Amazing Science
Follow
Find tag "nanotech"
359.2K views | +34 today
Your new post is loading...
Rescooped by Dr. Stefan Gruenwald from Dr. Goulu
Scoop.it!

Metamolecules that switch handedness at light speed

Metamolecules that switch handedness at light speed | Amazing Science | Scoop.it

The first artificial molecules whose chirality (handedness) can be rapidly switched from a right-handed to a left-handed orientation with a beam of terahertz light has been developed by a multi-institutional team including Lawrence Berkeley National Laboratory (Berkeley Lab).

 

The development holds potentially important possibilities for uses of terahertz technologies across a wide range of fields, including reduced energy use for data processing, homeland security and ultrahigh-speed communications, the researchers say.


Via Goulu
more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Biosynthesis of luminescent quantum dots in an earthworm

Biosynthesis of luminescent quantum dots in an earthworm | Amazing Science | Scoop.it

The synthesis of designer solid-state materials by living organisms is an emerging field in bionanotechnology. Key examples include the use of engineered viruses as templates for cobaltoxide (Co3O4) particles, superparamagnetic cobalt–platinum alloy nanowires and gold–cobalt oxide nanowires for photo-voltaic and battery-related applications. A group of scientists has now shown that the common earthworm’s metal detoxification pathway can be exploited to produce luminescent, water-soluble semiconductor cadmium telluride (CdTe) quantum dots that emit light in the green region of the visible spectrum when excited in the ultraviolet region. Standard wild type Lumbricus rubellus earthworms were exposed to soil spiked with CdCl2 and Na2TeO3 salts for 11days. Luminescent quantum dots were isolated from chloragogenous tissues surrounding the gut of the worm, and were successfully used in live-cell imaging. The addition of polyethyleneglycol on the surface of the quantum dots allowed for non-targeted, fluid-phase uptake by macrophage cells.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Tiny device to capture, release and study cancer cells

Tiny device to capture, release and study cancer cells | Amazing Science | Scoop.it
Researchers have developed a device that captures/preserves and releases cancer cells circulating in the bloodstream. This device has been developed by scientists from RIKEN Advanced Science Institute in Japan in collaboration with University of California Los Angeles and has been mentioned in the paper published online in the journal Advanced Materials.

This new device is a nanoscale Velcro-like device that can help not only in non-invasive diagnosis of cancer but also to study the mechanism involved in the spread of cancer in the body. With the help of this device doctors would be able to detect the cancer cells before their stay in the other organs. Moreover, the tumor cells would remain alive on the device, so the researchers would easily study them.

Blood passes through the device as a filter and the tumor cells adhere to the small molecules and separate them with 40%-70% of efficiency. Temperature at 37 degrees Celsius helps scientists to keep the tumor cells in tiny temperature-responsive polymer brushes or the temperature cooled to 4 degrees Celsius helps them to release and examine the cells.

Researchers wrote, “A platform for capture and release of circulating tumor cells is demonstrated by utilizing polymer grafted silicon nanowires. In this platform, integration of ligand-receptor recognition, nanostructure amplification, and thermal responsive polymers enables a highly efficient and selective capture of cancer cells. Subsequently, these captured cells are released upon a physical stimulation with outstanding cell viability.”

“Until now, most devices have demonstrated the ability to capture circulating tumor cells with high efficiency. However, it is equally important to release these captured cells, to preserve and study them in order to obtain insightful information about them. This is the big difference with our device.” Hsiao-hua Yu, who led the team that developed the technology to coat the device with polymer brushes, said in a statement.
more...
Roberto Insolia's curator insight, December 18, 2012 1:48 AM

Un innovativo micro-supporto consente di catturare singole cellule tumorali, libere nel sangue; è poi possibile liberarle, conservandole perfettamente integre, in modo da studiarne le caratteristiche a livello molecolare.

Scooped by Dr. Stefan Gruenwald
Scoop.it!

Caltech engineers have created a device that can focus light into a single point just a few nanometers across

Caltech engineers have created a device that can focus light into a single point just a few nanometers across | Amazing Science | Scoop.it
As technology advances, it tends to shrink. From cell phones to laptops—powered by increasingly faster and tinier processors—everything is getting thinner and sleeker. And now light beams are getting smaller, too.

