WATER BASED NANOTECHNOLOGY

Nanotechnology, commonly called as Nanotech, is the field of controlling matter on a molecular or atomic scale. It is an applied science that deals with microscopic engineering of drugs, bots and machines. Due to the developments in Nanotechnology, it has now become possible to make changes and control things at the molecular level in any compound. Numerous biotech companies are now commercializing and developing unique water based resources that will prove to be beneficial for numerous industries such as chemicals, pharmaceutical and biotechnology.

These water-based resources, with the help of nanoparticles present in the water alter the water properties and hence help to create water-based biomaterials. Many companies are now involved in research in the field of life sciences and have started commercializing the solubilization services and water-based products, which are easily soluble in water as well as other fluids.

Water-based Nanotechnology is nothing but these solubilization services. These services play an important role in nanotechnology drug delivery applications. Apart from this, they also play a vital role in the stabilization of a drug.
Benefits of Water-based Nanotechnology
One of the major advantages of Water-based Nanotechnology is its ability to alter the nanoparticles and the properties of water. This provides organization of the water molecules in and around the surroundings. Another benefit of this technology is they help various pharmaceutical companies to enhance the bioavailability and solubility of new and already existing drugs.

Owing to the development of this technology, a large number of fields of sciences will be able to develop eco-friendly technologies in the coming future. It will also help in reducing the water crisis in the near future. To sum up, we can say that water-based nanotechnology will surely pave the future of technology, which will lead us towards the path of sustainable development.

Nanotechnology could provide a rapid DNA sequencing and economic

Suite 3 billion of nitrogenous bases of four different types , the genome contains the plans of operation of our organization.

Its alteration by mutation causes the appearance of diseases or impairments such as cancer and muscular dystrophy . To decipher the genomes of individuals could target these mutations for patients to understand the changes causing the disease, can make predictions for predisposition to certain diseases, making early detection and propose targeted treatment. This is the key to both preventive medicine and completely personalized.

However , these promises can be held only if the decryption – the sequencing of DNA – is fast and inexpensive. Knowing that it took 15 years of efforts, between 1989 and 2004 , and over a billion dollars to achieve completely decipher the human genome under the Human Genome Project ( HUGO ) , must be put in place techniques reducing the costs and time by a factor of 100,000. That’s what the program ” $ 1,000 Genome ” in place in the United States since 2004 in which nanotechnology plays a central role [1,2] . $ 9.5 million of funding has been invested by the National Human Genome Research Institute ( NHGRI ) in this program for Fiscal Year 2010.

DNA and current methods of sequencing

Four building blocks (adenine , thymine, cytosine and guanine – A, T , C and G ) which follow two complementary strands coiled double helix DNA can be compared to a long string of characters . In the case of man, should be 1000 books 700 pages to write all 3 billion letters of the genome . DNA sequencing is complete reading of the 1000 book , letter by letter. The most effective method seems to start by the first page of the first book and perform the decryption letter after letter. But the double helix of DNA has a diameter of 4 nm and the nitrogen bases that constitute the concatenation are spaced 0.34 nm . No instrument can now go to “read ” the molecule at this scale . Researchers have developed the techniques with macroscopic methods available. The analogy with the books can get an idea of the monumental effort it represents .

You have before you 1000 pounds of 700 pages each. On each page , you know there are characters write in invisible ink . You can make a character appear randomly on both the page and whether it is an A, T, C or G. You can also make a layer of the page that allows you to copy the position of letter that you showed .

The Sanger method involves first to tear a page in a book . You get to see a letter on the page and you base the page . The letter goes. Can you get a second letter and get a new layer. The problem is that you can not choose the letter that you appear. We must therefore make thousands of layers to be on seeing all the letters appear on the page. The next step is to order all the layers obtained in order to reconstruct the full sequence of characters on the page . It ‘ll just repeat this work for each of the 700,000 pages to read . The last step is to put these pages in order . This is only possible using supercomputers, capable of finding the overlap between the different pages in order to reconstruct the succession .

This method , long expensive, was the one used in the HUGO project . Copies deciphered sections are made with enzymes whose reliability is not perfect and produce a number of errors. The multiplication of portions to decipher also causes the proliferation of reading errors . It is thus necessary to repeat the operation several times to achieve decoding error rates of 1 per 10,000 bases, set in the context of HUGO .

The pyrosequencing represents the second generation of methods and is now the most common technique employed . It is a sequencing by synthesis. An enzyme creates the complementary strand of the strand to sequence by adding nucleotides one after the other . At each addition, a chemical reaction causes the appearance of a light signal that identifies the nitrogenous base that has been integrated . This method has the advantage of not requiring the reproduction of multi -stranded DNA sequencing . It reduces the costs and delays of a factor 3 compared to the Sanger method .

These last three years, a third generation methods, ” Single Molecule Sequencing Real Time ” made its appearance . She is already using nanotechnology in progress to optimize the pyrosequencing methods . It is again to build the complementary strand of DNA using an enzyme. This time , the fluorophores are directly attached to nucleotides . A nanophotonic structure , called “zero -mode wave guide ” , composed of holes 70 nm in diameter and 100 nm long in a layer of aluminum deposited on a glass ensures effective detection of light signals and allows parallel sequencing many strands . The Companies Pacific Biosciences has received a grant of $ 6.6 million under the program ” $ 1000 genome ” the NHGRI to commercialize the method developed at Cornell University [ 3] .

The methods do not allow second- generation sequencing as pieces composed of a few tens of nitrogenous bases . The third generation improves the performance for the sequencing of strands up to 1000 bases at a speed of 10 bases per second. However , these techniques are limited by the relatively slow speed with which enzymes generate the complementary strand. To overcome these techniques , researchers are working on methods not requiring enzymes and based on “solid state nanopores ” .

The nanopores , key enablers of future sequencing

The development of nanotechnology now allow us to consider the drastic simplification of the sequencing methods . The control of matter at the nanometer scale allows one to create means of direct reading of the sequence of nitrogenous bases of DNA. These techniques are based on the translocation of a strand of DNA through a nanopore .

These nanopores are holes with a diameter of few nanometers , which are made in different materials depending on the technique used. The material separating two liquid media . The strand of DNA , negatively charged , is immersed in an environment negatively charged and is attracted by this solution of the other side of the nanopore , positively charged. This is where the DNA strand through the nanopore that scrolls the reading of nitrogenous bases that is can take place.

