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Small Wonders: Micro-Machines in Medicine

From the WebMD Archives

Nov 10, 2000 -- In the 1966 movie Fantastic Voyage, asurgical team is miniaturized and injected into the bloodstream of a dying manin a daring attempt to save his life. But that's doing it the hard way: why getsmall when you can make an army of microscopic robot paramedics that will do itfor 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 scienceof coaxing or manipulating atoms to assemble themselves into microscopicmachines or stable structures -- holds the promise of a new IndustrialRevolution.

 

In the 19th century, the tools of progress were coal, oil, andsteel. In the 21st century, they will be atoms, microscopic tubes carryingdrugs, and miniature disease-fighting robots, say small-thinking scientistswith big ideas, who met last week in Bethesda, Md. at a conference onnanotechnology.

 

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

 

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

 

In some ways, Mother Nature is proof of nanotechnology, saysconference co-chair Jan H. Hoh, PhD, associate professor of physiology at JohnsHopkins University School of Medicine in Baltimore. "People ask 'can youreally 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 ofcurrent efforts at nanotechnology are these lessons-from-nature kinds ofprojects, where you try to understand the design strategies and principlesnature uses, and then ask yourself 'how can I exploit these strategies to builddevices with entirely new functions and new properties?'"

 

Nanotechnology embraces many branches of science andtechnology, from space exploration, to energy conservation. One area ofparticularly bright promise is in medicine. Imagine, if you can, whatnanorobots or "nanobots" -- minuscule, single-minded automatonsdesigned for a specific purpose -- may be able to do:

 

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

 

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

 

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

 

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

 

Other medical applications of nanotechnology that at first seemto be far out in left field are in fact coming pretty close to home, saysLeslie Rubinstein, president of Renaissance Technologies in Lexington, Ky. Inan interview with WebMD, he describes the use of practical nanorobots fortreatment of various medical problems. The minimedic machines could be builtusing existing technology -- such as that used to make tiny computer chips. Therobots 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 goalis to get rid of something that shouldn't be there.

 

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

 

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

 

"They start talking to one another and pretty soon whatyou'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 thepossible existence of this thing," says Smalley.

 

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