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Rescooped by Dr. Stefan Gruenwald from DNA & RNA Research
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Nanomotors swiftly silence genes

Nanomotors swiftly silence genes | Amazing Science | Scoop.it

The promise of short interfering RNA (siRNA) is that it can be harnessed to turn off harmful genes in the cell. The difficulty is getting siRNA into the cell in the first place. In a new approach, nanoengineers have driven siRNA into the cell on acoustically-propelled nanomotors, silencing genes faster and more completely than with current methods (ACS Nano2016, DOI: 10.1021/acsnano.6b01415).

 

To silence a gene, researchers tap the cell’s own gene suppression system, which quashes the RNA messengers that are produced when a DNA sequence is expressed. The messengers are knocked out by siRNA, complementary to a given messenger RNA, which binds the mRNA and prevents it from being translated into a protein. Scientists can mooch off the cell’s gene suppression infrastructure simply by inserting an engineered siRNA specific to a target into the cell.

 

But that’s easier said than done. The negatively charged siRNA has to cross a negatively-charged cell membrane, traverse the intracellular milieu, and bump into the cell’s silencing complex before degradation enzymes destroy it.

 

The delivery challenge has spawned a bounty of possible siRNA carriers: metal particles, lipid bubbles, hydrogels, and more. Most of these strategies rely on some form of chemical camouflage to enter the cell and on diffusion to do the rest. But Yi Chen and Joseph Wang of the University of California, San Diego, thought that ultrasound-propelled nanowires might produce an siRNA transporter with more oomph.

 

When bombarded with ultrasound, these tiny gold rods—about 4 μm long, 200 nm in diameter, and concave at one end—scurry into motion. They penetrate cells, bounce around like pinballs, and even spin.


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Combining nanotextured surfaces with the Leidenfrost effect for extreme water repellency

Combining nanotextured surfaces with the Leidenfrost effect for extreme water repellency | Amazing Science | Scoop.it

Combining superhydrophobic surfaces with Leidenfrost levitation--picture a water droplet hovering over a hot surface rather than making physical contact with it--has been explored extensively for the past decade by researchers hoping to uncover the holy grail of water-repellent surfaces.

 

In a new twist, a group of South Korean researchers from Seoul National University and Dankook University report an anomalous water droplet-bouncing phenomenon generated by Leidenfrost levitation on nano-textured surfaces in Applied Physics Letters.

 

"Wettability plays a key role in determining the equilibrium contact angles, contact angle hysteresis, and adhesion between a solid surface and liquid, as well as the retraction process of a liquid droplet impinged on the surface," explained Doo Jin Lee, lead author, and a postdoctoral researcher in the Department of Materials and Engineering at Seoul National University.

 

Non-wetting surfaces tend to be created by one of two methods. "First, textured surfaces enable non-wettability because a liquid can't penetrate into the micro- or nano-features, thanks to air entrapment between asperities on the textured materials," Lee said.

 

Or, second, the Leidenfrost effect "can help produce a liquid droplet dancing on a hot surface by floating it on a cushion of its own vapor," he added. "The vapor film between the droplet and heated surface allows the droplet to bounce off the surface--also known as the 'dynamic Leidenfrost phenomenon.'"

 

Lee and colleagues developed a special "non-wetting, nano-textured surface" so they could delve into the dynamic Leidenfrost effect's impact on the material.

 

"Our nano-textured surface was verified to be 'non-wetting' via thermodynamic analysis," Lee elaborated. "This analytical approach shows that the water droplet isn't likely to penetrate into the surface's nanoholes, which is advantageous for designing non-wetting, water-repellant systems. And the water droplet bouncing was powered by the synergetic combination of the non-wetting surface--often called a 'Cassie surface'--and the Leidenfrost effect."

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New method to improve photoluminescence efficiency of 2-D semiconductors

New method to improve photoluminescence efficiency of 2-D semiconductors | Amazing Science | Scoop.it
A team led by researchers from the National University of Singapore has developed a method to enhance the photoluminescence efficiency of tungsten diselenide, a two-dimensional semiconductor, paving the way for the application of such semiconductors in advanced optoelectronic and photonic devices.

 

Tungsten diselenide is a single-molecule-thick semiconductor that is part of an emerging class of materials called transition metal dichalcogenides (TMDCs), which have the ability to convert light to electricity and vice versa, making them strong potential candidates for optoelectronic devices such as thin film solar cells, photodetectors flexible logic circuits and sensors. However, its atomically thin structure reduces its absorption and photoluminescence properties, thereby limiting its practical applications.

 

By incorporating monolayers of tungsten diselenide onto gold substrates with nanosized trenches, the research team, led by Professor Andrew Wee of the Department of Physics at the NUS Faculty of Science, successfully enhanced the nanomaterial's photoluminescence by up to 20,000-fold. This technological breakthrough creates new opportunities of applying tungsten diselenide as a novel semiconductor material for advanced applications.

 

Ms Wang Zhuo, a PhD candidate from the NUS Graduate School for Integrative Sciences and Engineering (NGS) and first author of the paper, explained, "This is the first work to demonstrate the use of gold plasmonic nanostructures to improve the photo-luminescence of tungsten diselenide, and we have managed to achieve an unprecedented enhancement of the light absorption and emission efficiency of this nanomaterial."

 

Elaborating on the significance of the novel method, Prof Wee said, "The key to this work is the design of the gold plasmonic nanoarray templates. In our system, the resonances can be tuned to be matched with the pump laser wavelength by varying the pitch of the structures. This is critical for plasmon coupling with light to achieve optimal field confinement."


