Nanotechnology Summary

Nanotechnology

From Wikipedia, the free encyclopedia

Nanotechnology (sometimes shortened to “nanotech“) is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures with at least one dimension sized from 1 to 100 nanometres. Quantum mechanical effects are important at this quantum-realm scale. Nanotechnology is considered a key technology for the future. Consequently, various governments have invested billions of dollars in its future. The USA has invested 3.7 billion dollars through its National Nanotechnology Initiative followed by Japan with 750 million and the European Union 1.2 billion.[1]

Nanotechnology is very diverse, ranging from extensions of conventional device physics to completely new approaches based upon molecular self-assembly, from developing new materials with dimensions on the nanoscale to direct control of matter on the atomic scale. Nanotechnology entails the application of fields of science as diverse as surface science, organic chemistry, molecular biology, semiconductor physics, microfabrication, etc.

Scientists debate the future implications of nanotechnology. Nanotechnology may be able to create many new materials and devices with a vast range of applications, such as in medicine, electronics, biomaterials and energy production. On the other hand, nanotechnology raises many of the same issues as any new technology, including concerns about the toxicity and environmental impact of nanomaterials,[2] and their potential effects on global economics, as well as speculation about various doomsday scenarios. These concerns have led to a debate among advocacy groups and governments on whether special regulation of nanotechnology is warranted.

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http://science.howstuffworks.com/nanotechnology.htm

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http://www.fda.gov/ScienceResearch/SpecialTopics/Nanotechnology/default.htm

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http://www.nanotechproject.org/

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http://www.foresight.org/nano/

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Nano.gov

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Philly.com: Science Hints at Alternative Recipes for Life. Evolution is the Common Thread

Sunday, February 12, 2012

Here’s my weekly evolution column, which appears Monday Feb 13 in the Philadelphia Inquirer:

On Star Trek, the aliens often look so human that crew members fall in love with them. But in real life, scientists in the field known as astrobiology can’t be sure alien life would even be carbon-based like us, or use DNA to carry a genetic code.

Some insight now is coming from earthly labs, where scientists are building alternative kinds of genetic codes, and showing how they can evolve.

Whether life could be built with an alien biochemistry was among the more interesting questions that came up during a public event with famed biologist Richard Dawkins and physicist Lawrence Krauss, author of the book The Physics of Star Trek.

Dawkins saw the question as a biological equivalent of one posed by Einstein: Did God have any choice in making the universe? Not that Einstein believed in a biblical God, as the famously atheistic Dawkins was quick to point out.

Dawkins noted that most of the species that ever existed are now extinct. The way carbon-based life works on Earth is downright wasteful, he said. “Any decent engineer would have sent it back to the shop.”

The event, which drew more than 3,000 people, was held at Arizona State University in Tempe. Dawkins didn’t lecture but instead took part in an onstage discussion with Krauss, who runs a multidisciplinary program there on the origins of humanity, life, and the cosmos.

Krauss — while not going so far as to say alien chicks would be hot — did say the laws of physics and chemistry might favor carbon-based life resembling ours.

Dawkins said he was inclined to think life could exist in more diverse forms, as long as it included some kind of code-carrying system equivalent to DNA, copying itself with high fidelity. Such genetic material is critical for Darwinian evolution, which, to Dawkins and many others, is the defining characteristic of life.

Perhaps it wasn’t a complete coincidence that at the same university, biochemist John Chaput was creating an alternative version of DNA, called TNA, and had last month published the first evidence that the stuff can undergo Darwinian evolution.

Chaput, who works at ASU’s Biodesign Institute, said Dawkins is correct to emphasize the need for genetic material — something that can carry a code. All known life does this with DNA and RNA.

NASA has taken a great interest in such possible alternative code-carriers. In late 2010 the space agency claimed that scientists had forced bacteria to substitute arsenic for phosphorus in its DNA. Despite the fanfare, the team never presented adequate evidence that alternative life really existed, said chemist Steve Benner of the Florida-based Foundation for Applied Molecular Evolution.

And when biochemist Rosemary Redfield of the University of British Columbia tried to replicate this, she discovered that the bacteria failed to grow when fed arsenic and no phosphorus.

Benner said the original arsenic life paper admitted to a small amount of phosphorus contamination. From the start, he said, he thought the contamination was fooling the team into thinking the organism was using arsenic the way we use phosphorus.

