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Graphene Sandwich Enables Clear Images of Biomolecules

New way to prepare biomolecules for electron microscopy clears things up

2 min read
Graphene Sandwich Enables Clear Images of Biomolecules
Illustration: Celia Gorman; Image: iStockphoto

Electron microscopy and spectroscopy are great tools for peering into matter on the molecular scale. But they’re not terribly effective if that matter happens to be biological.

Researchers at the University of Illinois in Chicago (UIC) may have changed that with a novel use of graphene in which a biomolecule is sandwiched between two sheets of graphene, making it possible to create much higher resolution images than in previous methods.

“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, in a press release.

In the research, which was published in the journal Advanced Materials (“High-Resolution Electron Microscopy and Spectroscopy of Ferritin in Biocompatible Graphene Liquid Cells and Graphene Sandwiches”), the molecule ferritin was imaged. Ferritin is an iron-storage protein, and itself has been proposed for developing magnetic nanoparticles to enable forward osmosis for water purification.

Prior to this research, if you wanted to image a biomolecule like ferritin with an electron microscope, you would need to use a container known as a “liquid stage” that is wedged between two thick windows of silicon nitrate to protect the sample from the vacuum.

Robert Klie, the senior investigator on the study, likened the difference between the liquid stage approach and the graphene sandwich as “…the difference between looking through Saran Wrap and thick crystal.”

The better resolution produced by the graphene sandwich is not just because of graphene’s superior transparency. The graphene sandwich also provides better protection from the electron beam that is fired at a sample during microscopy. Wang says that some have calculated that to visualize a sample requires 10 times the amount of radiation one would be exposed to from a 10-megaton hydrogen bomb when standing just 30 meters away.

To mitigate the deleterious effect of the electron beam, most electron microscopes use a low-energy beam that results in a fuzzy picture that has to be corrected by imaging algorithms. Because of graphene’s high thermal and electrical conductivity the material removes both the heat and electrons generated by the beam as it passes through the sample. So higher energy electron beams can be used on the sample, resulting in higher resolution images.

In their experiments with the ferritin, the researchers were able to image for the first time iron oxide in the core of ferritin changing its electric charge, leading to the release of iron. The imaging of this process could lead to a better understanding of some human disorders.

“Defects in ferritin are associated with many diseases and disorders, but it has not been well understood how a dysfunctional ferritin works towards triggering life-threatening diseases in the brain and other parts of the human body,” said Tolou Shokuhfar, assistant professor of mechanical engineering-engineering mechanics at Michigan Technological University and adjunct professor of physics at UIC, in a press release.

Illustration: Celia Gorman; Image: iStockphoto

The Conversation (0)
Illustration showing an astronaut performing mechanical repairs to a satellite uses two extra mechanical arms that project from a backpack.

Extra limbs, controlled by wearable electrode patches that read and interpret neural signals from the user, could have innumerable uses, such as assisting on spacewalk missions to repair satellites.

Chris Philpot

What could you do with an extra limb? Consider a surgeon performing a delicate operation, one that needs her expertise and steady hands—all three of them. As her two biological hands manipulate surgical instruments, a third robotic limb that’s attached to her torso plays a supporting role. Or picture a construction worker who is thankful for his extra robotic hand as it braces the heavy beam he’s fastening into place with his other two hands. Imagine wearing an exoskeleton that would let you handle multiple objects simultaneously, like Spiderman’s Dr. Octopus. Or contemplate the out-there music a composer could write for a pianist who has 12 fingers to spread across the keyboard.

Such scenarios may seem like science fiction, but recent progress in robotics and neuroscience makes extra robotic limbs conceivable with today’s technology. Our research groups at Imperial College London and the University of Freiburg, in Germany, together with partners in the European project NIMA, are now working to figure out whether such augmentation can be realized in practice to extend human abilities. The main questions we’re tackling involve both neuroscience and neurotechnology: Is the human brain capable of controlling additional body parts as effectively as it controls biological parts? And if so, what neural signals can be used for this control?

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