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Researchers create 1-step graphene patterning method

Researchers create 1-step graphene patterning method | Amazing Science | Scoop.it

Researchers from the University of Illinois at Urbana-Champaign have developed a one-step, facile method to pattern graphene by using stencil mask and oxygen plasma reactive-ion etching, and subsequent polymer-free direct transfer to flexible substrates.

 

Graphene, a two-dimensional carbon allotrope, has received immense scientific and technological interest. Combining exceptional mechanical properties, superior carrier mobility, high thermal conductivity, hydrophobicity, and potentially low manufacturing cost, graphene provides a superior base material for next generation bioelectrical, electromechanical, optoelectronic, and thermal management applications.

 

"Significant progress has been made in the direct synthesis of large-area, uniform, high quality graphene films using chemical vapor deposition (CVD) with various precursors and catalyst substrates," explained SungWoo Nam, an assistant professor of mechanical science and engineering at Illinois. "However, to date, the infrastructure requirements on post-synthesis processing--patterning and transfer--for creating interconnects, transistor channels, or device terminals have slowed the implementation of graphene in a wider range of applications."

 

"In conjunction with the recent evolution of additive and subtractive manufacturing techniques such as 3D printing and computer numerical control milling, we developed a simple and scalable graphene patterning technique using a stencil mask fabricated via a laser cutter," stated Keong Yong, a graduate student and first author of the paper, "Rapid Stencil Mask Fabrication Enabled One-Step Polymer-Free Graphene Patterning and Direct Transfer for Flexible Graphene Devices appearing in Scientific Reports.

 

"Our approach to patterning graphene is based on a shadow mask technique that has been employed for contact metal deposition," Yong added. "Not only are these stencil masks easily and rapidly manufactured for iterative rapid prototyping, they are also reusable, enabling cost-effective pattern replication. And since our approach involves neither a polymeric transfer layer nor organic solvents, we are able to obtain contamination-free graphene patterns directly on various flexible substrates."

 

Nam stated that this approach demonstrates a new possibility to overcome limitations imposed by existing post-synthesis processes to achieve graphene micro-patterning. Yong envisions this facile approach to graphene patterning sets forth transformative changes in "do It yourself" (DIY) graphene-based device development for broad applications including flexible circuits/devices and wearable electronics.

 

"This method allows rapid design iterations and pattern replications, and the polymer-free patterning technique promotes graphene of cleaner quality than other fabrication techniques," Nam said. "We have shown that graphene can be patterned into varying geometrical shapes and sizes, and we have explored various substrates for the direct transfer of the patterned graphene."

 

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Route to Carbyne: Scientists Create Ultra-Long 1D Carbon Chains

Route to Carbyne: Scientists Create Ultra-Long 1D Carbon Chains | Amazing Science | Scoop.it

Even in its elemental form, the high bond versatility of carbon allows for many different well-known materials, including diamond and graphite. A single layer of graphite, named graphene, can then be rolled or folded into carbon nanotubes or fullerenes, respectively. To date, Nobel prizes have been awarded for both graphene and fullerenes.

 

Although the existence of carbyne, an infinitely long carbon chain, was proposed in 1885 by Adolf von Baeyer, scientists have not yet been able to synthesize this material. Von Baeyer even suggested that carbyne (also known as linear acetylenic carbon) would remain elusive as its high reactivity would always lead to its immediate destruction. Nevertheless, carbon chains of increasing length have been successfully synthesized over the last five decades, with a record of around 100 carbon atoms.

To grow even longer carbon chains – up to 6,000 carbon atoms long – on a bulk scale, Dr. Pichler and his colleagues used the confined space inside a double-walled carbon nanotube as a nano-reactor.

 

“The direct experimental proof of confined ultra-long linear carbon chains, which are more than an order of magnitude longer than the longest proven chains so far, can be seen as a promising step towards the final goal of unraveling the ‘holy grail’ of carbon allotropes, carbyne,” said team member Lei Shi, from the Faculty of Physics at the University of Vienna. “Carbyne is very stable inside double-walled carbon nanotubes,” the scientists said. “This property is crucial for its eventual application in future materials and devices.”

 

“According to theoretical models, carbyne’s mechanical properties exceed all known materials, outperforming both graphene and diamond.”

 

“Carbyne’s electrical properties suggest novel nanoelectronic applications in quantum spin transport and magnetic semiconductors.” The results were published online April 4, 2016 in the journal Nature Materials (arXiv.org preprint).

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Penn Engineers Develop First Transistors Made Entirely of Nanocrystal Ink

Penn Engineers Develop First Transistors Made Entirely of Nanocrystal Ink | Amazing Science | Scoop.it

The transistor is the most fundamental building block of electronics, used to build circuits capable of amplifying electrical signals or switching them between the 0s and 1s at the heart of digital computation. Transistor fabrication is a highly complex process, however, requiring high-temperature, high-vacuum equipment. 

 

Now, University of Pennsylvania engineers have shown a new approach for making these devices: sequentially depositing their components in the form of liquid nanocrystal “inks.” Their new study, published in Science, opens the door for electrical components to be built into flexible or wearable applications, as the lower-temperature process is compatible with a wide array of materials and can be applied to larger areas. The researchers’ nanocrystal-based field effect transistors were patterned onto flexible plastic backings using spin coating but could eventually be constructed by additive manufacturing systems, like 3-D printers.

