One of biology's most powerful tools has an ironic limitation: It can only look at dead things. The field emission scanning electron microscope—let's just call it FE-SEM from here on out, deal?—gave scientists their first views of DNA's double helix, helped them understand how various insects are engineered, and revealed the human immunodeficiency virus—the germ that causes AIDS. The FE-SEM is great for seeing teeny tiny things in realistic detail, but in order to bounce electrons off those surfaces and produce an image, it needs a vacuum. And for living things, vacuum = death.
Well, not anymore. A team of Japanese researchers has developed a chemical coating that allows them to put living things inside an FE-SEM's vacuum chamber without first sucking the life out of them. This would give scientists the ability to observe biological processes as they happen. The researchers call their invention a NanoSuit. Chemically similar to a food preservative, the NanoSuit shields a specimen in a nanometer-thin, flexible coat that keeps moisture in without disturbing the electron backscatter that the microscope picks up. In short, NanoSuit saves lives. Germ lives and bug lives, but still.
NanoSuit also saves a ton of prep time. For a non-NanoSuited specimen, researchers first have to use chemicals to kill and dry out the target. But that technique distorts the way a specimen's surface actually looks. Takahiko Hariyama, a biomemetics researcher at Hamamatsu University School of Medicine in Japan and co-inventor of the NanoSuit, says the coating allowed him to see for the first time an insect's body unsullied by chemicals and dehydration. After being dipped, dried, and placed in the vacuum chamber, the beetles, sand hoppers, and mosquito larvae used in this experiment continued to wriggle and paw under the microscope. "Insects have plenty of air in their bodies, and therefore can survive for an hour with active movement," Hariyama says. The coating is a solution of distilled water and Tween 20, a food preservative.
But FE-SEM didn't make its mark on biology by only looking at bugs. Electrons are capable of letting researchers see things down to the cellular level—at a scale of around 0.6 nanometers. Hariyama says this scale should be no problem for NanoSuit. If true, this would allow people to see, in three dimensions, everything from genome transcription to the progression of cancerous tissue. With the FM-SEM's level of resolution, these real-time views could lead to new and better treatments. And while Hariyama says he and his co-authors have seen good results using NanoSuit to monitor living cellular life in the lab, the paper describing those experiments is still undergoing peer review. Proof of concept, in other words, is still pending.
Check out the full video of a living Shining leaf beetle (Lilioceris merdigera) under an FE-SEM, wearing a coat of NanoSuit.
