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Nanotechnology's Big Future

Nobel laureate Richard Smalleywith a nanotube model.

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Science and Space

Republished from the pages of National Geographic magazine

Written by Jennifer Kahn

June 2006

"I sit before you today with very little hair on my head. It fell out a

few weeks ago as a resul t of the

chemotherapy I've been

und erg oing. Twenty years ago,

without even this crude

chemotherapy, I would alr eady be

dead. But 20 years from now,

nanoscale missiles will target 

cancer cells in the human b ody 

and leave everything else

blissfully alone. I m ay not live to

see it. But I am confident it wi ll happen." Richard Smalley spoke

these words on Jun 22, 1999. He

died of non-Hodgkin's lymphoma

on October 28, 2005. The 62-year-

old Nobel Prize-winning chemist 

was a nanotech pioneer.

 A tsunam i is unnoticeable in the

open ocean—a long, low wave

whose power becomes clear only

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when it reaches shore and breaks.

Technological revolutions travel

with the sam e stealth. Spotting the

wave while it's still cross ing the ocean is tricky, which explains why so few of us are

aware of the one that's approaching. Nanotechnology has been around for two decades,

but the first wave of applications is only now beginni ng to break. As it does , it will affect

everything from the ba tteries we use to the pants we wear to the way we treat cancer.

The main thing to know about nanotechnology is that it's s mall. Really sm all. Nano, a

prefix that means "dwarf" in Greek, is sho rthand for nanom eter, one-billionth of a m eter: a

distance s o minu te that comparing it to anything in the regular world is a bit of a joke.

This comm a, for instance, spans about half a million nanom eters. To put it another way,

a nanom eter is the amount a man 's beard grows i n the time it takes him to lift a razor to

his face.

Nanotechnology matters because familiar materials begin to develop odd properties

when they're nanosize. Tear a pi ece of alum inum foil into tiny strips, and it will still behave

like aluminum—even afer the strips have become so small that you need a microscope

to see them. But keep chopping them smaller, and at some point—20 to 30 nanometers,

in this case,—the pieces can explode. Not all nanosize materials change properties so

usefully (there's talk of adding nano-alum inum to rocket fuel), but the fact that som e do is

a boon. With them, scientists can engineer a cornucopia o f exotic new materials, such as

plastic that conducts e lectricity and coatings that prevent iron from rusting. It's like youshrink a cat and keep shrinking it, and then at som e point, all at once, it turns into a dog.

Substances behave magically at the nanoscale because that's where the essential

properties of matter are determined. Arrange calcium carbona te molecules in a sawtooth

pattern, for ins tance, and you get fragile, crumbly chalk. Stack the same molecules like

bricks, and they help form the layers of the tough, iridescent she ll of an abalone .

It's a tantalizing idea: creating a material with ideal p roperties by customizing its atomic

structure. Scientists have already developed rarefied tools , such as the s canning

tunneling mi croscope, capable of viewing and m oving individual atoms via an exquisitely

honed tip just one atom wide.

"Nano's going to be like the invention of plas tic," says Paul Alivisatos, associate di rector 

of physical sciences at Lawrence Berkeley national Laboratory's new nanofabrication

center. "It'll be everywhere: in the s calpels doctors use for surgery and in the fabrics we

wear." Alivisatos already owns a pair of s tain-resistant nanopants from the Gap, m ade

from fibers treated with fluorinated nanopolymer. "I spilled coffee on them this morning,

and it roll ed right off."

On a table in a lab at Rice University, André Gobin, a graduate s tudent, is working with two

slices o f raw chicken. He nudges the s lices together so they touch and dribbles greenis h

liquid along the seam. The liquid is a s olution of nanoshells: minuscule silica beads

from our West Coast Adventure

Editor Steve Casimiro and go"Behind the Lens."

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covered, in this case, with gold. Switching on an infrared laser, Gobin deftly traces the

beam down the length of the green line . Tweezing the chicken up, he dangles what is

now a single piece of meat.

Someday soon surgeons may be able to use a nanoshell treatment like this to reconnect

veins that have been cut during su rgery. "One of the hardes t things a doctor has to do

during a kidney or heart transplant is reattach cut arteries," says Gobin. "They have to sew

the ends together with tiny stitches. Leaks a re a big probl em." With Gobin's nanoshell

solution a s urgeon could s imply meld the two ends and get a perfect seal. It would make

grafting veins as easy as soldering wire.