 

The study was lead by Cherie Kagan, the Stephen J. Angello Professor in the School of Engineering and Applied Science, and Ji-Hyuk Choi, then a member of her lab, now a senior researcher at the Korea Institute of Geoscience and Mineral Resources. Han Wang, Soong Ju Oh, Taejong Paik and Pil Sung Jo of the Kagan lab contributed to the work. They collaborated with Christopher Murray, a Penn Integrates Knowledge Professor with appointments in the School of Arts & Sciences and Penn Engineering; Murray lab members Xingchen Ye and Benjamin Diroll; and Jinwoo Sung of Korea’s Yonsei University.

The researchers began by taking nanocrystals, or roughly spherical nanoscale particles, with the electrical qualities necessary for a transistor and dispersing these particles in a liquid, making nanocrystal inks.

 

Kagan’s group developed a library of four of these inks: a conductor (silver), an insulator (aluminum oxide), a semiconductor (cadmium selenide) and a conductor combined with a dopant (a mixture of silver and indium). “Doping” the semiconductor layer of the transistor with impurities controls whether the device transmits a positive or negative charge. “These materials are colloids just like the ink in your inkjet printer,” Kagan said, “but you can get all the characteristics that you want and expect from the analogous bulk materials, such as whether they’re conductors, semiconductors or insulators.

 

“Our question was whether you could lay them down on a surface in such a way that they work together to form functional transistors.”

 

The electrical properties of several of these nanocrystal inks had been independently verified, but they had never been combined into full devices. “This is the first work,” Choi said, “showing that all the components, the metallic, insulating, and semiconducting layers of the transistors, and even the doping of the semiconductor could be made from nanocrystals.”

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Adding a topological fold to origami metamaterials

Adding a topological fold to origami metamaterials | Amazing Science | Scoop.it
Topological mechanics could play a key role in developing "smart" materials of the future

 

A metamaterial that is soft along one edge and rigid along the other, yet also displays mechanical topological properties, has been developed by an international team of researchers. This is the first time that topological origami and kirigami techniques have been applied experimentally to metamaterials – artificial materials with tunable, well-defined properties. Apart from having developed a metamaterial with two distinct topological phases, the team is also working on theoretical guidelines for the future design and development of such materials.

 

Researchers have become increasingly interested in recent years in using he ancient Japanese arts of paper folding and cutting – origami and kirigami, respectively – to build and create a variety of metamaterials. Indeed, Bryan Gin-ge Chen, at the University of Massachusetts Amherst, who led the latest work, sees origami as one of the earliest examples of a metamaterial. "All designs are folded from a square sheet of paper, but many different shapes and structures can result, which is exactly in line with the principle that a metamaterials' properties come from structure rather than composition," he explains.

 

Chen and colleagues in the US and the Netherlands were inspired by the novel idea of "topological mechanics", developed in 2014 by Charles Kane and Tom Lubensky from the University of Pennsylvania. Originating from the topological states seen in quantum physics, the idea was extended by Kane and Lubensky, who showed that there is a special class of mechanical structures that can be "polarized" so they are soft or floppy along one side, while being hard or rigid along the other.

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Metal foam obliterates bullets – and that's just the beginning

Metal foam obliterates bullets – and that's just the beginning | Amazing Science | Scoop.it

Composite metal foams (CMFs) are tough enough to turn an armor-piercing bullet into dust on impact. Given that these foams are also lighter than metal plating, the material has obvious implications for creating new type of protection.

 

Afsaneh Rabiei, a professor of mechanical and aerospace engineering at NC State, has spent years developing CMFs and investigating their unusual properties. The video seen here shows a composite armor made out of her composite metal foams. The bullet in the video is a 7.62 x 63 millimeter M2 armor piercing projectile, which was fired according to the standard testing procedures established by the National Institute of Justice (NIJ). And the results were dramatic.

 

"We could stop the bullet at a total thickness of less than an inch, while the indentation on the back was less than 8 millimeters," Rabiei says. "To put that in context, the NIJ standard allows up to 44 millimeters indentation in the back of an armor." The results of that study were published in 2015.

 

But there are many applications that require a material to be more than just incredibly light and strong. For example, applications from space exploration to shipping nuclear waste require a material to be not only light and strong, but also capable of withstanding extremely high temperatures and blocking radiation.

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Self-Propelled Nanomotors Autonomously Seek and Repair Cracks

Self-Propelled Nanomotors Autonomously Seek and Repair Cracks | Amazing Science | Scoop.it

Not all autonomous robots need artificial intelligence to power them. At the molecular level, nanobots can do pretty impressive things without lines of code dictating their moves. They do our bidding because the physical laws of their environment force them to do so.

 

By exploiting such quirks of nature, scientists have now built nanobots that can repair broken circuits that are too small for a human eye to see. Such tiny repairs could help modern electronics have a longer shelf life, but these proof-of-concept, autonomous nanobots have bigger potential. They could one day soon be used for self-healing materials and delivering drugs inside the human body.

 

To build them, Joseph Wang of the University of California at San Diego and Anna Balazs of the University of Pittsburgh took inspiration from nature. When you cut yourself, the platelets in your blood sense the wound and start aggregating to start the healing process. They wanted to create tiny robots that could do something similar.

 

So they started with Janus particles made of gold and platinum. These spherical nanobots (or “nanomotors” as the researchers call them) are thousands of times smaller than a pinhead and have two surfaces with distinct properties. This choice was critical to power the nanobots to act as Wang and Balazs wanted them to.

 

When these Janus particles are poured in a solution containing hydrogen peroxide, the platinum half of the particles reacts with the chemical, causing oxygen to be released. The reaction is so rapid that the released oxygen propels nanobots like a jet would be propelled by rocket fuel.

 

To test whether Janus particles in the chemical mixture would do their bidding, Wang and Balazs created a simple circuit that connected a battery to an LED light. Then they broke the circuit by making a scratch that was less than one-tenth the width of a human hair. When Janus particles and hydrogen peroxide solution was poured onto the circuit, the nanobots got into action.

