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Stanford bioengineers redesign protein motors to create novel nanomachines

Stanford bioengineers redesign protein motors to create novel nanomachines | Amazing Science | Scoop.it

Stanford scientists genetically engineer versions of myosin proteins that transport biological materials in cells to illuminate design features that keep these protein motors on track. Inside our cells, proteins known as myosins can act as a delivery service for biological materials. To better understand how molecular motors move, Stanford bioengineers have built experimental versions of the proteins, changing the way these transporters get around. Led by Zev Bryant, an assistant professor of bioengineering at Stanford, a team of researchers has genetically engineered “mutant” myosins with new features such as gearshifts and improved traction. The group’s most recent findings are published in the January issue of Nature Nanotechnology, where they are highlighted alongside other studies of molecular motors.


“You look at biology, and you see motors that have diverse mechanical properties, and you want to understand how these arise,” Bryant said. “You test your understanding by trying to build something new.” Molecular motors are a class of proteins that make up the moving machinery of cells. Myosins are one family of molecular motors. Some of them can shuttle biomolecules from one region of the cell to another.


These myosins move along microscopic filaments made of the protein known as actin. These actin filaments are one component of the cytoskeleton, or internal support structure of the cell. Bryant wanted to test his understanding of how evolution has designed these myosin proteins to shuttle cellular freight. Funded by an NIH “New Innovator” Award, members of the group launched a series of experiments in 2008 that steered their myosin research in a new direction. They began engineering myosins with extra parts to give natural myosins new capabilities.


Natural myosins, for example, see actin filaments as one-way tracks. To better understand this one-directional motion, Bryant challenged his group to design mutant myosins that could move forward and backward on command. The researchers engineered myosin motors with extra components that behaved like a molecular gearshift. In a 2012 Nature Nanotechnology report, the researchers showed that they could shift their mutant myosin motion between forward and reverse. However, these two-way myosins had trouble hanging onto their actin tracks.


“When we engineer motors to have new capabilities, we often sacrifice some capabilities that they already had,” Bryant said. So the group focused on creating motors that excelled at hanging on.

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DNA motor 'walks' along nanotube and transports a tiny particle

DNA motor 'walks' along nanotube and transports a tiny particle | Amazing Science | Scoop.it
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 findings were detailed in a research paper published in the journal Nature Nanotechnology.


In coming decades, such molecular motors might find uses in drug delivery, manufacturing and chemical processing. 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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Foresight Institute -- 2013 Sessions of the Foresight Technical Conference

Foresight Institute -- 2013 Sessions of the Foresight Technical Conference | Amazing Science | Scoop.it

A select set of videos from the 2013 Foresight Technical Conference: Illuminating Atomic Precision, held January 11-13, 2013 in Palo Alto, have been made available on Vimeo. Videos have been posted of those presentations for which the speakers have consented. This conference has brought together many of the world’s leading researchers on a wide range of work relating to atomically and molecularly precise processes, materials, and devices. The wide variety of topics stimulates interdisciplinary dialog, productive collaboration, and scientific and technical progress towards beneficial nanotechnologies.


Topic include:


  • Atomic Scale Devices
  • Molecular Machines and Non-Equillibrium Processes
  • Self Organizing and Adaptive Systems
  • Commercially Implemented Single Molecule Technologies
  • Computation and Molecular Nanotechnolgies
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Cellulose nanocrystals found to have stiffness of steel

Cellulose nanocrystals found to have stiffness of steel | Amazing Science | Scoop.it

Applications range from electronics and medical devices to structural components for the automotive, civil and aerospace industries.


The same tiny cellulose crystals that give trees and plants their high strength, light weight and resilience, have now been shown to have the stiffness of steel. The nanocrystals might be used to create a new class of biomaterials with wide-ranging applications, such as strengthening construction materials and automotive components.


Calculations using precise models based on the atomic structure of cellulose show the crystals have a stiffness of 206 gigapascals, which is comparable to steel, said Pablo D. Zavattieri, a Purdue University assistant professor of civil engineering.


The nanocrystals are about 3 nanometers wide by 500 nanometers long, making them too small to study with light microscopes and difficult to measure with laboratory instruments.


The findings represent a milestone in understanding the fundamental mechanical behavior of the cellulose nanocrystals. “It is also the first step towards a multiscale modeling approach to understand and predict the behavior of individual crystals, the interaction between them, and their interaction with other materials,” Zavattieri said.


“This is important for the design of novel cellulose-based materials as other research groups are considering them for a huge variety of applications, ranging from electronics and medical devices to structural components for the automotive, civil and aerospace industries.”


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‘Zero-dimensional’ carbon nanotubes may lead to superthin/superfast electronics and synthetic cells

‘Zero-dimensional’ carbon nanotubes may lead to superthin/superfast electronics and synthetic cells | Amazing Science | Scoop.it

Piles of zero-dimensional carbon nanotubes appear as gold “mountains” a few nanometers high on a substrate, viewed by atomic force microscopy.


Synthetic, man-made cells and ultrathin electronics built from a new form of “zero-dimensional” carbon nanotube (CNT) may be possible, thanks to research at the University of Pittsburgh Swanson School of Engineering.


When created, single-wall carbon nanotubes (SWNTs) have a length-to-diameter ratio of up to 132,000,000:1 (think long wires that entangle, forming a one-dimensional structure). This clustering makes it difficult to achieve high purity, water solubility, and wet nanoscale applications, such a biological uses.


