Category Archives: Nanotechnology

Nanorobotics: what it is, what it can do, and how it can become reality

They’re tiny machines that work on the nanoscale, being up to 100,000 times smaller than the width of a human hair. These machines, otherwise known as nanorobotics, are set to augment the human race in unforeseen ways.

However, this microscopic technology has remained in the prototype phase for the past two decades, failing to truly live up to its promise, and lagging due to difficult manufacturing processes, a lack of standardization, and scant reviews of the available literature.

Nanoscale canyons. Image credits: Brookhaven National Lab.

Picture a scenario where you’re ill and need to see your doctor. However, instead of giving you a pill or a shot, your doctor injects you with a swarm of tiny robots.

These nanomachines will then work together autonomously to scan their environment and detect your illness — after which they travel to the relevant organ to deliver a payload of slow-release medication deep within the infected area to cure you.

Sounds pretty sci-fi, right? Well, it may not be that far off.

This science is based on nanotechnology, a field of innovation concerning the building of materials and devices at the atomic and nanoscale. To give you a sense of how minute this scale is, a nanometre is just one-billionth of a meter, also known as the billionth-scale.

Because of this small scale, many of the ordinary rules of physics and chemistry no longer apply here, proffering unforeseen and alienlike properties. An example of these quantum-based properties is matter constructed in the nanoscale known as metamaterials.

One such material composed of carbon atoms is 100 times stronger than steel but six times lighter. Other metamaterials, such as quantum dots, can produce far more power than conventional solar or electrical cells despite being zero-dimensional. Remarkably, these nanoscale substances are predicted to produce an abundance of innovative materials used in manufacturing the world over, helping to end poverty and hunger, and possibly ushering in a period of peace and prosperity.

But things haven’t developed as quickly as many hoped.

What is nanorobotics?

Most theoreticians credit the concept of nanotechnology to physicist Richard Feynman and his speech in 1959 entitled: “There’s Plenty of Room at the Bottom”. In the speech, Feynman predicted the development of machines that could be miniaturized and huge amounts of information being encoded in minuscule spaces. However, it was K. Eric Drexler’s 1986 book, Engines of Creation: The Coming Era of Nanotechnology, which galvanized nanotechnological doctrine.  

Drexler floated the idea of programmable, self-replicating nanodevices. In effect, these ‘nanorobots’ would contain a blueprint to clone and build themselves, and any other device needed to fulfill their function. As this construction would take place on an atomic scale, these nanomachines would be able to pull apart any kind of material atom by atom and manufacture never-before-seen devices. Drexler conceived of a universe where nanorobots could perform tasks such as environmental cleaning and clear the human blood capillary system of toxins. The possibilities he theorized involving nanotechnology hinted at addressing contemporary global challenges and future dilemmas, with almost limitless potential once commercialized. 

In a practical sense, nanorobotics refers to nanoscale robots, which can accurately build and manipulate objects on a molecular scale. A leading study on the subject in The Frontiers journal series uses the term micro/nanorobots to refer to all nano- to micron-size programmable devices capable of traveling in the nanoscale using a power source. The process they describe there is the actuation or propulsion of nanomachines which they file into three categories.  

The first category encompasses biohybrid systems integrating synthetic materials with motile microorganisms acting as engines using their natural appendages. The next category involves chemically powered micro/nanorobots that are capable of converting chemical fuels into locomotion. And finally, the most populated category covers mechanically powered nanorobots that use external energy sources such as magnetic, ultrasound, or light fields to move.

A schematic of a molecular planetary gear, an example of nanomachinery. Image via Wikimedia.

The study also collates the percentage of nanobots within each category that have been trialed in living biological systems. They state that, as of 2018, 20% of biohybrid nanorobots, 30% are chemical nanomachines, and 50% of all mechanical systems in existence have been used inside living animals in trials.