Engineers at the California Institute of Technology (Caltech) have created a device that can focus light into a point just a few nanometers (billionths of a meter) across—an achievement they say may lead to next-generation applications in computing, communications, and imaging. Because light can carry greater amounts of data more efficiently than electrical signals traveling through copper wires, today's technology is increasingly based on optics. The world is already connected by thousands of miles of optical-fiber cables that deliver email, images, and the latest video gone viral to your laptop. As we all produce and consume more data, computers and communication networks must be able to handle the deluge of information. Focusing light into tinier spaces can squeeze more data through optical fibers and increase bandwidth. Moreover, by being able to control light at such small scales, optical devices can also be made more compact, requiring less energy to power them. But focusing light to such minute scales is inherently difficult. Once you reach sizes smaller than the wavelength of light—a few hundred nanometers in the case of visible light—you reach what's called the diffraction limit, and it's physically impossible to focus the light any further. But now the Caltech researchers, co-led by assistant professor of electrical engineering Hyuck Choo, have built a new kind of waveguide—a tunnellike device that channels light—that gets around this natural limit. The waveguide is made of amorphous silicon dioxide—which is similar to common glass—and is covered in a thin layer of gold. Just under two microns long, the device is a rectangular box that tapers to a point at one end.

Instead of focusing the light alone—which is impossible due to the diffraction limit—the new device focuses these coupled electron oscillations, called surface plasmon polaritons (SPPs). The SPPs travel through the waveguide and are focused as they go through the pointy end. Because the new device is built on a semiconductor chip with standard nanofabrication techniques, says Choo, the co-lead and the co-corresponding author of the paper, it is easy integrate with today's technology Previous on-chip nanofocusing devices were only able to focus light into a narrow line. They also were inefficient, typically focusing only a few percent of the incident photons, with the majority absorbed and scattered as they traveled through the devices. With the new device, light can ultimately be focused in three dimensions, producing a point a few nanometers across, and using half of the light that's sent through, Choo says. (Focusing the light into a slightly bigger spot, 14 by 80 nanometers in size, boosts the efficiency to 70 percent). The key feature behind the device's focusing ability and efficiency, he says, is its unique design and shape.
more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Princeton’s nanomesh nearly triples solar cell efficiency

Princeton’s nanomesh nearly triples solar cell efficiency | Amazing Science | Scoop.it

There is huge potential in solar power. The sun is a giant ball of burning hydrogen in the sky, and it’s going to be sticking around for at least a few more billion years. For all intents and purposes, it’s a free source of energy. Sadly, humanity hasn’t been very good at harnessing its power directly. Our current methods of capturing the sun’s energy are very inefficient. For example, modern silicon and indium-tin-oxide-based solar cells are approaching the theoretical limit of 33.7% efficiency. Well, a research team at Princeton has used nanotechnology to create a mesh that increases efficiency over organic solar cells nearly three fold.

Led by Stephen Chou, the team has made two dramatic improvements: reducing reflectivity, and more effectively capturing the light that isn’t reflected. As you can see by the illustration below by Dimitri Karetnikov, Princeton’s new solar cell is much thinner and less reflective. By utilizing sandwiched plastic and metal with the nanomesh, this so-called “Plasmonic Cavity with Subwavelength Hole array” or “PlaCSH” substantially reduces the potential for losing the light itself. In fact, it only reflects about 4% of direct sunlight, leading to a 52% higher efficiency than conventional, organic solar cells.

PlaCSH is also capable of capturing a large amount of sunlight even when the sunlight is dispersed on cloudy days, which results in an amazing 81% increase in efficiency under indirect lighting conditions when compared to conventional organic solar cell technology. All told, PlaCSH is up to 175% more efficient than conventional solar cells. As you can see in the image to the right, the difference in reflectivity between conventional and PlaCSH solar cells is really quite dramatic.

The gold mesh that sits on top is incredibly small. It’s only 30 nanometers thick. The holes in the mesh are a mere 175nm in diameter. This replaces the much thicker traditional top layer made out of indium-tin-oxide (ITO). This is the most important part of the innovation. Because the mesh is actually smaller than the wavelength of the light it’s trying to collect, it exploits the bizarre way that light works in subwavelength structures. This unique physical property allows the researchers to effectively capture the light once it enters the holes in the mesh instead of letting much of it reflect away. The bottom layer of the cell remains the same, but this implementation allows the semiconducting layer of plastic in the middle of the cell to be much thinner.

The research team believes that the cells can be made cost effectively using a nanofabrication method that Chou himself invented over a decade ago. Most importantly, it replaces the costly ITO element from solar cells. This will be affordable, and much more flexible than the brittle ITO layer of traditional solar cells. While research is still being done using semiconducting materials other than plastic, this method should work for silicon and gallium arsenide solar cells as well, so it will be able to reduce the size and cost of them drastically while providing similar efficiency benefits.

more...
No comment yet.
Rescooped by Dr. Stefan Gruenwald from Longevity science
Scoop.it!

"World's smallest wrench" is able to rotate individual cells

"World's smallest wrench" is able to rotate individual cells | Amazing Science | Scoop.it

A team from the University of Texas at Arlington, led by assistant professor Samarendra Mohanty, created the device.

 

The business end of the fiber-optic spanner consists of two optical fibers, which are situated end-to-end with a small gap between them. A beam of laser light is emitted from each of these fibers – when the two beams are lined up, the force of the streaming photons is sufficient to trap a microscopic object such as a cell between them. If the fibers are slightly offset, however, and their beams hit that cell on either side, they can actually spin it around in place.