But what if the nanotube length could be reduced to roughly the size of its diameter — about 1 nanometer — thus creating a “zero-dimensional” carbon nanotube? That’s what Pitt researchers have achieved.


These extremely short nanotubes would be more soluble and would have the same dimensions as many proteins that compose the basic machinery of living cells. That suggests the potential for cell- or protein-level biomedical imaging, protein or nucleic acid vaccination carriers, drug-delivery vehicles, or even components of synthetic cells, the researchers say.


In addition, “zero-dimensional carbon nanotubes present the possibility to build ultrathin, superfast electronic devices, far superior to the best existing ones and it could be possible to build strong and ultralight cars, bridges, and airplanes,” said Steven R. Little, PhD, associate professor, CNG Faculty Fellow and Chair of the Department of Chemical and Petroleum Engineering, a principal investigator.


The researchers expect the process will be available commercially as soon as the process can be scaled up to manufacture bulk quantities, which is underway currently.


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Micro-robots will become soft and move like biological organisms, experts predict

Micro-robots will become soft and move like biological organisms, experts predict | Amazing Science | Scoop.it

Increasingly small robots can carry out their functions even inside the human body. No, this isn’t a sci-fi dream. The technology is almost ready. However there is still one condition they must meet to be effective: these devices need to have the same "softness" and flexibility as biological tissues.


This is the opinion of scientists like Antonio De Simone, from SISSA (the International School for Advanced Studies of Trieste) and Marino Arroyo from the Polytechnic University of Catalonia, who have just published a paper in the Journal of the Mechanics and Physics of Solids. Taking inspiration from unicellular water micro-organisms, they studied the locomotion mechanisms of "soft robots."

 

Forget cogwheels, pistons and levers: miniaturized robots of the future will be 'soft.' "If I think of the robots of tomorrow, what comes to mind are the tentacles of an octopus or the trunk of an elephant rather than the mechanical arm of a crane or the inner workings of a watch. And if I think of micro-robots then I think of unicellular organisms moving in water. The robots of the future will be increasingly like biological organisms" explains Antonio De Simone.


De Simone and his team at SISSA have been studying the movement of euglenids, unicellular aquatic animals, for several years. One of the aims of De Simone's research -- which has recently been awarded a European Research Council Advanced Grant of 1,300,000 euro -- is to transfer the knowledge acquired in euglenids to micro-robotics, a field that represents a promising challenge for the future. Micro-robots may in fact carry out a number of important functions, for example for human health, by delivering drugs directly to where they are needed, re-opening occluded blood vessels, or helping to close wounds, to name just a few.


To do this, these tiny robots will have to be able to move around efficiently. "Imagine trying to miniaturize a device made up of levers and cogwheels: you can't go below a certain minimal size. Instead, by mimicking biological systems we can go all the way down to cell size, and this is exactly the direction research is taking. We, in particular, are working on movement and studying how certain unicellular organisms with highly efficient locomotion move."

 

In their study, De Simone and Arroyo simulated euglenid species with different shapes and locomotion methods, based chiefly on cell body deformation and swelling, to describe in detail the mechanics and characteristics of the movement obtained.

 

"Our work not only helps to understand the movement mechanism of these unicellular organisms, but it provides a knowledge base to plan the locomotion system of future micro-robots."


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Super-thin membranes clear the way for chip-sized pumps

Super-thin membranes clear the way for chip-sized pumps | Amazing Science | Scoop.it

The ability to shrink laboratory-scale processes to automated chip-sized systems would revolutionize biotechnology and medicine. For example, inexpensive and highly portable devices that process blood samples to detect biological agents such as anthrax are needed by the U.S. military and for homeland security efforts. One of the challenges of "lab-on-a-chip" technology is the need for miniaturized pumps to move solutions through micro-channels. Electroosmotic pumps (EOPs), devices in which fluids appear to magically move through porous media in the presence of an electric field, are ideal because they can be readily miniaturized. EOPs however, require bulky, external power sources, which defeats the concept of portability. But a super-thin silicon membrane developed at the University of Rochester could now make it possible to drastically shrink the power source, paving the way for diagnostic devices the size of a credit card.

 

"Up until now, electroosmotic pumps have had to operate at a very high voltage—about 10 kilovolts," said James McGrath, associate professor of biomedical engineering. "Our device works in the range of one-quarter of a volt, which means it can be integrated into devices and powered with small batteries."

 

McGrath and his team use porous nanocrystalline silicon (pnc-Si) membranes that are microscopically thin—it takes more than one thousand stacked on top of each other to equal the width of a human hair. And that's what allows for a low-voltage system.

 

A porous membrane needs to be placed between two electrodes in order to create what's known as electroosmotic flow, which occurs when an electric field interacts with ions on a charged surface, causing fluids to move through channels. The membranes previously used in EOPs have resulted in a significant voltage drop between the electrodes, forcing engineers to begin with bulky, high-voltage power sources. The thin pnc Si membranes allow the electrodes to be placed much closer to each other, creating a much stronger electric field with a much smaller drop in voltage. As a result, a smaller power source is needed.

 

A microfluidic bioreactors consists of two chambers separated by a nanoporous silicon membrane. It allows for flow-based assays using minimal amounts of reagent. The ultra-thin silicon membrane provides an excellent mimic of biological barrier properties. The shown image combines two exposures in order to capture the brighter and darker parts of the scene, which exceed the dynamic range of the camera sensor. The resulting composite is truer to what the eye actually sees.