Despite remarkable progress, many hurdles exist when manufacturing at the billionth scale, in a process known as nanomanipulation which is performed under electron or scanning probe microscopy using tools such as optical and magnetic tweezers or grippers. Here, nanodevices are being manipulated and welded or soldered together at the molecular scale making the process expensive and time-consuming, and commercialization unfeasible. As it stands, the whole field of nanotechnology, including nanorobotics, is heavily reliant on the development of nanomanipulation. 

The types of nanorobotics

Nanorobotics falls into four broad groupings.

  1. The first classification encompasses purely mechanical nanobots containing no biological material. Here, physically powered nanorobots constructed of synthetic and/or metallic material can be actuated via a chemical reaction or external energy inputs such as magnetic, ultrasound, and light fields. These nanobots are intricate on the billionth scale, containing joints and appendages to enable flexible swimming or walking capabilities.

    Mechanical nanobots consist of multiple materials and coatings. The coating or the body of the machine itself is designed to degrade in bodily fluids to propel the nanorobot in the case of chemical propulsion and/or release the salient therapeutic to treat the disease. Due to the ease of actuation, by far the most popular model in this classification is the magnetic-propelled nanobot where nanorobots integrating magnetic parts are moved using an innocuous external magnetic force. Due to the magnetic torque produced, blood clots are invariably targeted by these nanomachines using a ‘corkscrew’ motion to drive through the embolism. Likewise, these nanobots can also be coated with a substance to elicit an immune response to help break up the clots whilst ‘boring’ through the thrombosis. 

  2. The second category of nanobots is inspired by nature and involves the synthetic biological construction of DNA computers. Also known as DNA nanorobots, they are assembled using origami, where DNA molecules are folded into a 3D configuration to expand surface area for the storage of data and to enable chemical propulsion.

    The desired function or shape of these machines is achieved by ‘gluing’ the nucleic code at salient base-pair junctions to create various configurations. This is how appendages, cargo holds, and switches can be fashioned. Presently, scientists are using DNA origami technology to engineer DNA computers that can monitor and record their surroundings, carry out programs, and store information within its nucleic code. One such example comes from Caltech who designed self-assembling DNA computers that can carry out reprogrammable computations, in effect creating a nanorobot or six-bit ‘hardware’ that can run different software in this fast-moving field.

  3. The third category involves both native and synthetic biologics, known as biohybrid nanorobotics. These hybrid systems integrate inorganic nanomaterials with live microscopic organisms that can propel themselves or use external sources for propulsion. Biohybrid nanorobots have many advantages over traditional artificial nanobots. The most significant advantage is their biocompatibility, with particular regard to components originating from biological organisms such as minimalized immune cells, DNA, or sperm.

    Properties of native cells can also be exploited in unnatural situations. An example of this is biohybrid nanobots or neutrobots developed by the Harbin Institute of Technology capable of traversing the blood-brain barrier (BBB) by manipulating the immune system. The neutrobots do this via the E. coli bacterial membrane housing a core comprised of the Paclitaxel cancer drug mixed with a magnetic hydrogel. When the nanobots were injected into a mouse model of glioma and actuated towards the brain using an external magnetic field, they were engulfed by mouse neutrophils in vitro attracted by their bacterial membrane shell. Thus, they were then able to pass over the BBB in the bellies of the white blood cells to treat glioma tumors in the mouse brain.

    Nevertheless, despite their improved biocompatibility, biohybrid microbots remain potentially harmful due to their extraneous components. Therefore, a completely natural and programmable alternative engineered from only biological tissues is highly desirable.

  4. Our final classification covers the aforementioned where never before seen synthetic biological life forms are engineered. An archetypal study on the subject from the University of Vermont successfully bioengineered thousands of unknown life forms derived from frog embryos. These living exobiologics, which carried out a variety of programs, possessed no reproductive organs, and simply degraded safely to become unfunctional after 7 days.

    Just recently, the same team upgraded their xenobots to move faster, navigate different environments, and live longer than the first edition. Similarly, they can still work together in swarms and heal themselves if damaged. But now the upgraded astrobiologics can record memory and use that information to modify their actions and behavior. Their read/write capability can record one bit of information, using a fluorescent reporter protein. It is in this way the alien lifeforms can ‘write’ their travel experience which could prove invaluable for in vivo applications.

