Researchers grow liquid crystal 'flowers' that can be used as lenses

In continuation of my update on liquid crystals

The researchers' ongoing work with liquid crystals is an example of a growing field of nanotechnology known as "directed assembly," in which scientists and engineers aim to manufacture structures on the smallest scales without having to individually manipulate each component. Rather, they set out precisely defined starting conditions and let the physics and chemistry that govern those components do the rest.

The starting conditions in the researchers previous experiments were templates consisting of tiny posts. In one of their studies, they showed that changing the size, shape or spacing of these posts would result in corresponding changes in the patterns of defects on the surface of the liquid crystal resting on top of them. In another experiment, they showed they could make a "hula hoop" of defects around individual posts, which would then act as a second template for a ring of defects at the surface.

In their latest work, the researchers used a much simpler cue.

"Before we were growing these liquid crystals on something like a trellis, a template with precisely ordered features," Kamien said. "Here, we're just planting a seed."

The seed, in this case, were silica beads -- essentially, polished grains of sand. Planted at the top of a pool of liquid crystal flower-like patterns of defects grow around each bead.

The key difference between the template in this experiment and ones in the research team's earlier work was the shape of the interface between the template and the liquid crystal.

In their experiment that generated grid patterns of defects, those patterns stemmed from cues generated by the templates' microposts. Domains of elastic energy originated on the flat tops and edges of these posts and travelled up the liquid crystal's layers, culminating in defects. Using a bead instead of a post, as the researchers did in their latest experiment, makes it so that the interface is no longer flat.

"Not only is the interface at an angle, it's an angle that keeps changing," Kamien said. "The way the liquid crystal responds to that is that it makes these petal-like shapes at smaller and smaller sizes, trying to match the angle of the bead until everything is flat."

Surface tension on the bead also makes it so these petals are arranged in a tiered, convex fashion. And because the liquid crystal can interact with light, the entire assembly can function as a lens, focusing light to a point underneath the bead.

"It's like an insect's compound eye, or the mirrors on the biggest telescopes," said Kamien. "As we learn more about these systems, we're going to be able to make these kinds of lenses to order and use them to direct light."

Researchers grow liquid crystal 'flowers' that can be used as lenses

Ref : http://prx.aps.org/abstract/PRX/v3/i4/e041026

Researchers split water into hydrogen, oxygen using light, nanoparticles

Researchers from the University of Houston have found a catalyst that can quickly generate hydrogen from water using sunlight, potentially creating a clean and renewable source of energy.

Researchers prepared the nanoparticles in two ways, using femtosecond laser ablation and through mechanical ball milling. Despite some differences, Bao said both worked equally well.

Different sources of light were used, ranging from a laser to white light simulating the solar spectrum. He said he would expect the reaction to work equally well using natural sunlight.

Once the nanoparticles are added and light applied, the water separates into hydrogen and oxygen almost immediately, producing twice as much hydrogen as oxygen, as expected from the 2:1 hydrogen to oxygen ratio in H2O water molecules, Bao said.

The experiment has potential as a source of renewable fuel, but at a solar-to-hydrogen efficiency rate of around 5 percent, the conversion rate is still too low to be commercially viable. Bao suggested a more feasible efficiency rate would be about 10 percent, meaning that 10 percent of the incident solar energy will be converted to hydrogen chemical energy by the process.

Other issues remain to be resolved, as well, including reducing costs and extending the lifespan of cobalt oxide nanoparticles, which the researchers found became deactivated after about an hour of reaction.

"It degrades too quickly," said Bao, who also has appointments in materials engineering and the Department of Chemistry.

Researchers split water into hydrogen, oxygen using light, nanoparticles

Nanotechnology Now - Press Release: "Curing Cancer with Magnetic Nanoparticles"

Curing Cancer with Magnetic Nanoparticles: 

Nanoprobes, Inc. is a nanoparticle research collaborative, dedicated to finding cures for cancer and other diseases. Our technology is helping save lives around the world, at the core of the HER2 breast cancer test. Located in Yaphank, NY, our funding comes from research grants, and sales of nanoparticle products to the scientific community; all profits support our research. 

Scientists at Nanoprobes, Inc. are heralding a major breakthrough in cancer research, using their new magnetic nanoparticles. After a quick intravenous injection and just three minutes inside a magnetic field, 80% of test animals are completely cured of cancer. Their spectacular results have just been published in The International Journal of Nanomedicine.

Six years of research were built on a simple idea: iron particles inside an alternating magnetic field will spin back and forth, and generate significant heat. If enough iron particles were delivered to a tumor, you could cook the cancer. For many years, however, researchers had been stymied by the toxic amount of iron required. To avoid poisoning the body, researchers had tried injecting iron particles directly into tumors, but areas missed would always regrow.

At Nanoprobes, a different approach held the key. Senior scientist Dr. James F. Hainfeld, one of the original fathers of the nanoparticle, decided to make the iron itself non-toxic. Together with colleague Hui Huang, he engineered a nanoparticle with an iron core and a biocompatible shell, which could safely be injected into the bloodstream. Sized to specifically leak out of newly-formed blood vessels in tumors, these iron nanoparticles will find and load cancerous tissue anywhere in the body, even targeting metastases.

The iron-laden cancer is then easily heated in a magnetic field; the tumors actually liquefy, while adjacent, healthy tissue stays cool and unharmed. Afterwards, the neutralized liquid is quickly absorbed by the body, while the nanoparticles break down slowly, allowing the iron to be safely assimilated. The research team has achieved a cure rate of 78-90% in mice, ablating tumors with an accuracy finer than a surgeon's knife.