 Although much of nanotechnology's promis e remains unrealized, investment in the field

is boom ing. The U.S. governmen t allocated more than a billion dolla rs to nanotechnology

research in 2005—more than twice what it spent on sequencing the human genome

when that project was at its height. Japans and the European Union have spent sim ilar 

amounts, and even sm aller countries are hurrying to get a foot in the door. A Korean

company has used nanosilver-based antibacterials in refrigerator interiors. The same

material can be incorporated in bandages . The hopes is the sam e on all fronts: to get the

 jump on a growing global m arket that the National Science Foundation estim ates will be

worth a trillion dollars by 2015.

One reason for the rapid global s pread of nanotechnology is that the entry cost is

comparatively low. Countries that mis sed ou t on the computer revolution because theylacked the capital to build vast, high-tech factories that make s ilicon chips a re less likely

to miss the nanotech wave.

"It's science you can do in a beaker," says Stephen Em pedocles , vice president of 

Nanosys, a company that's developing cheap s olar nanos tructures. Traditionally the

manu facture of solar-energy cells has requi red a multimi llion-dollar fabrication facility

that cooks s heets of glass at extremely high temperatures until the atoms order 

themse lves into a receptive latticework. Solar nanostructures, on the other hand, grow

like rock candy. You can "mi x them up in a beaker with a hundred dollars' worth of s tarter 

chemicals ," Empedocles says, and then paint them on window glas s to turn an entire

building i nto a solar-ene rgy generator. Or, they migh t be embedded in the plas tic body of 

a cell phone or a laptop computer.

For a hundred dollars, in fact, anyone can buy nanoparticles—s pecifically a gram (.04

ounce) of carbon nanotubes —online. Place the order, and you'll receive a small ziplock

bag of what looks like soot tucked inside a cardboard FedEx envelope along with some

safety instructions. (They recommend gloves to keep the carbon slivers off the skin and a

respirator to keep the tiny black specks from entering the lungs .)

There's not much you can do at home wi th a thimbleful of carbon nanotubes. But some

of their mysteries are revealed in another Rice University lab, where Matteo Pasquali

holds up a test tube containing a few dark threads so s tiff that they seem to have been

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starched and ironed. These are fibers spun from carbon nanotubes—several billion of 

them—which, in theory, should be s tronger than Kevlar, the material in bulletproof vests.

For now, however, the threads are only about as tough as the acrylic found in an ordinary

sweater. The reason the threads are weak, Pasquali believes, is because some portion

of the billion nanotubes bundled together have hidden b reaks. A photo taken through a

microscope shows fibers that look like pale gray hairs, som e perfectly straight, others

frayed and curling . "We have split ends ," Pasqua li says with a sigh. "We need a nanotube

conditioner."

Carbon has proved a useful element in nanotechnology. One of the science's buildingblocks is a m olecule that contains 60 carbon atoms a rranged in a sphere. A molecule of 

C looks like the geodesic dome invented by Buckminster Fuller, thus its nickname:

buckyball.

Richard Smalley and colleagues discovered the buckyball in 1985, and in 1996 Smalley

and two others earned a Nobel Prize in chemis try for the deed. Until his recent death,

Smalley was a bucky fanatic. He renovated his house , close to the Rice University

campus in Houston, with a glass s kylight shaped like ha lf a buckyball, with precisely

proportioned steel struts representing the bonds between atoms.

Smalley was openly proselytical about the merits o f buckyballs and a particular fan of 

their relatives, carbon nano tubes. ("Fifty to a hundred times s tronger than steel and one-sixth the weight!" he often pronounced as though reporting the achievements of a

precocious child.)

Because of their light, stiff compos ition, merely sprinkling carbon nanotubes into epoxy

strengthens the glue by more than 30 percent. The tubes have also begun turning up in

high-end s porting equipm ent. They strengthen tennis rackets, moun tain-bike

handlebars, frames for racing bikes, and golf-club shafts. Carbon nantubes also show

promise for use in transparent conductive films for displays on computers, cell phones,

PDAs, and automatic teller machines .

Smalley was also an ardent advocate of nanotubes as a solution to the world's

impending engery crisis. His plan was to replace old copper and alum inum power lines

with wires spun from carbon nanotubes. Nanotubes can carry far more current thantraditional metal wires—over a billion amps of current per square centimeter (0.16

square inches)—and, unl ike metal wires , they lose very little of that energy as heat. In

theory, the nanotube power lines would carry electricity over thousands of m iles. Rather 

than relying on local coal-fired power plants, cities could us e energy generated by giant

solar farms in deserts or by wind farms off coasts. "This is the great getting-up morning

of nano," Smally said. "If Mother Nature allows it, we could restring the e lectrical grid of 

the world."