How will the human race apply nanorobotics?

Tiny nanomachine consisting of a one-wheeled vehicle fashioned out of DNA rings. Image credits: Julián Valero.

Given their small size, nanobots are mainly tested in the health industry, although they are used in a vast array of industries such as climate control and the military. Regarding medical applications, functions such as healing wounds, atomic-scale surgical equipment, and traversing through the body to find and treat ailments are most commonly theorized. According to a study from Guangdong Medical University, nanomedicines can reduce toxicity, prolong the controlled-release of drugs, and increase permeability. 

To add to this, nanorobots are small enough to pass through the vascular endothelial cell gap of a tumor, causing what is known as the enhanced permeability and retention effect (EPR effect). This augmented action is expected to enable the detection of cancer on a single-cell level. Moreover, this deep penetration married with the ability to traverse many organ barriers and films within the body means increased drug efficacy for existing pharmaceuticals. Likewise, the aforementioned EPR function may prove invaluable for medical imaging with magnetic or contrast nanorobotics easily directed to the tissue or structure of choice to enhance pre-existing imaging technology. 

Analogous to this, the potential capitalization of nanorobotics for health sensing technology in vivo is extensive and could even make the need for a biopsy defunct. To date, microbots the size of a human egg cell already in existence can store data, sense their environment, and carry out computational tasks. As seen in a study from the University of Alberta consisting of autonomous DNA nanomachines capable of performing biological functions in live cells and detecting a specific microRNA sequence found in breast cancer cells. As this nanobot can detect breast cancer cells in trace amounts, it is expected to detect target molecules missed by other techniques once in the clinic.

Not only are health sensors being planned but sensory perception involving our surroundings is also being trialed. This ‘sensory perception’ is expected to unlock new augmented capabilities, with nanorobotics allowing us to sense and interact with our environment in ways never seen before. Indeed, eminent futurist Ray Kurzweil, predicted in 2005 that nanoscience will render humans immortal by 2040, gifting us superhuman abilities. In tantalizing statements, Kurzweil posits that nanobots could replace native blood cells to cure cancer and back up memories whilst replenishing aging cells, in effect ending dementia. And while this may sound exciting, one must ask when exactly does this augmentation become forced evolution? As scientists create new lifeforms and synthesize DNA, what exactly will be passed down genetically via augmented humans? Just how symbiotic will nanorobotics become? Certainly, there are many ethical questions to answer regarding long-term enhancement and health-sensing using nanotechnology.

Wound-healing, including regenerative medicine, is another popular premise in nanorobotics.  To this end, researchers from DGIST have developed a scaffold-based microbot with the ability to precisely deliver stem cells to target damaged tissue in a rat’s brain. The nickel and titanium coated microbot transplanted stem cells quickly and precisely where the stem cells in turn proliferated and differentiated into astrocytes, oligodendrocytes, and neurons successfully. To add to this, chemically-propelled calcium carbonate-based microrobots have also reportedly delivered thrombin to halt the bleeding of wounds in the vasculature of mouse and pig models.

It has also been suggested by Kurzweil that nanobots will allow us to connect our nervous systems to the cloud by 2030 with these neutrobots playing a major part in connecting our brains to neural interfaces via artificial intelligence. This will be done by developing nanodevices that can traverse the blood-brain barrier, bypassing the need for clumsy electrodes or invasive brain surgery. Once these nanobots reach the brain they would then begin to scan brainwaves to communicate with external hardware, such as bionic limbs. In an exciting development, DARPA recently announced their study to develop magnetoelectric nanoparticles that can permeate the blood-brain barrier and transmit individual neurons’ signals to a brain-computer interface for military applications.

Environmental cleaning has also gained a lot of traction with biohybrid nanorobots the preferred mode of device. Here, a rotifer bacterium was modified to build a live biohybrid microrobot. Rotifers are marine microorganisms possessing sensing ability and autonomy. They also provide large-scale fluid mixing capability making them excellent candidates for filtering polluted water. With this in mind, functionalized microbeads were attached within the rotifer’s mouth forcing efficient transport of the contaminated water over the active surfaces of the microbeads coated with decontaminant.  

