The protagonists of the Crysis videogame series wear a “nanosuit”, which allows them to temporarily shield themselves in tough armour. In real life, humans have no such suits, but insects do. Japanese scientists have found a way of bestowing insects with a coat of armour that would allow them to survive the kind of empty vacuum they would encounter in space. And they’re calling it a nanosuit too.
Insects are unlikely to encounter vacuums in the wild, but in a lab, it’s another story. Vacuums are a standard part of ‘scanning electron microscopes’, which scientists use to capture jaw-dropping images of extremely small animals. The microscopes bombard the subjects with a focused beam of electrons and analyse how the beam interacts with their bodies. But they only works if the creature being photographed sits in a vacuum—otherwise, gas molecules would distort the electron beam and lead to fuzzy images.
Normally, if you put an insect in a vacuum, it dies. Its bodily fluids are rapidly sucked out of its body, which then collapses inwards into a crumpled husk. This is why SEMs are used on already dead specimens, which have been specially preserved. But Takahiko Hariyama from Hamamatsu University School of Medicine found that fruit fly maggots can survive these harsh conditions.
Bizarrely, Hariyama found that the microscope’s electron beam was somehow protecting the maggots. Indeed, if he turned the beam off before putting the insects in the vacuum chamber, their bodies crumpled in the usual horrific way.
Hariyama’s hunch was that the energetic electrons fuse molecules in the larvae’s cuticle (its outer layer) into a defensive coating, creating a hard but flexible barrier over their bodies. This barrier is just 50 to 100 nanometres (billionths of a metre) thick, but it’s enough to stop gases and liquids from leaving the larva’s body.
The maggots, and a few other insects, already have the right combination of molecules in their cuticles to make nanosuits. The team hasn’t identified the exact substances, but they seem to be amphiphilic—that is, they can dissolve in both water and fat.
Soaps and detergents are good examples of amphiphilic molecules, and Hariyama used these to create nanosuits for animals that can’t make them naturally. They dunked them in a non-toxic detergent called Tween-20, which is commonly used in biological experiments. They then exposed the coated creatures to plasma—ionised gas that, like an electron beam, has enough energy to fuse the detergent molecules into an artificial nanosuit.
This technique protected ants, mosquito larvae, honeybees, and fly maggots in an SEM’s vacuum chamber. It even worked on a soft-bodied flatworm. The animals survived their experience, and most of the mosquito larvae even transformed into adults later.
Only a few animals have been known to survive a vacuum, including a tick that waved hello from an SEM chamber, and cute pond creatures called tardigrades, which have survived in the vacuum of space. The tardigrades cheated—they first dried themselves into a dormant and far more durable state. If you took a normal hydrated tardigrade and put it in a vacuum, including in an SEM, it would die. But with a nanosuit, these hardy survivors could become even hardier.
This technique could allow scientists to regularly photograph living, moving animals under an SEM—something that been done only a few times before, and usually under a low vacuum. It means that the stunningly detailed images that these microscopes have captured might eventually give way to stunningly detailed movies, showing how the body parts of this miniscule menagerie move and interact.
More details about this study appear in my write-up at The Scientist.
Reference: Takaku, Suzuki, Ohta, Ishii, Muranaka, Shimomura & Hariyama. 2013. A thin polymer membrane, nano-suit, enhancing survival across the continuum between air and high vacuum. PNAS http://dx.doi.org/10.1073/pnas.1221341110