It's also great news for combination therapy, where pre-treatment with heat (hyperthermia), greatly amplifies chemotherapy and radiation. Since magnetic fields easily pass through the human body, these iron nanoparticles will heat previously inaccessible, deep tumors. Brain cancer too is in their sights: where nothing else works, the lab has achieved highly specific iron loading of brain tumors. The precision of magnetic heating would vitally spare healthy brain tissue, compared to the collateral damage of radiation or surgery.

The National Institutes of Health recently granted the research group roughly a million dollars' worth of laboratory testing, in preparation for FDA approval. "We need to bring this to patients, as soon as possible," says Huang, now in medical school and soon to be treating patients himself. Nanoprobes is currently organizing funding for the clinical trials to come.

"After so many years in the trenches, I tend to be cautious," says Dr. Hainfeld, "but I've never seen such promising results. We're very hopeful." Because, he adds, "No one should ever have to hear, "There's nothing more we can do."

Nanotechnology Now - Press Release:

"Curing Cancer with Magnetic Nanoparticles"

Nanotechnology Now - Press Release: "Graphene-based nano-antennas may enable networks of tiny machines"

With antennas made from conventional materials like copper, communication between low-power nanomachines would be virtually impossible. But by taking advantage of the unique electronic properties of the material known as graphene, researchers now believe they're on track to connect devices powered by small amounts of scavenged energy.

Based on a honeycomb network of carbon atoms, graphene could generate a type of electronic surface wave that would allow antennas just one micron long and 10 to 100 nanometers wide to do the work of much larger antennas. While operating graphene nano-antennas have yet to be demonstrated, the researchers say their modeling and simulations show that nano-networks using the new approach are feasible with the alternative material.

"We are exploiting the peculiar propagation of electrons in graphene to make a very small antenna that can radiate at much lower frequencies than classical metallic antennas of the same size," said Ian Akyildiz, a Ken Byers Chair professor in Telecommunications in the School of Electrical and Computer Engineering at the Georgia Institute of Technology. "We believe that this is just the beginning of a new networking and communications paradigm based on the use of graphene."

Sponsored by the National Science Foundation, the research is scheduled to be reported in the journal IEEE Journal of Selected Areas in Communications (IEEE JSAC). In addition to the nanoscale antennas, the researchers are also working on graphene-based nanoscale transceivers and the transmission protocols that would be necessary for communication between nanomachines.

The communications challenge is that at the micron scale, metallic antennas would have to operate at frequencies of hundreds of terahertz. While those frequencies might offer advantages in communication speed, their range would be limited by propagation losses to just a few micrometers. And they'd require lots of power – more power than nanomachines are likely to have.

Akyildiz has studied nanonetworks since the late 1990s, and had concluded that traditional electromagnetic communication between these machines might not be possible. But then he and his Ph.D. student, Josep Jornet - who graduated in August 2013 and is now an assistant professor at the State University of New York at Buffalo - began reading about the amazing properties of graphene. They were especially interested in how electrons behave in single-layer sheets of the material.

"When electrons in graphene are excited by an incoming electromagnetic wave, for instance, they start moving back and forth," explained Akyildiz. "Because of the unique properties of the graphene, this global oscillation of electrical charge results in a confined electromagnetic wave on top of the graphene layer."

Known technically as a surface plasmon polariton (SPP) wave, the effect will allow the nano-antennas to operate at the low end of the terahertz frequency range, between 0.1 and 10 terahertz - instead of at 150 terahertz required by traditional copper antennas at nanoscale sizes. For transmitting, the SPP waves can be created by injecting electrons into the dielectric layer beneath the graphene sheet.

Materials such as gold, silver and other noble metals also can support the propagation of SPP waves, but only at much higher frequencies than graphene. Conventional materials such as copper don't support the waves.

By allowing electromagnetic propagation at lower terahertz frequencies, the SPP waves require less power - putting them within range of what might be feasible for nanomachines operated by energy harvesting technology pioneered by Zhong Lin Wang, a professor in Georgia Tech's School of Materials Science and Engineering.

"With this antenna, we can cut the frequency by two orders of magnitude and cut the power needs by four orders of magnitude," said Jornet. "Using this antenna, we believe the energy-harvesting techniques developed by Dr. Wang would give us enough power to create a communications link between nanomachines."

The nanomachines in the network that Akyildiz and Jornet envision would include several integrated components. In addition to the energy-harvesting nanogenerators, there would be nanoscale sensing, processing and memory, technologies that are under development by other groups. The nanoscale antenna and transceiver work being done at Georgia Tech would allow the devices to communicate the information they sense and process to the outside world.

"Each one of these components would have a nanoscale measurement, but in total we would have a machine measuring a few micrometers," said Jornet. "There would be lots of tradeoffs in energy use and size”.

Beyond giving nanomachines the ability to communicate, hundreds or thousands of graphene antenna-transceiver sets might be combined to help full-size cellular phones and Internet based laptops communicate faster.

"The terahertz band can boost current data rates in wireless networks by more than two orders of magnitude," Akyildiz noted. "The data rates in current cellular systems are up to one gigabit-per-second in LTE advanced networks or 10 gigabits-per-second in the so-called millimeter wave or 60 gigahertz systems. We expect data rates on the order of terabits-per-second in the terahertz band."

The unique properties of graphene, Akyildiz says, are critical to this antenna - and other future electronic devices.