There is also much excitement surrounding the development of metamaterials engineered using nanomanipulation which possesses quantum-based physical properties. For instance, Swedish researchers have already constructed the strongest biomaterial in existence, a nanocellulose which they have successfully transferred to the macro world. The biomaterial outperforms steel and dragline spider silk, the preceding strongest biomaterial on earth. These supra properties could also extend to new energy systems and hopefully end the rare mineral war which recently caused a new general election in Iceland. Logically, nanorobots are expected to be composed of these metamaterials, as well as fabricate them in situ.

It should be noted that the host of potential applications of nanorobotics are simply too extensive to list here with the whole spectrum of global industry and enterprise already heavily invested in this technology.

How can autonomous nanorobots become reality?

As we come to the end of our exploratory journey into quantum nanorobotics, there is no doubt we are entering the next phase of our evolutionary process. But is this is a good thing? Indeed, many ethical questions must be answered before we enter the next stage of our bio-transformation.  

In summary, we know that nanorobotics comprised of nanoscale components are plausible because many examples exist in nature such as intracellular transport involving kinesin and dynein motor proteins. Be that as it may, nature is a highly evolved system developed over billions of years, making the synthesis of unnatural nanoscale devices painfully slow and difficult. Therefore, the development of nanomanipulation is crucial to the development of nanobots, and by extension, the furtherment of the human race. Remaining static over many decades, nanomanipulation is still in its infancy with quantum-physical and chemical phenomena at this scale not completely understood or explored. In short, the cheap, bulk manufacture of small-scale robots moving them toward commercial availability is highly desirable, whilst conjointly providing more studies and exploration into the quantum world.

On the practical side, micro/nanorobots have the potential to accomplish complex tasks within the human body, but there are also many challenges including robot localization in vivo. Issues such as communication, swarm behavior, ease of fabrication, biocompatibility, biodegradability, and difficulty in the control of nanorobots in deep tissues must be met head-on.  To address all of these problems research efforts must become concerted to provide standardization of terms, techniques, models, and functions of the devices, as well as regular literature reviews.  Multidisciplinary studies of this nature can help to point out trends in research and identify areas that may benefit from collaborative research aimed at overcoming the current challenges regarding the development of these devices.

To conclude, we need regular standardized reports covering trial design, device classification, and actuation, as well as results. Only then will we witness the successful translation of multidisciplinary research into workable nanorobotics and their associated manufacturing processes. The author sincerely hopes that this article plays a small part in this movement.

Extremely efficient microprocessors can make your computer more eco-friendly

Researchers in Japan have developed a new type of superconductor microprocessor that uses far less energy than today’s microprocessors. That’s good news for you and for the planet.

The diagram for the world’s first adiabatic superconductor processor.

Our use of computers and smartphones has grown tremendously in recent years. It’s hard to even imagine what life would be like nowadays without these devices (which are used not just for communication and enjoyment, but also have important economic roles).

But this has come at a cost. It’s not just the materials we use to create these devices, but also the electricity that these devices use. This figure has grown more and more, up to the point where data centers are being built near lakes and rivers to help cool them down.

Around 10% of the global use of electricity goes to electronic communications, researchers say, and that figure is only expected to grow.

“The digital communications infrastructure that supports the Information Age that we live in today currently uses approximately 10% of the global electricity. Studies suggest that in the worst-case scenario, if there is no fundamental change in the underlying technology of our communications infrastructure such as the computing hardware in large data centers or the electronics that drive the communication networks, we may see its electricity usage rise to over 50% of the global electricity by 2030,” says Christopher Ayala, an associate professor at Yokohama National University, and lead author of the study.

