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The Future of Nanotechnology: Molecular Manufacturing
Permanent link to this article: http://www.kurzweilai.net/meme/frame.html?main=/articles/art0559.html
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The Future of Nanotechnology: Molecular Manufacturing
The future generations of nanotechnology will rely on being able to effectively arrange atoms. Molecular manufacturing, and the use of molecular assemblers to hold and position molecules, will be key to the future, controlling how molecules react and allowing scientists to build complex structures with atomically precise control. In this essay, Dr. Drexler discusses the benefits and challenges of future molecular manufacturing.
Originally published on EurekaAlert!
April 2003. Published on KurzweilAI.net April 14, 2003.
The future of technology is sometimes easy to predict. Computers
will compute faster, materials will become stronger, and medicine
will cure more diseases. Nanotechnology, which works on the nanometer
scale of molecules and atoms, will be a large part of this future,
enabling great improvements in all these fields. Advanced nanotechnology
will work with molecular precision, making a wide range of products
that are impossible to make today.
.jpg)
Institute
of Molecular Manufacturing
A proposed fine-motion controller for guiding molecular assembly.
Molecular machinery driving rotation of the blue rings (below) would
move the tool-holder (above) with precise control of angle and position.
Why focus on molecular manufacturing? Every manufacturing method
is a method for arranging atoms. Most methods arrange atoms crudely;
even the finest commercial microchips are grossly irregular at the
atomic scale, and much of today's nanotechnology faces the same
limit.
Chemistry and biology, however, make molecules defined by particular
arrangements of atoms—always the same numbers, kinds, and linkages.
Chemists use clever tricks that don't scale up well. Biology, however,
uses a more powerful method: cells contain molecular
machines that read genetic data to guide the assembly of large
molecules (proteins) that they serve as parts of molecular machines.
Molecular manufacturing will likewise use stored data to guide construction
work done by molecular machines, greatly extending abilities in
nanotechnology.
The basic idea is simple: where chemists mix molecules in solution,
allowing them to wander and bump together at random, molecular
assemblers will instead position molecules, bringing them together
to the specific location at the desired time. Letting molecules
bump at random leads to unwanted reactions—a problem that grows
worse as products get larger. By holding and positioning molecules,
assemblers will control how the molecules react, building up complex
structures with atomically precise control.
.jpg)
Theoretical and Computational Biophysics Group/Beckman
Institute, University of Illinois at Urbana-Champaign
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The energy-carrying molecule ATP is manufactured by a
molecular machine, ATPase,
mounted in a membrane. The lower part is a motor powered by
protons flowing through it across the membrane; the motor
turns a shaft that drives the mechanosynthesis of ATP in the
upper part.
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Picture an industrial robot arm standing next to an unfinished
work piece. A conveyor belt supplies the arm with parts, each mounted
on a handle. Step after step, the belt advances, the robot grips
a fresh handle, plugs the attached part into the work piece, then
puts the empty handle back on the belt. Eventually, the work piece
is finished and another belt moves it away, shifting a new unfinished
work piece into place.
To picture a molecular assembler in a manufacturing system, imagine
that all the parts are measured in nanometers, and that the transferred
parts are just a few atoms, shifting from handle to work piece through
a chemical reaction at a specific site. An assembler works as part
of a larger system that prepares tools, puts them on the conveyor,
and controls the robotic positioning mechanism.
This will be a complex system that no one will build any time soon.
Indeed, no one is even trying to build molecular assemblers today,
because nanotechnology is still in its infancy. We can see a path
to assemblers, just as the rocketry pioneers of the 1930s and 1940s
could see a path to the Moon. But like those pioneers, we aren't
ready to attempt the final goal. They knew they must first launch
many satellites, just as we must first build many molecular machines.
Confusion and controversy: Developing assemblers
While nano assembly has been described as "building things
atom by atom," an expression that has caught on in the press,
this is a misconception. Molecular assemblers will build with atomic
precision by mechanically guiding chemical reactions that typically
add a few atoms at a time, but some researchers have criticized
this misconception as if it were the actual proposal. It is correct
that assemblers can't build things by using tiny tweezers to pick
up and put down atoms one at a time, but even from the start this
was never the idea.
The apparent controversy over "molecular assemblers"
is thus an illusion: the critics are talking about something else.
The idea of building things by mechanically guiding chemical reactions
has withstood scientific scrutiny for over 20 years, and seems sound.