"
The researchers have so far evaluated numerous nano-antenna designs using modeling and simulation techniques in their laboratory. The next step will be to actually fabricate a graphene nano-antenna and operate it using a transceiver also based on graphene.

Nanotechnology Now - Press Release: "Graphene-based nano-antennas may enable networks of tiny machines"

Turning waste into power with bacteria — and loofahs

Loofahs, best known for their use in exfoliating skin to soft, radiant perfection, have emerged as a new potential tool to advance sustainability efforts on two fronts at the same time: energy and waste. The study describes the pairing of loofahs with bacteria to create a power-generating microbial fuel cell (MFC) and appears in the ACS journal Environmental Science & Technology.

Shungui Zhou and colleagues note that MFCs, which harness the ability of some bacteria to convert waste into electric power, could help address both the world’s growing waste problem and its need for clean power. Current MFC devices can be expensive and complicated to make. In addition, the holes, or pores, in the cells’ electrodes are often too small for bacteria to spread out in. Recently, researchers have turned to plant materials as a low-cost alternative, but pore size has still been an issue. Loofahs, which come from the fully ripened fruit of loofah plants, are commonly used as bathing sponges. They have very large pores, yet are still inexpensive. That’s why Zhou’s team decided to investigate their potential use in MFCs.

When the scientists put nitrogen-enriched carbon nanoparticles on loofahs and loaded them with bacteria, the resulting MFC performed better than traditional MFCs. “This study introduces a promising method for the fabrication of high-performance anodes from low-cost, sustainable natural materials,” the researchers state.

Turning waste into power with bacteria — and loofahs

DNA nanotechnology opens new path to super-high-resolution molecular imaging : Wyss Institute at Harvard

The DNA-based microscopy method could potentially lead to new ways of diagnosing disease by distinguishing healthy and diseased cells based on sophisticated molecular details. It could also help scientists uncover how the cell's components carry out their work inside the cell.

"If you want to study physiology and disease, you want to see how the molecules work, and it's important to see them in their native environments," said Peng Yin, Ph.D., a core faculty member at the Wyss Institute and Assistant Professor of Systems Biology at Harvard Medical School. Yin will lead the project, and he will collaborate with Samie Jaffrey, M.D., Ph.D., a Professor of Pharmacology at Weill Cornell Medical College, and Ralf Jungmann, Ph.D., a postdoctoral scholar in Yin's Wyss Institute lab, among others.

Biologists have used microscopes to reveal how tiny structures inside cells prop them up and help them move, reproduce, activate genes, and much more. But although microscope makers have honed the technology for centuries to get ever-clearer images, they have been limited by the laws of physics. When two objects are closer than about 0.2 micrometers, or about one five-hundredth the width of a human hair, the scientists can no longer distinguish them using traditional light microscopes. As a result, the viewer sees one blurry blob where in reality there are two objects. This behavior occurs because of the way light rays bend around objects, and is known as the diffraction limit.

Molecules such as enzymes, receptors, RNA and DNA that do most of the work of the cell are typically far smaller than 0.2 micrometers, and to visualize them microscopists have struggled to overcome this limitation. They have developed several clever methods that accomplish this, but some of them require special microscopes that tend to be very expensive, and others require cumbersome procedures. What's more, today's methods can only reveal a handful of distinct molecule species at a time, and the images remain blurrier than many scientists would like.

The Wyss Institute-led team plans to overcome these challenges by combining single-molecule imaging methods with molecular tools from DNA nanotechnology. Using an imaging method called DNA-PAINT, they created so-called "imager strands" by tagging small pieces of DNA with a fluorescent dye. Each of these imager strands binds transiently to a matching DNA strand that is attached to a target molecule, which makes the target appear to blink. Such blinking, when done right, enables scientists to beat the diffraction limit and obtain sharper images of the targets than otherwise possible.

"The powerful thing about using DNA lies in its amazing programmability," Yin said. "We plan to use that capability to make molecules in cells blink in a programmable and autonomous way. This will allow us to see things that were previously invisible."

DNA nanotechnology opens new path to super-high-resolution molecular imaging : Wyss Institute at Harvard

Advances in nanotechnology's fight against cancer

Advances in nanotechnology's fight against cancer

Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity : Nature : Nature Publishing Group

To address the challenges like limited oleophobicity, researchers have reported a strategy to create self-healing, slippery liquid-infused porous surface(s) (SLIPS) with exceptional liquid- and ice-repellency, pressure stability and enhanced optical transparency.  Researchers claim  that the properties are insensitive to the precise geometry of the underlying substrate, making their approach applicable to various inexpensive, low-surface-energy structured materials (such as porous Teflon membrane). Researchers envision that the  slippery surfaces will be useful in fluid handling and transportation, optical sensing, medicine, and as self-cleaning and anti-fouling materials operating in extreme environments.

Bioinspired self-repairing slippery surfaces with pressure-stable omniphobicity : Nature : Nature Publishing Group

Researchers design a new catalyst to produce hydrogen from water and sunlight — Sala de Premsa - Universitat Politècnica de Catalunya (UPC)

The scientists behind the project have fused the optical properties of three dimensionalphotonic crystals (inverse opals of titanium dioxide, TiO2) and 2-3 nm gold nanoparticles to develop a highly active catalyst powder. The research paper has been published in Scientific Reports, the open-access journal of Nature.

This new photocatalyst produces more hydrogen than others developed so far by harnessing the properties of both photonic crystals and nanoparticles of a metal. According to Jordi Llorca, a researcher at the UPC's Institute of Energy Technology, the process involves "tuning" the two materials to amplify the effect. "You have to choose the right photonic crystal and the right nanoparticles", he adds.

