Carbon Nanotubes Capture Electrical Signals Between Neurons

Initial applications could be in brain mapping and someday lead to brain-computer interfaces

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Carbon Nanotubes Capture Electrical Signals Between Neurons

President Obama’s BRAIN initiative, which was launched back in April, may already have a new tool for mapping the human brain in its arsenal . Researchers at Duke University have used a carbon nanotube to capture electrical signals from individual neurons.

With a complete 3-D digital map of the human brain now available as part of the European Human Brain Project, brain research is gaining a lot of momentum. The carbon nanotube probe developed by the Duke team, which acts like a sort of harpoon, first spearing the neurons and then collecting the electrical signals they send to communicate with other neurons, is expected to provide a new level of insight into the human brain.

“To our knowledge, this is the first time scientists have used carbon nanotubes to record signals from individual neurons, what we call intracellular recordings, in brain slices or intact brains of vertebrates," said Bruce Donald, a professor of computer science and biochemistry at Duke University, in a press release.

The research (“Intracellular Neural Recording with Pure Carbon Nanotube Probes”), which was published in the journal PLoS ONE, overcame the shortcomings (literally) of other attempts to use carbon nanotubes (CNTs) as neuron probes. Previously, CNTs have proven to be too short or too thick for the job. But the Duke team was able to make their CNT probe one millimeter long (quite long for CNTs) and capable of monitoring the electrical signals between neurons more precisely than the glass or metallic electrodes that are typically used.

The researchers were able to achieve these unique CNT characteristics with a specially devised technique. They accumulated carbon nanotubes at the tip of a tungsten wire until the tubes took the shape of a needle-like probe. Next, they coated the probe with an insulating material and then removed the insulating material with a focused ion beam. This process of applying, then removing the insulating material gave the probe an extremely fine point.

"The results are a good proof of principle that carbon nanotubes could be used for studying signals from individual nerve cells," said Duke neurobiologist Richard Mooney, a study co-author, in press release. "If the technology continues to develop, it could be quite helpful for studying the brain."

While the researchers concede that more research needs to be done to improve the electrical recording capabilities of the probes—even as improvements are made to their geometry and the insulating layers—the Duke team has applied for a patent on the probe. The researchers expect that the technology could not only prove useful for mapping the brain but for creating brain-computer interfaces.

Photo: Inho Yoon and Bruce Donald, Duke

 

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A photo showing machinery in a lab

Foundries such as the Edinburgh Genome Foundry assemble fragments of synthetic DNA and send them to labs for testing in cells.

Edinburgh Genome Foundry, University of Edinburgh

In the next decade, medical science may finally advance cures for some of the most complex diseases that plague humanity. Many diseases are caused by mutations in the human genome, which can either be inherited from our parents (such as in cystic fibrosis), or acquired during life, such as most types of cancer. For some of these conditions, medical researchers have identified the exact mutations that lead to disease; but in many more, they're still seeking answers. And without understanding the cause of a problem, it's pretty tough to find a cure.

We believe that a key enabling technology in this quest is a computer-aided design (CAD) program for genome editing, which our organization is launching this week at the Genome Project-write (GP-write) conference.

With this CAD program, medical researchers will be able to quickly design hundreds of different genomes with any combination of mutations and send the genetic code to a company that manufactures strings of DNA. Those fragments of synthesized DNA can then be sent to a foundry for assembly, and finally to a lab where the designed genomes can be tested in cells. Based on how the cells grow, researchers can use the CAD program to iterate with a new batch of redesigned genomes, sharing data for collaborative efforts. Enabling fast redesign of thousands of variants can only be achieved through automation; at that scale, researchers just might identify the combinations of mutations that are causing genetic diseases. This is the first critical R&D step toward finding cures.

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