Benner said this new TNA work is just as exciting and relevant to astrobiology as the arsenic bacteria would have been if it had been proved.

This alternative genetic material is like RNA in that it’s single-stranded and it carries a chemical code with four different units. But the backbone that holds it together has a different structure, incorporating a sugar called threose where RNA has a sugar called ribose.

Threose is found in meteorites, said Chaput, suggesting it can form spontaneously in the absence of life. It’s also simpler than RNA, making it a reasonable candidate for a precursor to our current genetic material.

The existence of a precursor fits with the widely held view that life didn’t start out as complex as even the simplest microbes today. Instead, the simplest known living things evolved from yet simpler life that no longer exists.

Chaput showed that, like RNA, TNA can undergo Darwinian evolution. In theory, then, life elsewhere could use TNA as its genetic code, and if early life on Earth used it, TNA-based life could evolve into DNA-based life.

To demonstrate TNA evolution, he used selection to prompt the molecules to do a fairly simple task — to stick to a specific protein. This is what so-called receptors do in our bodies. He continued to select those TNA molecules that best stuck to the protein until he had a decent receptor.

TNA evolution worked the same way as in DNA, with accidental mutations leading to variation, and natural selection amplifying those variants that are best at surviving and reproducing themselves. He published the results last month in the journal Nature Chemistry.

That suggests the possibility of TNA-based life elsewhere, said Benner. It’s also possible, he said, that arsenic-using DNA would be stable, say, under the frigid conditions of Saturn’s moon Titan.

So now we have TNA as well as PNA, GNA, FNA and code-carrying molecules that use six or 12 characters rather than the usual four. With these increasing possibilities known, Benner sides more closely with Dawkins on the question of life forms with alternative chemistries.

Our life is not the best of all possible forms, Benner said, but a product of chance, our biochemistry hinging on which molecules happened to bump into each other. God did have alternatives, in other words, but perhaps no power to choose which one would evolve to create works like Star Trek.

Contact staff writer Faye Flam at 215-854-4977, fflam@phillynews.com, on her blog at www.philly.com/evolution, or @fayeflam on Twitter.

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Scienceray.com: Nanotech’s Next Step

While nature has used nanotechnology for millennia in the form of DNA, a team of scientists have created GNA as a less expensive and more durable replacement. Until a better replacement comes along, GNA is looking to be the building block for future nanotechnology.

Imagine any piece of technology in science fiction you have ever read or watched on film, and then realize that, barring self-destruction, it is only a matter of time before those capabilities become reality. If you have doubts, just taking a look around at what has already become commonplace over the last century or so that was once considered impossible.

Unfortunately, a lot of those people who dreamt of the possibilities in the past have not lived to see the reality. Therein lies what is a major part of the problem, our own mortality.

While a few may want death to come unexpectedly and without warning at any time in their lives, or trust in their own deity of choice, perhaps helping ourselves to not only extend life, but make death an option, would be preferable to inevitability.

Realizing that any problem today, including death, could be solved through nanotechnology, one would think it would be the utmost priority. Unfortunately, some Luddite type thinking, fear mongering, ignorance, and religious absolutism have delayed or even stopped technological progress in some areas of the globe.

Fortunately, this is not the case with the United States and other developed countries, at least when it comes to nanotechnology or technology on the scale of a billionth of a meter. At the atomic and molecular scale, however, many difficulties occur.

While Deoxyribose Nucleic Acid (DNA), or Nature’s nanotechnology, has proven to be useful for evolution over millennia, adapting it for use in recently developed nanotechnology has proven difficult, time-consuming, and expensive.

Helping to solve this problem is John Chaput and his research team at the Biodesign Institute of Arizona State University, who have now created a more flexible alternative: Glycerol Nucleic Acid (GNA). The advantages include faster mirror image replication, less expense, greater connectivity, and a higher heat tolerance. While still fairly new, the Journal of the American Chemical Society claims the team has been the first to make self-assembled nanostructures with GNA.

With these and many other tools currently available and on the horizon, the only problems left in the future seem to be those we create. Perhaps with enough foresight and responsibility, we will succeed in becoming more than human.

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ASU Biodesign Institute:

Chemical cousin of DNA new nanotechnology building block

April 28, 2008

In the rapid and fast-growing world of nanotechnology, researchers are continually on the lookout for new building blocks to push innovation and discovery to scales much smaller than the tiniest speck of dust.