 

Along with medical applications, it's been suggested that EOPs could be used to cool electronic devices. As electronic devices get smaller, components are packed more tightly, making it easier for the devices to overheat. With miniature power supplies, it may be possible to use EOPs to help cool laptops and other portable electronic devices.

 

McGrath said there's one other benefit to the silicon membranes. "Due to scalable fabrication methods, the nanocrystalline silicon membranes are inexpensive to make and can be easily integrated on silicon or silica-based microfluid chips."

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Diamond ‘flaws’ may pave the way for nanoscale MRI and thermometry of single cells

Diamond ‘flaws’ may pave the way for nanoscale MRI and thermometry of single cells | Amazing Science | Scoop.it

Breakthrough offers high-sensitivity nanoscale sensors, and could lead to magnetic imaging of neuron activity and thermometry on a single living cell. - See more at:

 

By exploiting flaws in miniscule diamond fragments, researchers say they have achieved enough coherence of the magnetic moment inherent in these defects to harness their potential for precise quantum sensors in a material that is 'biocompatible'.

 

Nanoscopic thermal and magnetic field detectors - which can be inserted into living cells - could enhance our understanding of everything from chemical reactions within single cells to signalling in neural networks and the origin of magnetism in novel materials.

 

Atomic impurities in natural diamond structure give rise to the colour seen in rare and coveted pink, blue and yellow diamond. But these impurities are also a major research focus in emerging areas of quantum physics.

 

One such defect, the Nitrogen-vacancy Centre (NVC), consists of a gap in the crystal lattice next to a nitrogen atom. This system tightly traps electrons whose spin states can be manipulated with extreme precision.

Electron coherence - the extent to which the spins of these particles can sustain their quantum mechanical properties - has been achieved to high levels in the NVCs of large 'bulk' diamonds, with coherence times of an entire second in certain conditions - the longest yet seen in any solid material.

 

However in nanodiamonds - nanometer sized crystals that can be produced by milling conventional diamond - any acceptable degree of coherence has, until now, proved elusive.

 

Nanodiamonds offer the potential for both extraordinarily precise resolution, as they can be positioned at the nano-scale, and biocompatibility - as they have can be inserted into living cells. But without high levels of coherence in their NVCs to carry information, these unique nanodiamond benefits cannot be utilised.

 

By observing the spin dynamics in nanodiamond NVCs, researchers at Cambridge's Cavendish Laboratory, have now identified that it is the concentration of nitrogen impurities that impacts coherence rather than interactions with spins on the crystal surface.

 

By controlling the dynamics of these nitrogen impurities separately, they have increased NVC coherence times to a record 0.07 milliseconds longer than any previous report, an order of significant magnitude - putting nanodiamonds back in play as an extremely promising material for quantum sensing.

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Scientists create single-atom bit, smallest memory in the world

Scientists create single-atom bit, smallest memory in the world | Amazing Science | Scoop.it

Karlsruhe Institute of Technology (KIT) researchers have taken a big step towards miniaturizing magnetic data memory down to a single-atom bit: they fixed a single atom on a surface so the magnetic spin remained stable for ten minutes.

 

“A single atom fixed to a substrate is [typically] so sensitive that its magnetic orientation is stable only for less than a microsecond,” said Wulf Wulfhekel of KIT.

 

A compound of several million atoms has been needed to stabilize a magnetic bit longer than that. That’s because the magnetic moments of these atoms are normally easily destabilized by interactions with electrons, nuclear spins, and lattice vibrations of the substrate.

 

The finding opens up the possibility of designing more compact computer memories and could also be the basis for quantum computers, Wulfhekel said.

 

In their experiment, the researchers placed a single holmium atom onto a platinum substrate. At temperatures close to absolute zero (about 1 degree Kelvin), the atom was nearly vibration-free. They measured the magnetic orientation of the atom using the fine tip of a scanning tunneling microscope. The magnetic spin changed after about 10 minutes — “about a billion times longer than that of comparable atomic systems,” Wulfhekel said.


Reference: 

Toshio Miyamachi et al., Stabilizing the magnetic moment of single holmium atoms by symmetry, Nature, 2013, DOI: 10.1038/nature12759
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Wyss Institute at Harvard: "Watermark Ink" device (W-INK) wins R&D 100 Award

Wyss Institute at Harvard: "Watermark Ink" device (W-INK) wins R&D 100 Award | Amazing Science | Scoop.it

A device that can instantly identify unknown liquids based on their surface tension has been selected to receive the 2013 R&D 100 Award—known as “the Oscar of Innovation”—from R&D Magazine.

 

Invented in 2011 by a team of materials scientists and applied physicists at the Harvard School of Engineering and Applied Sciences (SEAS) and the Wyss Institute for Biologically Inspired Engineering at Harvard, the “Watermark Ink” (W-INK) device offers a cheap, fast, and portable way to perform quality control tests and detect liquid contaminants.

 

W-INK fits in the palm of a hand and requires no power source. It exploits the chemical and optical properties of precisely nanostructured materials to distinguish liquids by their surface tension.

 

Winners of the R&D 100 Awards are selected by an independent judging panel and by the editors of R&D Magazine, which covers cutting-edge technologies and innovations for research scientists, engineers, and technical experts around the world.

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A single-atom light switch

A single-atom light switch | Amazing Science | Scoop.it

With just a single atom, light can be switched between two fiber optic cables at the Vienna University of Technology. Such a switch enables quantum phenomena to be used for information and communication technology.

 

Fiber optic cables are turned in to a quantum lab: scientists are trying to build optical switches at the smallest possible scale in order to manipulate light. At the Vienna University of Technology, this can now be done using a single atom. Conventional glass fibre cables, which are used for internet data transfer, can be interconnected by tiny quantum systems.

