Monday, December 22, 2008
Carbon nanotubes on and in the brain
Now that the embargo is lifted, I can talk about an interesting little ditty in Nature Nanotechnology on the use of carbon nanotubes as electrodes (kinda).
The miracle material that has been lauded as the solution to all the world's problems, from space elevators to unsightly scars, appears to integrate with neuronal membrane and conduct electricity with the greatest of ease. One interesting use being discussed is bridging between distal and proximal locations on a single neuron, which would effectively increase the response to inputs that would generally be more muffled by the distance from the soma.
Other possible uses include use as deep stimulating electrodes or electrode tips. Current DBS electrodes are huge compared to the areas they target, and damage is a very real possibility. On the topic of damage, carbon nanotubes are perhaps best known for their tensile strength and flexibility, making them perfect for navigating the densely packed, 3 pound lump of existence creating muck in the skull.
The paper is geared toward the interaction with the neuron's membrane. One thing that might shed some light on this interaction (my words, and I'm not a materials scientist, so i could be completely wrong on this) is a couple previous studies on nanotubes causing cancerous tumors. The effect was likened to asbestos, and injection caused significant inflammation. This could be due to these being shorter fragments or location of the injection, but the interaction with cellular membranes could also be key. To be fair, carbon nanotubes are also being touted as a means to precisely deliver anti-cancer treatments and drugs, so don't think I'm poo-pooing the research by bringing up the cancer link. I'm just pointing out the phenomenon because it might help explain or support the present paper.
It would be worth looking into the scale of the tubes, since a nanotube bridge would also be a cytoplasmic bridge (they are 'tubes'). How big that empty core is would be an important question, since other macromolecules and ions could be shuttled through the new proximal dendrite bypass. As a final thought, if the material itself is conductive, any passing active fiber could unintentionally influence the neuron. If carbon nanotubes are good conductors, then every segment becomes an en passant synapse without any neurotransmitter specificity. Maybe that matters, maybe not. I'm sure we'll see.
I did a quick once over of the paper, and might post a little more later, but I thought it was worth mentioning ASAP and in its own post. At this time of year, interesting papers can sneak by without much notice.