The use of nanopores allows playback of long chains of DNA directly without having to duplicate them in quantities as important as what was required by the old methods. The recombination sequences decoded is also simplified because they are much less numerous.

Optical detection

The group of Prof. Amit Meller of Boston University College of Engineering has developed a method for optical detection [4 ]. The technique used is an indirect method of reading DNA . The rope is first converted , each base is translated as a single assembly of two oligonucleotides (series of some bases ) , a method called circular DNA conversion . This single strand of DNA “lying ” is then probed using fluorophore labeled oligonucleotides to obtain double stranded helix ( Figure 2 ).

Passing through the nanopore , drilled in a silicon nitride layer 50 nm thick, the hybridized portion of the strand is detached causing the excitation of fluorophores and the emission of a characteristic light signal . The registration of the succession of these signals by a CCD camera to trace the sequence of oligonucleotides and therefore nitrogenous bases of DNA strand initial [5,6].

The frequency of reading is between 50 and 250 bases per second. By improving the technology through the use of four fluorophores instead of 2 now, researchers hope to reach frequencies of 500 bases per second. Restricting the technique is linked to the procurement capacity of the CCD camera becomes the limiting factor . By improving the camera, it will be possible to accelerate the process since the speed of the blade through the nanopore is controlled precisely.

A quick calculation to realize that even at a rate of 500 continuous bases read per second , it takes 70 days in order to decipher the entire genome of an individual. The main advantage of optical detection lies in the fact that the parallel between nanopores presents no difficulty. Thus , instead of using a single pore , the researchers plan to build hundreds of nanopore arrays facing an acquisition matrix CCD ( Figure 3 ) . Each pixel of the CCD acquires the light signals emitted by a nanopore.

This net benefit outweighs the main drawback of the method is the conversion step of the DNA strand in a string of oligonucleotides and hybridization . The commercialization of this method is considered by the creation of a start – up, NobleGen Biosciences , Inc. .

Electrical detection

Other methods are developed based on the detection of variation of electric current at the nanopore during the passage of different nitrogen bases during translocation . These techniques require immobilization of the DNA strand at each nitrogenous base to allow the acquisition of the measure .

To check this , the IBM researchers have developed a transistor DNA . It is a multilayer structure of nanometric thickness is dug in which a nanopore . The succession of conductive and insulating layers of the structure to control the passage of DNA strands in the nanopore to carry out the measures necessary for the identification of nitrogenous bases. To conduct this work, the IBM researchers are associate researchers at Roche to combine expertise in microelectronics , information technology and computational biology skills in the first sequencing of the second. Roche is in fact the current leader of the sequencing methods with automatic equipment developed by his firm 454 Life Sciences was founded in June 2000 [7] .

The main advantage of the electrical detection comes from the fact that the strands of DNA can be analyzed directly . However , the nitrogen bases are separated by only 0.34 nm , this involves securing an extreme precision in the manufacture of multilayer transistor DNA . For now , theoretical models and numerical simulations indicate that this is possible . The practical realization of the structure remains to be demonstrated. A conversion step , identical to that used by the team of Prof. Miller might be necessary.

This need for precision could be obtained using graphene . A team from the University of Pennsylvania has developed a structure comprising a nanopore in a graphene layer (Figure 1) [ 8]. The layer is monatomic, its thickness is less than the distance between two nitrogen bases . However, to improve the robustness of the nanopore and improve the signal to noise ratio of the measurement of electric current , the graphene layer is coated with titanium oxide . If the detection step is improved by the layer of graphene , the team must work on controlling the scrolling of the strand of DNA in the nanopore.

A team of researchers at Arizona State University have used carbon nanotubes as nanopores [9] . Variations of currents in the nanotubes recorded during the passage of DNA strands that would suggest possible to control and perform a reading of nitrogenous bases using nanotubes. However, modeling is needed to understand the mechanisms of electronic interaction between the nanotubes and the DNA strands .

The main difficulty of using nanopore technology is to control the speed of DNA migration . The methods developed using all cylindrical nanopores . A team from Sandia National Laboratories in New Mexico is developing a nanopore sawtooth slowing the translocation of DNA by a factor of 5 (Figure 4 ) [ 10 ].

Another advance has been published by researchers at the University of Washington [ 11 ]. Jens Gundlach ‘s team used a nanopore of organic origin . This is a barrel -shaped protein , porin , which ensures the exchange of certain molecules in the membranes of bacteria. It took a change of these bacteria , M. smegmatis to produce a suitable nanopore . The transition of DNA in the nanopore is a variation of ion current to the translocation of the strand . Each nitrogenous base induces a different variation of this current which identifies them .

But it takes a millionth of a second nitrogenous base that passes through the nanopore. Too fast for a reading of the strand. To control the speed of translocation , the researchers used a method of extending the genome. They have added a section of DNA double strand between each of the nitrogenous bases of single-stranded sequence . The double strands are too large to pass through the pore . They then blocked the translocation till they split . Researchers have created a barrier that stops the translocation for a few milliseconds, the time to capture the signal of the nitrogen base to identify.

Conclusion

In 10 years, the evolution of techniques of DNA sequencing has been spectacular . The first generation method is exceeded, the second is heavily used , the third is nearing commercialization , and in their laboratories , researchers are preparing already the fourth generation that looks revolutionary.

Nanotechnology will soon allow ” read “the DNA in the same way that a laser beam reads the estate of a CD . However, beyond the technical difficulty of developing an effective reader , the sequencing of DNA leads to other problems . How , for example , store and manage the huge amount of data represented by the DNA sequencing of millions of people ? How to protect data ?

If knowledge of the individual genome will provide individualized medical responses , it may also be the source of discrimination, particularly on the part of health insurance policies . To solve these ethical problems, Congress passed, almost unanimously , May 21, 2008 , the Genetic Information Nondiscrimination Act (GINA) . This law prohibits discrimination on the genome. Will there be enough to ensure a beneficial use of sequencing the human genome?

Atomic antennas transmit quantum information across a microchip

Quantum Computer – Tune in Now!

The Austrian research group led by physicist Rainer Blatt suggests a fundamentally novel architecture for quantum computation. They have experimentally demonstrated quantum antennae, which enable the exchange of quantum information between two separate memory cells located on a computer chip. This offers new opportunities to build practical quantum computers.