 

By changing the orientation of the fibers, the cell can be turned on any axis. It’s similar to the technology used in “optical tweezers,” although those are used more just for pushing or holding microscopic objects, not for rotating them.

 

Along with its use for examining cells, the researchers believe that the fiber-optic spanner could also be used for applications such as untwisting DNA strands, guiding neurons within the spinal cord, or mixing fluids in lab-on-a-chip devices.


Via Ray and Terry's
more...
mdashf's curator insight, December 13, 2012 1:40 PM

the wrench .. hmm its called a wrenchie in Odia (obviously a borrowed word from English) there is a formula why ie is used for ee, ii, i, and y or yi etc

Scooped by Dr. Stefan Gruenwald
Scoop.it!

UCSB sensors sniff explosives through microfluidics, might replace sniffing dogs at the airport

UCSB sensors sniff explosives through microfluidics, might replace sniffing dogs at the airport | Amazing Science | Scoop.it

We're sure that most sniffer dogs would rather be playing fetch than hunting for bombs in luggage. If UC Santa Barbara has its way with a new sensor, those canines will have a lot more free time on their hands. The device manages a snout-like sensitivity by concentrating molecules in microfluidic channels whose nanoparticles boost any spectral signatures when they're hit by a laser spectrometer.

 

Although the main technology fits into a small chip, it can detect vapors from explosives and other materials at a level of one part per billion or better; that's enough to put those pups out of work. To that end, the university is very much bent on commercializing its efforts and has already licensed the method to SpectraFluidics. We may see the technology first on the battlefield when the research involves funding from DARPA and the US Army, but it's no big stretch to imagine the sensor checking for drugs and explosives at the airport -- without ever needing a kibble break.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Biologically Inspired Droplets Move Themselves Continuously without External Force

Biologically Inspired Droplets Move Themselves Continuously without External Force | Amazing Science | Scoop.it

The gel droplets mimic the molecular motors inside living cells.

 

Using biological building blocks found inside a living cell, researchers have created a material that moves itself. The researchers first made a gel comprising microtubules — stiff polymer filaments that, in living cells, act as guiding tracks for kinesin, a ‘motor protein’ that is propelled along the microtubule cables by the cellular fuel ATP. “It’s like a tyre,” says Zvonimir Dogic, a physicist at Brandeis University in Waltham, Massachusetts, who led the study. Adding a small polymer to the mix encouraged the microtubules to form bundles and create a moving network. Water droplets containing this gel move continuously — in an oil emulsion and on flat surfaces — without external force, the researchers found.

 

Each molecule of ATP propels a kinesin molecule 8 nanometers forward along the microtubule track. With thousands of kinesins rumbling along multiple microtubules, a droplet that is 100 micrometers across spontaneously begins rolling when it touches a flat surface. “It’s a startling advance because of the macro-scale movement that it produces,” says Raymond Goldstein, a biological physicist at the University of Cambridge, UK.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Nanotube Muscles Bench 50,000 Times Their Own Weight

Nanotube Muscles Bench 50,000 Times Their Own Weight | Amazing Science | Scoop.it
Yarns woven from carbon nanotubes can contract like muscles at extremely high speeds to lift large weights. These carbon nanotube muscles can lift loads 200 times greater than natural muscles the same size. Videos made by researchers at the University of Texas at Dallas show the nanotube yarns lifting loads as much as 50,000 times greater than their own weight.

 

Artificial muscles might be used as actuators in robotics and surgical tools, and drive tiny motors and flywheels. The nanotube muscles can be powered by electricity, but they also contract in response to light and certain chemicals. And they work at temperatures as high as 2,500 degrees Celsius, an extreme that reduces other strong actuating materials to a molten puddle. And unlike previous carbon nanotube muscles, these materials require no packaging or battery-like electrolytes to function.

 

Individual carbon nanotubes are stronger than steel, highly conductive, have great optical properties, and so on—you’ve heard the hype. But single nanotubes are not so useful. For many years, when researchers tried to build things out of them, they had trouble getting these properties to scale from single tubes to larger structures. One problem is the tendency for nanotubes to form spaghetti-like tangles, where each point of tube-to-tube contact can compromise strength. But over the past few years materials scientists have been learning how to straighten out these tangles and build large, useful things.

 

The trick in this case is a set of yarn-weaving techniques developed by Ray Baughman at the University of Texas at Dallas. His group starts by growing a vertical forest of carbon nanotubes, then dragging a roller over the top. As the tubes are pulled, they come together in a thin, stretchy sheet. The nanotubes in the sheet are all lined up like spaghetti in a box, and this alignment helps maintain their individual strength on a collective level. To make the nanotube muscles, the Texas researchers coat this sheet with a filler material that expands dramatically when heated. Then they weave the sheet into yarns with different twisting configurations. When the yarns are heated, the filler expands dramatically, and the yarn will contract in a way that’s determined by its coiling configuration.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Stanford's touch-sensitive plastic skin heals itself

Stanford's touch-sensitive plastic skin heals itself | Amazing Science | Scoop.it

A team of Stanford chemists and engineers has created the first synthetic material that is both sensitive to touch and capable of healing itself quickly and repeatedly at room temperature. The advance could lead to smarter prosthetics or resilient personal electronics that repair themselves.

