March 29, 2004

Buckyball Brouhaha

The recent reports on the toxicity of buckyballs leave us, as ususal, with more questions than answers. It is important to address, study, and explain the results in detail without jumping to conclusions. Our scientific curiosity was piqued in a number of areas.

How exactly were the buckyballs stabilized in the media (water?), because C60 is practically insoluble in water? New Scientist says 'waterborne fullerenes" while Eureka Alert reports "a form of water soluble C60," while the Washington Post refers to microscopic, manufactured "nanoparticles"

More importantly, how does the process work? What are the mechanisms of uptake by the body? What are the mechanisms of interaction with the cell surface, interior and the exact effect on the cell.

It is important to understand this, as biochemical processes are significantly dependent on surface chemistry. The outside coating of a chemical or biological entity will determine in most cases how it interacts with living cells. The coating can be as important as the content, sometimes even more. Solubility, size and stability are also other key factors. That's one of the reasons large pharmaceutical companies spend so much money on the R&D of drug delivery forms, and why nanotechnology is being applied extensively in this area.

While many may be jumping to the immediate conclusion that this is bad news, the preliminary results imply quite an important discovery. Many highly toxic substances can form the basis of drugs that save hundreds of thousands of lives, once the mechanisms of interaction are well known, controlled and used for our benefit. Highly toxic and dangerous compounds are used in many industries and most labs. Taxol for example, derived from Yew Trees forms the basis for many cancer drugs. Hydrofluoric acid is no less useful because it is corrosive, and gasoline, as everyone knows, is extremely flammable. The point is that we know that these substances are dangerous, and take the appropriate precautions.

While organisations such as ETC and the Institute of Nanotechnology may be calling for bans and moratoria on nanomaterials, we, in common with most of industry, are simlply calling for more research leading to better labelling.

Posted by Cientifica at March 29, 2004 06:35 PM | TrackBack
Comments

I had the same questions. I phoned Eva Oberdoerster last week and got some answers.

The buckyballs were solubilized/suspended by a published technique. Dissolve them in THF (tetrahydrofuran). Then mix in water, evaporate the THF, mix in more water, evaporate... repeat until you have buckyballs suspended in water. They form clumps 30-100 nm wide. There may be tiny amounts of THF inside the clumps, but not biologically significant. The outer buckyballs may be slightly hydroxylated, which could increase solubility.

Also, apparently buckyballs do dissolve in water, but very slowly.

At some point after the buckyballs enter the body, the clumps are thought to break up and the individual buckyballs dissolve in the lipid membranes.

Buckyballs are not highly toxic. (So they might not make good targeted-toxicity drugs. But they will likely make good drugs for other reasons.) Eva said that 10X damage was about the threshold where they started to worry. So 17X is definitely significant, but not a massive problem.

Incidentally, buckyballs appear to be metabolizable/decomposable by an enzyme called cytochrome P450-2K4. This surprised me.

We didn't talk about uptake or transport mechanisms.

Josh Wolfe promptly shot the messenger, writing in his weekly newsletter that Eva should somehow have kept her research out of the press. What's amusing is that Josh recommended Vicki Colvin as a good scientist who knew how to avoid scaring people. Guess who Eva's collaborator on this experiment was?

http://crnano.typepad.com/crnblog/2004/04/dont_shoot_the_.html

Chris

Posted by: Chris Phoenix, CRN at April 3, 2004 09:04 PM
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