Photo: Quantum antennae enable the exchange of quantum information between two separate memory cells located on a computer chip. (Graphics: Harald Ritsch)

Six years ago scientists at the University of Innsbruck realized the first quantum byte – a quantum computer with eight entangled quantum particles; a record that still stands. “Nevertheless, to make practical use of a quantum computer that performs calculations, we need a lot more quantum bits,” says Prof. Rainer Blatt, who, with his research team at the Institute for Experimental Physics, created the first quantum byte in an electromagnetic ion trap. “In these traps we cannot string together large numbers of ions and control them simultaneously." To solve this problem, the scientists have started to design a quantum computer based on a system of many small registers, which have to be linked. To achieve this, Innsbruck quantum physicists have now developed a revolutionary approach based on a concept formulated by theoretical physicists Ignacio Cirac and Peter Zoller. In their experiment, the physicists electromagnetically coupled two groups of ions over a distance of about 50 micrometers. Here, the motion of the particles serves as an antenna. “The particles oscillate like electrons in the poles of a TV antenna and thereby generate an electromagnetic field,” explains Blatt. “If one antenna is tuned to the other one, the receiving end picks up the signal of the sender, which results in coupling.” The energy exchange taking place in this process could be the basis for fundamental computing operations of a quantum computer.

Antennae amplify transmission

“We implemented this new concept in a very simple way,” explains Rainer Blatt. In a miniaturized ion trap a double-well potential was created, trapping the calcium ions. The two wells were separated by 54 micrometers. “By applying a voltage to the electrodes of the ion trap, we were able to match the oscillation frequencies of the ions,” says Blatt. “This resulted in a coupling process and an energy exchange, which can be used to transmit quantum information.” A direct coupling of two mechanical oscillations at the quantum level has never been demonstrated before. In addition, the scientists show that the coupling is amplified by using more ions in each well. “These additional ions function as antennae and increase the distance and speed of the transmission,” says Rainer Blatt, who is excited about the new concept. This work constitutes a promising approach for building a fully functioning quantum computer. “The new technology offers the possibility to distribute entanglement. At the same time, we are able to target each memory cell individually,” explains Rainer Blatt. The new quantum computer could be based on a chip with many micro traps, where ions communicate with each other through electromagnetic coupling. This new approach represents an important step towards practical quantum technologies for information processing.

The quantum researchers are supported by the Austrian Science Fund FWF, the European Union, the European Research Council and the Federation of Austrian Industries Tyrol.

Implant Micro-Worms Under Your Skin To Monitor Your Long-Term Health

Researchers at MIT and Northeastern have come up with a new system for monitoring biomedical indicators — such as levels of sodium or glucose in the blood — that could someday lead to implantable devices that would allow, for example, people with diabetes to check their blood sugar just by glancing at an area of skin.

A scanning electron microscope image shows a bundle of 'microworms' produced using a vapor-deposition process developed by researchers at MIT and Northeastern.
Photo courtesy of Gleason Lab

A number of researchers have developed microparticle-based systems — hollow, microscopic particles filled with specific chemicals — for monitoring biomedical conditions or for the selective delivery of drugs to certain organs or areas of the body. But one drawback of these systems is that the particles are small enough to be swept away from the initial site over time. The new system involves a different kind of microparticle that can avoid this problem.

While traditional particles are spherical, the new particles are shaped like long tubes. The tubes’ narrow width, which is comparable to that of the previously studied microparticles, keeps the tubes’ contents in close proximity to blood or body tissue, making it easy for the particles to sense and respond to chemical or other conditions in their surroundings. The tubes’ relatively greater length keeps the tubes very well anchored in place for long-term monitoring, perhaps for months on end.

The particles eventually could be used to monitor the glucose levels of diabetics or the salt levels of those with a condition that can cause swings in blood salt concentrations.

The new findings are being reported in the journal Proceedings of the National Academy of Sciences, in a paper published online in January and soon to appear in the print version. It was co-authored by Karen Gleason, the Alexander and I. Michael Kasser Professor of Chemical Engineering at MIT; Heather Clark, professor of pharmaceutical science at Northeastern University; MIT postdoctoral researcher Gozde Ozaydin-Ince; and Northeastern doctoral student J. Matthew Dubach.

The process of creating the new nanoparticles is an offshoot of Gleason’s work on a method of coating materials by vaporizing the coating material and letting it deposit on a surface to be coated. In work published last month, she and her co-workers had shown that this technique — called chemical vapor deposition (CVD) — could be used to coat a material containing microscopic pores, thus making the pores even smaller and giving them a surface that could respond to the chemical properties of materials passing through them.

This new work uses CVD to coat an aluminum oxide layer that has been etched to contain tiny pores, and, as in the previous work, the coating extends down onto the walls of these pores. But then the coated material itself is dissolved away, leaving just a series of hollow tubes where the pores used to be. Before that, though, another material can be added — something that responds to the environment, or a drug to be delivered, for example. The tubes are then capped at either end.

Gleason explains that these “microworms,” as she calls them, can then be injected under the skin to form a fluorescent “tattoo.” By filling the tiny hollow tubes with a material that fluoresces — that is, emits light of a particular color — in response to the presence of a specific chemical, “the degree of fluorescence provides continuous physiological monitoring of a specific chemical” in the body, and can be monitored right through the skin. The light emitted by the fluorescing chemical “is visible to the human eye, and thus can be directly interpreted by the patient without the need for bulky monitors,” she says.

While the initial microworms were made to detect salt levels, and were successfully tested in mice, there are a variety of potential applications, Gleason says. One significant possibility is measuring glucose levels: “Tight control over glucose levels can help individuals stave off the devastating side-effects of diabetes, the number one cause of kidney failure, blindness in adults, nervous system damage, and amputations and also a major risk factor for heart failure, stroke and birth defects,” she says. Diabetes currently affects more than 20 million people in the U.S., and that is expected to double in 25 years.

The tubes are so tiny — about 200 nanometers across, or less than one-hundredth the width of a human hair — that “the body doesn’t even think they’re there,” Gleason says, allowing them to operate in “stealth mode” without triggering any physical response.

Raoul Kopelman, the Richard Smalley Distinguished University Professor of Chemistry, Physics and Applied Physics and Research Professor of Biomedical Engineering at the University of Michigan, calls this “high quality work by an expert team,” and says, “In principle, this could open the way for avoiding blood tests, which need a central lab, expert nurses, extra time and extra costs. It could be done in a doctor's office, or even at home. It will also avoid complications for patients with ‘difficult,’ or ‘used-up’ veins, patients on blood thinners, etc.” However, he cautioned that “The biggest stumbling block is the safety factor, i.e. FDA approval. FDA might not only worry about long-term chemical toxicity and bio-elimination, but also about complications — i.e., could it trigger blood clots?”