Professor Arno Rauschenbeutel and his team at the Vienna University of Technology capture light in so-called "bottle resonators". At the surface of these bulgy glass objects, light runs in circles. If such a resonator is brought into the vicinity of a glass fibre which is carrying light, the two systems couple and light can cross over from the glass fibre into the bottle resonator.

 

"When the circumference of the resonator matches the wavelength of the light, we can make one hundred percent of the light from the glass fiber go into the bottle resonator – and from there it can move on into a second glass fiber", explains Arno Rauschenbeutel.


This system, consisting of the incoming fiber, the resonator and the outgoing fiber, is extremely sensitive: "When we take a single Rubidium atom and bring it into contact with the resonator, the behaviour of the system can change dramatically", says Rauschenbeutel. If the light is in resonance with the atom, it is even possible to keep all the light in the original glass fiber, and none of it transfers to the bottle resonator and the outgoing glass fiber. The atom thus acts as a switch which redirects light one or the other fiber.

 

In the next step, the scientists plan to make use of the fact that the Rubidium atom can occupy different quantum states, only one of which interacts with the resonator. If the atom occupies the non-interacting quantum state, the light behaves as if the atom was not there. Thus, depending on the quantum state of the atom, light is sent into either of the two glass fibers. This opens up the possibility to exploit some of the most remarkable properties of quantum mechanics: "In quantum physics, objects can occupy different states at the same time", says Arno Rauschenbeutel. The atom can be prepared in such a way that it occupies both switch states at once. As a consequence, the states "light" and "no light" are simultaneously present in  each of the two glass fiber cables.

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How nanotechnology can advance regenerative medicine

How nanotechnology can advance regenerative medicine | Amazing Science | Scoop.it

Nanotechnology may provide new strategies for regenerative medicine, including better tools to improve or restore damaged tissues, according to a review paper that summarizes the current state of knowledge on nanotechnology with application to stem cell biology.

 

Researchers have found that the adhesion, growth, and differentiation of stem cells are likely controlled by their surrounding microenvironment, which contains both chemical and physical cues. These cues include the “nanotopography” of the complex extracellular matrix or architecture that forms a network for human tissues.

 

In their review paper published in the journal Science and Technology of Advanced Materials (open access), Yang-Kao Wang and colleagues describe studies showing how this nanotopography (which includes nanosized pores, grooves, ridges, etc.) plays important roles in the behavior and fate of stem cells.

 

The authors also discuss the application of nanoparticles to stem cell isolation, tracking and imaging; how to translate nanotechnology from two to three dimensions; and the potential limitations of using nanomaterials in stem cell biology.

 

The paper concludes that “understanding [the] interactions of nanomaterials with stem cells may provide knowledge applicable to [the development of improved] cell-scaffold combinations in tissue engineering and regenerative medicine.”

 


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Everything from ions to living cells can be directed to self-assemble using magnetic fields

Everything from ions to living cells can be directed to self-assemble using magnetic fields | Amazing Science | Scoop.it

Scientists in the US have devised a stunningly simple way to direct colloids to self-assemble in an almost infinite variety of configurations, in both two and three dimensions. The technique, which relies on the creation of a pre-determined pattern of magnetic fields to generate a ‘virtual mould’ to dictate the final position of the particles, can be used to separate and distribute, in a controlled way, anything from living cells to ions.

 

‘The concept is trivial,’ Bartosz Grzybowski, who led the research team at Northwestern University, cheerfully concedes. ‘Why no-one thought of it before now is a good question.’

 

The system consists of a patterned grid of nickel, generated by photolithography, embedded in a layer of poly(dimethyl siloxane) (PDMS). This is placed on a permanent magnet. This forms a patterned magnetic field on the grid: on the nickel the field is strong, on the adjacent ‘islands’ where there is no nickel, the field is weak.

 

When a colloidal mixture containing magnetic (paramagnetic) and non-magnetic (diamagnetic) particles is placed on the nickel grid and a magnetic field applied, the paramagnetic particles are drawn to the nickel regions, pushing aside any diamagnetic particles and directing them to the adjacent non-magnetic islands or voids.

 

The ability to construct three-dimensional architectures from the colloids also arises, given that the magnetic field penetrates the space above the nickel regions. An excess of diamagnetic colloid, for example, will coalesce on a low-field island to build a pillar. A further excess of particles can build bridges between pillars to produce arches. Such complex three-dimensional structures could be useful for electronic circuitry. To illustrate the versatility of the approach, the research team patterned a grid in such a way to fashion  a microscopic facsimile of the Blue Mosque in Istanbul, featuring large ‘domes’ connected by arches, and surrounded by four unconnected satellite domes.

 

‘For me, one of the main aspects of this work is in being able to position particles, and in particular living cells,’ says Grzybowski. ‘We should be able to address things that cannot be addressed by other means.’

Stefano Sacanna, who researches colloid self-assembly at New York University, says: ‘This is the kind of work that makes you think how come nobody has ever thought of this before?’ Sacanna says that while template-assisted self-assembly is a well-known technique the new work has ‘completely redefined this concept, introducing virtual magnetic moulds that can manipulate either paramagnetic or diamagnetic colloids simultaneously’.

