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Thursday, July 10, 2003

NATURAL SELECTIONS

NANOTECHNOLOGY

Sifting through the goo


It's been hailed as the first major scientific breakthrough of the 21st century, but in his recent book, "Prey," Michael Crichton envisioned it taking over the world.

Nanotechnology is the science of the very small. It works on the scale of the nanometer, one billionth of a meter, about the size of a string of five atoms. A human hair is about 80,000 nanometers wide.

It was only recently that scientists became able to work on such a small scale, but already the research field is attracting big money.

And nowhere more so than in Japan. In the last five years, funding for nanotechnology has risen from $120 million to $750 million. Less money has been poured into the nascent technology in Europe (over five years the amount has grown from $126 million to more than $350 million), but public concern in the West is greater.

A lot of fuss was caused in Britain a few months ago when Prince Charles warned that nanotechnology could lead to tiny, malevolent robots ("nanobots"). The self-replicating nanobots might turn the world into "gray goo," the prince warned. (Incidentally, like the rest of us, the prince's own head is already full of "gray goo.")

Amid the furor, Britain's Royal Society and Royal Academy of Engineering launched an investigation into the potential benefits and possible risks of nanotechnology. The inquiry is headed by Ann Dowling, professor of mechanical engineering at Cambridge University and is expected to report back next year.

"Some unease about nanotechnology was expressed earlier this year with suggestions that plagues of self-replicating nanobots could turn the world into gray goo," she said. "A key role of the project will be to separate the hype and hypothetical from the reality."

The public concern is real, but most scientists agree that the scenario envisaged by Prince Charles is science fiction. Instead, for a tangible example of what nanotechnology might bring us, look to research presented Tuesday at the American Society for Microbiology's conference on Bio- Micro- Nano-systems.

Scientists from Harvard Medical School and the Massachusetts Institute of Technology announced a strategy that could one day be used to create functional human organs such as kidneys and livers. Tissue engineering (as it is known) has been successful in the creation of new tissues including skin and cartilage, but has failed to create large, functional vital organs, such as the kidneys and liver.

That's because while structural support has provided "scaffolding" for the cells to grow over -- there hasn't been adequate vascular support. That is, there haven't been blood vessels to bring oxygen and nutrients at the scale necessary to maintain the cells of the growing organs. The new process addresses this need. The technique involves creating a network of microscopic tubes that branch out in a pattern similar to that seen in the circulatory system. The tiny, artificial blood vessels provide oxygen and nutrients to liver or kidney cells that have been cultured in a lab.

The vascular network is designed using new fractal computational models, and then etched onto silicon surfaces. The silicon is then used as a mold to transfer the pattern to a biocompatible polymer film. The technique is known as nanoimprintation. Two films are then sealed together with a microporous membrane sandwiched between them.

"These technologies create a precise architectural framework for the liver or kidney cells that are responsible for the functional replacement of the vital organs," said Mohammad Kaazempur-Mofrad of MIT's department of mechanical engineering and division of biological engineering, the lead researcher on the study.

"Our microfabricated devices can efficiently supply oxygen and nutrients to sustain the viability of human liver and kidney cells for at least one week in the lab," he added. Experiments showed that 96 percent of kidney cells survived for one week and 95 percent of liver cells survived for two weeks.

The scientists also implanted an experimental liver device that lasted a week into rats. The device was only a single layer (researchers expect it could take from 30 to 50 layers to represent a fully functioning liver) so it did not replace the existing liver. Kaazempur-Mofrad and his colleagues plan to investigate if this approach works in other animals.

"So far we have succeeded in making individual, functioning units, but the ultimate goal is to make whole, functional organs," said Kaazempur-Mofrad.

The nanotechnology issue is threatening to become as polarized as the GM food issue, and no one wants that. No rational scientist is claiming that nanotechnology will eradicate poverty, hunger and drudgery, yet that is how scientists' views are sometimes represented.

The reason? So they can be mocked when we see that all nanotechnology has promised us so far is stain-resistant clothes and, worse, specialist weaponry.

But of course nanotechnology is about more than this. As seen in the tissue-engineering research reported in the United States on Tuesday, some of its greatest potential is in medicine and biology. We all want to see adequate safeguards and regulation, but the only way of doing that is through scientific evaluation of the facts of nanotechnology.

Here's what Dowling said in her statement: "Before nanotechnology grows up we -- society -- need to determine where exactly we are with this technology, what we want from it and what safeguards need to be in place."

Rowan Hooper welcomes comments at rowan.hooper@tcd.ie


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