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What's New in Nanotechnology?

January 16, 2014

This illustration depicts the walking mechanism of a new type of DNA motor that researchers have demonstrated by using it to transport a nanoparticle along the length of a carbon nanotube.Image Credit: Purdue University image/Tae-Gon Cha

Researchers have created a new type of molecular motor made of DNA and demonstrated its potential by using it to transport a nanoparticle along the length of a carbon nanotube. The design was inspired by natural biological motors that have evolved to perform specific tasks critical to the function of cells, said Jong Hyun Choi, a Purdue University assistant professor of mechanical engineering. Whereas biological motors are made of protein, researchers are trying to create synthetic motors based on DNA, the genetic materials in cells that consist of a sequence of four chemical bases: adenine, guanine, cytosine and thymine. The walking mechanism of the synthetic motors is far slower than the mobility of natural motors. However, the natural motors cannot be controlled, and they don't function outside their natural environment, whereas DNA-based motors are more stable and might be switched on and off, Choi said. "We are in the very early stages of developing these kinds of synthetic molecular motors," he said. The new motor has a core and two arms made of DNA, one above and one below the core. As it moves along a carbon-nanotube track it continuously harvests energy from strands of RNA, molecules vital to a variety of roles in living cells and viruses.

Categories : University News
January 09, 2014

 

This graphic shows how a laser pulse creates a vapor nanobubble in a malaria-infected cell and is used to noninvasively diagnose malaria rapidly and with high sensitivity. Image Credit: E. Lukianova-Hleb/Rice University

Rice University researchers have developed a noninvasive technology that accurately detects low levels of malaria infection through the skin in seconds with a laser scanner. The “vapor nanobubble” technology requires no dyes or diagnostic chemicals, and there is no need to draw blood. A preclinical study shows that Rice’s technology detected even a single malaria-infected cell among a million normal cells with zero false-positive readings. The new diagnostic technology uses a low-powered laser that creates tiny vapor “nanobubbles” inside malaria-infected cells. The bursting bubbles have a unique acoustic signature that allows for an extremely sensitive diagnosis.  “Ours is the first through-the-skin method that’s been shown to rapidly and accurately detect malaria in seconds without the use of blood sampling or reagents,” said lead investigator Dmitri Lapotko, a Rice scientist who invented the vapor nanobubble technology. The diagnosis and screening will be supported by a low-cost, battery-powered portable device that can be operated by nonmedical personnel. One device should be able to screen up to 200,000 people per year, with the cost of diagnosis estimated to be below 50 cents, he said. Malaria, one of the world’s deadliest diseases, sickens more than 300 million people and kills more than 600,000 each year, most of them young children. Despite widespread global efforts, malaria parasites have become more resistant to drugs, and efficient epidemiological screening and early diagnosis are largely unavailable in the countries most affected by the disease.

Categories : University News
January 02, 2014

This atomic force microscope image shows directed self-assembly of a printed line of block copolymer on a template prepared by photolithography. The microscope’s software colored and scaled the image. The density of patterns in the template (bounded by the thin lines) is two times that of the self-assembled structures (the ribbons). Image Credit: Serdar Onses/University of Illinois-Urbana.

A multi-institutional team of engineers has developed a new approach to the fabrication of nanostructures for the semiconductor and magnetic storage industries. This approach combines top-down advanced ink-jet printing technology with a bottom-up approach that involves self-assembling block copolymers, a type of material that can spontaneously form ultrafine structures. The team, consisting of nine researchers from the University of Illinois at Urbana-Champaign, the University of Chicago and Hanyang University in Korea, was able to increase the resolution of their intricate structure fabrication from approximately 200 nanometers to approximately 15 nanometers. A nanometer is a billionth of a meter, the width of a double-stranded DNA molecule. The ability to fabricate nanostructures out of polymers, DNA, proteins and other “soft” materials has the potential to enable new classes of electronics, diagnostic devices and chemical sensors. The challenge is that many of these materials are fundamentally incompatible with the sorts of lithographic techniques that are traditionally used in the integrated circuit industry.  Recently developed ultrahigh resolution ink-jet printing techniques have some potential, with demonstrated resolution down to 100-200 nanometers, but there are significant challenges in achieving true nanoscale dimension. “Our work demonstrates that processes of polymer self-assembly can provide a way around this limitation,” said John Rogers, the Swanlund Chair Professor in Materials Science and Engineering at Illinois. Engineers use self-assembling materials to augment traditional photolithographic processes that generate patterns for many technological applications. They first create either a topographical or chemical pattern using traditional processes.