To tackle this issue, a team of researchers set out to design an extremely efficient structure with the dazzling name of adiabatic quantum-flux-parametron (AQFP). In thermodynamics, something is “adiabatic” if it occurs without transferring heat or mass to the surroundings. A quantum-flux-parametron is essentially a digital logic system based on superconductivity.

Armed with this efficient AQFP, the team used it as a building block for low-power high-performance microprocessors, demonstrating their new processor in a new paper. It’s 80 times more efficient and scalable, the team explains.

“These demonstrations show that AQFP logic is capable of both processing and memory operations and that we have a path toward practical adiabatic computing operating at high-clock rates while dissipating very little energy,” the study authors write.

The demonstration shows that the AQFP is capable of “all aspects of computing”, Ayala explains — namely data processing and data storage. It can be clocked up to 2.5 GHz, making it comparable to today’s existing technologies. “We even expect this to increase to 5-10 GHz as we make improvements in our design methodology and our experimental setup,” Ayala said.

But there’s a tiny catch: superconductors need freezing cold temperatures to operate. This means that the chips would, by default, need more power for cooling. As it turns out, even when you factor in this extra power, the devices are still more efficient.

“The AQFP is a superconductor electronic device, which means that we need additional power to cool our chips from room temperature down to 4.2 Kelvin to allow the AQFPs to go into the superconducting state. But even when taking this cooling overhead into account, the AQFP is still about 80 times more energy-efficient when compared to the state-of-the-art semiconductor electronic devices found in high-performance computer chips available today.”

Of course, there are still major challenges. For instance, price remains a big issue, and may very well be the ultimate constraint that dictates whether the technology will catch on or not. For now, researchers are working on bringing the technology from a working prototype to a more scalable and faster design, something that can compete with or even surpass existing technology.

“We are now working towards making improvements in the technology, including the development of more compact AQFP devices, increasing the operation speed, and increasing the energy-efficiency even further through reversible computation,” Ayala said. “We are also scaling our design approach so that we can fit as many devices as possible in a single chip and operate all of them reliably at high clock frequencies.”

The study has been published in IEEE Explore.

Scientists create new fiber that’s as flexible as skin, but tougher

Credit: North Carolina State University.

Researchers at the North Carolina State University have devised a new material that combines the elasticity of rubber with the strength of steel. The resulting material can stretch up to seven times its original length before failure while simultaneously being able to undergo a lot of strain. The material can also conduct electricity and regenerate itself, making it a promising candidate for stretchable electronics and soft robotics.

The fiber mimics human tissue which often combines several components to obtain a greater resilience against external loads. For instance, skin is made of a network of collagen bundled fibers which dissipate energy and prevent cuts from spreading. Human muscle absorbs tensile loads in a similar way with the help of the biomolecule titin.

“A good way of explaining the material is to think of rubber bands and metal wires,” said Professor Michael Dickey, lead author of the new study published in Science Advances.  “A rubber band can stretch very far, but it doesn’t take much force to stretch it. A metal wire requires a lot of force to stretch it, but it can’t take much strain – it breaks before you can stretch it very far. Our fibers have the best of both worlds.”

Dickey and colleagues took a gallium metal core and covered it in an elastic polymer sheath. The fiber basically has the strength of the metal core. However, it won’t fail when the metal breaks because the polymer absorbs the strain between the breaking points, transferring the stress back to the metal. This is similar to how human tissue will still hold together broken bones.

You can see the fiber in action in the video below:

“Every time the metal core breaks it dissipates energy, allowing the fiber to continue to absorb energy as it elongates,” Dickey says. “Instead of snapping in two when stretched, it can stretch up to seven times its original length before failure, while causing many additional breaks in the wire along the way.

“To think of it another way, the fiber won’t snap and drop a heavy weight. Instead, by releasing energy repeatedly through internal breaks, the fiber lowers the weight slowly and steadily.”

The galium core is also conductive, making the fiber ideal in electronics and soft robotics, besides applications such as packaging materials or next-generation textiles.

“We used gallium for this proof of concept work, but the fibers could be tuned to alter their mechanical properties, or to retain functionality at higher temperatures, by using different materials in the core and shell.”

