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Roy’s team used an imprinting technology that works like a cookie cutter but on the nanoscale. Drugs are mixed with a polymer solution and dispensed on a silicon wafer. Then a shape is imprinted onto the polymer-drug mixture using a quartz template. The material is then solidified using UV light. Whatever the cookie cutter’s template – triangle, rod, disc – a nanoparticle with that shape is produced.Image Source: Georgia Tech, Image Credit: Rob Felt

For years scientists have been working to fundamentally understand how nanoparticles move throughout the human body. One big unanswered question is how the shape of nanoparticles affects their entry into cells. Now researchers have discovered that under typical culture conditions, mammalian cells prefer disc-shaped nanoparticles over those shaped like rods. Understanding how the shape of nanoparticles affects their transport into cells could be a major boost for the field of nanomedicine by helping scientists to design better therapies for various diseases, such as improving the efficacy and reducing side effects of cancer drugs. In addition to nanoparticle geometry, the researchers also discovered that different types of cells have different mechanisms to pull in nanoparticles of different sizes, which was previously unknown. The research team also used theoretical models to identify the physical parameters that cells use when taking in nanoparticles. “This research identified some very novel yet fundamental aspects in which cells interact with the shape of nanoparticles,” said Krishnendu Roy of Department of Biomedical Engineering at Georgia Tech and Emory University. He conducted this research at The University of Texas at Austin in collaboration with Profs. S. V. Sreenivasan and Li Shi, but is continuing the work at Georgia Tech. Roy’s team used a unique approach to making the differently shaped nanoparticles. The researchers adapted an imprinting technology used in the semiconductor industry and rigged it to work with biological molecules, Roy said. This imprinting technique, which they developed at UT-Austin, works like a cookie cutter but on the nanoscale. Drugs are mixed with a polymer solution and dispensed on a silicon wafer. Then a shape is imprinted onto the polymer-drug mixture using a quartz template. The material is then solidified using UV light. Whatever the cookie cutter’s template – triangle, rod, disc – a nanoparticle with that shape is produced.

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An electron microscope image (left) shows a faceted single crystal consisting of nanoparticles brought together using DNA interactions. A schematic (right) illustrates how the lattice of nanoparticles is held together by DNA, taken from a simulation used to model the system. The observed crystal shape is a rhombic dodecahedron, a 12-sided polyhedron made up of congruent rhombic faces.Image Credit: Northwestern University

Nature builds flawless diamonds, sapphires and other gems. Now a Northwestern University research team is the first to build near-perfect single crystals out of nanoparticles and DNA, using the same structure favored by nature. “Single crystals are the backbone of many things we rely on -- diamonds for beauty as well as industrial applications, sapphires for lasers and silicon for electronics,” said nanoscientist Chad A. Mirkin. “The precise placement of atoms within a well-defined lattice defines these high-quality crystals. “Now we can do the same with nanomaterials and DNA, the blueprint of life,” Mirkin said. “Our method could lead to novel technologies and even enable new industries, much as the ability to grow silicon in perfect crystalline arrangements made possible the multibillion-dollar semiconductor industry.” His research group developed the “recipe” for using nanomaterials as atoms, DNA as bonds and a little heat to form tiny crystals. This single-crystal recipe builds on superlattice techniques Mirkin’s lab has been developing for nearly two decades. In this recent work, Mirkin, an experimentalist, teamed up with Monica Olvera de la Cruz, a theoretician, to evaluate the new technique and develop an understanding of it. Given a set of nanoparticles and a specific type of DNA, Olvera de la Cruz showed they can accurately predict the 3-D structure, or crystal shape, into which the disordered components will self-assemble.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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