Categories : University News
December 26, 2013

Edith Mathiowitz: “The distribution [of orally delivered protein-based medicines] in the body can be somehow controlled with the type of polymer that you use.” Image Credit: Mike Cohea/Brown University. For protein-based drugs such as insulin to be taken orally rather than injected, bioengineers need to find a way to shuttle them safely through the stomach to the small intestine where they can be absorbed and distributed by the bloodstream. Progress has been slow, but in a new study, researchers report an important technological advance: They show that a “bioadhesive” coating significantly increased the intestinal uptake of polymer nanoparticles in rats and that the nanoparticles were delivered to tissues around the body in a way that could potentially be controlled. “The results of these studies provide strong support for the use of bioadhesive polymers to enhance nano- and microparticle uptake from the small intestine for oral drug delivery,” wrote the researchers, led by corresponding author Edith Mathiowitz, professor of medical science at Brown University. Mathiowitz, who teaches in Brown’s Department of Molecular Pharmacology, Physiology, and Biotechnology, has been working for more than a decade to develop bioadhesive coatings that can get nanoparticles to stick to the mucosal lining of the intestine so that they will be taken up into its epithelial cells and transferred into the bloodstream. The idea is that protein-based medicines would be carried in the nanoparticles. In the recent study, Mathiowitz put one of her most promising coatings, a chemical called PBMAD, to the test both on the lab bench and in animal models. Mathiowitz and her colleagues have applied for a patent related to the work, which would be assigned to Brown University.

Categories : University News
December 19, 2013

Rice University researchers discovered a meniscus-mask technique to make sub-10-nanometer ribbons of graphene. From left, graduate students Alexander Slesarev and Vera Abramova and Professor James Tour. Image CCredit: Tour Group/Rice University.

Research at Rice University has shown how water makes it practical to form long graphene nanoribbons less than 10 nanometers wide. A bit of water adsorbed from the atmosphere was found to act as a mask in a process that begins with the creation of patterns via lithography and ends with very long, very thin graphene nanoribbons. The ribbons form wherever water gathers at the wedge between the raised pattern and the graphene surface. The water formation is called a meniscus; it is created when the surface tension of a liquid causes it to curve. In the Rice process, the meniscus mask protects a tiny ribbon of graphene from being etched away when the pattern is removed. Methods to form long wires only a few nanometers wide should catch the interest of microelectronics manufacturers as they approach the limits of their ability to miniaturize circuitry. The researchers had set out to fabricate nanoribbons by inverting a method developed by another Rice lab to make narrow gaps in materials. The original method utilized the ability of some metals to form a native oxide layer that expands and shields material just on the edge of the metal mask. The new method worked, but not as expected. It took two years to develop and test the meniscus theory, during which the researchers also confirmed its potential to create sub-10-nanometer wires from other kinds of materials, including platinum. They also constructed field-effect transistors to check the electronic properties of graphene nanoribbons. To be sure that water did indeed account for the ribbons, they tried eliminating its effect by first drying the patterns by heating them under vacuum, and then by displacing the water with acetone to eliminate the meniscus. In both cases, no graphene nanoribbons were created. The researchers are working to better control the nanoribbons’ width, and they hope to refine the nanoribbons’ edges, which help dictate their electronic properties.

Categories : University News
December 12, 2013

Image Credit: UCLA.

Your smartphone now can see what the naked eye cannot: A single virus and bits of material less than one-thousandth of the width of a human hair.  Aydogan Ozcan, a professor of electrical engineering and bioengineering at UCLA, and his team have created a portable smartphone attachment that can be used to perform sophisticated field testing to detect viruses and bacteria without the need for bulky and expensive microscopes and lab equipment. The device weighs less than half a pound. "This cellphone-based imaging platform could be used for specific and sensitive detection of sub-wavelength objects, including bacteria and viruses and therefore could enable the practice of nanotechnology and biomedical testing in field settings and even in remote and resource-limited environments," Ozcan said. "These results also constitute the first time that single nanoparticles and viruses have been detected using a cellphone-based, field-portable imaging system." The new research comes on the heels of Ozcan's other recent inventions, including a cellphone camera–enabled sensor for allergens in food products and a smart phone attachment that can conduct common kidney tests. Capturing clear images of objects as tiny as a single virus or a nanoparticle is difficult because the optical signal strength and contrast are very low for objects that are smaller than the wavelength of light. Using this device, Ozcan's team detected nanoparticles — specially marked fluorescent beads made of polystyrene — as small as 90–100 nanometers. To verify these results, researchers in Ozcan's lab used other imaging devices, including a scanning electron microscope and a photon-counting confocal microscope. These experiments confirmed the findings made using the new cellphone-based imaging device.

Categories : University News
December 05, 2013

 

A micrograph of the nanosensor array. The florescence of each carbon nanotube changes in intensity upon binding to a target molecule. Image Credit: MIT.

