Small Wonders: Micro-Machines in Medicine

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Nov 10, 2000 -- In the 1966 movie Fantastic Voyage, a surgical team is miniaturized and injected into the bloodstream of a dying man in a daring attempt to save his life. But that's doing it the hard way: why get small when you can make an army of microscopic robot paramedics that will do it for you?

 

A few years ago that would have sounded like an absurd fantasy, something out of Jules Verne or H.G. Wells. But nanotechnology -- the science of coaxing or manipulating atoms to assemble themselves into microscopic machines or stable structures -- holds the promise of a new Industrial Revolution.

 

In the 19th century, the tools of progress were coal, oil, and steel. In the 21st century, they will be atoms, microscopic tubes carrying drugs, and miniature disease-fighting robots, say small-thinking scientists with big ideas, who met last week in Bethesda, Md. at a conference on nanotechnology.

 

The prefix nano-, from the Greek word for "dwarf" is used in medicine and science to denote things that are vanishingly small -- technically 1-billionth of a 'whatever'. So, a nanosecond is a billionth of a second, and a nanometer is a billionth of meter.

 

The idea of making molecule-sized machines may seem bizarre or silly to some people, but nanotechnology scientists are actually holding the mirror up to nature.

 

In some ways, Mother Nature is proof of nanotechnology, says conference co-chair Jan H. Hoh, PhD, associate professor of physiology at Johns Hopkins University School of Medicine in Baltimore. "People ask 'can you really build devices on a length scale of a few nanometers?' And the answer is, 'We know you can, because nature already has,' Hoh tells WebMD. "Part of current efforts at nanotechnology are these lessons-from-nature kinds of projects, where you try to understand the design strategies and principles nature uses, and then ask yourself 'how can I exploit these strategies to build devices with entirely new functions and new properties?'"

 

Nanotechnology embraces many branches of science and technology, from space exploration, to energy conservation. One area of particularly bright promise is in medicine. Imagine, if you can, what nanorobots or "nanobots" -- minuscule, single-minded automatons designed for a specific purpose -- may be able to do:

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  • Manufacture and deliver cancer drugs to specific places within a tumor
  • Scour blood vessels clean of fatty deposits that block flow to the heart
  • Bombard isolated pockets of infection with a barrage of antibiotics
  • Search for and destroy blood clots that could lead to a heart attack or stroke

 

"All the machinery of life is molecularly precise machinery that works on a nanometer scale, so it is nanotechnology -- nature's version of it," says Rick Smalley, professor of chemistry and physics and director of the Center for Nanoscale Science & Technology at Rice University in Houston. "So to the extent we're going to ever learn how to diagnose it, to probe it, to figure it out, to alter it and fix its problems, that too will have to be a nanotechnology."

 

Smalley tells WebMD that nanotechnology is already used in medicine in the form of man-made molecules that are coupled with toxic chemicals or radioactive particles. These molecules, which do not exist in nature, can deliver drugs or lethal doses of radiation to cancerous tumors, for example. From there, it's not much of a leap, he says, to imagine drug delivery using micromanufactured tubes, so-called nanotubes.

 

In testimony before Congress in 1999, Smalley forecast other uses for nanotechnology in medicine. They include rapid genetic analysis that would allow diagnosis and treatment customized to fit an individual patient based on his or her genetic profiles; more durable artificial organs that would be less likely to be rejected by the recipient's immune system; and "sensing systems, which will allow the detection of emerging disease in the living body, and will ultimately shift the focus of patient care from disease treatment to early detection and/or prevention," he says.

 

Other medical applications of nanotechnology that at first seem to be far out in left field are in fact coming pretty close to home, says Leslie Rubinstein, president of Renaissance Technologies in Lexington, Ky. In an interview with WebMD, he describes the use of practical nanorobots for treatment of various medical problems. The minimedic machines could be built using existing technology -- such as that used to make tiny computer chips. The robots themselves would be designed to boldly go where no robot has gone before -- that is, into areas of the body that are hard to reach -- and where the goal is to get rid of something that shouldn't be there.

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Similar work is being performed at the Massachusetts Institute of Technology in Cambridge, where Ian Hunter, PhD, professor of mechanical engineering and bioengineering and his colleagues are developing "nanowalkers" that would do for medicine what robotic probes have done for space exploration. The nanowalkers could crawl over, around, or through the body to image and diagnose diseases that lie hidden from conventional scanning techniques, deliver drugs to tumors, or repair organs without the need for surgery.

 

There are those who worry that once we've started down the path to fashioning self-assembling robots, there may be no turning back, and that one day, we may wake up and find that the robots have multiplied and taken on life of their own.

 

"They start talking to one another and pretty soon what you've really got is a wholly alien artificial life form, a true Franken-thing. And I agree that would be terrifying if it were true, but I deny even the possible existence of this thing," says Smalley.

 

"We're so far away from anything remotely resembling a self-assembling robot that it's silly to worry about it right now."


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