In addition to the fact that these microworms stay in place when injected into the body, their manufacturing process itself provides a significant advantage, Gleason says. Because CVD is a standard manufacturing method used in the semiconductor industry, the manufacture of these devices should be relatively easy and inexpensive.

Gleason says, “One can imagine using these kinds of tubes to shrink-wrap just about anything,” including drugs that could be delivered slowly over time through small openings in the tubes.

Power All Over Your Body...Just Do it

We know that you can transform the mechanical motions of your body into electrical energy, like when you turn the crank or shake a mechanically-powered flashlight. These types of mechanical motions are quite large compared to many of the day-to-day (and minute-to-minute) actions you perform–for example walking, breathing, and thumb wrestling.

What if we could harvest energy from these tiny movements? Researchers at the Korea Advanced Institute of Science and Technology are seeking the answer to this question with piezoelectric barium titanate. The electrical output of their devices is very small (in the nanoAmps) but over a long period and over many repetitions it would be possible to run a small electric device–even a biologically-embedded one. An alternative to blood power?

There is clearly a lot of potential in this technology, and we’ll be interested to see if and when we can start messing around with this stuff. Heck, it’s already been used to power a small LED and you all know just how much everyone would jump at the chance to cover themselves in self-powered LEDs…

Everything from industrial equipment to the human body loses some of the energy it uses to things like heat and vibrations. The ability to harvest some of this energy is usually pretty limited, as small heat differences and weak movements are difficult to concentrate into significant amounts of useful energy. But even an inefficient conversion can be sufficient to provide power for small energy-efficient devices, such as medical implants and short-range transmitters, so researchers are working on developing materials that can convert environmental noise into small amounts of useful energy. In a recent example of this work, researchers have demonstrated that they can print a bio-compatible device that can harvest the stress created when it's flexed to produce over 10 nanoAmps of current.

The device relies on the piezoelectric effect. A number of crystals, when stressed, create small amounts of current. That stress doesn't have to be extreme—the vibrations, flexing, and twisting that normally occur in many situations is sufficient to create a small charge. The individual events may not be enough to do much, but combined with a good rechargeable battery or capacitor, they can be sufficient to provide enough power for devices that only operate intermittently. The lab behind the new work, for example, created a piezoelectric device that filled capacitors with enough power to run an LED.

There have been a number of hurdles to clear in order to make these devices, however. If they're overly large, the crystals can break under the strain of typical flexing, ruining the hardware. So both the piezoelectric material, along with the wiring necessary to harvest the potential that develops in it, have to be made at very small scales (on the order of tens of micrometers). For common usage, we'd also have to avoid using any materials that have problems with toxicity, especially if we're considering these for use in medical devices.

The new work involves barium titanate (BaTiO₃), which is apparently biocompatible and comes from a family of materials that have excellent piezoelectric performance. But, perhaps more significantly, it describes how to print a large number of piezoelectric crystals onto a flexible substrate.

The first step in the process is a layer-by-layer deposition of the barium titanate and two conductive metals on top of a hard silicon substrate. That material is then etched to both cut it free from the underlying silicon (which doesn't flex well) and to create an array micrometer-sized piezoelectric device. This is where the printing comes in. A flexible plastic stamp can be used to pick up these pieces and deposit them in an organized array within some epoxy, which is then cured to lock them in place. Wiring is dropped on top to link everything up, and then a new layer of epoxy seals the whole thing up. A flexible plastic sheet gives the whole thing some robustness.

With everything wired up, the researchers put it to the test by having someone pick it up and flex the plastic (don't worry—he or she was wearing gloves). Each flex triggered a short pulse of current (about 10 nanoAmps); releasing the strain produced a similar burst with an opposite polarity. Each of these was about a third of a volt. The authors calculate the power density of their device as about seven milliWatts per cubic centimeter.

Again, that's not going to power the next-generation electric car. But it could be sufficient to charge a small device that only needs to operate sporadically. The researchers envision harvesting power from things like the flexing of hiking boots or the changes in the chest that accompany breathing.

The authors wrap up by pointing out that there are other materials similar to barium titanate that have even better piezoelectric properties, so this new device may be on the low end of what's possible. They're not the only lab working on this, so these flexible devices may find their way into some real-world applications before too long.

Researchers Shine Light on Gold Nanoparticles to Produce Electricity

Not only are these gold nanoparticles gorgeous to look at – they may one day act as microscopic powerhouses for molecular machines. Researchers at the Nano/Bio Interface Center at the University of Pennsylvania recently discovered a novel to way to generate solar power by shining light onto gold nanoparticles. The discovery has far-reaching implications in the realm of nanotechnology, and may open the door for everything from self-powering molecular circuits to super-efficient data storage.

To generate current the researchers first packed a bunch of light-sensitive gold nanoparticles together on a glass substrate and then exposed them to optical radiation (light). This knocks conductive electrons free from the gold particles, which run along the surface to create surface plasmons, which in turn induce an electrical current across the molecules.

The amount of electricity generated is minute, but the researchers believe that by optimizing size, shape, and orientation of the nanparticles they could create a current strong enough to power nano-sized circuits. Professor Bonnell, who participated in the experiment, said “If the efficiency of the system could be scaled up without any additional, unforeseen limitations, we could conceivably manufacture a 1A, 1V sample the diameter of a human hair and an inch long“.

Turning sunlight into electrical power is all but a new problem, but recent advancements made by researchers at the University of Pennsylvania have given a new twist to the subject. While not currently aimed at solar panel technology, their research has uncovered a way to turn optical radiation into electrical current that could lead to self-powering molecular circuits and efficient data storage.

Professor of materials science Dawn Bonnell and colleagues placed light-sensitive gold nanoparticles on a glass substrate, minimizing the distance between the nanoparticles. The team then stimulated conductive electrons with optical radiation to ride the surface of the gold nanoparticles, creating so-called "surface plasmons" that induce electrical current across molecules.

Under these conditions, surface plasmons were found to increase the efficiency of current production by a factor of four to 20. The size, shape and separation of the array of golden nanoparticles can be customized independently of the optical characteristics of the molecule, and optimization of these parameters could, the researchers say, produce enhancement factors of thousands, and the resulting electrical current could be easily transported to the outside world.