Not everyone is so s ure. Carbon nanotubes come in three types. They all conduct

60

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electricity, but only one does it especially well. And so far no one has com e up wi th a way

to make those nanotubes very long. Right now, the longest electricity-conducting

nanotube in existence meas ures a fraction of an inch.

 At the root of the problem is the fact that there are two ways to make nanoparticles: "top

down," where a bulk material gets chopped down into nanosize bits, and "bottom up,"

where molecules grow under controlled conditions, as in crystals, and then snap

together into particular configurations bas ed on their charge and mo lecular chemis try.

Bottom-up constructions—which long carbon nanotubes would require—are where the

real power of nano lies. But they're also far more complicated, subject to all the laws of bonding that limit the ways atoms and m olecules can be a rranged. Getting carbon to curl

into a perfectly aligned tube rather than a thick, twisted scroll is exceedingly complex.

Scientists are still relatively ham-fisted when it comes to the finer points of bottom-up

ass embly, particularly compared wi th a far m ore prolific nanofactory: the hum an body.

The human body makes quick and constant work of assembling raw materials like

calcium and keratin to create elaborate structures like bones and skin. Compared with

the work a blood cell does, scientists a re "pretty much inept," admits Jim Heath, a

Caltech chemist who is developing nanoscale sensors capable of detecting and

diagnos ing cancers. "But we're learning. We've come a long way in the past two years."

Heath's goal is to identify cancers early, when they are still jus t a few thousand cells

strong and far eas ier to treat. Unlike HIV or malaria , which produce unique antibodies

identifiable from a s imple blood test, cancers are difficult to spo t. Nonetheles s, they do

leave what Heath calls a fingerprint: a change in the num ber and type of proteins that

regularly circulate in the blood.

Determining which combination of proteins makes up the unique signature of a

particular cancer is an ongoing project. "To diagnose one cancer reliably in early stages,

we probably need to measure 20 or 25 different proteins," Heath says. "So to develop a

test that would identify 20 different cancers, we'd need about 500 meas uremen ts. And we

would wan t to be able to do that easily, with just a finger prick of blood ."

Heath has already developed nanosize sensors called nanowires that can electronicallydetect a few protein molecules along with other biochemical m arkers that are early signs

of cancer. Heath's strategy is to coat a collection of nanowires with different compounds,

each of which binds to one particular marker. When the marker, which can be a protein,

an an tibody, or DNA, latches on, it changes the conductivity of the nanowire, creating a

tiny but measu rable alteration in current. Heath has comb ined tens of thousands of 

these sensors onto a single chip, which allows h im to detect cancer-signifying

molecules in blood wh ile their concentration is s till low. The chips als o allow him to

identify what types of cancer are present. Currently, heath reports, his chip can detect

between 20 and 30 relevant biomolecules. He plans to begin us ing the chip to detect

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brain cancers this s ummer.

Richard Smalley was one scientist who followed Heath's progres s carefully. Smalley's

non-Hodgkin's l ymphoma was a relatively slow-m oving cancer, but even when he was in

remission, between a hundred million and billion cancer cells circulated in his body (a

number that doctors conside r relatively low).

One of the advantages of treating cancer in an early stage is that the cells a re less likely

to have mutated and become res istant. Drug resistance is one of the trickiest things

about cancer, which adapts so rapidly that medications can ra rely keep up. "You don't

want a killing m echanism to be fancy," Smalley said. It needs to be fast and thorough.

But targeting a brute-force treatment is difficult, says Jennifer West, a bioengineer who is

treating tumors in mice us ing gold nanoshell s. Difficult because things that kill cancer 

cells typically kill hea lthy cells as well. "That's what we'd like to avoid," West says, Her 

approach relies on the fact that tumors grow b lood vessels so qu ickly to keep up with the

rapidly multiplying tumor cells that they don't have time to knit tightly and instead leak like

rusted pipes. West's gold nanoshells are about 120 nanometers in diameter—a cancer 

cell is 170 times bigger. So the nanoshells are minute enough to seep through the

cracks in the tumor capillaries and become lodged in the tumor.

To kill the tumor, West activates the s hells with infrared rays that pass harmles sly through

the skin but heat the gold, killing the adjacent tumor cells . Because the cancer cells die,they don't develop the res istance that can plague drug-based cures .