“This is only a proof of concept, but it holds a lot of potential. We are interested to see how these fibers could be used in soft robotics or when woven into textiles for various applications.”

Scientists use nano-ink to 3D print color-changing cup

Researchers have built a plastic cup that changes its color and transparency, using gold nanoparticles and 3D printing.

Although they may have not realized it, humans have been using nanotechnology since the Antiquity. Shiny colors in pottery and glass made hundreds and thousands of years ago represent an early usage of nanoparticles — though not many of these ornaments still survive.

The most famous example is probably the Lycurgus cup — a 4th-century Roman glass cage cup made of a dichroic (two-colored) glass, which is red when lit from behind and green when lit from in front. The Lycurgus cup is the only complete Roman object made from this type of glass, and the one exhibiting the most impressive change in color.

This dichroic effect was achieved by including tiny proportions of gold and silver nanoparticles in the glass material. The exact process remains unclear, and it’s not clear if the makers understood or controlled it or if it came as an accident. The quantities of gold and silver are so minute that they may have been included by accident, as a residue in the workshop or on the tools.

Metallic nanoparticles were also used for staining glass during medieval times, the new study reads. Examples of which can still be found in many churches and cathedrals in Europe. Now, researchers have recreated that technique and brought it to the 21st century — using 3D printing.

Vittorio Saggiomo and colleagues from Wageningen University have shown how to fabricate a 3D printable dichroic material using gold nanoparticles, jumping from the 4th century Roman glassmiths’ methods to a modern technology.

The team used a modified version of something called the Turkevich method to create the color-changing coating. The presented synthesis is easy and fast, taking only a few minutes. During this time, the color changes several times, from the initial yellow solution of the gold ions, to a blue about one minute after the addition of another ingredient (a citrate solution). Two minutes later, the solution turns to a deep black color, before ultimately becoming dichroic after two minutes of boiling.

“The time dependent study shows the formation of small gold nuclei that in time cluster together forming nanowire-like structures concomitant to the firstcolor change,” researchers write. “The second change of color, from ink-black to purple, is accompanied by an enhancement of the scattering, giving the purple solution a brown reflection. While boiling, the gold nanowires fragment, creating nanoparticles with a large head and a slim and long tail, comparable to a tadpole. Over time the tail starts to shrink.” Both steps, individually, have been previously studied.

Ultimately, the material is dichroic because the gold particles interact differently with different wavelengths, absorbing some and reflecting the others.
 
The coating obtained thusly is 3D-printing compatible, and was used for printing plastic “21st century Lycurgus cups”. These particles don’t influence any other physical or chemical characteristics of the cup.
 
The study was published in ChemRxiv.

 

Meet the world’s smallest snowman

He’s under 3 micrometers tall and was carved with an electron microscope.

Image credits: Credit: Todd Simpson, Western University Nanofabrication Facility, Ontario, Canada.

It’s always nice when you see a snowman in wintertime, but you won’t see one on the side of the road — unless you happen to have an electron microscope on you.

It all started in 2005, when Todd Simpson from Western University was working on creating isolated silica spheres. He used a relatively common technique in the field, taking a polymer layer with tiny holes and depositing a silica solution inside these holes. When the film is removed, round silica spheres are left behind.

However, in some cases, the silica fell through the hole, creating what is called a “dimer” — a group of two monomers joined by chemical bonds. In a few rare cases, the dimer fell on a pre-formed silica sphere, forming a three-sphere stack. That’s when Simpson realized he had all the makings of a snowman.

Image credits: Western University Nanofabrication Facility, Ontario, Canada and Dr. Todd Simpson

Of course, it didn’t have any face or arms so Simpson got to work. He took out an old sample and used the lab’s focused ion beam instrument to carve out eyes and mouth in the top sphere. He used the same instrument to deposit platinum arms to complete his work. In total, each sphere has a diameter of about 0.9 micrometers (μm) in diameter which means that in total, the snowman is just under 3 μm tall. Just so you can get an idea of how small that is, a micrometer is 1,000 times smaller than a millimeter. The diameter of human hair ranges from about 10 to 200 µm.