MIT chemical engineers have discovered that arrays of billions of nanoscale sensors have unique properties that could help pharmaceutical companies produce drugs — especially those based on antibodies — more safely and efficiently. Using these sensors, the researchers were able to characterize variations in the binding strength of antibody drugs, which hold promise for treating cancer and other diseases. They also used the sensors to monitor the structure of antibody molecules, including whether they contain a chain of sugars that interferes with proper function. “This could help pharmaceutical companies figure out why certain drug formulations work better than others, and may help improve their effectiveness,” says Michael Strano, an MIT professor of chemical engineering. The team also demonstrated how nanosensor arrays could be used to determine which cells in a population of genetically engineered, drug-producing cells are the most productive or desirable, Strano says. Strano and other scientists have previously shown that tiny, nanometer-sized sensors, such as carbon nanotubes, offer a powerful way to detect minute quantities of a substance. Carbon nanotubes are 50,000 times thinner than a human hair, and they can bind to proteins that recognize a specific target molecule. When the target is present, it alters the fluorescent signal produced by the nanotube in a way that scientists can detect.

Categories : University News
November 28, 2013

The world’s first low cost Atomic Force Microscope (AFM) has been developed in Beijing by a group of PhD students from University College London (UCL), Tsinghua University and Peking University - using LEGO. In the first event of its kind, LEGO2NANO brought together students, experienced makers and scientists to take on the challenge of building a cheap and effective AFM, a device able to probe objects only a millionth of a millimeter in size – far smaller than anything an optical microscope can observe. Research-grade AFMs typically cost $100,000 or more, and use custom hardware, however, the newly designed low-cost version could cost less than $500 to produce. The design brief for the student teams was to build a functional nanoscope, using only LEGO, Arduino microcontrollers, 3D-printed parts and consumer electronics. The event was co-sponsored by the LEGO Foundation, and involved active participation by Chinese high-school students, as potential users of such low-cost science tools. It took just five days for the student team to demonstrate the scanning functionality of their AFM, earning them the award for Best Technical Design.

Categories : University News
November 21, 2013

This research-microscope image shows the increasing density at the bone-crack site during a 40-minute test of particles carrying the bone-healing medication. The particles were treated with a red-glowing fluorescent dye. Image Credit: Sen laboratory/Penn State University.

A novel method for finding and delivering healing drugs to newly formed microcracks in bones has been invented by a team of chemists and bioengineers at Penn State University and Boston University. The method involves the targeted delivery of the drugs, directly to the cracks, on the backs of tiny self-powered nanoparticles. The energy that revs the motors of the nanoparticles and sends them rushing toward the crack comes from a surprising source -- the crack itself. "When a crack occurs in a bone, it disrupts the minerals in the bone, which leach out as charged particles -- as ions -- that create an electric field, which pulls the negatively charged nanoparticles toward the crack," said Penn State Professor of Chemistry Ayusman Sen, a co-leader of the research team. "Our experiments have shown that a biocompatible particle can quickly and naturally deliver an osteoporosis drug directly to a newly cracked bone." Sen said that the formation of this kind of an electric field is a well-known phenomenon, but other scientists previously had not used it as both a power source and a homing beacon to actively deliver bone-healing medications to the sites most at risk for fracture or active deterioration. "It is a novel way to detect cracks and deliver medicines to them," said team co-leader and Boston University Professor Mark Grinstaff. The method is more-energetic and more-targeted than current methods, in which medications ride passively on the circulating bloodstream, where they may or may not arrive at microcracks in a high-enough dosage to initiate healing. The new method holds the promise of treating -- as soon as they form -- the microcracks that lead to broken bones in patients with osteoporosis and other medical conditions.

Categories : University News
November 14, 2013

A DNA cage (at left), with lipid-like molecules (in blue). The lipids come together in a ‘handshake’ within the cage (center image) to encapsulate small-molecule drugs (purple). The molecules are released (at right) in response to the presence of a specific nucleic acid. Image Credit: Thomas Edwardson/McGill University.

Nanoscale “cages” made from strands of DNA can encapsulate small-molecule drugs and release them in response to a specific stimulus, McGill University researchers report in a new study. The research marks a step toward the use of biological nanostructures to deliver drugs to diseased cells in patients. The findings could also open up new possibilities for designing DNA-based nanomaterials. “This research is important for drug delivery, but also for fundamental structural biology and nanotechnology,” says McGill Chemistry professor Hanadi Sleiman, who led the research team. DNA carries the genetic information of all living organisms from one generation to the next. But strands of the material can also be used to build nanometre-scale structures. (A nanometre is one billionth of a metre – roughly one-100,000th the diameter of a human hair.) In their experiments, the McGill researchers first created DNA cubes using short DNA strands, and modified them with lipid-like molecules. The lipids can act like sticky patches that come together and engage in a “handshake” inside the DNA cube, creating a core that can hold cargo such as drug molecules. The McGill researchers also found that when the sticky patches were placed on one of the outside faces of the DNA cubes, two cubes could attach together. This new mode of assembly has similarities to the way that proteins fold into their functional structures, Sleiman notes.  “It opens up a range of new possibilities for designing DNA-based nanomaterials.”

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