By sandwiching a biological molecule between sheets of graphene, researchers at the University of Illinois at Chicago have obtained atomic-level images of the molecule in its natural watery environment.
The results are published online in advance of print in the journal Advanced Materials.
The molecule, ferritin, is a highly conserved protein that regulates the levels of iron in animals and plants. Ferritin can sequester excess iron, which can be toxic, and release it when it is needed.
"We found a way to encapsulate a liquid sample in two very thin layers of graphene sheets of carbon that are only one atom thick," said Canhui Wang, UIC graduate student in physics and first author of the study.
Electron microscopes let researchers see at the level of individual atoms. But to do so they must put the samples in a vacuum, making it impossible to image biomolecules in water in their natural, functional state. Biological samples have usually been placed in a container called a "liquid stage," wedged between relatively thick windows of silicon nitrate.
Robert Klie, the senior investigator on the study, says the thin layers of graphene in the new system work better, being nearly transparent.
"It's like the difference between looking through Saran Wrap and thick crystal," said Klie, who is associate professor of physics and mechanical and industrial engineering at UIC.
Not only resolution improved compared to the liquid stage. The graphene sandwich also minimizes damage to the sample from radiation, said Wang.
According to Wang, some people have calculated that just to barely visualize a sample requires the equivalent of 10 times the radiation 30 meters away from a 10 megaton hydrogen bomb. "We often use an electron beam that is several orders of magnitude more intense in our experiments," he said.
Graphene has an extraordinarily high thermal and electro-conductivity, said Klee, and is
|Contact: Jeanne Galatzer-Levy|
University of Illinois at Chicago