This isn’t the first extra-small snowman ever created. In 2009, David Cox, a National Physical Laboratory research fellow at the University of Surrey, UK, created another nanoscale snowman using a similar technology — though that one is much taller, at 30μm. They’re both adorable and they both go to show how much our technology has progressed lately.

The Wreck.

Novel nanocomposite material might prevent shipwrecks from rotting

Shipwrecks are coming — soon, to a museum near you. And it’s all thanks to nanotechnology.

The Wreck.

“The Wreck”, Knud-Andreassen Baade.
Image via Wikimedia.

A novel approach hopes to turn the damp, pitted wood of ancient shipwrecks into a showstopper. The team is currently using ‘smart’ nanocomposites to conserve the 16th-century British warship, the Mary Rose, and its artifacts. Should the process prove effective, museums will be able to display salvaged wrecks in all their glory without them rotting away.

The old that is strong does not wither

Thousands of shipwrecks have come to rest on ocean floors through the centuries. These drowned leviathans spark the passion of both researchers — who can learn a lot about past battles and ways of life from the wrecks — and public alike.

However, it’s very risky to go in and try to recover shipwrecks. Metal ships tend to weather the years underwater with some grace, but the wooden ones quickly rot away — after roughly a century, the only parts that remain are those that were buried in silt or sand soon after the sinking. Even worse, these timber skeletons quickly deteriorate once brought up to the surface.

While underwater, sulfur-reducing bacteria from the sea floor move into the wood and secrete hydrogen sulfide. This reacts with iron ions (rust) from items like nails or cannonballs, forming iron sulfide. This compound remains stable in environments that sport low levels of oxygen but binds with the gas to form acids that attack the wood.

In a paper being presented today at the 256th National Meeting & Exposition of the American Chemical Society (ACS), one team of researchers detail their efforts to keep wooden shipwrecks intact after recovery.

“This project began over a glass of wine with Eleanor Schofield, Ph.D., who is head of conservation at the Mary Rose Trust,” recalls Serena Corr, Ph.D., the project’s principal investigator.

“She was working on techniques to preserve the wood hull [of the Mary Rose] and assorted artifacts and needed a way to direct the treatment into the wood. We had been working with functional magnetic nanomaterials for applications in imaging, and we thought we might be able to apply this technology to the Mary Rose.”

Mary Rose.

Mary Rose in its specially-designed building at the Historic Dockyard in Portsmouth, United Kingdom.
Image via Wikimedia.

The Mary Rose was one of the first sailing ships built for war. Work on the wooden carrack (three-masted ship) began in 1510, and she was set to sea in July 1511. She remained one of the largest ships in the English navy for over three decades, during which she fought against the French, Scottish, and Brythonic navies — a task at which the Mary Rose excelled. The ship bristled with heavy cannons that popped out from gun-ports (which were cutting-edge technology at the time), and one of the first ships in the world capable of firing a full broadside.

Still, for reasons not yet clear, the ship sank in 1545 off the south coast of England. It was re-discovered in 1971 and recovered in 1982 by the Mary Rose Trust, along with over 19,000 artifacts and pieces of timber. The wreck helped provide a unique snapshot of seafaring and daily life in the Tudor period. It was displayed in a museum in Portsmouth, England, alongside the recovered artifacts.

Only 40% of the initial wooden structure survived the centuries underwater, and even this was rapidly degrading on the surface. So the Trust set out to preserve their invaluable wreck.

Corr’s goal was to avoid acid production by removing free iron ions from the wreck. She and her team at the University of Glasgow started by spraying the wood with cold water to keep it from drying out, which prevented further microbial activity, they explain. Afterward, they applied different types of polyethylene glycol (PEG) — a common polymer —  to the wreck. The PEG replaced water in the wood’s cells, forming a more robust outer layer.

The team, alongside researchers from the University of Warwick, are also working on a new family of magnetic nanoparticles to help in the conservation effort. They analyzed the sulfur species in the wood before the PEG treatment was applied, and then periodically as the ship dried.