It is time to move on, to consider the consequences of molecular
assemblers and what they will be able to build.
Understanding advanced capabilities
We can catch a glimpse of future technologies because we sometimes
can understand things that we can't yet build. Chemistry, biology,
engineering, and applied physics all provide useful perspectives.
Chemistry shows what can happen when reactive molecules meet. By
using molecular machinery to guide reactive molecules, similar structures
can be built at larger scales. The products can be stronger, tougher,
and more capable than the delicate structures found in living cells.
Biology shows that molecular machines can exist, can be programmed
with genetic data, and can build more molecular machines. Biology
shows that the products of molecular machine systems can be as cheap
as potatoes. Molecular manufacturing will make a far wider range
of products for similarly low costs.
Engineering shows that strong, precise parts can be combined to
make computers, robots, and a host of useful gadgets. Applied physics,
aided by computer modeling, shows that these sorts of devices can
be built from atomically precise parts of nanometer scale. These
glimpses of future technologies are enough to establish the potential
for molecular manufacturing.
Directions and applications
Molecular manufacturing will bring both great opportunities and
great dangers. Nanocomputers will extend desktop computational power
by a factor of a billion or more. Nanoscale sensors, computers,
and tools will bring surgical control to the molecular level, enabling
a revolution in medicine.
Light, strong, and inexpensive aerospace structures will make spaceflight
easy.
But the future's faster, cheaper, cleaner production of better
products will also bring disruption. Advanced lethal and nonlethal
weapons, deployed quickly and cheaply, could make the world a more
dangerous place. The list of consequences is long, much of it sounding
like science fiction.
The tools required to develop nanotechnologies are typically small
and unobtrusive. The pace of research is accelerating worldwide.
Some suggest stopping it, but it is hard to imagine how. Thus, it
seems that this technology, with all its challenges and opportunities,
is an unavoidable part of our future.
Sponsored by the U.S.
Department of Energy. For more information about nanotechnology,
visit EurekAlert!'s Nanotechnology
In-Context Module.
© 2002 American
Association for the Advancement of Science. Reprinted with permission.
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Mind·X Discussion About This Article:
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Re: tweaking dna into a "anything assembler"
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Bioengineering may just be getting started but the sky is no limit and the number of jobs it may make available is hard to estimate.
The following article shows that the technology is being taken very seriously by some universities.
DNA forms building block for next breed of computer
By Jonathan Sidener
STAFF WRITER
September 1, 2003
For years, researchers have taken advantage of the ever-increasing power of computers to crack the genetic code.
But Scripps Research Institute chemist Ehud Keinan and a handful of scientists around the world are going in the opposite direction, using DNA ' the blueprint for cellular life ' to crunch numbers inside a new breed of computer.
If the research is successful, children one day might operate a computer powered not by silicon chips, but by "biochips" that run software and store data using the same double-helix of DNA that determines whether our eyes are blue or peas are green.
And it is conceivable that future generations may have microscopic DNA computers coursing through their veins, capable of diagnosing and perhaps treating a variety of ills at the molecular level.
"You can't compare and say a DNA computer is or isn't faster than this," Keinan said, gesturing toward a sleek, metallic Macintosh PowerBook in his Scripps office. "It's a different type of computer."
DNA computers don't have keyboards and monitors. The computing takes place on the laboratory bench as complex molecular-chemical reactions.
The first calculations, nearly 10 years ago, took place inside beakers and test tubes.
A new generation of DNA computing uses biochips, devices built using semiconductor manufacturing technology. A biochip has millions of pieces of DNA on its surface instead of the millions of electronic circuits on a computer chip.
At the moment, DNA computers are laboratory curiosities. One computer can play a respectable game of tick-tack-toe. Another can solve chess riddles. The computations they handle would make the least powerful of today's computers yawn.
But DNA computers show some intriguing qualities.
DNA is extremely efficient, both in storing data and in its use of energy. One gram of DNA, which would take up about as much space as an ice cube, can hold as much information as 1 trillion compact discs.
With today's computer chips, energy consumption and the heat produced as a byproduct can cause malfunctions. But the chemical reactions that make a DNA computer work require little energy.
Most significantly, the biomolecular computers operate on different underlying principles.
Electronic computers make their calculations by processing a series of zeroes and ones, or binary code, one character at a time in a rapid sequence, like a machine gun that fires a series of bullets from a single barrel in succession.