 

After about 30 minutes, they removed the solution and turned the battery on to find that the LED light was working again. In another broken circuit, simply adding the Janus particles without hydrogen peroxide solution did not lead to repair. The results of the study have been published in the journal Nano Letters.

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Newly discovered organic nanowires leave manmade technologies in their dust

Newly discovered organic nanowires leave manmade technologies in their dust | Amazing Science | Scoop.it

The discovery, featured in the current issue of Scientific Reports, describes the high-speed protein fiber produced by uranium-reducing Geobacter bacteria. The fibers are hair-like protein filaments called "pili" that have the unique property of transporting charges at speeds of 1 billion electrons per second.

 

"This microbial nanowire is made of but a single peptide subunit," said Gemma Reguera, lead author and MSU microbiologist. "Being made of protein, these organic nanowires are biodegradable and biocompatible. This discovery thus opens many applications in nanoelectronics such as the development of medical sensors and electronic devices that can be interfaced with human tissues."

 

Since existing nanotechnologies incorporate exotic metals into their designs, the cost of organic nanowires is much more cost effective as well, she added.

 

How the nanowires function in nature is comparable to breathing. Bacterial cells, like humans, have to breathe. The process of respiration involves moving electrons out of an organism. Geobacter bacteria use the protein nanowires to bind and breathe metal-containing minerals such as iron oxides and soluble toxic metals such as uranium. The toxins are mineralized on the nanowires' surface, preventing the metals from permeating the cell.

 

Reguera's team purified their protein fibers, which are about 2 nanometers in diameter. Using the same toolset of nanotechnologists, the scientists were able to measure the high velocities at which the proteins were passing electrons.

"They are like power lines at the nanoscale," Reguera said. "This also is the first study to show the ability of electrons to travel such long distances - more than a 1,000 times what's been previously proven—along proteins."

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No more washing: Nano-enhanced textiles clean themselves with light

No more washing: Nano-enhanced textiles clean themselves with light | Amazing Science | Scoop.it

Researchers at RMIT University in Melbourne, Australia, have developed a cheap and efficient new way to grow special nanostructures—which can degrade organic matter when exposed to light—directly onto textiles.

 

The work paves the way towards nano-enhanced textiles that can spontaneously clean themselves of stains and grime simply by being put under a light bulb or worn out in the sun.

 

Dr Rajesh Ramanathan said the process developed by the team had a variety of applications for catalysis-based industries such as agrochemicals, pharmaceuticals and natural products, and could be easily scaled up to industrial levels.

 

"The advantage of textiles is they already have a 3D structure so they are great at absorbing light, which in turn speeds up the process of degrading organic matter," he said.

 

"There's more work to do to before we can start throwing out our washing machines, but this advance lays a strong foundation for the future development of fully self-cleaning textiles."

 

The researchers from the Ian Potter NanoBioSensing Facility and NanoBiotechnology Research Lab at RMIT worked with copper and silver-based nanostructures, which are known for their ability to absorb visible light.

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Magnetic nanoparticles show promise in biomedical applications

Magnetic nanoparticles show promise in biomedical applications | Amazing Science | Scoop.it
Recent developments and research related to iron oxide nanoparticles confirm their potential in biomedical applications – such as targeted drug delivery – and the necessity for further studies.

 

Iron oxides are widespread in nature and can be readily synthesized in the laboratory. Among them, hematite, magnetite and maghemite nanoparticles have particularly promising properties for biomedical applications.

 

Researchers in China and Korea reviewed recent studies on the preparation, structure and magnetic properties of iron oxide nanoparticles (IONPs) and their corresponding applications. The review, published in the journal Science and Technology of Advanced Materials, emphasized that the size, size distribution (the relative proportions of different-sized particles in a given sample), shape and magnetic properties of IONPs affect the location and mobility of IONPs in the human body. However, having complete control over the shape and size distribution of magnetic IONPs remains a challenge. For example, magnetic IONPs are promising for carrying cancer drugs that target specific tissues. For this to happen, they are coated with a biocompatible shell that carries a specific drug. If this "functionalized" magnetic IONP is too large, it may be cleared from the blood stream. Thus, it is very important to be able to control the size of these particles. Researchers found that IONPs with diameters ranging from 10 to 100 nanometres are optimal for intravenous injection and can remain in the blood stream for the longest period of time.

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Stretchable electronics with liquid metal in them quadruple in length

Stretchable electronics with liquid metal in them quadruple in length | Amazing Science | Scoop.it

EPFL researchers have developed conductive tracks that can be bent and stretched up to four times their original length. They could be used in artificial skin, connected clothing and on-body sensors.

 

Conductive tracks are usually hard printed on a board. But those recently developed at EPFL are altogether different: they are almost as flexible as rubber and can be stretched up to four times their original length and in all directions. And they can be stretched a million times without cracking or interrupting their conductivity. The invention is described in an article published today in the journal Advanced Materials.

 

Both solid and flexible, this new metallic and partially liquid film offers a wide range of possible applications. It could be used to make circuits that can be twisted and stretched – ideal for artificial skin on prosthetics or robotic machines. It could also be integrated into fabric and used in connected clothing. And because it follows the shape and movements of the human body, it could be used for sensors designed to monitor particular biological functions.

 

“We can come up with all sorts of uses, in forms that are complex, moving or that change over time,” said Hadrien Michaud, a PhD student at the Laboratory for Soft Bioelectronic Interfaces (LSBI) and one of the study authors.