"If the efficiency of the system could be scaled up without any additional, unforeseen limitations, we could conceivably manufacture a 1A, 1V sample the diameter of a human hair and an inch long," Prof Bonnell explained.

The results may lead to better nano-sized circuits that can power themselves, potentially through sunlight. Another interesting application suggested by the researchers could be for data storage, where a photovoltaic circuit could encode bits using wavelengths of light rather than electrical charge.

The study, published in the current issue of the journal ACS Nano, was supported by the Nano/Bio Interface Center, National Science Foundation, the John and Maureen Hendricks Energy Fellowship and the US Department of Energy.

Embed tiny solar cells in your body to fight cancer

By bringing the field of photovoltaics into medicine, researchers hope to create a far more precise method of drug delivery for fighting cancer. That's right - this cancer cure involves tiny photovoltaic particles like the kind used in solar cells.

One of the major drawbacks of chemotherapy is that it damages far more of the body than just the malignant tumors it's used to fight. In order to target just the cancerous areas, and not hit everything on the way there, researchers from the University of Texas in El Paso created a tiny solar cell. They attached model drugs to each side of the cell, one of which was positively charged, the other negatively. Once the tiny solar devices are in the body, they're targeted with an infrared or laser light blast, causing it to release the drugs.

This would mean the medication would only be released at a specific juncture, and could be used to deliver the medical payload extremely specifically, and altering the intensity of light would control how much of the drug would be released.

At present, this work is just a proof of concept, and has a significant amount of work to go. We reported on a similar technique in November using fuzzy nanocubes.

Drugs Encapsulated in Nanoparticles

Clinical trials using patients’ own immune cells to target tumors have yielded promising results. However, this approach usually works only if the patients also receive large doses of drugs designed to help immune cells multiply rapidly, and those drugs have life-threatening side effects.
MIT engineers have developed a way to attach drug-carrying pouches (yellow) to the surfaces of cells.
Image: Darrell Irvine and Matthias Stephan
Now a team of MIT engineers has devised a way to deliver the necessary drugs by smuggling them on the backs of the cells sent in to fight the tumor. That way, the drugs reach only their intended targets, greatly reducing the risk to the patient.

The new approach could dramatically improve the success rate of immune-cell therapies, which hold promise for treating many types of cancer, says Darrell Irvine, senior author of a paper describing the technique in the Aug. 15 issue of Nature Medicine.

“What we’re looking for is the extra nudge that could take immune-cell therapy from working in a subset of people to working in nearly all patients, and to take us closer to cures of disease rather than slowing progression,” says Irvine, associate professor of biological engineering and materials science and engineering and a member of MIT’s David H. Koch Institute for Integrative Cancer Research.

The new method could also be used to deliver other types of cancer drugs or to promote blood-cell maturation in bone-marrow transplant recipients, according to the researchers.

T-cell therapy

To perform immune-cell therapy, doctors remove a type of immune cells called T cells from the patient, engineer them to target the tumor, and inject them back into the patient. Those T cells then hunt down and destroy tumor cells. Clinical trials are under way for ovarian and prostate cancers, as well as melanoma.

Immune-cell therapy is a very promising approach to treating cancer, says Glenn Dranoff, associate professor of medicine at Harvard Medical School. However, getting it to work has proved challenging. “The major limitation right now is getting enough of the T cells that are specific to the cancer cell,” says Dranoff, who was not involved in this study. “Another problem is getting T cells to function properly in the patient.”

To overcome those obstacles, researchers have tried injecting patients with adjuvant drugs that stimulate T-cell growth and proliferation. One class of drugs that has been tested in clinical trials is interleukins — naturally occurring chemicals that help promote T-cell growth but have severe side effects, including heart and lung failure, when given in large doses.

Irvine and his colleagues took a new approach: To avoid toxic side effects, they designed drug-carrying pouches made of fatty membranes that can be attached to sulfur-containing molecules normally found on the T-cell surface.

In the Nature Medicine study, the researchers injected T cells, each carrying about 100 pouches loaded with the interleukins IL-15 and IL-21, into mice with lung and bone marrow tumors. Once the cells reached the tumors, the pouches gradually degraded and released the drug over a weeklong period. The drug molecules attached themselves to receptors on the surface of the same cells that carried them, stimulating them to grow and divide.

Within 16 days, all of the tumors in the mice treated with T cells carrying the drugs disappeared. Those mice survived until the end of the 100-day experiment, while mice that received no treatment died within 25 days, and mice that received either T cells alone or T cells with injections of interleukins died within 75 days.

The study was funded by the National Institutes of Health, the National Science Foundation, the National Cancer Institute and a gift to the Koch Institute from Curtis ’63 and Kathy Marble.

‘A much simpler procedure’

Irvine’s approach to delivering the adjuvant drugs is both simple and innovative, says Dranoff. “The idea of modifying T cells in the lab to make them work better is something many people are exploring through more complicated approaches such as gene modification,” he says. “But here, the possibility of just attaching a carefully engineered nanoparticle to the surface of cells could be a much simpler procedure.”

While he is now focusing on immune-cell therapy, Irvine believes his cell pouches could be useful for other applications, including targeted delivery of chemotherapy agents. “There are lots of people studying nanoparticles for drug delivery, especially in cancer therapy, but the vast majority of nanoparticles injected intravenously go into the liver or the spleen. Less than 5 percent reach the tumor,” says Irvine, who is also a Howard Hughes Medical Institute Investigator.

With a new way to carry drugs specifically to tumors, scientists may be able to resurrect promising drugs that failed in clinical trials because they were cleared from the bloodstream before they could reach their intended targets, or had to be given in doses so high they had toxic side effects.

Irvine and his colleagues also demonstrated that they could attach their pouches to the surface of immature blood cells found in the bone marrow, which are commonly used to treat leukemia. Patients who receive bone-marrow transplants must have their own bone marrow destroyed with radiation or chemotherapy before the transplant, which leaves them vulnerable to infection for about six months while the new bone marrow produces blood cells.

Delivering drugs that accelerate blood-cell production along with the bone-marrow transplant could shorten the period of immunosuppression, making the process safer for patients, says Irvine. In the Nature Medicine paper, his team reports successfully enhancing blood-cell maturation in mice by delivering one such drug along with the cells.

Irvine is now starting to work on making sure the manufacturing process will yield nanoparticles safe to test in humans. Once that is done, he hopes the particles could be used in clinical trials in cancer patients, possibly within the next two or three years.