 

Nobody knows the remarkable properties of human skin like the researchers struggling to emulate it. Not only is our skin sensitive – sending the brain precise information about pressure and temperature – but it also heals efficiently to preserve a protective barrier against the world. Combining these two features in a single synthetic material presented an exciting challenge for Stanford chemical engineering Professor Zhenan Bao and her team. Now, they have succeeded in making the first material that can both sense subtle pressure and heal itself when torn or cut.

 

The researchers succeeded by combining two ingredients to get what Bao calls "the best of both worlds" – the self-healing ability of a plastic polymer and the conductivity of a metal. They started with a plastic consisting of long chains of molecules joined by hydrogen bonds – the relatively weak attractions between the positively charged region of one atom and the negatively charged region of the next.

 

"These dynamic bonds allow the material to self-heal," said Chao Wang, another member of the research team. The molecules easily break apart, but then when they reconnect, the bonds reorganize themselves and restore the structure of the material after it gets damaged, he said. The result is a bendable material, which even at room temperature feels a bit like saltwater taffy left in the fridge. To this resilient polymer, the researchers added tiny particles of nickel, which increased its mechanical strength. The nanoscale surfaces of the nickel particles are rough, which proved important in making the material conductive. Tee compared these surface features to "mini-machetes," with each jutting edge concentrating an electrical field and making it easier for current to flow from one particle to the next. The result was a polymer with uncommon characteristics. "Most plastics are good insulators, but this is an excellent conductor," Bao said.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Science About Stickiness: The Secret Of Gecko Climbing And How To Apply It

Science About Stickiness: The Secret Of Gecko Climbing And How To Apply It | Amazing Science | Scoop.it

A. The toes of geckos are covered in ridge-like lamellae, producing a tyre tread pattern

B. Millions of microscopic hairs, or setae, cover each toe. These are only as long as two diameters of a human hair

C. Each seta ends in up to 1000 even tinier tips, called spatulae

D. The spatular tips are only 200 billionths of a metre wide -below the wavelength of visible light

 

Several institutes have been developing robots that can climb walls - Stanford University's "Sticky-bot" can be seen in action here. Some scientists envisage "geckobots" being used to search for survivors in a burning building or disaster zone, to explore the rocky terrain of Mars, or even as toys.

 

Stanford University's Stickybot uses the principles of gecko climbing. But many in the field are most excited by more routine applications. Medicine is one target area for these adhesives. They could spawn advanced bandages that can be removed easily after healing or gripping surfaces on instruments designed for delicate surgery. Since the mechanism works in the wet, it could be used to affix implants within the body.

 

Stanislav Gorb, from the University of Kiel, studies biological adhesion; his work also looks at the way beetles stick to surfaces. He says gecko material has several advantages when compared with generic sticky tape. There is no "visco-elastic" adhesive to dry out, so it stays attached for longer and leaves no residue.

 

But he says that with current production methods, they are unlikely to replace classical sticky tape. "Maybe in 5-10 years we will have a method that will make the tape very cheap - right now it isn't. Secondly, right now, the forces are in the range or even lower than traditional sticky tape."

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

A Microscopic Maze Game of Plinko for Cancer Cells: Metastatic Cells Are Squishier

A Microscopic Maze Game of Plinko for Cancer Cells: Metastatic Cells Are Squishier | Amazing Science | Scoop.it

A new tool developed by scientists at The Methodist Hospital separates tumor-causing cancer cells from more benign cells by subjecting the cells to a microscopic game of Plinko -- except only the squishiest cells make it through.

 

The more flexible, tumor-causing cells navigated a gamut of tiny barriers, whereas the more rigid, more benign cells had trouble squeezing through 7 micrometer holes. Methodist scientists worked with University of Texas MD Anderson Cancer Center researchers to test the device with different kinds of cancer cells. The work supports the hypothesis that cell squishiness indicates tumor potential. Most normal cells contain a developed cytoskeleton -- a network of tiny but strong rod-shaped proteins that give cells their shape and structure. In their feverish drive to divide, cancer cells may be diverting resources away from developing a cytoskeleton in favor of division, hence the squishiness.


"We have created many pathways for cells to cross barriers," said Methodist nanomedical faculty Lidong Qin, Ph.D., the project's principal investigator. "The throughput of a MS-Chip is at the level of one million cells. When a stiff cell blocks one particular barrier, many other bypasses will allow flexible cells to flow through."