  

In any photocatalyst made from gold nanoparticles and titanium dioxide crystals using ultraviolet light, which is only a small part of solar radiation (less than 3%), the process is the same: light excites the TiO2 electrons and promotes them to the conduction band, leaving holes on the other side. The electrons interact with the gold nanoparticles and are captured by them. According to the scientists, the novelty in this case is the use of a 3D photonic crystal that captures the visible part of the solar spectrum, precisely at the energy level at which the gold nanoparticles "resonate". As a result, it's possible to take advantage of the visible part of the solar spectrum rather than just the ultraviolet part. This translates into a significant boost in the performance of the process.

The new catalyst has great potential for application in industrial processes. According to researcher Jordi Llorca, making the move from the laboratory to an industrial plant would mean designing a reactor to operate outdoors in the sun, and using a solar collector to capture more sunlight.

A conventional plant for the production of hydrogen from natural gas generates about 300 tons of hydrogen a day. With the new catalyst developed at the UPC, researchers have managed to produce 0.025 litres of hydrogen in one hour using one gram of catalyst. Assuming eight hours of sunlight a day, the scientists estimate that an area measuring 10 x 10 km would be needed to produce hydrogen on an industrial scale.

More

Researchers design a new catalyst to produce hydrogen from water and sunlight — Sala de Premsa - Universitat Politècnica de Catalunya (UPC)

KIT - Visiting - Current Topics - Press Releases - PI 2013 - POPUP – Novel Organic Solar Cells

Future solar cells will be light and mechanically flexible. They will be produced at low costs with the help of printing processes. POPUP, the new BMBF-funded research project, aims at developing more efficient materials and new architectures for organic photovoltaic devices. An interdisciplinary team headed by Dr. Alexander Colsmann of the KIT Light Technology Institute (LTI) works on improving the basic understanding and developing new architectures for semitransparent and non-transparent solar cells and modules. 

Depending on the application, solar cells are manufactured on flexible plastic foils or rigid glass carriers. In the area of organic photovoltaics, KIT scientists work on two objectives, namely, full printability of solar cells and replacing indium tin oxide (ITO) as the electrode material. Instead, the scientists use conductive and transparent foils for flexible carriers. For glass carriers, they study the deposition of transparent electrodes from metallic microstructures and conductive buffer layers. In addition, the KIT team studies highly efficient semi-transparent solar cells in mini-modules made of organic semiconductors. Hence, KIT research concentrates on one of the key technologies of organic photovoltaics.

In the medium and long term, the industry partners plan to manufacture organic solar modules by competitive mass production methods. Later on, the solar modules are planned to be integrated into vehicles for electricity supply to onboard electronics, in buildings and glass facades, for energy supply of free-standing buildings and devices, emergency systems, transport and navigation aids. The novel technologies will also be used for off-grid electricity supply in the leisure activity sector or for charging mobile consumer devices. The results obtained by the KIT researchers will have direct impact on various applications.

The POPUP consortium comprises ten partners who have many years of experience in the organic photovoltaics field and are technology leaders in their respective areas of work: Merck, Darmstadt; Center for Applied Energy Systems, Erlangen; PolyIC GmbH & Co. KG, Fürth; Karlsruhe Institute of Technology, Karlsruhe; Leonhard Kurz Stiftung & Co. KG, Fürth; Belectric OPV GmbH, Nuremberg; Webasto Group, Stockdorf; Siemens AG, Erlangen; Centrosolar Glas GmbH & Co. KG, Fürth; Center for Solar Energy and Hydrogen Research, Stuttgart. The companies, universities and institutes are cooperating along a cross-sectoral and multidisciplinary value chain characterized by the division of labor.

KIT - Visiting - Current Topics - Press Releases - PI 2013 - POPUP – Novel Organic Solar Cells

The promise of nanotechnology

The promise of nanotechnology

Pills of the future: Nanoparticles; Researchers design drug-carrying nanoparticles that can be taken orally

Now, researchers from MIT and Brigham and Women's Hospital (BWH) have developed a new type of nanoparticle that can be delivered orally and absorbed through the digestive tract, allowing patients to simply take a pill instead of receiving injections.

In a paper appearing in the Nov. 27 online edition of Science Translational Medicine, the researchers used the particles to demonstrate oral delivery of insulin in mice, but they say the particles could be used to carry any kind of drug that can be encapsulated in a nanoparticle. The new nanoparticles are coated with antibodies that act as a key to unlock receptors found on the surfaces of cells that line the intestine, allowing the nanoparticles to break through the intestinal walls and enter the bloodstream.

This type of drug delivery could be especially useful in developing new treatments for conditions such as high cholesterol or arthritis. Patients with those diseases would be much more likely to take pills regularly than to make frequent visits to a doctor's office to receive nanoparticle injections, say the researchers.

"If you were a patient and you had a choice, there's just no question: Patients would always prefer drugs they can take orally," says Robert Langer, the David H. Koch Institute Professor at MIT, a member of MIT's Koch Institute for Integrative Cancer Research, and an author of the Science Translational Medicine paper.

Lead authors of the paper are former MIT grad student Eric Pridgen and former BWH postdoc Frank Alexis, and the senior author is Omid Farokhzad, director of the Laboratory of Nanomedicine and Biomaterials at BWH. Other authors are Timothy Kuo, a gastroenterologist at BWH; Etgar Levy-Nissenbaum, a former BWH postdoc; Rohit Karnik, an MIT associate professor of mechanical engineering; and Richard Blumberg, co-director of BWH's Biomedical Research Institute.