Extensive research has gone into developing an elastic electronic circuit. It is a real challenge, as the components traditionally used to make circuits are rigid. Applying liquid metal to a thin film in polymer supports with elastic properties naturally seems like a promising approach.

 

Owing to the high surface tension of some of these liquid metals, experiments conducted so far have only produced relatively thick structures. “Using the deposition and structuring methods that we developed, it’s possible to make tracks that are very narrow – several hundredths of a nanometer thick – and very reliable,” said Stéphanie Lacour, holder of the Bertarelli Foundation Chair in Neuroprosthetic Technology and who runs the lab.

 

Apart from their unique fabrication technique, the researchers’ secret lies in the choice of ingredients, an alloy of gold and gallium. “Not only does gallium possess good electrical properties, but it also has a low melting point, around 30o,” said Arthur Hirsch, a PhD student at LSBI and co-author of the study. “So it melts in your hand, and, thanks to the process known as supercooling, it remains liquid at room temperature, even lower.” The layer of gold ensures the gallium remains homogeneous, preventing it from separating into droplets when it comes into contact with the polymer, which would ruin its conductivity.

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Self-healing, flexible electronic material restores functions after many breaks

Self-healing, flexible electronic material restores functions after many breaks | Amazing Science | Scoop.it

Electronic materials have been a major stumbling block for the advance of flexible electronics because existing materials do not function well after breaking and healing. A new electronic material created by an international team, however, can heal all its functions automatically even after breaking multiple times. This material could improve the durability of wearable electronics.

 

"Wearable and bendable electronics are subject to mechanical deformation over time, which could destroy or break them," said Qing Wang, professor of materials science and engineering, Penn State. "We wanted to find an electronic material that would repair itself to restore all of its functionality, and do so after multiple breaks."

 

Self-healable materials are those that, after withstanding physical deformation such as being cut in half, naturally repair themselves with little to no external influence.

 

In the past, researchers have been able to create self-healable materials that can restore one function after breaking, but restoring a suite of functions is critical for creating effective wearable electronics. For example, if a dielectric material retains its electrical resistivity after self-healing but not its thermal conductivity, that could put electronics at risk of overheating.

 

The material that Wang and his team created restores all properties needed for use as a dielectric in wearable electronics -- mechanical strength, breakdown strength to protect against surges, electrical resistivity, thermal conductivity and dielectric, or insulating, properties. They published their findings online in Advanced Functional Materials.

 

Most self-healable materials are soft or "gum-like," said Wang, but the material he and his colleagues created is very tough in comparison. His team added boron nitride nanosheets to a base material of plastic polymer. Like graphene, boron nitride nanosheets are two dimensional, but instead of conducting electricity like graphene they resist and insulate against it.

 


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Two-beam super-resolution lithography to make 3D photonic 'gyroid' nanostructures

Two-beam super-resolution lithography to make 3D photonic 'gyroid' nanostructures | Amazing Science | Scoop.it

"A team of researchers with Swinburne University of Technology in Australia has found a way to use two-beam super-resolution lithography to create 3D photonic "gyroid" nanostructures—similar to those found in butterfly wings. In their paper published in the journal Science Advances, the team describes their technique and some applications to which it might be applied.


Scientists have known for some time that butterfly wings have "gyroid" nanostructures in them (arranged in grid patterns), that serve the butterflies by manipulating light in useful ways. In addition to their photonic properties, the structures, which are made of intertwining curved surfaces, were also found to be very strong for their size, which has caused scientists to see if they might find a way to create them artificially. Up till now, such efforts have left a lot to be desired—most do not have a high enough resolution or are too fragile. In this new effort, the researchers report that rather than rely on traditional methods, such as two-photon polymerization, the team went with optical two-beam super-resolution lithography—they compare it to direct laser writing techniques, noting that it has two major advantages over other techniques used in the past. The first is that it offers much better resolution and the second is that the resulting structure has more mechanical strength."


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The next step in DNA computing: GPS mapping?

The next step in DNA computing: GPS mapping? | Amazing Science | Scoop.it

Conventional silicon-based computing, which has advanced by leaps and bounds in recent decades, is pushing against its practical limits. DNA computing could help take the digital era to the next level. Scientists are now reporting progress toward that goal with the development of a novel DNA-based GPS. They describe their advance in ACS' The Journal of Physical Chemistry B.

 

Jian-Jun Shu and colleagues note that Moore's law, which marked its 50thanniversary in April, posited that the number of transistors on a computer chip would double every year. This doubling has enabled smartphone and tablet technology that has revolutionized computing, but continuing the pattern will come with high costs. In search of a more affordable way forward, scientists are exploring the use of DNA for its programmability, fast processing speeds and tiny size. So far, they have been able to store and process information with the genetic material and perform basic computing tasks. Shu's team set out to take the next step.

 

The researchers built a programmable DNA-based processor that performs two computing tasks at the same time. On a map of six locations and multiple possible paths, it calculated the shortest routes between two different starting points and two destinations. The researchers say that in addition to cost- and time-savings over other DNA-based computers, their system could help scientists understand how the brain's "internal GPS" works.

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Injectable nanoparticles deliver cancer therapy in mice

Injectable nanoparticles deliver cancer therapy in mice | Amazing Science | Scoop.it

Researchers designed and tested a system that delivered nanometer-sized particles of a cancer drug to tumors in mice, improving survival.

 

Many drugs for treating cancer work by slowing or stopping the growth of cancerous cells. However, there are numerous barriers that can hinder a drug’s ability to work successfully. A drug needs to reach and get inside cancerous cells—whether they’re in the liver, breast, or lung. The drug must also avoid damaging healthy, non-cancerous tissues—such as the heart and kidneys—to prevent side effects.