 

Cancer stem cells are known to be squishier than other cancer cells. The team of scientists showed that flexible cells separated by the MS-Chip exhibited gene expression patterns consistent with cancer stem cells.

 

"Our microfluidics cell separation via MS-Chip provides a high throughput method that can particularly sort cells to different levels of stiffness, which opens a new avenue to study stiffness related cellular and molecular biology," Qin said. "Downstream molecular analysis, including genomic and proteomic profiling of the cell subtypes, provides an approach to identifying new biomarkers relevant to cancer stem cells and cancer metastasis." Right now, each MS-Chip costs about $10 to produce.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Current state: materials that repair themselves

Current state: materials that repair themselves | Amazing Science | Scoop.it

Biology is inspiring an effort to create new materials that can repair themselves when damaged. According to experts, the first products with truly self-healing properties may be just around the corner. But it was a 2001 study led by Scott White from the University of Illinois at Urbana-Champaign, that really helped to kick-start the field. The group infused a plastic-like polymer with microscopic capsules containing a liquid healing agent. Cracking open the material caused the capsules to rupture, releasing the healing agent. When the agent made contact with a catalyst embedded in the material, a chemical reaction bonded the two faces of the crack together. The polymer recovered some 75% of its original toughness. In the last decade, the team has developed and refined its capsule-based systems, recently demonstrating an electrical circuit that healed itself when damaged. Microcapsules in the gold circuit released liquid metal in response to damage, swiftly restoring electrical conductivity, and bringing self-repairing electronic chips a step closer.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

How big is the printed human genome?

How big is the printed human genome? | Amazing Science | Scoop.it

How big is the printed human genome? Leicester University’s GENIE (Genetics Education Networking for Innovation and Excellence) decided to find out. And it’s big. To be precise, it’s 130 volumes, printed in 4-point font, with 43,000 characters per page. It fills 26 boxes, and would take around 95 years to read.

 

The printout, bound in volumes colour-coded for each chromosome, was originally produced for the University of Leicester’s exhibit Breathless Genes: the lung and the short of it. It is now being displayed as part of the Inside DNA: A Genomic Revolution travelling exhibition, which as well as entertaining and educating, gives the public the chance to have a say in future science policy.

 

Funded by the Wellcome Trust and put together through a partnership betweenEcsite-UK and At-Bristol, Inside DNA: A Genomic Revolution is the first UK major touring exhibition on genomics. The exhibition is at the New Walk Museum & Art Gallery in Leicester until 7 April 2013.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Hydroglyphs: Writing Messages With Water

Hydroglyphs: Writing Messages With Water | Amazing Science | Scoop.it

Scientists have used nanotechnology to create “selectively wet” materials that can be used to write long-lasting messages with water. The concept, called "hydroglyphics," was exhibited by scientists at Harvard who recently teamed up with a group of Merrimack, N.H., high school students and faculty to make an educational demo.

 

The demo, appropriately entitled "Hydroglyphics," helps people visualize the difference between water repelling and wetting surfaces. The main principle behind hydroglyphics (a combination of the words “hydro” and “hieroglyphics”) is that by changing the properties of a surface, you can make your own special prints using water. All you need is some foam stickers, a modified Tesla coil and a Petri dish.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Fast DNA origami opens way for nanoscale machines - molecules can now be folded into shapes in minutes, not days

Fast DNA origami opens way for nanoscale machines - molecules can now be folded into shapes in minutes, not days | Amazing Science | Scoop.it
DNA strands can be coaxed to fold up into shapes in a matter of minutes, reveals a study. The finding could radically speed up progress in the field of DNA origami. Biotechnologists are itching to be able to use DNA to make nanoscale machines, but so far they have made only simple forms — tubes, boxes, triangles — and the process has been laborious and time-consuming.

The technique involves using short DNA strands to hold a longer, folded strand in place at certain points, like sticky tape. Until now, assembling the shape has involved heating the DNA and allowing it to cool slowly for up to a week.

But that time has now been slashed to minutes. Hendrik Dietz, a biophysicist at the Technical University of Munich in Germany, and his colleagues stained the DNA with fluorescent dye and watched what happened as it cooled and folded. By stopping the reaction at different stages, they could check how far the folding and sticking had gone.

They discovered something striking: “It turns out that almost for the entire temperature range, nothing happens," says Dietz. But when a crucial temperature is reached, the whole structure forms suddenly. Dietz analysed the folding of 19 different DNA shapes, including cylindrical, brick-like and cog-like objects. Each shape folded in a specific narrow temperature range somewhere between 45 °C and 60 °C.

After working out which temperature corresponded to which shape, Dietz subjected the unfolded DNA reaction mixtures to these pre-determined temperatures for just a few minutes to see whether they would fold into the desired shape. They did — and with high yield.