Ref : http://stm.sciencemag.org/content/5/213/213ra167

Pills of the future: Nanoparticles; Researchers design drug-carrying nanoparticles that can be taken orally

Inexpensive 'nano-camera' can operate at the speed of light

Inexpensive 'nano-camera' can operate at the speed of light

Copper promises cheaper, sturdier fuel cells

The copper nanowire films consist of networks of microscopic metal rods, the properties and applications of which Wiley's lab has studied for years. The nanowires provide a high surface area for catalyzing chemistry, and Wiley's team experimented with coating them in either cobalt or nickel -- metals that serve as the actual chemical catalyst. Even with a coat of cobalt or nickel, the nanowire films allow nearly seven times more sunlight to pass through than ITO. The films are also flexible, leading Wiley to imagine the completed fuel cells one day being attached to backpacks or cars.

In the meantime, engineering and chemistry challenges remain. The nanowire films carry out only one half of the water-splitting equation, a process called water oxidation. The other half of the reaction involves using the electrons obtained from water oxidation to reduce water to hydrogen. Wiley's team expects to publish their work on this process in the coming year.

"A lot of groups are working on putting together complete devices to generate fuels from sunlight," he said, but "the efficiencies and costs of these systems have to be improved for them to get to commercial [production]."

Wiley noted that solar energy production is just one application of the copper nanowire films they study. The nanowires also show promise for use in flexible touch screens, organic LED (or OLED) lights and smart glass.

Copper promises cheaper, sturdier fuel cells

Nanotechnology-based technique: A painless method for maintaining healthy blood sugar levels

A new nanotechnology-based technique for regulating blood sugar in diabetics may give patients the ability to release insulin painlessly using a small ultrasound device, allowing them to go days between injections - rather than using needles to give themselves multiple insulin injections each day. The technique was developed by researchers at North Carolina State University and the University of North Carolina at Chapel Hill.

"This is hopefully a big step toward giving diabetics a more painless method of maintaining healthy blood sugar levels," says Dr. Zhen Gu, senior author of a paper on the research and an assistant professor in the joint biomedical engineering program at NC State and UNC-Chapel Hill.

The technique involves injecting biocompatible and biodegradable nanoparticles into a patient's skin. The nanoparticles are made out of poly(lactic-co-glycolic) acid (PLGA) and are filled with insulin.

Each of the PLGA nanoparticles is given either a positively charged coating made of chitosan (a biocompatible material normally found in shrimp shells), or a negatively charged coating made of alginate (a biocompatible material normally found in seaweed). When the solution of coated nanoparticles is mixed together, the positively and negatively charged coatings are attracted to each other by electrostatic force to form a "nano-network." Once injected into the subcutaneous layer of the skin, that nano-network holds the nanoparticles together and prevents them from dispersing throughout the body.

Nanotechnology-based technique: A painless method for maintaining healthy blood sugar levels

Nanotech drug smugglers

Sergey Shityakov and Carola Förster of the University of Würzburg, Germany, explain that the protein, P-glycoprotein, acts as a gatekeeper, flushing out potentially harmful chemicals that enter the body as well as the naturally-occurring products of metabolism. The protein thus plays a vital role in the health of the cell. Unfortunately, it is a strong modulator of chemical traffic across the cell membrane that it can also prevent therapeutic agents from working properly, flushing them out as if they were simply harmful compounds. This process underpins the emergence of multidrug resistance in several diseases, including various forms of cancer.

Shityakov and Förster have revealed recently that if there were a way to mask the presence of the therapeutic agent, later the gatekeeper would not see them as "unwanted molecular entities" to be eradicated, and therefore, these drugs might be able to carry out their job unhindered and so overcome drug resistance. However, some of the chemical substances have turned to the realm of nanotechnology, and in particular, tiny capsules of carbon atoms known as fullerenes and the related molecules, the carbon nanotubes. The latter synthetic materials are not recognized by P-glycoprotein and so can penetrate lipid membranes moving freely in and out of cells.

The team has investigated whether it might be possible to carry drug molecules inside these nanocapsules so that they are unimpeded by interactions with P-glycoprotein or other receptors. They used high-power computational techniques to demonstrate that carbon nanotubes are not able to "dock" with the gatekeeper protein. Moreover, their analysis of the binding energy needed to push a nanotube into P-glycoprotein shows that the process is unfavourable and so rather than "docking" with this gatekeeper protein these peculiar materials are repelled by it to maintain the interior of the cell and so have the potential to act as a molecular drug smuggler.

Ref : http://www.inderscience.com/offer.php?id=56801

Nanotech drug smugglers

Graphene nanoribbons with nanopores created for fast DNA sequencing

The instructions for building all of the body's proteins are contained in a person's DNA, a string of chemicals that, if unwound and strung end to end, would form a sentence 3 billion letters long. Each person's sentence is unique, so learning how to read gene sequences as quickly and inexpensively as possible could pave the way to countless personalized medical applications. 

heir DNA sensor is based on graphene, an atomically thin lattice of carbon. Earlier versions of the technique only made use of graphene's unbeatable thinness, but the Penn team's research shows how the Nobel Prize-winning material's unique electrical properties may be employed to make faster and more sensitive sequencing devices.

Critically, the team's latest study shows how to drill these nanopores without ruining graphene's electrical sensitivity, a risk posed by simply looking at the material through an electron microscope.

