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 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.

“We found a way to encapsulate a liquid sample in two very thin layers of graphene..."Canhui Wang, UIC graduate student in physics

“It’s like the difference between looking through Saran Wrap and thick crystal,” said Klie, 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.

Instead of using a low-energy beam to minimize damage, which yields a fuzzy picture that must be refined using a mathematical algorithm, the scientists were able to use high energies to generate images of ferritin at atomic level resolution. This enabled them to see, in a single functioning molecule, that iron oxide in ferritin’s core changes its electrical charge, initiating the release of iron.

This insight into how the ferritin core handles iron may lead to a better understanding of what goes wrong in many human disorders, said Tolou Shokuhfar, professor of physics at UIC, the principal investigator of the study..

The graphene sandwich, said Klie, will now “open up analysis of biological and other difficult to image samples to almost anyone with an electron microscope.” In contrast, he said, the standard liquid stage requires a large upfront investment in equipment and expensive preparation of each sample.

With graphene, once the technique is mastered, preparation of samples can be done quickly and cheaply.

This story is reprinted from material from the University of Illinois at Chicago, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.