Computer models how nanoparticles harm cells

The good news: Tieleman's group reports that the simulation shows buckyball-clumps do not rupture cell membranes when they pass through them. Thus, Tieleman's group now claims to have eliminated the hypothesis that fish brain damage was caused when clumps of buckyballs penetrated their cell membranes.

The bad news: The simulation revealed a mechanism by which buckyballs can migrate to any location in the body, enabling them to accumulate into clumps in any place that could damage cells--such as deactivating DNA, which contains the instructions for normal cell functions.

"What our simulation shows is that the cell membranes dissolve individual buckyballs off the big clumps, so that they can move through the membrane--a process that, in itself, does not damage cells," said Tieleman. "But, of course, once they are inside the cell membrane they could clump-up again anywhere in the body, which could cause all kinds of problems, such as free-radicals--highly chemically reactive molecules that cause damage to cells similar to UV exposure."

Next, the researchers plan to try to come up with functional coatings for nanoparticles that will prevent them from clumping. Their hypothesis is that if manufacturers of nanoparticles used safe coatings on them--ones that kept them from clumping--then all the normal mechanisms that flush foreign matter could cleanse nanoparticles from human, animal and plant cells. The group plans to run simulations on the effects of various coatings for buckyballs so that they can make recommendations to manufacturers on how to coat buckyballs to make them non-toxic.

"What we now need is for qualified toxicologists to develop their science--the toxicology of nanoparticles. They need to use live animals to see where the different particles are likely to accumulate, because the results of our simulation apply to any kind of cell--we didn't program anything about preferential accumulation in the brain or wherever," said Tieleman.

Since 2004, professor Eva Oberdorster of Southern Methodist University has called for a moratorium on nanoparticle manufacture after reporting experimental evidence that buckballs in water killed water fleas and damaged the brains of fish. Oberdorster found concentrations of buckyballs in fish gills and brains. Since then, watchdog groups like the Project on Emerging Nanotechnologies at the Woodrow Wilson International Center for Scholars have called for developing the toxology of nanoparticles, for regulating nanoparticles according to their toxicity, and to require manufacturers to install aerosol monitors that track employees exposure to potentially toxic airborne nanomaterials.