The team includes Marija Drndić, professor of physics in the School of Arts and Sciences, and members in her laboratory, including graduate student Matthew Puster and postdoctoral researchers Julio Rodríguez-Manzo and Adrian Balan.

Their research was published in the journal ACS Nano.

Drndić's group has previously demonstrated a series of advancements towards reading genes by passing them through a tiny hole, or nanopore. Their 2010 study involved drilling a hole in a sheet of graphene, then putting it in an ionic bath along with the strands of DNA to be detected. Because each of the four bases, the letters in DNA's alphabet, have a different size, a different number of ions would be expected to squeeze through along with each base as the strand passes through the pore. Researchers could then interpret the sequence of the DNA's bases by measuring the electrical signal of the ions. However, those current signals are weak, limiting the speed at which DNA could be sequenced.

Many research groups are now exploring multiple ways to improve the sensitivity and speed of the technique, including new materials and new ways of fashioning nanopores in them. Drndić's group has experimented with different membranes, as well as adding improved electronics to measure at faster speeds, but its latest study represents an entirely new way of generating an electrical signal unique to each base.

http://pubs.acs.org/doi/abs/10.1021/nn405112m

Graphene nanoribbons with nanopores created for fast DNA sequencing

Nanotechnology researchers prove two-step method for potential pancreatic cancer treatment

The dual-wave nanotherapy method employed by Drs. Nel and Meng in their research uses two different kinds of microscopic particles (nanoparticles) intravenously injected in a rapid sequence into the vein of the tumor-bearing mouse. The first wave of nanoparticles carries a substance that removes the pericytes' vascular gates to access the pancreatic cancer cells and the second wave carries the chemotherapy drug that kills the cancer cells.

Drs. Nel and Meng and their colleagues Dr. Jeffrey Zink, UCLA professor of chemistry and biochemistry and Dr. Jeffrey Brinker, University of New Mexico professor of chemical and nuclear engineering, sought to contain chemotherapy in nanoparticles that could more directly target pancreatic cancer cells, but they needed to find a way for those nanoparticles to get through the sites of vascular obstruction caused by the pericytes, which restricts access to the cancer cells. Through experimentation they discovered they could interfere with a cellular signaling pathway (the communication mechanism between cells) that governs the pericyte attraction to the tumor blood vessels. By making nanoparticles that effectively bind a high load of the signaling pathway inhibitor, they developed a first wave of nanoparticles that separates the pericytes from the endothelial cells (on the blood vessel). This opens the vascular gate for the next wave of nanoparticles, which carry the chemotherapeutic agent to the cancer cells inside the tumor.

To test this two-wave nanotherapy, the researchers used immuno-compromised mice that were used to grow human pancreatic tumors (called xenografts) under the mouse skin. With the two-wave method, the xenograft tumors had a significantly higher rate of shrinkage compared to those exposed to chemotherapy given the standard way as a free drug or carried in nanoparticles without first wave treatment.

"This two-wave nanotherapy is an existing example of how we seek to improve the delivery of chemotherapy drugs to their intended targets using nanotechnology to provide an engineered approach," said Nel, chief of the division of nanomedicine. "It shows how the physical and chemical principles of nanotechnology can be integrated with the biological sciences to help cancer patients by increasing the effectiveness of chemotherapy while also reducing side effects and toxicity. This two-wave treatment approach can also address biological impediments in nanotherapies for other types of cancer."

Ref : http://pubs.acs.org/doi/abs/10.1021/nn404083m

Nanotechnology researchers prove two-step method for potential pancreatic cancer treatment

Better batteries through biology? Modified viruses boost battery performance

MIT researchers have found a way to boost lithium-air battery performance, with the help of modified viruses. 

MIT researchers have found that adding genetically modified viruses to the production of nanowires -- wires that are about the width of a red blood cell, and which can serve as one of a battery's electrodes -- could help solve some of these problems.

The new work is described in a paper published in the journal Nature Communications, co-authored by graduate student Dahyun Oh, professors Angela Belcher and Yang Shao-Horn, and three others. The key to their work was to increase the surface area of the wire, thus increasing the area where electrochemical activity takes place during charging or discharging of the battery.

The researchers produced an array of nanowires, each about 80 nanometers across, using a genetically modified virus called M13, which can capture molecules of metals from water and bind them into structural shapes. In this case, wires of manganese oxide -- a "favorite material" for a lithium-air battery's cathode, Belcher says -- were actually made by the viruses. But unlike wires "grown" through conventional chemical methods, these virus-built nanowires have a rough, spiky surface, which dramatically increases their surface area.

Belcher, the W.M. Keck Professor of Energy and an affiliate of MIT's Koch Institute for Integrative Cancer Research, explains that this process of biosynthesis is "really similar to how an abalone grows its shell" -- in that case, by collecting calcium from seawater and depositing it into a solid, linked structure.

The increase in surface area produced by this method can provide "a big advantage," Belcher says, in lithium-air batteries' rate of charging and discharging. But the process also has other potential advantages, she says: Unlike conventional fabrication methods, which involve energy-intensive high temperatures and hazardous chemicals, this process can be carried out at room temperature using a water-based process.

Also, rather than isolated wires, the viruses naturally produce a three-dimensional structure of cross-linked wires, which provides greater stability for an electrode.