 

A team led by Drs. Mauro Ferrari and Haifa Shen at Houston Methodist Research Institute has been working to overcome the many hurdles to successful cancer treatment by harnessing nanotechnology to deliver drugs directly into cancerous cells. The group set out to develop and test an injectable carrier of nanoparticles that contain a chemotherapy drug. The work was funded in part by NIH’s National Cancer Institute. Results were published on March 14, 2016, in Nature Biotechnology.

 

The scientists turned to doxorubicin (dox), a drug used to treat many cancer types. They attached dox to string-like molecules, known as poly(L-glutamic acid), through a pH-sensitive link. This formed a drug complex called pDox. The team made disk-shaped, micrometer-sized silicon particles to serve as a carrier for the pDox. The pDox was loaded into the particles through nanometer-sized pores.

 

When the researchers injected pDox-containing silicon particles intravenously into mice with cancerous tumors, the particles traveled through the blood stream and accumulated at the site of tumors, where blood vessels are leakier. The silicon, which was designed to degrade, released pDox molecules at the tumor site. These molecules spontaneously formed nanoparticles, which were then taken up by tumor cells.

 

Once inside cancerous cells, the pDox was transported to the area around the nucleus through vesicular transport. Due to the acidic environment near the nucleus, the dox was cleaved from its attachment to the poly(L-glutamic acid). This resulted in a high concentration of dox within the nuclei of the cancerous cells.

 

In contrast, when the researchers injected the drug dox alone, high levels appeared in non-cancerous tissues, such as the heart, leading to damage.

 

The team tested the therapy in several mouse cancer models, including triple-negative breast cancer, which is difficult to treat. Mice treated with the pDox-containing particles had much smaller and fewer tumors. They also had a longer survival time than mice given a saline control. The group found that 40-50% of cancer-bearing mice given the treatment showed no signs of metastatic tumors 8 months later. “We invented a method that actually makes the nanoparticles inside the cancer and releases the drug particles at the site of the cellular nucleus,” Ferrari says.

 

The silicon-based carrier could transport other chemicals, or combinations of chemicals, besides dox. The team plans to begin safety and efficacy studies in humans in the future.


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Wafer-scale Nanotube Film Is Finally Here

Wafer-scale Nanotube Film Is Finally Here | Amazing Science | Scoop.it
Wafer-scale production technique could lead to single-walled carbon nanotubes finally fulfilling their promise in a range of applications

 

Single-walled carbon nanotubes (SWCNTs) used to be the darling of those who were looking for an alternative to silicon in digital electronics. The first SWCNT-based transistors were fashioned almost twenty years ago, but scaling up the use of SWCNTs since then to very large scale integration (VLSI) processes has remained elusive.

 

There were two persistent problems with SWCNTs that led to much of theresearch community pursuing graphene instead of SWCNTs as the next great post-silicon hope: an inconsistency between semiconducting and metallic nanotubes and the frustration of trying to get all of the nanotubes to align on a wafer.

 

Now researchers at Rice University claim that they have struck upon a method that produces a uniform and wafer-scale film of highly aligned and densely packed SWCNTs that may finally deliver on the long-promised potential of SWCNTs.

 

In research published in the journal Nature Nanotechnology, the Rice researchers’ method starts by preparing a well-dispersed CNT suspension, which requires getting just the right concentration of CNT powder with a surfactant in water. The next step involves a vacuum filtration method that has long been the established technique for creating wafer-scale films of CNTs with controllable thickness. The CNT suspension is poured into a filtration funnel with small pores. Pressure pushes the suspension through those pores so that CNTs are left behind on the filter membrane.

 

The SWCNTs spontaneously align as long as both the surfactant level in the dispersion and the CNT concentration are just right and the filtration process is done slowly and carefully. When these criteria are met, a wafer-scale, uniform and aligned SWCNT film forms on the filter membrane.

 

The film can be easily transferred onto a substrate by dissolving the filter membrane on the substrate, which leaves perfectly aligned SWCNTs in place. In addition to the problem of alignment, many methods that have been used for aligning SWCNTs result in low density. However, in this method the density is quite high with 1×106 CNTs found in a cross-sectional area of 1 square micrometer. Finally, the film can be patterned by standardphotolithography methods.

 

The researchers have put the resulting material to the test by producing terahertz/infrared polarizers using a mix of metallic and semiconductor CNTs; and they fabricated thin-film transistors, polarized light-emission devices and polarization-sensitive photodetectors using only semiconducting CNTs.

 

The Rice team believes that this method should create not only new avenues for fundamental research in physics, chemistry and materials science, but will also enable the use of SWCNTs in electronics, optoelectronics, sensing, imaging and medicine.

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Artificial DNA could build new generation of cancer drugs

Artificial DNA could build new generation of cancer drugs | Amazing Science | Scoop.it

Scientists have built the first 3D nano-sized objects using artificial DNA, which could be used to deploy cancer treatments inside tumor cells. The team from The Institute of Cancer Research, London, and the University of Cambridge created microscopic pyramid- and diamond-shaped 3D ‘packets’ by folding together artificial nucleic acid building blocks called Xeno nucleic acids (XNAs).

 

They saw that XNA made pyramid packets that were more stable in biological environments than DNA-made structures, keeping their shape for eight days compared with DNA nanostructures, which degraded after two.

 

The research was published in ChemBioChem and funded by the Medical Research Council and the Biotechnology and Biological Sciences Research Council, with additional support from Cancer Research UK and the European Science Foundation.

