun
NIce article Bronwyn. It is a shame the source article did not discuss the drying effect of the CNC/indole/glycerin coating upon the skin. Only reference to drying and cracking was the pre-glycerin compound cracking on the skin. And the timeline for testing was too short to determine if the subjects could sweat or allow things to permeate through the barrier and start attracting the insects. Good to have another short term barrier for ourselves or our animals. I like DEET although "skin so soft" also seemed to work.
Aross
Hope they spend some time researching how to get this off of the skin without polluting an already over polluted world.
Jeff7
Lemon eucalyptus oil bug repellent has been tested by local consumer magazines to work as well as DEET. If you’re lucky enough to live in Oz or NZ you can buy it from Chemist Warehouse as BuggrOff (how very Australian - in the best way).
TpPa
It sounds like how it would feel on the skin would be enough for people not to use it. Then if gases can't get through it, I really doubt sweat will, that would make everyone sitting on the beach have heat stroke.
Kpar
So many unanswered questions. How long does it last, particularly on hot days or when the "protectee" is working and sweating? What are the ramifications of a coating on skin?