Ref : http://www.nature.com/ncomms/2013/131113/ncomms3756/full/ncomms3756.html

Better batteries through biology? Modified viruses boost battery performance

Breathalyzer technology detects acetone levels to monitor blood glucose in diabetics

A novel hand-held, noninvasive monitoring device that uses multilayer nanotechnology to detect acetone has been shown to correlate with blood-glucose levels in the breath of diabetics. This research is being presented at the 2013 American Association of Pharmaceutical Scientists (AAPS)Annual Meeting and Exposition, the world’s largest pharmaceutical sciences meeting, in San Antonio, Nov. 10–14. Read more 

Breathalyzer technology detects acetone levels to monitor blood glucose in diabetics

All aboard the nanotrain network: Tiny self-assembling transport networks, powered by nano-scale motors and controlled by DNA

Tiny self-assembling transport networks, powered by nano-scale motors and controlled by DNA, have been developed by scientists at Oxford University and Warwick University.

The system can construct its own network of tracks spanning tens of micrometres in length, transport cargo across the network and even dismantle the tracks.

The work is published in Nature Nanotechnology and was supported by the Engineering and Physical Sciences Research Council and the Biotechnology and Biological Sciences Research Council.

Researchers were inspired by the melanophore, used by fish cells to control their colour. Tracks in the network all come from a central point, like the spokes of a bicycle wheel. Motor proteins transport pigment around the network, either concentrating it in the centre or spreading it throughout the network. Concentrating pigment in the centre makes the cells lighter, as the surrounding space is left empty and transparent.

The system developed by the Oxford University team is very similar, and is built from DNA and a motor protein called kinesin. Powered by ATP fuel, kinesins move along the micro-tracks carrying control modules made from short strands of DNA. 'Assembler' nanobots are made with two kinesin proteins, allowing them to move tracks around to assemble the network, whereas the 'shuttles' only need one kinesin protein to travel along the tracks.

'DNA is an excellent building block for constructing synthetic molecular systems, as we can program it to do whatever we need,' said Adam Wollman, who conducted the research at Oxford University's Department of Physics. 'We design the chemical structures of the DNA strands to control how they interact with each other. The shuttles can be used to either carry cargo or deliver signals to tell other shuttles what to do.

'We first use assemblers to arrange the track into 'spokes', triggered by the introduction of ATP. We then send in shuttles with fluorescent green cargo which spread out across the track, covering it evenly. When we add more ATP, the shuttles all cluster in the centre of the track where the spokes meet. Next, we send signal shuttles along the tracks to tell the cargo-carrying shuttles to release the fluorescent cargo into the environment, where it disperses. We can also send shuttles programmed with 'dismantle' signals to the central hub, telling the tracks to break up.'

This demonstration used fluorescent green dyes as cargo, but the same methods could be applied to other compounds. As well as colour changes, spoke-like track systems could be used to speed up chemical reactions by bringing the necessary compounds together at the central hub. More broadly, using DNA to control motor proteins could enable the development of more sophisticated self-assembling systems for a wide variety of applications.

Ref : http://www.nature.com/nnano/journal/vaop/ncurrent/full/nnano.2013.230.html

All aboard the nanotrain network: Tiny self-assembling transport networks, powered by nano-scale motors and controlled by DNA

Nanotechnology Now - "Laser diodes versus LEDs"

Solid-state lighting (SSL) has recently become competitive with conventional light sources and is now the most efficient source of high color quality white light ever created. At the heart of SSL is the light-emitting diode (LED). The current standard architecture for SSL is the phosphor-converted light-emitting diode (PCLED) in which high-brightness InGaN blue LEDs are combined with one or more wavelength-downconverting phosphors to produce composite white light of virtually any color temperature and color rendering quality. Despite this success, blue LEDs still have significant performance limitations, especially a nonthermal drop in efficiency with increasing input power density called "efficiency droop" which limits operation to relatively low input power densities, contrary to the desire to produce more photons per unit area of the LED chip and to thereby make SSL more affordable.

An alternative could be a blue laser diode (LD). LDs can in principle have high efficiencies at much higher input power densities than LEDs. Above the lasing threshold, parasitic nonradiative recombination processes, including those likely responsible for efficiency droop in LEDs, are clamped at their rates at lasing threshold. Indeed, at high input power densities state-of-the-art, high-power, blue, edge-emitting LDs already have reasonably high (30%) power-conversion efficiencies, with the promise someday of even higher efficiencies. A team from Sandia National Laboratories, Albuquerque (NM, USA) and Corning Incorporated, Corning (NY, USA) compared LEDs and LDs and discuss their economics for practical SSL

The scientists refer to the tremendous progress made in both device types, with current state-of-the-art power-conversion efficiencies (PCEs) of 70% for LEDs and 30% for LDs. The input power densities, at which these PCEs peak, are vastly different at about 10 W/cm2 for LEDs and 25 kW/cm2 for LDs. As the areal chip cost necessary for economical lighting scales as input power density, areal chip cost can be much higher for LDs than for LEDs. The authors conclude that it appears to be much more challenging to achieve areal chip costs low enough for LEDs than for LDs to be operated at the input

Power densities at which their PCEs peak.

Yet, as heat-sink-limited single-chip white-light output scales inversely as input power density, heat-sink-limited single-chip white-light output can be much higher for LEDs than for LDs. A white-light output high enough for practical illumination applications should be more challenging to achieve for LDs than for LEDs.