DNA-origami experts are excited at the prospect of speeding up their work. “It makes our lives a lot easier,” says William Shih, who works in the field at Harvard University in Boston, Massachusetts, and whose group has already benefited from Dietz’s work. Easier, quicker and more efficient folding will help to take DNA origami beyond simple shapes, he adds.

Dietz hopes that he will be able to use his findings to build a computer model to predict how to make other DNA objects. He noticed that certain traits of the shapes that he made were correlated with the temperature at which they folded — for example, shapes that used longer binding strands folded at higher temperatures. Dietz aims to design nanostructures with optimal folding temperatures close to 37 °C, the temperature at which mammalian cell cultures are grown, so that DNA machines could one day be used in biological settings.
more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

New optical tweezers trap specimens just a few nanometers wide

New optical tweezers trap specimens just a few nanometers wide | Amazing Science | Scoop.it
A technique known as optical trapping uses beams of light as tweezers to hold and manipulate tiny particles. Stanford researchers have found a new way to trap particles smaller than 10 nanometers — and potentially down to just a few atoms in size — which until now have escaped light’s grasp. This new technique allows for studying individual proteins and unraveling them.

To grasp and move microscopic objects, such as bacteria and the components of living cells, scientists can harness the power of concentrated light to manipulate them without ever physically touching them. Now, doctoral student Amr Saleh and Assistant Professor Jennifer Dionne, researchers at the Stanford School of Engineering, have designed an innovative light aperture that allows them to optically trap smaller objects than ever before — potentially just a few atoms in size.

The process of optical trapping — or optical tweezing, as it is often known — involves sculpting a beam of light into a narrow point that produces a strong electromagnetic field. The beam attracts tiny objects and traps them in place, just like a pair of tweezers.

Unfortunately, there are natural limits to the technique. The process breaks down for objects significantly smaller than the wavelength of light. Therefore, optical tweezers cannot grasp super-small objects like individual proteins, which are only a couple of nanometers in diameter.

Saleh and Dionne have shown theoretically that light passed through their novel aperture would stably trap objects as small as 2 nanometers. Saleh is now building a working prototype of the microscopic device.

Dionne says that the most promising method of moving tiny particles with light relies on plasmonics, a technology that takes advantage of the optical and electronic properties of metals. A strong conductor like silver or gold holds its electrons weakly, giving them freedom to move around near the metal’s surface.

When light waves interact with these mobile electrons, they move in what Dionne describes as “a very well-defined, intricate dance,” scattering and sculpting the light into electromagnetic waves called plasmon-polaritons. These oscillations have a very short wavelength compared to visible light, enabling them to trap small specimens more tightly.

Dionne and Saleh applied plasmonic principles to design a new aperture that focuses light more effectively. The aperture is structured much like the coaxial cables that transmit television signals, Saleh said. A nanoscale tube of silver is coated in a thin layer of silicon dioxide, and those two layers are wrapped in a second outer layer of silver. When light shines through the silicon dioxide ring, it creates plasmons at the interface where the silver and silicon dioxide meet. The plasmons travel along aperture and emerge on the other end as a powerful, concentrated beam of light.

The Stanford device is not the first plasmonic trap, but it promises to trap the smallest specimens recorded to date. Saleh and Dionne have theoretically shown that their design can trap particles as small as 2 nanometers. With further improvements, their design could even be used to optically trap molecules even smaller.

Dionne said she would first like to trap a single protein, and try to unravel its twisted structure using visible light alone. Dionne points out that the beam of light could also be used to exert a strong pulling force on stem cells, which has been shown to change how the these important building blocks differentiate into various kinds of cells. Saleh, on the other hand, is particularly excited about moving and stacking tiny particles to explore their attractive forces and create new, “bottom-up” materials and devices.
more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Organic metamaterial remembers its shape and flows like a liquid

Organic metamaterial remembers its shape and flows like a liquid | Amazing Science | Scoop.it

A bit reminiscent of the Terminator T-1000, a new material created by Cornell researchers is so soft that it can flow like a liquid and then, strangely, return to its original shape. Rather than liquid metal, it is a hydrogel, a mesh of organic molecules with many small empty spaces that can absorb water like a sponge. It qualifies as a "metamaterial" with properties not found in nature and may be the first organic metamaterial with mechanical meta-properties.


Under an electron microscope the material is revealed to consist of tiny "bird's nests" of tangled DNA, top, which are tied together by more DNA stands into a mass, bottom. The tangled structure creates many tiny spaces that absorb water like a sponge. Hydrogels have already been considered for use in drug delivery -- the spaces can be filled with drugs that release slowly as the gel biodegrades -- and as frameworks for tissue rebuilding. The ability to form a gel into a desired shape further expands the possibilities. For example, a drug-infused gel could be formed to exactly fit the space inside a wound.

Dan Luo, professor of biological and environmental engineering, and colleagues describe their creation in the Dec. 2 issue of the journal Nature Nanotechnology.