 

‘Their idea of modulating magnetic fields at the micron-scale using a combination of paramagnetic fluids and magnetisable composite films is, in its simplicity, extremely powerful,’ he adds. ‘Not only can these virtual moulds extend in the third dimension, but they can also be switched on and off on demand, allowing for the creation of dynamic and reconfigurable three-dimensional colloidal architectures. As if this was not impressive enough already, they showed how magnetic moulds can manipulate objects other than colloids, including ions and colonies of – live! – bacteria. This work greatly extends our ability to manipulate colloidal matter and holds the promise for new exciting opportunities in nano-fabrication.’

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LOL  It often is...    ‘The concept is trivial,’ Bartosz Grzybowski, who led the research team at Northwestern University, cheerfully concedes. ‘Why no-one thought of it before now is a good question.’

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Engineer designs self-powered nanoscale devices that never need new batteries

Engineer designs self-powered nanoscale devices that never need new batteries | Amazing Science | Scoop.it

It's relatively simple to build a device capable of detecting wireless signals if you don't mind making one that consumes lots of power.


That's what Peter Kinget, a professor of electrical engineering, works on. He and his colleagues at the Engineering School are attempting to build self-powered systems using nanoscale devices that can transmit and receive wireless signals using so little power that their batteries never need replacing.


Rather, they rely on tiny bits of ambient solar energy to recharge themselves. Such energy efficiencies could dramatically cut down on the cost to operate a variety of these devices at once, while eliminating the need for maintenance. These sensors would only need to be installed once, and could remain in place functioning autonomously—practically until they wear out or disintegrate on their own.


Kinget's work is made possible by recent advances in nanotechnology—in general, he explains, the smaller the components of the tiny devices, the less energy is required to allow them to operate.


"We are using and exploiting the fact that power consumption—and the energy you need to do things—becomes very, very low as you pack more and more functionality into smaller and smaller spaces," he says.


"The bad news," he adds, "is that as the transistors become smaller, there are also clear disadvantages—nanoscale transistors are not as reliable, they cannot sustain large signal levels. The only way to deal with them is to come up with new design concepts."


Kinget's chips—some of them 100 times more energy efficient than most standard technologies—could be deployed for many different uses in future. Embedded in clothing, they could transmit the location of victims during disasters. They could be affixed to the walls of apartments across New York City and monitor heating or energy consumption patterns, which could then be analyzed to manage the heating systems or the power grid better. They could even collect and transmit data about humidity and temperature to computers designed to recognize and predict weather patterns.



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MIT: Colored Plastic Doubles Solar Cell Power

MIT: Colored Plastic Doubles Solar Cell Power | Amazing Science | Scoop.it
Using plastic to absorb light could lower the cost of solar power.


A thin sheet of dyed plastic could cut the cost of solar power, particularly for applications that require solar cells to be highly efficient and flexible. Researchers at the University of Illinois at Urbana-Champaign are using the plastic to gather sunlight and concentrate it onto a solar cell made of gallium arsenide in an experimental setup. Doing so doubled the power output of the cells.


So far, the researchers have shown that the approach works with a single solar cell, but they plan to make larger sheets of plastic dotted with arrays of many tiny solar cells. The approach could either let a smaller solar panel produce more electricity, or make a panel cheaper by reducing the amount of photovoltaic material needed.


“It’s lower cost compared to what you would have to do to get the same efficiency by completely coating the surface with active solar material,” says John Rogers, professor of materials science and engineering and chemistry at the University of Illinois. The work was presented at the Materials Research Society conference in Boston this week.


As light hits the plastic sheet, a specially selected dye absorbs it. The dye is luminescent—meaning that after it absorbs light, it reëmits it. But the light it emits is largely confined inside the plastic sheet. So it bounces along inside the plastic until it reaches a solar cell, much in the same way light is guided along inside a fiber optic cable. The dye absorbs only part of the solar spectrum. So to further boost power output, the researchers added a reflective material that directs some of the light that the dye doesn’t absorb to the solar cell.


The approach could be compatible with another innovation from the same group of researchers—a technique for making flexible and stretchable solar cells that can conform to irregular surfaces (see “Making Stretchable Electronics”).


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Nanotechnology for self-powered systems

Nanotechnology for self-powered systems | Amazing Science | Scoop.it

There is an almost infinite number of mechanical energy sources all around us – basically, anything that moves can be harvested for energy. These environmental energy sources can the very large, like wave power in the oceans, or very small, like rain drops or biomechanical energy from heart beat, breathing, and blood flow. With the increasing use of nanotechnology materials and applications in energy research, scientists are finding more and more ways to tap into these pretty much limitless sources of energy.


The continued miniaturization of portable electronics is increasingly challenged by the reliance on conventional battery technology. But for the near future, micro- and even nanoscale devices will be widely used in health monitoring; infrastructure and environmental monitoring; internet of things; and of course defense technologies. In these application areas, battery design will have to go way beyond today's typical lithium-ion batteries. Rather than relying on stored power, nanodevices will probably rely on novel, also nanoscale, power sources.


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Cobalt Oxide Nanoparticles Can Split Water Into Hydrogen and Oxygen Using Natural Sunlight

Cobalt Oxide Nanoparticles Can Split Water Into Hydrogen and Oxygen Using Natural Sunlight | Amazing Science | Scoop.it

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. Their research, published in Nature Nanotechnology, involved the use of cobalt oxide nanoparticles to split water into hydrogen and oxygen.


Jiming Bao, lead author of the paper and an assistant professor in the Department of Electrical and Computer Engineering at UH, said the research discovered a new photocatalyst and demonstrated the potential of nanotechnology in engineering a material’s property, although more work remains to be done.