 

DNA nanotechnology is an exciting new way to manipulate genetic material, which could have huge benefits for biomedical research and clinical care.

 

Strands of DNA or RNA can be folded to make microscopic packets which could detect important biological markers of cancer, or be used to transport cancer treatments into cells to make them more effective. However, DNA-cutting enzymes in human tissue can break down these nanostructures very rapidly, limiting their use as medical treatments.

 

The 3D nanostructures using XNA building blocks – in which the sugar backbone of human nucleic acid strands is chemically altered in ways that do not occur in nature – were first developed by the University of Cambridge and had greater bio-stability and wider ranging physical and chemical properties than DNA.

 

They saw that XNAs behaved in a similar way to DNA nanostructures, folding to produce 3D tetrahedrons (pyramid shaped) and octahedrons (diamond shaped) as intended, which ICR researchers confirmed using electron microscopy.

 

When tested inside cell cultures, tetrahedral XNA packets kept their shape inside for eight days, compared with structures made from DNA which degraded after two days.

 

Dr Edward Morris, Leader of the ICR’s Structural Electron Microscopy team, said: “DNA has shown great promise as a potential building material for nano-molecular scale objects, but unfortunately they tend to get broken down quite quickly by our bodies and this may limit their clinical use. Our research with scientists from the University of Cambridge shows that you can make robust microscopic 3D shapes using this novel XNA chemistry which can stand up to conditions inside the body.


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Nanopillars on drone fly larvae allow them to avoid bacterial contamination

Nanopillars on drone fly larvae allow them to avoid bacterial contamination | Amazing Science | Scoop.it
Rat-tailed maggots are known to live in stagnant, fetid water that is rich in bacteria, fungi, and algae. However, they are able to avoid infection by these microorganisms due to nanopillars on their cuticles.

 

The immature stage of the drone fly (Eristalis tenax) is known as a "rat-tailed maggot" because it resembles a hairless baby rodent with a "tail" that is actually used as a breathing tube. Rat-tailed maggots are known to live in stagnant, fetid water that is rich in bacteria, fungi, and algae. However, despite this dirty environment, they are able to avoid infection by these microorganisms. Recently, Matthew Hayes, a cell biologist at the Institute of Ophthalmology at University College London in England, discovered never-before-seen structures that appear to keep the maggot mostly free of bacteria, despite living where microorganisms flourish. His findings appear in an article in the Journal of Insect Science.

 

With scanning and transmission electron microscopes, Hayes carefully examined the larva and saw that much of its body is covered with thin spines, or "nanopillars," that narrow to sharp points. Once he confirmed the spiky structures were indeed part of the maggot, he noticed a direct relationship between the presence of the spines and the absence of bacteria on the surface of the larva. He speculated that the carpet of spines simply makes it impossible for the bacteria to find enough room to adhere to the larva's body surface. "They're much like anti-pigeon spikes that keep the birds away because they can't find a nice surface to land on," he said.

 

Hayes also ventured that the spines could possibly have superoleophobic properties (the ability to repel oils), which would also impede the bacteria from colonizing and forming a biofilm that could ultimately harm or kill the maggot. The composition of the spines is as unique as the structures themselves, Hayes said. Each spine appears to consist of a stack of hollow-cored disks, the largest at the bottom and the smallest at the top.

 

"What I really think they look like is the baby's toy with the stack of rings of decreasing size, but on a very small scale," he said. "I've worked in many different fields and looked at lots of different things, and I've never seen anything that looks like it."

This work with the rat-tailed maggot is leading him to examine other insects as well, including the ability of another aquatic invertebrate -- the mosquito larva -- to thwart bacteria. Such antibacterial properties have applications in many different fields, including ophthalmology and other medical fields where biofilms can foul surgical instruments or implanted devices.

 

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Nanoparticles can grow in a perfect cubic shape

Nanoparticles can grow in a perfect cubic shape | Amazing Science | Scoop.it

The efficiency of many applications deriving from natural sciences depends dramatically on a finite-size property of nanoparticles, so-called surface-to-volume ratio. The larger the surface of nanoparticles for the same volume is achieved, the more efficiently nanoparticles can interact with the surrounding substance. However, thermodynamic equilibrium forces nanostructures to minimize open surface driven by energy minimization principle. This basic principle predicts that the only shape of nanoparticles can be spherical or close-to-spherical ones.

 

Nature, however, does not always follow the simple principles. An intensive collaboration between University of Helsinki, Finland, and Okinawa Institute of Science and Technology, Japan, showed that in some condition iron nanoparticles can grow in cubic shape. The scientists also succeeded in disclosing the mechanisms behind this.

 

"Now we have a recipe how to synthesize cubic shapes with high surface-to-volume ratio which opens the door for practical applications", says Dr. Flyura Djurabekova from the University of Helsinki.

 

In the researcher's work, experiment and theory were brought together via a new mathematical model, which gives a recipe on how to select macroscopic experimental conditions to achieve the formation of nanoparticles of desired shape.

 

The computational work carried out in the group of Djurabekova showed the importance of kinetical processes in this surprising phenomenon, namely the competition between surface diffusion and deposition rate of atoms. The simulations showed how an originally spherical nucleus transforms into a perfect cube.

The results were recently published in the high-impact factor journal ACS Nano.

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Nature-inspired precisely assembled nanotubes

Nature-inspired precisely assembled nanotubes | Amazing Science | Scoop.it

Berkeley Lab scientists discovered a polymer composed of two chemically distinct blocks (shown in orange and blue) that assembles itself into complex nanotubes.

 

When placed in water, this new family of nature-inspired polymers spontaneously assemble into hollow crystalline nanotubes up to 100 nanometers long with the same diameter.