Moreover, because the nanoshells lodge only in the tumor and are nontoxic unles s

activated by infrared light, West expects her treatment to be nearly side-effect free

—particularly compared with treatments like chem otherapy and radiation. As part of the

FDA approval process, West has i njected mice with increasi ngly large doses of 

nanoshells. Not a single mouse has died. "We injected mice with increasingly large

doses of nanoshel ls. Not a single mouse has died. "We haven't even been able to

induce any adverse effects," she says with a s hrug. "If we had injected these m ice with

the sam e amount of table salt, they would have keeled over long ago.

Unfortunately, the very thing that makes nanoshells such a promis ing therapy—their 

ability to m ove easily through the body and to interact with different cells—is a downs idewhen it comes to the problem of nanoparticle pollution.

In 2004 Eva Oberdörs ter, a toxicologist at Sothern Methodist University in Dall as, repo rted

that largemouth bas s exposed to water containing buckyballs at a concentration of 500

parts per b illion s uffered brain dam age. And people are s imilarly vulnerable. After 

exposing lab-grown hum an skin and li ver cells to an even weaker solution—a mere 20

parts per billion—Rice Un iversity chemis t Vicki Colvin found that fully half the exposed

cells died.

Results like these are troublin , in part because of the rapidl rowin number of 

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l li li i i l i

products already on the market that contain nanoparticles. "With nanom aterials, it's not

enough to look at the properties of the bulk material," Colvin warns. "Whether you're

working with gold or lead, the toxicity will be hard to predict." There is s ome evidence, for 

example, that the nanoscale particles of titanium dioxide used in s unscreen, depending

on the way they are nanosized, can produce high am ounts of free radicals when exposed

to sunlight. Free radicals can damage cells, making some more likely to turn cancerous.

Colvin's concern is that companies are currently optimizing their particles for 

process ability rather than for human health. A recent study found that buckyballs could be

made less toxic fairly easily—by attaching inert molecules known as hydroxyl groups . Themore hydroxyl groups attached, the less dangerous the buckyballs became. For the mos t

thoroughly coated, the s afe exposure level went up by a factor of ten thous and.

But it's hard to get funding for this kind of research, Colvin says. "Funding managers wan t

a sexy story at the end of the day. They want to be able to say that they're helping to cure

cancer. It doesn't sound as glorious when your finding is that a certain particle you were

hoping to use ought to have hydroxyl groups put on it in o rder to be s afe."

Still, researchers are m aking im portant advances. They are finding new ways to use

nanos ize sensors in water purification systems that will filter everything from bacteria to

indus trial pollutants like ars enic. The key feature of the new filters is the fact that

nanoparticles have a vast amount of surface area for their weight: One ounce (28.3

grams) of nanobeads, for instance, contains a staggering 300,000 square feet (27,871square meters) of su rface area. Because the chemical reactions that neutralize

pollutants take place on the s urface of the beads , the greater the available area, the more

effective the filter.

The potential impact of nanofilters is s ubstantial. Many regions in China have drinking

water that contains dangerously high levels of arsenic and other industrial pollutants.

Because o f this, Colvin predicts that Asia wi ll be a test bed for point-of-use water 

treatment systems that utilize nanoparticles to elim inate toxic chemicals . "Right now,

nanos cale iron is a bit too expensive to be us ed to treat wastewater," she s ays. "But it's

the best way to clean up concen trated ars enic, and I expect the cost will come down

soon."

Because nano tech applications are so po tentially useful, Colvin doesn't think research

shoul d be stopped, or even slowed. But she does think that a larger proportion of 

government money should be di rected toward safety and related ques tions—like whether 

nanoparticles could accum ulate undetected in the water and food chains.

Such safety issues are key, given the speed with which the nanotech tsunam i is m oving.

Corporations will invest more than four billion dolla rs in nanotech this year alone, and a

recent nanotech conference in Japan drew a crowd of 30,000.

Meanwhile, commercial applications continue to spread. Homeowners now have the

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option of installing windows m anufactured by PPG Indus tries, a company that uses

nanos cale particles of titanium d ioxide to make glas s that doesn't streak and never 

needs washing. Food companies have begun experimenting with nanopackaging that

changes color when food spoils or contains bacteria like E. coli . The prefix has even

trickled over into popular culture, where it's the advertising hit du jour, with GM hawking a

"nano" Humm er, and Apple its iPod Nano digital m usic player.

"What's am azing is how quickly this is evolving," Colvin s ays. "Even ten years ago, a lo t of 

these applications would have seem ed pretty unrealis tic."

The boom left Richard Smalley downright nostalgic: "Nano is a baby that's all g rowed up,"he mused s hortly before his death. Perhaps, but we've still got some interes ting years

ahead.

Extras: See photos, field notes, and more from this National Geographic article.

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