 

The new hydrogel is made of synthetic DNA. In addition to being the stuff genes are made of, DNA can serve as a building block for self-assembling materials. Single strands of DNA will lock onto other single stands that have complementary coding, like tiny organic Legos. By synthesizing DNA with carefully arranged complementary sections Luo's research team previously created short stands that link into shapes such as crosses or Y's, which in turn join at the ends to form meshlike structures to form the first successful all-DNA hydrogel. Trying a new approach, they mixed synthetic DNA with enzymes that cause DNA to self-replicate and to extend itself into long chains, to make a hydrogel without DNA linkages.

 

"During this process they entangle, and the entanglement produces a 3-D network," Luo explained. But the result was not what they expected: The hydrogel they made flows like a liquid, but when placed in water returns to the shape of the container in which it was formed. Exactly how this works is "still being investigated," the researchers said, but they theorize that the elastic forces holding the shape are so weak that a combination of surface tension and gravity overcomes them; the gel just sags into a loose blob. But when it is immersed in water, surface tension is nearly zero -- there's water inside and out -- and buoyancy cancels gravity.

 

To demonstrate the effect, the researchers created hydrogels in molds shaped like the letters D, N and A. Poured out of the molds, the gels became amorphous liquids, but in water they morphed back into the letters. As a possible application, the team created a water-actuated switch. They made a short cylindrical gel infused with metal particles placed in an insulated tube between two electrical contacts. In liquid form the gel reaches both ends of the tube and forms a circuit. When water is added. the gel reverts to its shorter form that will not reach both ends. (The experiment is done with distilled water that does not conduct electricity.)

 

The DNA used in this work has a random sequence, and only occasional cross-linking was observed, Luo said. By designing the DNA to link in particular ways he hopes to be able to tune the properties of the new hydrogel.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Pretty amazing: Living individual cells captured in pyramid cages

Pretty amazing: Living individual cells captured in pyramid cages | Amazing Science | Scoop.it

This microscopic pyramid is actually a cage for a living cell, constructed to better observe cells in their natural 3D environment, as opposed to the usual flat plane of a Petri dish.

 

Researchers from the University of Twente in the Netherlands made the cage by depositing nitrides over silicon pits. When most of the material is peeled away, a small amount of material remains in the corners to create a pyramid.

 

Because the pyramids have holes in the sides and are close together, the cells can interact for the most part as they naturally do. "The thing is because they're so open, cells can easily make connections to the outside," said Aart van Apeldoorn, one of the researchers. "The 3D surface is more or less mimicking how cells act in actual tissues. Everything in our body is three-dimensional."

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

New injectable gels toughen up after entering the body

New injectable gels toughen up after entering the body | Amazing Science | Scoop.it

Gels that can be injected into the body, carrying drugs or cells that regenerate damaged tissue, hold promise for treating many types of disease, including cancer. However, these injectable gels don’t always maintain their solid structure once inside the body.

 

MIT chemical engineers have now designed an injectable gel that responds to the body’s high temperature by forming a reinforcing network that makes the gel much more durable, allowing it to function over a longer period of time. However, a drawback of these materials is that after they are injected into the body, they are still vulnerable to mechanical stresses. If such stresses make them undergo the transition to a liquid-like state again, they can fall apart.

 

The MIT team answered that question by creating a reinforcing network within their gels that is activated only when the gel is heated to body temperature (37 degrees Celsius). Shear thinning gels can be made with many different materials (including polymers such as polyethylene glycol, or PEG), but Olsen’s lab is focusing on protein hydrogels, which are appealing because they can be designed relatively easily to promote biological functions such as cellular adhesion and cell migration.

 

The protein hydrogels in this study consist of loosely packed proteins held together by links between protein segments known as coiled coils, which form when two or three helical proteins coil into a ropelike structure. The MIT researchers designed their hydrogel to include a second reinforcing network, which takes shape when polymers attached to the ends of each protein bind together. At lower temperatures, these polymers are soluble in water, so they float freely in the gel. However, when heated to body temperature, they become insoluble and separate out of the watery solution. This allows them to join together and form a sturdy grid within the gel, making it much more durable.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Super Material Can Stop Speeding Bullet

Super Material Can Stop Speeding Bullet | Amazing Science | Scoop.it

Researchers at a Rice University lab are researching technology that that could potentially stop a 9-millimeter bullet and seal the entryway behind it - an advance that may have huge implications for ballistic protection for soldiers, as well as other uses.

 

During tests, the researchers were able to shoot tiny glass beads at the material, which effectively stopped bullets in their paths. The group, which included scientist Thomas, Rice research scientist Jae-Hwang Lee and a team from MIT's Institute for Soldier Nanotechnologies, was looking for ways to make materials "more impervious to deformation or failure." The result would be better, stronger, lighter armor for soldiers and police, and protection for sensitive materials subject to small, fast moving objects, such as aircraft and satellites.