Tiny Titanium Origami Highlights New Method Of Micro-Construction

Origami Crane Folded From Printed Sheet of Titanium Hydride This crane is only the size of a penny. University of Illinois , via EurekAlert

While three-dimensional printing has come a long way, engineers still struggle with fabricating objects smaller than a quarter. In those small structures, the upper layers crush and distort the weak lower ones. To solve this problem, researchers at the University of Illinois have come up with a novel solution: print out a flat sheet, and then fold it, origami style, into the desired shape. Creating this origami crane as proof of concept, the researchers have hit upon a technique that could produce any number of microscopic medical or mechanical devices through folding, rather than layered printing.

The researchers start by printing out a flat sheet of titanium hydride. Normally, this material is too rigid to fold, but the printing process imbues the "ink" with a number of solvents that soften it up enough for manipulation. In the case of the crane, it took 15 steps to go from a flat sheet to a finished bird.

This material is malleable enough to fold, but strong enough to retain its shape once the folding process is complete. Additionally, titanium hydride can be treated after folding to become pure metallic titanium. That way, a potential medical device could be folded into the desired shape, and then transformed into a substance that the body wouldn't reject.

The scientists have just begun to explore the implications of this technique, so it might be a while before a doctor actually uses a stent or implant created by folding titanium hydride. However, Japanese legend holds that if someone folds 1,000 origami cranes, a real crane will grant their wish. So all the researchers need to do is fabricate 999 more of these, and just wish for a practical application for this technology to arrive within a year. Easy!

Computer-Controlled Swarm of Bacteria Builds Tiny Pyramid

Researchers are putting swarms of bacteria to work, using them to perform micro-manipulations, propel microrobots, and act as biosensors

Researchers at the NanoRobotics Laboratory of the École Polytechnique de Montréal, in Canada, are putting swarms of bacteria to work, using them to perform micro-manipulations and even propel microrobots.

Led by Professor Sylvain Martel, the researchers want to use flagellated bacteria to carry drugs into tumors, act as sensing agents for detecting pathogens, and operate micro-factories that could perform pharmacological and genetic tests.

They also want to use the bacteria as micro-workers for building things. Things like a tiny step pyramid.

The video below shows some 5000 bacteria moving like a swarm of little fish, working together to transport tiny epoxy bricks and assemble a pyramidal structure -- all in 15 minutes. The video was presented at IROS last year, along with a wonderfully titled paper, "A Robotic Micro-Assembly Process Inspired By the Construction of the Ancient Pyramids and Relying on Several Thousands of Flagellated Bacteria Acting as Workers."

The bacteria, of a type known as magnetotactic, contain structures called magnetosomes, which function as a compass. In the presence of a magnetic field, the magnetosomes induce a torque on the bacteria, making them swim according to the direction of the field. Place a magnetic field pointing right and the bacteria will move right. Switch the field to point left and the bacteria will follow suit.

Each bacterium has flagella capable of generating about 4 picoNewtons. It's a very small amount of thrust force, but put thousands of bacteria to work together and they can move mountains. Well, micro mountains.

Several research groups are trying to develop MEMS devices that emulate the propulsion mechanisms of bacteria. Martel asks, Why mimic the bacteria when you can use the little things themselves?

Martel and his colleagues developed an electronic microcircuit that contains both the bacteria and an array of conductors that produce magnetic fields. By carefully controlling which conductors are active, the microcircuit can make the bacteria move in specific directions. A computer and an optical microscope provide a feedback loop, tracking the motion of the bacteria and adjusting the conductors to achieve the desired behavior.

In addition to pyramid building, Martel's bacteria has done some other neat tricks, such as traveling through the bloodstreams of rats, steered by an MRI system, a la "Fantastic Voyage."

One of their current projects is developing an autonomous bacterial microrobot. They plan to use standard CMOS processes to create a chip containing both electronics and bacteria. The bacteria would reside in micro-reservoirs designed to generate thrust. For control, small conductors inside each reservoir would produce magnetic fields.

Several of these microrobots could then be used to perform tasks collectively, perhaps one day swimming inside our bodies, delivering drugs, detecting disease, and fixing an organ here, a blood vessel there. Who knew bacteria could be good robots?

UPDATE: If you're wondering which ancient pyramid inspired the researchers -- and is shown in the video on the left bottom corner -- it's the Djoser step pyramid, in Egypt, which the researcher note was "an important, initial milestone in the history of man-made structures."

Images and video: NanoRobotics Laboratory, École Polytechnique de Montréal

Self-Assembling DNA Makes Super 3-D Nano Machines

William Shih has a bridge to sell, but you’ll need a powerful microscope to see it: It’s built entirely from DNA strands, handrails and all.

The bridge is just one of a whole range of intricate three-dimensional shapes Shih has crafted using DNA’s unique capacity for precise self-assembly. In a study Thursday in Science, his team has shown they can even control the precise curvature of these tiny structures, which is key to making wheels, hooks and gears.

Unlike building nano portraits of Obama, This isn’t just an artistic exercise. Scientists in the burgeoning field of structural DNA nanotechnology are exploring DNA’s potential as raw material for next-generation circuits, sensors and biomedical devices. Advocates say it could become the new go-to material for engineers, scientists and clinicians.

“DNA is the world’s greatest architectural material, in my opinion,” said NYU chemist Ned Seeman, the field’s founder and lonely apostle.

In addition to its well-known sequence specificity — A only binds T, G only binds C — DNA’s structural properties have been intensely studied for over half a century, and one can predict the atomic-level structure of virtually any DNA construct with remarkable accuracy. Since the 1980s, Seeman has been quietly designing DNA strands that self-assemble into interlocking tiles, three-dimensional polyhedrons and even nanomachines that automatically ‘walk’ along other DNA strands.

In 2006, the technology finally entered the scientific limelight, heralded by a Nature cover festooned with cheerful smiley faces, each composed of a long, folded strand of DNA meticulously wrangled into shape with tiny DNA “staples,” a technique that its inventor, CalTech computer scientist Paul Rothemund, termed “DNA origami.”

“There are at least a dozen groups focusing on things [Seeman] invented, and a larger number working on this at the periphery,” said Shih, who is at the Dana-Farber Cancer Institute.