In the Biodesign Institute at Arizona State University, researchers are using DNA to make intricate nano-sized objects. Working at this scale holds great potential for advancing medical and electronic applications. DNA, often thought of as the molecule of life, is an ideal building block for nanotechnology because they self-assemble, snapping together into shapes based on natural chemical rules of attraction. This is a major advantage for Biodesign researchers like Hao Yan, who rely on the unique chemical and physical properties of DNA to make their complex nanostructures.

The first self-assembled nanostructures composed entirely of glycerol nucleic acid.

Mirror, mirror
Biodesign Institute scientist John Chaput and his research team have made the first self-assembled nanostructures composed entirely of glycerol nucleic acid — a synthetic analog of DNA. The nanostructures contain additional properties not found in natural DNA, including the ability to form mirror image structures. The ability to make mirror image structures opens up new possibilities for nanotechnology.

While scientists are fully exploring the promise of DNA nanotechnology, Biodesign Institute colleague John Chaput is working to give researchers brand new materials to aid their designs. In an article recently published in the Journal of the American Chemical Society, Chaput and his research team have made the first self-assembled nanostructures composed entirely of glycerol nucleic acid (GNA)—a synthetic analog of DNA.

“Everyone in DNA nanotechnology is essentially limited by what they can buy off the shelf,” said Chaput, who is also an ASU assistant professor in the Department of Chemistry and Biochemistry. “We wanted to build synthetic molecules that assembled like DNA, but had additional properties not found in natural DNA.”

The DNA helix is made up of just three simple parts: a sugar and a phosphate molecule that form the backbone of the DNA ladder, and one of four nitrogenous bases that make up the rungs. The nitrogenous base pairing rules in the DNA chemical alphabet fold DNA into a variety of useful shapes for nanotechnology, given that A can only form a zipper-like chemical bond with T and G only pair with C.

In the case of GNA, the sugar is the only difference with DNA. The five carbon sugar commonly found in DNA, called deoxyribose, is substituted by glycerol, which contains just three carbon atoms.

Chaput has had a long-standing interest in tinkering with chemical building blocks used to make molecules like proteins and nucleic acids that do not exist in nature. When it came time to synthesize the first self-assembled GNA nanostructures, Chaput had to go back to basics. “The idea behind the research was to start with a simple DNA nanostructure that we could just mimic.”

The first self-assembled DNA nanostructure was made by Ned Seeman’s lab at Columbia University in 1998, the very same laboratory where ASU professor Hao Yan received his Ph.D. Chaput’s team, which includes graduate students Richard Zhang and Elizabeth McCullum were not only able to duplicate these structures, but, unique to GNA, found they could make mirror image nanostructures.

GNA uses a three carbon sugar called glycerol rather than the five carbon deoxyribose used in DNA.

GNA nanotechnology
The only chemical difference between DNA and a synthetic cousin, GNA, is in the sugar molecule. GNA uses a three carbon sugar called glycerol rather than the five carbon deoxyribose used in DNA. The sugar provides the chemical backbone for nucleic acid polymers, anchoring a phosphate molecule and nitrogenous base (B).

In nature, many molecules important to life like DNA and proteins have evolved to exist only as right-handed. The GNA structures, unlike DNA, turned out to be ‘enantiomeric’ molecules, which in chemical terms means both left and right-handed.

“Making GNA is not tricky, it’s just three steps, and with three carbon atoms, only one stereo center,” said Chaput. “It allows us to make these right and left-handed biomolecules. People have actually made left-handed DNA, but it is a synthetic nightmare. To use it for DNA nanotechnology could never work. It’s too high of a cost to make, so one could never get enough material.”

The ability to make mirror image structures opens up new possibilities for making nanostructures. The research team also found a number of physical and chemical properties that were unique to GNA, including having a higher tolerance to heat than DNA nanostructures. Now, with a new material in hand, which Chaput dubs ‘unnatural nucleic acid nanostructures,’ the group hopes to explore the limits on the topology and types of structure they can make.

“We think we can take this as a basic building block and begin to build more elaborate structures in 2-D and see them in atomic force microscopy images,” said Chaput. “I think it will be interesting to see where it will all go. Researchers come up with all of these clever designs now.”

To read the online publication, go to:
http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/asap/abs/ja800079j.html

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Agenda 21 Summary

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