The researchers were looking at a complex polyurethane material that they saw was able to stop a 9 mm slug and seal its entryway. When penetrated by a tiny projectile at a high velocity, the material melted into a liquid that stopped the fast-moving object and actually sealed the hole it made. "There's no macroscopic damage; the material hasn't failed; it hasn't cracked," Thomas said.


During their research, they found an excellent model material called a polystyrene-polydimethylsiloxane diblock-copolymer. Using two different methods, the team was eventually able to cross-section the structure to determine the depth of the bullets, and according to their study, the layers showed the ability to deform without breaking.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Nanoscale neuronal implant developed that accesses single neurons

Nanoscale neuronal implant developed that accesses single neurons | Amazing Science | Scoop.it

A thin, flexible electrode developed at the University of Michigan is 10 times smaller than the nearest competition and could make long-term measurements of neural activity practical at last.

This kind of technology could eventually be used to send signals to prosthetic limbs, overcoming inflammation larger electrodes cause that damages both the brain and the electrodes.

 

The main problem that neurons have with electrodes is that they make terrible neighbors. In addition to being enormous compared to the neurons, they are stiff and tend to rub nearby cells the wrong way. The resident immune cells spot the foreigner and attack, inflaming the brain tissue and blocking communication between the electrode and the cells.

 

The new electrode developed by the teams of Daryl Kipke, a professor of biomedical engineering, Joerg Lahann, a professor of chemical engineering, and Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering, is unobtrusive and even friendly in comparison. It is a thread of highly conductive carbon fiber, coated in plastic to block out signals from other neurons. The conductive gel pad at the end cozies up to soft cell membranes, and that close connection means the signals from brain cells come in much clearer.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

'Perfect' invisibility: How to escape from being seen?

'Perfect' invisibility: How to escape from being seen? | Amazing Science | Scoop.it

Scientists have succeeded in "cloaking" an object perfectly for the first time, rendering a centimetre-scale cylinder invisible to microwaves. Many "invisibility cloak" efforts have been demonstrated, but all have reflected some of the incident light, making the illusion incomplete.

 

A Nature Materials study has now shown how to pull off the trick flawlessly. However, the illusion only works from one direction and would be difficult to achieve with visible light.

 

The idea of invisibility cloaking got its start in 2006 when John Pendry of Imperial College London and David Schurig and David Smith of Duke University laid out the theory of "transformation optics" in a paper in Science, demonstrating it for the first time using microwaves (much longer wavelengths than we can see) in another Science paper later that year. The papers sparked a flurry of activity to move the work on to different wavelengths - namely those in which we see.

 

The structures that can pull off this extraordinary trick of the light are difficult to manufacture, and each attempt has made an approximation to the theoretical idea that results in reflections. So someone would not see a cloaked object but rather the scene behind it - however, the reflections from the cloak would make that scene appear somewhat darkened. The trick was to use a diamond-shaped cloak, with properties carefully matched at the diamond's corners, to shuttle light perfectly around a cylinder 7.5cm in diameter and 1cm tall.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Nano-material copies butterfly colors

Nano-material copies butterfly colors | Amazing Science | Scoop.it

A new nano-material mimics the brilliant color and water resistance of butterfly wings. "Specifically, we’re interested in putting this kind of material on the outside of buildings," says Shu Yang. "The structural color we can produce is bright and highly decorative, and it won’t fade away like conventional pigmentation color does.

more...
No comment yet.
Scooped by Dr. Stefan Gruenwald
Scoop.it!

Nanolayers make a coating of many colors

Nanolayers make a coating of many colors | Amazing Science | Scoop.it

Researchers at Harvard University in the US have made a new type of optical coating that appears to change colour when its thickness is varied by just a few nanometres. The film, which is less than 20 nm thick, could be used to customize the colour of metal surfaces – a phenomenon that could not only be exploited to make pretty jewellery, but also a host of technologically advanced devices, including ultrathin light detectors and filters, displays, modulators and even solar cells.


Conventional dielectric optical coatings, which are a key component of almost every optical device, are typically made of layers of transparent (or "lossless") material, with each layer being at least a quarter wavelength of light in thickness. The new ultrathin optical coatings made by Federico Capasso's team are different in that they comprise nanometre-thick, and nearly opaque, highly light-absorbing dielectric materials, such as semiconductors. The researchers have shown, for example, that adding a 7 nm layer of germanium to the surface of a gold sample changes its colour from gold to pink. Adding another 4 nm layer makes it violet, and another 4 nm turns the coating dark blue (4 nm is less than 15 atoms thick).


The effect is similar to what we see when there is a thin film of oil of the road on a wet day and we see many different colours, explains Capasso. The colours appear thanks to interfering light waves as they pass through the oil into the water below and then are reflected back up. Some wavelengths of incident and reflected light constructively interfere with one another and are "boosted", while others destructively interfere and are absorbed.

more...
No comment yet.