In May, scientists at Copenhagen’s Center for DNA Nanotechnology described a DNA-based box with a lid that stays locked until exposed to a DNA-based key, which prompts the lid to pop open and potentially release a drug. A team led by McGill University chemist Hanadi Sleiman is also building DNA cages and nanotubes for delivering treatments.

“This might be the kind of thing that comes into cells and only opens up when it’s triggered by a gene that’s overexpressed in very specific cells,” Sleiman said.

But perhaps the field’s greatest promise is in using DNA as a foundation for more sophisticated devices.

Because complementary DNA sequences recognize each other, short DNA strands can act as “address labels” to direct cargos to exact locations on a larger DNA origami scaffold. Tagged proteins, chemical compounds and even nanoscale electronic components are able to find and claim their proper positions with atomic-scale precision to form complex molecular machines that essentially build themselves.

In the latest study, Shih’s team created curves in DNA structures by adding or deleting DNA base pairs to create tension that causes the strands to bend.

“DNA structures are the ’smart’ materials which we use to assemble ‘dumb’ materials, but these dumb materials can have other interesting properties,” said Duke University chemist/computer scientist Thom LaBean, who is currently working on tiny DNA-templated wires and single-electron transistors that could convert DNA scaffolds into nanoscale circuitboards.

LaBean is also working on ‘biocomputers’ made from DNA, RNA and protein that respond to biological signals. For example, A DNA-based sensor that recognizes RNA messages produced because of cancer or viral infection could trigger the release of RNA or DNA strands with therapeutic properties.

Such applications should benefit considerably from the new three dimensional opportunities.

“Distances can be shorter, and you can get a lot more stuff into 3D than 2D,” Seeman said. “Ultimately, self-assembly in 3D will enable things that self-assembly in 2D won’t.”

One possibility, being developed by Sleiman, is a DNA solar cell that incorporates metal atoms and other chemical components to mimic the efficient mechanisms bacteria use to derive energy from the sun.

“Nature just positions all these different functional elements exactly right in three-dimensional space in order to create this bacterial photosynthesis machine,” she said. “And no self-assembling system can rival what DNA can do in terms of positioning.”

There are of course obstacles, such as finding cheaper ways to produce bulk quantities of DNA, optimizing the design and construction process, and demonstrating safety in humans.

Even more fundamental are the matters of convincing a skeptical scientific community and acquiring funding. Recruiting people who can wrap their heads around such highly interdisciplinary work, which brings together elements of biology, physics, chemistry, computer science and materials, is also a challenge.

On the other hand, the inherent sexiness of DNA nanotechnology makes it an easy sell for prestigious journals like Science and Nature, and most practitioners seem optimistic that the scientific community will ultimately recognize the power of structural DNA nanotech.

“I think the general idea of being able to control the fine structure of matter… could potentially affect a lot of areas of technological interest,” Shih said. “We need some more killer applications, and then we’ll punch through the threshold, and there will be more general appreciation for this field.”

Image: Science/AAAS

Silicone Implants Become Energy-Harvesting Devices

Bringing cosmetic implants into the new energy age

Energy-Harvesting Implant Flexing our way into the future -- Princeton engineer Michael McAlpine and colleagues have turned silicone rubber sheets into electrical generators. Frank Wojciechowski/Princeton University

Natural body movements such as breathing and walking could soon power pacemakers and maybe even give some extra juice to your future iPad purchase. Princeton University engineers have turned silicone rubber sheets into piezoelectric materials that create electricity when flexed, which opens up a whole range of possible applications worn outside the body or implanted in strategic locations. The Register also highlights a researcher statement about how silicone has already proven "biocompatible" through usage in cosmetic implants.

This latest research represents the first successful combination of silicone and nanoribbons made of lead zirconate titanate (PZT). The latter has piezoelectric characteristics that allow it to generate electrical voltage when squeezed or pressured, and can convert 80 percent of mechanical energy into electrical energy -- the most efficient piezoelectric material of the moment.

"PZT is 100 times more efficient than quartz, another piezoelectric material," said Michael McAlpine, a mechanical and aerospace engineer at Princeton, who led the project. "You don't generate that much power from walking or breathing, so you want to harness it as efficiently as possible."

McAlpine and his colleagues suggested applications such as shoes that help power mp3 players or smart phones. There's even the thought of placing silicone sheets against the lungs to harness natural breathing motions to power pacemakers, as opposed to using batteries that require surgical replacement when they run down.

The Princeton work received funding from the U.S. Intelligence Community, a cooperative of federal intelligence and national security agencies. So it's a safe bet that for the moment, spooks may benefit from this work more than top-heavy celebrities. But anyone hankering to get their power walk on now can consult one of Popsci's own DIY gurus.

Heat-Channeling Carbon Nanotubes Produce 100 Times More Energy than Li-ion Batteries

Nanotube Heat Wave And it burns, burns, burns ... MIT

Johnny Cash can't have known about carbon nanotubes when he sang about that burning ring of fire, but MIT scientists have shown how the tiny tubes can channel a ring of heat that creates electrical current -- about 100 times as much energy per unit of weight when compared with a lithium-ion (Li-ion) battery.

The new experiments involved nanotubes, or submicroscopic structures just a few billionths of a meter in diameter, that can conduct both electricity and heat. Engineers coated the nanotubes with reactive fuel that produces heat by decomposing, and then ignited it with laser beams or high-voltage sparks.

That set off a fast-moving heat wave that traveled through the nanotube's hollow cylinder 10,000 times faster than in the reactive fuel itself, and reached a temperature of 4,940 degrees F (3,000 Kelvin). The fast-moving heat also pushed electrons along the tube and created a noticeable electrical current.

Such combustion waves were studied mathematically for a century, according to Michael Strano, a chemical engineer at MIT. Strano first predicted that a nanotube or nanowire could channel the heat pulse and create electrical current, but now his group has realized that prediction.

Some semiconductor materials can also produce an electric current when heated, but the carbon nanotube experiments defy predictions by thermoelectric calculations. Strano noted that the heat wave seemed to carry along electrons or other electrical charge carriers, not unlike how an ocean wave can pick up debris.

The possibility of creating substantial energy on such a tiny scale could lead to new ultra-small electronic devices the size of rice grains, whether for implantable medical chips or other tiny sensor applications.

Strano's MIT group plans to continue improving the efficiency and cut back on wasted energy given off as heat and light. Strano also suggested that a different reactive fuel coating for the nanotubes might produce alternating current -- an intriguing contrast to current energy-storage systems that all produce direct current.