The researchers conclude, that for both, LEDs and LDs, the solution will be to shift the input power density at which their PCEs peak. Whereas LEDs need to shift to higher input power density to offset higher areal chip cost, LDs need to shift to lower input power density to enable higher white-light output. In other words, both LEDs and LDs will be made more practical and economical if they can move into and fill the "valley of droop". (Text contributed by K. Maedefessel-Herrmann)

Nanotechnology Now - Press Release: "Laser diodes versus LEDs"

"Nanogrid, activated by sunlight, breaks down pollutants in water, leaving biodegradable compounds: Innovation Corps project explores how to bring technology to the field"

Pelagia-Irene (Perena) Gouma, a professor in the Department of Materials Science and  Engineering at the State University of New York (SUNY) Stony Brook, created a novel "nanogrid," a large net consisting of metal grids made of a copper tungsten oxide, that, when activated by sunlight, can break down oil from a spill, leaving only biodegradable compounds behind.

"We have made a new catalyst that can break down hydrocarbons in water, and it does not contaminate the water," says Gouma, who also directs SUNY's Center for Nanomaterials and Sensor Development. "It utilizes the whole solar spectrum and can work in water for a long time, which no existing photocatalyst can do now. Ours is a unique technology. When you shine light on these grids, they begin to work and can be used over and over again.

"Something like this would work fine for any oil spill," Gouma adds. "Any ship can carry them, so if they have even a small amount of spill, they can take care of it."

Initially, the grids, which resemble non-woven mats of miniaturized ceramic fishing nets, probably will be used for oil spills, although they potentially could prove valuable in other applications, such as cleaning contaminated water produced by "fracking," the process of hydraulic fracturing to extract natural gas from shale, and as well as from other industrial processes.

"Fracking is a reality," she says. "It is happening. If the science and engineering we produce in the lab can help alleviate environmental problems, we will be happy about that."

Because they work well both in water and air, they also could be a chemical-free, possibly even water-free, method of cleaning clothes in the future. "The dry cleaning process that we now use involves a lot of contaminants that have to be remediated and treated, such as benzene," she says. "This could be a dry cleaning substitute that would be more environmentally friendly than current dry cleaning approaches."

Moreover, "imagine you lay this over your clothes, and expose them to light. You won't need a washing machine, or chemicals, or even water," she adds.

The photocatalytic nanogrids™ invented in her lab are made by a unique self-assembly process that occurs "during the nanomanufacturing on non-woven nanofibrous mats deposited on metal meshes," according to Gouma. "Upon heating, metal clusters diffuse inside polymeric nanofibers, then turn into single crystal nanowires, then oxidize to form metal oxide--ceramic--nanoparticles that are interconnected, like links in a chain," she says.

These form an unusual and "robust third architecture that allows for the highest surface area, providing maximum exposure to the contaminant to be remediated, while the nanoscale particle sizes enable fast catalytic action," she adds. "The result is a self-supported water remediation targeted photocatalytic technology that has no precedent."

In the fall of 2011, Gouma was the first scientist to receive a $50,000 NSF Innovation Corps (I-Corps) award, which supports a set of activities and programs that prepare scientists and engineers to extend their focus beyond the laboratory into the commercial world.

Such results may be translated through I-Corps into technologies with near-term benefits for the economy and society. It is a public-private partnership program that teaches grantees to identify valuable product opportunities that can emerge from academic research, and offers entrepreneurship training to faculty and student participants.

Nanotechnology Now - Press Release: "Nanogrid, activated by sunlight, breaks down pollutants in water, leaving biodegradable compounds: Innovation Corps project explores how to bring technology to the field"

Carbon nanotube jungles created to better detect molecules

Researchers from Lawrence Livermore National Laboratory (LLNL) and the Swiss Federal Institute of Technology (ETH) in Zurich have developed a new method of using nanotubes to detect molecules at extremely low concentrations enabling trace detection of biological threats, explosives and drugs.

The joint research team, led by LLNL Engineer Tiziana Bond and ETH Scientist Hyung Gyu Park, are using spaghetti-like, gold-hafnium-coated carbon nanotubes (CNT) to amplify the detection capabilities in surface-enhanced Raman spectroscopy (SERS).

SERS is a surface-sensitive technique that enhances the inelastic scattering of photons by molecules adsorbed on rough metal surfaces or by nanostructures.

Bond and her collaborators are using metal-coated nanotubes bunched together like a jungle canopy to amplify the signals of both the incident and Raman scattered light by exciting local electron plasmons.

Their real breakthrough, however, is discovering the use of an intermediate dielectric coating (hafnium) to block the quenching of the free electrons in the metal by the CNTs, allowing the nanotubes to function uninhibited. By preserving the electrons and enhancing the light through the use of nanotube jungles, the team is able to significantly increase the SERS' detection sensitivities in CNTs structures.

The hafnium coating enables the bunching of gold nanotubes that creates a thick canopy full of sensitive spots for detection. The nanotubes enable incident light to be trapped and focused at the numerous contact points and crevices, allowing the Raman-scattered light to pass through. This enables portable Raman devices to detect and identify specific airborne substances randomly.

"This is a very important discovery in our efforts to improve the use of SERS devices," Bond said. "We gained this valuable knowledge through multidisciplinary basic research and approaching the problem with a rational design."

Bond and Park hope their engineered material will eventually be used in portable devices to conduct on-site analysis of chemical impurities such as environmental pollutants or pharmaceutical residues in water. Other applications include the real-time point-of-care monitoring of physiological levels for the biomedical industry and fast screening of drugs and toxins for law enforcement.

"We are in the process of filing a patent for our new discovery," Bond said.

Ref : http://onlinelibrary.wiley.com/doi/10.1002/adma.201300571/abstract

Carbon nanotube jungles created to better detect molecules