Not so with DNA computers. Because millions of DNA snippets can fit into a drop of water, DNA computers can make many parallel calculations at once, more comparable to a shrapnel grenade that launches many projectiles at the same instant.
To Keinan and other researchers, this parallel processing provides much of the allure of DNA computing, the idea that machines built with a fundamentally different computing engine will be able to tackle fundamentally different questions.
A young science
DNA computing was born in 1994 when University of Southern California researcher Leonard Adleman devised a way to solve a mathematical brain teaser using fragments of DNA.
Several research teams around the globe have taken different approaches to this computing via biology, and it remains unclear which approach, if any, will emerge from the laboratory.
Electronic computers read a language consisting of two characters, 0 and 1. DNA computers read a language of four characters, the four molecules that make up DNA, known by their initials A, T, G and C.
Like its electronic brother, a DNA computer has software and hardware. The software is the DNA string. The hardware consists of enzymes that "read" the DNA strand and snip it at precise, known locations.
After each enzyme snip, four unbonded molecules remain at the end of the DNA snippet. DNA does not like to have unbonded molecules, so a second enzyme repairs the strand according to a set of rules hard-wired into DNA's biology.
DNA computers use the predictability of these repairs to perform their calculations.
The enzymes make a series of snips. At the final snip, the four letters of the unbonded molecules provide the answer or output of the calculation.
'Language of biology'
Keinan is part of a team from the Technion, Israel's Institute of Technology, that built the first autonomous DNA computer.
In addition to his work at Scripps, Keinan is the founder and head of the Institute of Catalysis Science and Technology at the Technion.
Before the Technion's work, molecular computers had required human guidance through a series of chemical reactions.
Keinan, an organic chemist who drifted into bio-molecular computing after a chance meeting with another Israeli researcher, won't guarantee that DNA computers will ever get beyond the laboratory.
"Maybe in 10, 20, 30 years, maybe not at all," he said. "The parameters are so attractive that I believe something wonderful will come out of this. But it would be foolish to make a prediction."
Pavel Pevzner, a computer science and engineering professor at the University of California San Diego Jacobs School of Engineering, agrees that it is too early to divine the future of DNA computers.
"The problem is how to prove that this is not just an intellectual game," Pevzner said.
So far, researchers are missing a breakthrough, he said.
"They have not found a problem DNA computers can solve that cannot be solved with conventional computers. They need that killer application if they're going to be taken seriously."
Keinan and his colleagues in Israel are about to publish the results of research in which the output from a calculation turns on or off the pigment gene in a colony of bacteria.
The answer "Yes" might produce a beaker full of blue bacteria, while "No" would produce a colorless fluid.
While this is a simple example, it is a first step toward devices that can interact with biology.
DNA researchers hope that one day DNA computers will deliver drugs or repair cells from inside the bloodstream.
"DNA computers talk molecules, which is the language of biology, and therefore they can talk directly to cells and tell them what to do," Keinan said.
"It is true that DNA computers still lag behind silicon computers. Nevertheless, even today, DNA devices have already been able to do things in my lab, and go to places, that silicon computers cannot."
Jonathan Sidener: (619) 293-1239; jonathan.sidener@uniontrib.com
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Re: tweaking dna into a "anything assembler"
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It seems to me you can assemble something in a wet environment that is able to work in a dry environment. Take people for example. Sure, we start out in a wet environment, but once we leave the womb, the growth process continues in an externally dry environment. In other words, such products can be wet on the inside and dry on the outside. Look what shellfish are capable of making with DNA instructions. Wet shellfish can make a dry shell of incredible complexity.
Anther consideration is that carbon, which diamonds are composed of, is manipulated by DNA and protiens on an atom-by-atom basis. Placing carbon atoms precisely is one of the things DNA does best. Without the precise manipulation of carbon atoms, the double helix would not exist.
I foresee a time when DNA will enable us to manufacture sheets of nanotubes. A single cell containing DNA may be slow but when you have them multiplying exponentially, the final result can come about rather quickly. Besides, it's not the DNA itself that does the manufacturing of things like skin, bones, liver and brain -- it's the proteins built by DNA working with RNA that do the manufacturing.
Who knows what kinds of proteins we'll be able to create with the models provided by nature to guide our efforts? That's where bioengineering will come into it's own -- using DNA code to set up and run the self-assembly process. A protein is, after all, a type of manufacturing machine. The sum total of all possible proteins is roughly equal to the total of all possible words in all the languages on Earth. Most of the possibilities haven't even been explored yet.
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