NANOTECHNOLOGY TO TREAT CANCER

NANOTECHNOLOGY TO TREAT CANCER

Nanotechnology To Treat Cancer
U.S. - A team of researchers from Harvard University and the Institute of Technology Massachusetts (MIT) has developed a new way of treating cancer by administering the treatment only to diseased cells without killing cells.

Current treatments against cancer certainly target the diseased cells but also reach those in good health. This new treatment will prevent the growth of cancer cells with cytotoxic agents, while preserving tissue not involved.

This team of researchers led by Dr Basu has made chemically modified nanoparticles to target and prevent signaling pathway proteins providing cellular proliferation. By blocking these signaling pathways, cancer cells were not able to multiply.

Nanoparticles target cancer cells while and allow chemotherapy agents act directly on them. Targeting only those cells and predispose them to receive treatment would use doses of medication weaker and more tailored to the patient. Side effects are less evident and treatment easier to live for the patient.

Tests performed in the laboratory, combining nanoparticles and a drug cisplatin (which is used to treat several types of cancer) have demonstrated the effectiveness of this process to inhibit the development of cancerous cells and even kill them. Tests on mice with melanoma have also proved inconclusive. In the group of mice treated with the combination of nanoparticles and the drug, 50% of mice had their tumors regress, no cons in the group treated with medication alone.

NEW WAY TO TREAT ADDICTION

NEW WAY TO TREAT ADDICTION

New Way To Treat Addiction
U.S. - Researchers from the University of Buffalo have developed a new nanoparticle that can disable a gene involved in many forms of addiction.

The team of researchers has discovered a way to "turn off" the signal sent by the brain protein DARPP-32 neurons, which indicates the drug addiction. The short interfering ribonucleic acids (siRNA), cellular components were fixed on nanoparticels of gold using nano-rods.

Modified and stabilized, these bars microscopic penetrate better into the cells. In the case of siRNA, the nano-bar may carry 40% of the acid through the blood-brain barrier, a result judged very high by the researchers. The "nano-bar complex siRNA" is able to extinguish the signal of the gene, remain stable and cross this barrier without being affected in its effectiveness.

This technique could allow the treatment of addiction. In vivo tests should be made in the hope of adding a new pharmaceutical agent to the existing arsenal in the fight against addiction. It could also be applied to Parkinson's disease, cancer and, in general, any condition requiring medication administration in the brain.

More information:
See the paper, Nanotechnology approach for drug addiction therapy: Gene silencing using delivery of gold nanorod-siRNA nanoplex in dopaminergic neurons , in the Proceedings of the National Academy of Sciences.

Carbon Nanotubes with a Memory

Carbon Nanotubes with a Memory

Carbon nanotubes have successfully been made into a variety of nanoscale circuit components, including transistors, inverters, and switches. Now, a pair of scientists has made a rough, yet promising, flash memory device out of carbon nanotubes. The device is a long way from a finished, marketable product, but it nonetheless represents a significant step in the drive to incorporate carbon nanotubes into mainstream electronics.

“Unlike similar devices that have been made, which use carbon nanotubes but can only operate at very low, very impractical temperatures, our device displays impressive long-term information retention characteristics at room temperature,” said lead researcher Jiyan Dai, a physicist at The Hong Kong Polytechnic University, to PhysOrg.com. “This indicates that mainstream carbon nanotube-based flash memory devices are a real possibility.”

Flash memory devices are currently used to store data in many types of electronic items, including digital cameras, USB memory sticks, and cell phones. Flash memory is considered a “non-volatile” form of memory, meaning it can retain data without a constant supply of power.

A typical flash memory device stores information within a grid of transistors called cells. Each cell consists of three layers: a “control gate” compound and a “floating gate” compound separated by a thin layer of an insulating oxide compound. When a voltage is applied to the cell, electrons build up as negative electric charge in the floating gate. At a certain threshold of charge, the floating gate is considered closed and the cell is thought to have a value of “0.” When the charge drops below that level, the gate is open and the cell has a value of “1.” In this way, each cell is able to hold one bit of information (there are eight bits in one byte).

Dai and co-researcher X.B. Lu created their flash memory device using carbon nanotubes as the charge-storage layer. As described in a paper in the online edition of Applied Physics Letters, they embedded the nanotubes in a compound made of the elements hafnium, aluminum, and oxygen, abbreviated HfAlO, which serves as both the control gate and the oxide layer. This carbon-nanotube “sandwich,” with each layer only several nanometers in thickness, sits on a substrate of silicon.

via http://www.physorg.com/news63291916.html

Carbon Nanotubes with a Memory

Carbon nanotubes have successfully been made into a variety of nanoscale circuit components, including transistors, inverters, and switches. Now, a pair of scientists has made a rough, yet promising, flash memory device out of carbon nanotubes. The device is a long way from a finished, marketable product, but it nonetheless represents a significant step in the drive to incorporate carbon nanotubes into mainstream electronics.

“Unlike similar devices that have been made, which use carbon nanotubes but can only operate at very low, very impractical temperatures, our device displays impressive long-term information retention characteristics at room temperature,” said lead researcher Jiyan Dai, a physicist at The Hong Kong Polytechnic University, to PhysOrg.com. “This indicates that mainstream carbon nanotube-based flash memory devices are a real possibility.”

Flash memory devices are currently used to store data in many types of electronic items, including digital cameras, USB memory sticks, and cell phones. Flash memory is considered a “non-volatile” form of memory, meaning it can retain data without a constant supply of power.

A typical flash memory device stores information within a grid of transistors called cells. Each cell consists of three layers: a “control gate” compound and a “floating gate” compound separated by a thin layer of an insulating oxide compound. When a voltage is applied to the cell, electrons build up as negative electric charge in the floating gate. At a certain threshold of charge, the floating gate is considered closed and the cell is thought to have a value of “0.” When the charge drops below that level, the gate is open and the cell has a value of “1.” In this way, each cell is able to hold one bit of information (there are eight bits in one byte).

Dai and co-researcher X.B. Lu created their flash memory device using carbon nanotubes as the charge-storage layer. As described in a paper in the online edition of Applied Physics Letters, they embedded the nanotubes in a compound made of the elements hafnium, aluminum, and oxygen, abbreviated HfAlO, which serves as both the control gate and the oxide layer. This carbon-nanotube “sandwich,” with each layer only several nanometers in thickness, sits on a substrate of silicon.

via http://www.physorg.com/news63291916.html