Bao said photocatalytic water-splitting experiments have been tried since the 1970s, but this was the first to use cobalt oxide and the first to use neutral water under visible light at a high energy conversion efficiency without co-catalysts or sacrificial chemicals. The project involved researchers from UH, along with those from Sam Houston State University, the Chinese Academy of Sciences, Texas State University, Carl Zeiss Microscopy LLC, and Sichuan University.


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.

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Free-swimming, self-propelled micromotors to clean up polluted water

Free-swimming, self-propelled micromotors to clean up polluted water | Amazing Science | Scoop.it
Researchers in Germany have invented micromotors that can propel themselves through water while degrading organic pollutants. The micromotors, which run on dilute hydrogen peroxide, could be used to clean up small reservoirs, pipes and other hard to reach places.


Organic pollutants are found in many industrial wastewaters, including those of textile companies, pharmaceutical companies and agriculture. They are an increasing problem, because they are often resistant to environmental degradation and cannot be processed with conventional biological or chemical water treatments.

 

Micromotors could help. Last year, building on previous uses of micromotors as on-chip biosensors and cell transporters, Joseph Wang, at the University of California, San Diego in the US, and colleagues developed self-propelled micromotors that could capture oil droplets – thereby offering a means to clean up small oil spills. Only now, however, have micromotors been used to actually degrade pollutants. ‘This study indicates the great potential of micromotors for environmental monitoring and remediation,’ says Wang.

 

Developed by Samuel Sanchez and colleagues at the Leibniz Institute for Solid State and Materials Research (IFW) the latest micromotors consist of a tubular core of platinum that is surrounded by iron. Releasing them into polluted water containing dilute hydrogen peroxide results in the motors’ platinum cores converting the peroxide into oxygen bubbles and the surrounding iron produces hydroxyl radicals. The bubbles propel the micromotors along, while the hydroxyl radicals oxidise organic pollutants.

 

Two experts in micromotors, Ayusman Sen at Penn State University in the US and Martin Pumera at Nanyang Technological University in Singapore, both say that the big advantage of the micromotors is their self-propulsion, which speeds up reaction rates and, therefore, quickly degrades pollutants. ‘The hydroxyl radicals can reach the target pollutant molecules much faster than would be possible by simple diffusion,’ says Pumera.

 

The micromotors would probably not be able to remediate ‘huge amounts’ of waste water, says Sanchez. ‘We aim to clean contaminated capillaries, small pipes and places difficult to reach,’ he adds. ‘We are dealing with applications especially for the microscale and environments hard to get to.’

 

Li Zhang at the Chinese University of Hong Kong says the results are ‘striking’, and hold promise for environmental applications. ‘To date, though several research groups have been working on micromotors, they have mainly put great efforts on biological and biomedical applications,’ he says. ‘It is apparent that for industrial application, such as wastewater treatment, this process needs to be further scaled-up and the micromotors require multi-functionality. I think it is worth doing those trials and continuing this research topic.’

   
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The first step has been taken towards developing a nanorobot to deliver drugs inside the body

The first step has been taken towards developing a nanorobot to deliver drugs inside the body | Amazing Science | Scoop.it

Using DNA self-assembly, the Aarhus University researchers Magnus Stougaard, Oskar Franch and Brian Christensen designed eight unique DNA molecules from the body’s own natural molecules. When these molecules are mixed together, they spontaneously aggregate in a usable form – the nanocage (see figure).

 

The nanocage has four functional elements that transform themselves in response to changes in the surrounding temperature. These transformations either close (figure 1A) or open (figure 1B) the nanocage. By exploiting the temperature changes in the surroundings, the researchers trapped an active enzyme called horseradish peroxidase (HRP) in the nanocage (figure 1C). They used HRP as a model because its activity is easy to trace.

 

This is possible because the nanocage’s outer lattice has apertures with a smaller diameter than the central spherical cavity. This structure makes it possible to encapsulate enzymes or other molecules that are larger than the apertures in the lattice, but smaller than the central cavity.

 

The researchers have just published these results in the renowned journal ACS Nano. Here the researchers show how they can utilise temperature changes to open the nanocage and allow HRP to be encapsulated before it closes again.

 

They also show that HRP retains its enzyme activity inside the nanocage and converts substrate molecules that are small enough to penetrate the nanocage to products inside.

 

The encapsulation of HRP in the nanocage is reversible, in such a way that the nanocage is capable of releasing the HRP once more in reaction to temperature changes. The researchers also show that the DNA nanocage – with its enzyme load – can be taken up by cells in culture.

 

Looking towards the future, the concept behind this nanocage is expected to be used for drug delivery, i.e. as a means of transport for medicine that can target diseased cells in the body in order to achieve a more rapid and more beneficial effect.

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Elena Ortés's curator insight, December 5, 2013 8:13 AM

De gran ayuda en la lucha contra el cancer.

Directo al foco.

Dmitry Alexeev's curator insight, December 5, 2013 11:37 PM

drug delivery as well as novell instrument)

 

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Photon-plasmon nanowire laser offers new opportunities in light manipulation

Photon-plasmon nanowire laser offers new opportunities in light manipulation | Amazing Science | Scoop.it
Recently, researchers have been developing a new type of laser that combines photons and plasmons (electron density oscillations) into a single radiation-emitting device with unique properties.

 

The hybrid photon-plasmon nanowire laser is composed of a Ag nanowire and a CdSe nanowire coupled into an X-shape. This type of coupling enables the photonic and plasmonic modes to be separated, which gives the hybrid laser advantageous features.