 

“Creating uniform structures in high yield is a goal in nanotechnology,” says Ron Zuckermann, who directs the Biological Nanostructures Facility in Berkeley Lab’s Molecular Foundry, where much of this research was conducted. “For example, if you can control the diameter of nanotubes, and the chemical groups exposed in their interior, then you can control what goes through — which could lead to new filtration and desalination technologies, to name a few examples.”

 

Creating a large quantity of nanostructures with the same trait, such as millions of nanotubes with identical diameters, has been difficult. For the past several years, the Berkeley Lab scientists studied a polymer that is a member of the peptoid family. Peptoids are rugged synthetic polymers that mimic peptides, which nature uses to form proteins.

 

The researchers studied a particular type of peptoid, called a diblock copolypeptoid, because it binds with lithium ions and could be used as a battery electrolyte. In their research, they serendipitously found these compounds form nanotubes in water. They don’t know how exactly, but the important thing with this new research is that it sheds light on their structure, and hints at a new design principle that could be used to precisely build nanotubes and other complex nanostructures.

 

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3-D printer and 'Gecko Grippers' head to space station

3-D printer and 'Gecko Grippers' head to space station | Amazing Science | Scoop.it

A United Launch Alliance Atlas 5 rocket loaded with supplies and science experiments blasted off from Florida on Tuesday, boosting an Orbital ATK cargo capsule toward the International Space Station.

 

The 194-foot (59-meter) rocket soared off its seaside launch pad at Cape Canaveral Air Force Station at 11:05 p.m. EDT/0305 GMT. United Launch Alliance is a partnership of Lockheed Martin and Boeing.

 

Perched on top of the rocket was a Cygnus capsule loaded with nearly 7,500 pounds (3,400 kg) of food, science experiments and equipment including a 3-D printer to build tools for astronauts and non-stick grippers modeled after gecko feet.

 

The printer works by heating plastic, metal or other materials into streams that are layered on top of each other to create three-dimensional objects.

 

“If we had a choice of what we could use that printer for, I’m sure we could be quite creative,” station commander Tim Kopra said during an inflight interview on Tuesday.

 

The experimental Gecko Gripper is a new kind of adhesive that mimics the way gecko lizards cling to surfaces without falling. It aims to test a method of attaching things in the weightless environment of space.

 

NASA is looking at robotic versions of gecko feet to attach sensors and other instruments onto and inside satellites.

The Gecko Gripper technology may lead to terrestrial versions of grippers that could, for example, hold flat-screen TVs to walls without anchoring systems and adhesives, said lead researcher Aaron Parness with NASA’s Jet Propulsion Laboratory in Pasadena, California.

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High-power biological wheels and motors imaged for first time

High-power biological wheels and motors imaged for first time | Amazing Science | Scoop.it

 

Behold – the only known example of a biological wheel. Loved by creationists, who falsely think they are examples of “intelligent design”, the bacterial flagellum is a long tail that is spun like a propeller by nano-sized protein motors.

 

Now these wheels and their gearing have been imaged in high resolution and three dimensions for the first time.Morgan Beeby and his colleagues at Imperial College London used an electron microscope to resolve the mechanisms that provide different amounts of torque to the motors.

 

The motors are diverse, coming in a wide variety of shapes, sizes and power outputs. Indeed, the diversity of the motors and the fact that they have evolved many times in different bacterial lineages, scuppers the creationist view that the machinery is “irreducibly complex”.


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Nano-walkers take speedy leap forward with first rolling DNA-based motor

Nano-walkers take speedy leap forward with first rolling DNA-based motor | Amazing Science | Scoop.it

Physical chemists have devised a rolling DNA-based motor that’s 1,000 times faster than any other synthetic DNA motor, giving it potential for real-world applications, such as disease diagnostics. Nature Nanotechnology is publishing the finding.

“Unlike other synthetic DNA-based motors, which use legs to ‘walk’ like tiny robots, ours is the first rolling DNA motor, making it far faster and more robust,” says Khalid Salaita, the Emory University chemist who led the research. “It’s like the biological equivalent of the invention of the wheel for the field of DNA machines.”

The speed of the new DNA-based motor, which is powered by ribonuclease H, means a simple smart phone microscope can capture its motion through video. The researchers have filed an invention disclosure patent for the concept of using the particle motion of their rolling molecular motor as a sensor for everything from a single DNA mutation in a biological sample to heavy metals in water.

“Our method offers a way of doing low-cost, low-tech diagnostics in settings with limited resources,” Salaita says.

The field of synthetic DNA-based motors, also known as nano-walkers, is about 15 years old. Researchers are striving to duplicate the action of nature’s nano-walkers. Myosin, for example, are tiny biological mechanisms that “walk” on filaments to carry nutrients throughout the human body.

“It’s the ultimate in science fiction,” Salaita says of the quest to create tiny robots, or nano-bots, that could be programmed to do your bidding. “People have dreamed of sending in nano-bots to deliver drugs or to repair problems in the human body.”

So far, however, mankind’s efforts have fallen far short of nature’s myosin, which speeds effortlessly about its biological errands. “The ability of myosin to convert chemical energy into mechanical energy is astounding,” Salaita says. “They are the most efficient motors we know of today.”

Some synthetic nano-walkers move on two legs. They are essentially enzymes made of DNA, powered by the catalyst RNA. These nano-walkers tend to be extremely unstable, due to the high levels of Brownian motion at the nano-scale. Other versions with four, and even six, legs have proved more stable, but much slower. In fact, their pace is glacial: A four-legged DNA-based motor would need about 20 years to move one centimeter.

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