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Carbon Nanotubes Show Promise in Neural Engineering

Carbon nanotubes regulate excessive levels of chloride in nerve cells that occurs in epilepsy and chronic pain

2 min read
Carbon Nanotubes Show Promise in Neural Engineering
iStockphoto/Sebastian Kaulitzki

Research this summer out of Rice University showed that newly developed nanoparticles could be an effective emergency treatment for traumatic brain injuries.

Now researchers at Duke University have come up with an ultra-pure carbon nanotube—dubbed “few-walled carbon nanotubes” (a reference to the single-walled and multi-walled varieties)—that can regulate excessive levels of chloride in nerve cells.

The research, which was published in the Wiley journal Small (“Highly Conductive Carbon Nanotube Matrix Accelerates Developmental Chloride Extrusion in Central Nervous System Neurons by Increased Expression of Chloride Transporter KCC”), was specifically focused on the impact of carbon nanotubes on neurons.

Carbon nanotubes have been a source of great interest for neuroscientists because of the material’s electrical and mechanical properties. The hope has been that those properties could be exploited in creating devices that could interface with nervous tissue. However, previous experiments with neurons and carbon nanotubes came up with mixed results, largely due to the impurities within the carbon nanotubes.

The Duke team found that by employing the high purity few-walled carbon nanotubes that not only did the nanotubes not harm the nerve cells but they actually seemed to nourish the neurons.

"Previous studies have looked at the behavior of carbon nanotubes on neurons. However, the impurity in the nanotubes significantly affected the results. After we developed pure few-walled carbon nanotubes in our lab, we discovered that nanotubes actually accelerated the growth of the neuronal cells significantly," said Jie Liu, Professor of Chemistry at Duke University and senior author of the study, in a press release.

This accelerated growth of neuronal cells also can regulate chloride levels in the nerve cells. Excessive amounts of chloride can disrupt a neuron's proper function. Epilepsy, chronic pain, and traumatic brain injury all involve this kind of neural circuit damage.

The human body typically regulates these chloride levels by producing a protein known as KCC2 (chloride-extruding transporter, potassium chloride cotransporter 2). As nerve cells mature their KCC2 levels increase and their ability to regulate chloride levels becomes more powerful. By exposing the nerve cells to the carbon nanotubes the researchers found that neurons matured faster and the chloride levels in them dropped rapidly.

This research does not appear intended to serve as a treatment in itself but a step towards developing neural engineering devices that employ the carbon nanotubes.

Lead author Wolfgang Liedtke, associate professor of medicine and neurobiology at Duke, adds: "We hope that carbon nanotubes will work as well in injured nerves as they did in our study of developing neurons...The use of carbon nanotubes is just in its infancy, and we are excited to be part of a developing field with so much potential."

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Two Startups Are Bringing Fiber to the Processor

Avicena’s blue microLEDs are the dark horse in a race with Ayar Labs’ laser-based system

5 min read
Diffuse blue light shines from a patterned surface through a ring. A blue cable leads away from it.

Avicena’s microLED chiplets could one day link all the CPUs in a computer cluster together.

Avicena

If a CPU in Seoul sends a byte of data to a processor in Prague, the information covers most of the distance as light, zipping along with no resistance. But put both those processors on the same motherboard, and they’ll need to communicate over energy-sapping copper, which slow the communication speeds possible within computers. Two Silicon Valley startups, Avicena and Ayar Labs, are doing something about that longstanding limit. If they succeed in their attempts to finally bring optical fiber all the way to the processor, it might not just accelerate computing—it might also remake it.

Both companies are developing fiber-connected chiplets, small chips meant to share a high-bandwidth connection with CPUs and other data-hungry silicon in a shared package. They are each ramping up production in 2023, though it may be a couple of years before we see a computer on the market with either product.

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