"Compared to conventional photon lasers, the hybrid photon-plasmon nanowire laser offers two outstanding possibilities: the extremely thin laser beam (e.g., down to the size of a single molecule) and the ultrafast modulation (e.g., >THz repetition rate), both stemming from the longitudinally separable pure plasmon nanowire mode," Limin Tong, Professor at Zhejiang University in Hangzhou China, told Phys.org. "Owing to the above-mentioned merits, photon-plasmon lasers are potentially better for certain applications such as strong coupling of quantum nanoemitters, ultra-sensitivity optical sensing, and ultrafast-modulated coherent sources."


In a new study, the researchers have demonstrated that the photon and plasmon nanowire waveguides can be coupled in the longitudinal direction; that is, along the direction of the beams. This type of coupling makes it possible to spatially separate the plasmonic mode from the photonic mode, and to simultaneously use both modes. Under excitation, strong luminous spots are observed at both ends of the hybrid cavity, with interference rings indicating strong spatial coherence of the light emitted. The output spot of the Ag nanowire is much smaller than that of the CdSe nanowire, indicating much tighter confinement of the plasmon radiation.


The advantages of ultratight confinement and ultrafast modulation offered by side-coupling a plasmonic nanowire waveguide to a photonic one enable the hybrid laser to provide very precise lasing, which could be delivered to very small areas such as quantum dots. Photon-plasmon lasers can also have applications for nanophotonic circuits, biosensing, and quantum information processing. The researchers plan to make further improvements to the laser in the future.

 

"One of our future plans is to introduce the ultrafast nonlinear effects of the plasmonic nanowire into the hybrid laser, and explore the possibility of ultrafast-modulation of the nanolaser, while offering a far-field-accessible pure plasmon cavity mode with sub-diffration-limited beam size," Tong said.

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Detecting Molecules Through 14 mm Thick Bone

Detecting Molecules Through 14 mm Thick Bone | Amazing Science | Scoop.it

To understand the brain and its chemical complexities, researchers would like to peer inside the skull and observe neurotransmitters at work. Unfortunately, research methods to measure levels of certain chemicals in the brain require drilling holes in the skull, and noninvasive imaging techniques, such as MRI, can’t detect specific molecules. Now, as a first step toward a new imaging tool, researchers have shown that they can use Raman spectroscopy todetect chemical signatures through bone (J. Am. Chem. Soc. 2013, DOI: 10.1021/ja409378f).

 

With Raman spectroscopy, chemists can look for chemicals of interest sitting inside a range of materials, such as explosives inside plastic bottles. Richard P. Van Duyne’s group at Northwestern University has used the technique to monitor glucose levels through the skin of living rats (Anal. Chem. 2011, DOI: 10.1021/ac202343e).

 

To peer through bone, Sharma and colleagues combined two spectroscopic techniques: surface-enhanced and spatially offset Raman spectroscopy. Both methods involve exciting samples with laser light and then monitoring for specific Raman signals from the sample that are characteristic of a chemical of interest.

 

In the surface-enhanced variety, gold nanoparticles boost the Raman signal produced by molecules bound to their surfaces. The spatially offset method allows researchers to detect a useful signal from molecules located up to 20 mm within a sample. Researchers can isolate signals from these buried compounds by observing Raman signals at a different spot from where they shine the laser light. The separation ensures that the molecule’s signal isn’t dwarfed by scattered laser light from the sample’s surface.

 

As a test of the combination method, the researchers went to the market and bought a cut of lamb shoulder with a bone 3 to 8 mm thick. The human skull is 3 to 14 mm thick. The team then injected 90 trillion gold nanoparticles into the meat behind the bone. They had decorated the particles with a compound that has a strong Raman signature. When they shined 785-nm laser light on the bone, they could immediately detect the chemical signature of the reporter molecule. Sharma jumped up and down when she saw the results. “Everything I read and everyone we talked to said, ‘No, this shouldn’t work,’” through bone because the material isn’t transparent enough, Sharma says.

 

Right now the researchers cannot detect where the nanoparticles are located within the tissue, Van Duyne says, only that they are on the other side of the bone. And even with further refinements, the depth of tissue penetration is likely to be limited to areas close to the tissue’s outer surface.

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Organic semiconductor transistor made of a single nanoparticle achieves highest mobility yet

Organic semiconductor transistor made of a single nanoparticle achieves highest mobility yet | Amazing Science | Scoop.it

Organic semiconducting devices have many positive attributes, such as their low cost, high flexibility, light weight, and ease of processing. However, one drawback of organic semiconductors is that they generally have a low electron mobility, resulting in a weak current and poor conductivity.

 

In a new study, scientists from Taiwan have designed and built an organic semiconductor transistor with a mobility that is 2-3 orders of magnitude higher than that of conventional organic semiconductor transistors. The benefits of a high mobility could extend to a wide range of applications, such as organic LED displays, organic solar cells, and organic field-effect transistors.

The biggest reason for low electron mobility in conventional organic semiconductors is electron scattering due to structural defects in the form of grain boundaries. By designing an organic semiconductor transistor containing only a single grain, the scientists could avoid the problem of grain boundary scattering.

 

In their experiments, the researchers demonstrated that a device containing a single organic nanoparticle (perylene tetracarboxylic dianhydride, PTCDA) embedded in a nanopore and surrounded by electrodes achieves the highest electron mobility value to date by 1 order of magnitude, and is 2-3 orders of magnitude higher than the values reported for conventional organic semiconductor transistors made of polycrystalline films. The new device's mobility values are 0.08 cm2/Vs at room temperature and 0.5 cm2/Vs at a cool 80 K, which are approaching the intrinsic mobility of PTCDA.

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Strange Nanophotonic Materials Bend and Trap Light to Make Iridenscent Colors

Strange Nanophotonic Materials Bend and Trap Light to Make Iridenscent Colors | Amazing Science | Scoop.it

Normally, the colors we perceive are determined by the wavelengths of light reflected by objects in the world around us. But not all surfaces reflect light the same way. Picture an iridescent butterfly, for example. It might look drab from one direction, but explode into bright yellows or purples from another. That's because of microscopic structures that alter the way light bounces off the butterfly's wings.

 

At the NanoPhotonics Centre at the University of Cambridge, scientists are tinkering with tiny structures like the ones in butterfly wings to create crazy new materials that manipulate light and change color in strange ways.

 

“A lot of this stuff is not completely mainstream,” said Jeremy Baumberg, who directs the center. “People think it’s a bit weird.”

 

During a recent visit to Cambridge, I sat down with Baumberg to talk about some of the projects he and his colleagues -- engineers, physicists, chemists, materials scientists, and biologists -- are working on. This gallery shows off a few highlights.

 

The secrets behind these multicolored materials lie in the tiny nanostructures they’re made from: spheres, helices, tangled gyroids, lattices, super-thin membranes, and stacks. “The nice thing about all these materials is they’re a very visual example of nanotechnology,” Baumberg said. “The features and the color all come from structure.”


Via Chuck Sherwood, Senior Associate, TeleDimensions, Inc
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New Trick Produces Whole Wafers of Perfectly Aligned Nanowires

New Trick Produces Whole Wafers of Perfectly Aligned Nanowires | Amazing Science | Scoop.it

Korean researchers use semiconductor manufacturing processes rather than chemical synthesis to build better nanowires faster.

 

Nanowires don’t quite get the recognition that their high-profile nanomaterial cousins carbon nanotubes and graphene receive. But nanowires are quietly leading toward big improvements in a new generation of photovoltaics, plastic OLEDs (organic light-emitting devices), and a bunch of other applications.

 

Nanowires have suffered from the same manufacturing issues that other nanomaterials have endured, namely achieving large scale production while maintaining quality. One of the key problems nanowire developers have had to overcome is getting the nanowires to orient themselves in perfectly even arrays.

 

Researchers at the Korea Advanced Institute of Science and Technology (KAIST) in cooperation with LG Innotek have found a solution to that problem. And that solution moves away from traditional chemical synthesis to toward tricks common to semiconductor manufacturing.

 

In research published in the journal Nano Letters (“High Throughput Ultralong (20 cm) Nanowire Fabrication Using a Wafer-Scale Nanograting Template”), the Korean team leveraged semiconductor processes  to produce highly-ordered and arrays of long (up to 20 centimeters) nanowires, eliminating the need for post-production arrangement.

 

The process involves a photo engraving technique on a 20-centimeter diameter silicon wafer. First the researchers created a template on the wafer consisting of an ultrafine 100-nanometer linear grid pattern. Then they used this pattern to lay down the nanowires using a sputtering process. The method produces nanowires in bulk in perfect shapes of 50-nm width and 20 cm maximum length.

 

“The significance is in resolving the issues in traditional technology, such as low productivity, long manufacturing time, restrictions in material synthesis, and nanowire alignment,” commented Professor Jun-Bo Yoon of KAIST in a press release. “Nanowires have not been widely applied in the industry, but this technology will bring forward the commercialization of high performance semiconductors, optic devices, and biodevices that make use of nanowires.”

 

Because the process doesn’t require a long synthesis time and results in perfectly aligned nanowires, the industrial partners in the research believe that it’s a technique that should lend itself to commercialization.

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Iron Nano-Ants: Light-activated colloidal dockers to haul huge loads

Iron Nano-Ants: Light-activated colloidal dockers to haul huge loads | Amazing Science | Scoop.it
Beads of haematite can pick up and carry other particles more than 10 times their size with the flick of a switch

 

Ant-like beads of haematite could be the giants of nanoscale construction. Tiny particles of the iron mineral have been made to pick up and carry cargo more than 10 times their size. The feat could be used in targeted drug delivery or building artificial muscles.

Iron-based nanoparticles are ideal cargo-carriers because they can be steered using magnetic fields or by following a thinly etched track. Previous versions relied on chemical glues to pick up stuff, but getting them to drop it has proved difficult.

 

To tackle that problem, Jérémie Palacci at New York University and his colleagues started by suspending haematite nano-beads and a variety of cargo particles in a hydrogen peroxide solution. Shining a light gave the haematite electrical charge, which broke bonds in the neighbouring solution.

 

The resulting halo of water and oxygen was not in chemical balance with its surroundings, a disturbance which drew larger particles to the beads. A bead and its cargo could then be steered together. To make the bead release its load, the team simply turned off the light.

 

"The drop-off has been problematic in other papers. We had to come up with really jerry-rigged situations in order to do it," says Ayusman Sen at Pennsylvania State University in University Park, who was not involved in the new work. "They have a better way of picking up and dropping particles than anyone else." The same iron bead can even be used repeatedly to round up a whole flock of larger particles.

 

Palacci's team envision using the nano-beads in future micro-manufacturing plants, for instance, to create artificial muscles by laying down the required particles and building fibres along tiny tracks. "That would be really cool," he says. "If you can make that, you can start thinking about everything muscles are used for in biology and try to see if you can mimic it."

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