This process will help the team design new targeted treatments to scrub sulfur compounds from the wood of the Mary Rose.

The next step, Schofield says, will be to use a nanocomposite material — based on magnetic iron oxide nanoparticles coated in active chemical agents — to remove these sulfur and iron ions. The nanoparticles will be applied directly to the wood and later guided through its pores to any particular areas using external magnetic fields. Such an approach should allow the team to completely remove the ions from the wood, they say.

“Conservators will have, for the first time, a state-of-the-art quantitative and restorative method for the safe and rapid treatment of wooden artifacts,” Corr says. “We plan to then transfer this technology to other materials recovered from the Mary Rose, such as textiles and leather.”

The paper “Magnetic nanocomposite materials for the archeological waterlogged wood conservation” has been presented today, Tuesday 21th August, at the 256th National Meeting & Exposition of the American Chemical Society (ACS).

Credit: American Chemical Society.

Thermal camouflage can disguise you in both warm and cold environments

Hunters or soldiers wear camouflage to blend with the surroundings and make themselves inconspicuous. Modern thermal vision, however, will make any warm-blooded animal pop up like a light bulb even in pitch-black darkness. This is where thermal-camo comes in.

After some previous failed attempts, an international team of researchers has now demonstrated one of the most promising thermal-camouflages to date. Their device made a hand’s thermal signature blend with the environment in a matter of minutes after it was switched on. It worked for both hot and cold environments.

Credit: American Chemical Society.

Credit: American Chemical Society.

Thermal cameras detect objects by reading the infrared radiation emitted by it. Infrared light is invisible to the naked eye but can be felt as heat if the intensity is high enough. In other words, thermal cameras more or less record the temperature of various objects in their line of sight, and then assign each temperature a shade of a color, allowing you to see how much heat its radiating compared to objects around it. Colder temperatures are typically given a shade of blue, purple, or green, while warmer temperatures can be assigned a shade of red, orange, or yellow. This is just a matter of visual representation.

In police helicopters, for instance, thermal night vision is very important since it allows officers to quickly differentiate a person from the rest of the environment. Utility and energy companies use it to see where a house might be losing heat through door and window cracks, or whether a heating system is functioning properly. Doctors sometimes use thermal vision to diagnose various disorders and diseases.

But does this mean that there’s no escaping thermal imaging?

Writing in the journal Nano LettersCoskun Kocabas, a professor of 2D materials at the University of Manchester, UK — where graphene was also first developed — describes a new system that can relatively quickly reconfigure its thermal appearance to blend with the environment.

Previous attempts had encountered various problems such as slow response speed, lack of adaptability to different temperature regimes, and the exclusive use of rigid materials. Kocabas and colleagues have worked around all of these challenges by working with a fast, rapidly adaptable, and flexible material.

Their camouflage system is comprised of a membrane soaked with an ionic liquid sandwiched between a top electrode made of graphene and a bottom electrode from a gold coating on a heat-resistant nylon. The ionic liquid, which contains both positively and negatively charged ions, responds to a small voltage by releasing ions into the graphene, thereby reducing infrared radiation emissions from its surface.

“The demonstrated devices are light (30 g/m2), thin (<50 μm), and ultraflexible, which can conformably coat their environment. In addition, by combining active thermal surfaces with a feedback mechanism, we demonstrate realization of an adaptive thermal camouflage system which can reconfigure its thermal appearance and blend itself with the varying thermal background in a few seconds,” the authors of the new study wrote.

The whole system is thin, light, and can bend around objects, such as a person’s body parts. To demonstrate all these features, the researchers bent the system around a person’s hand, whose thermal signature then became indistinguishable from its surroundings, in both warmer and cooler environments. Besides camouflage, the new system could be used in a number of technical systems, such as adaptive heat shields for satellites.

Blood.

Cell-membrane-coated nanobots successfully clear out 66% of bacteria and toxins in blood samples

Medical nanobots are one step closer, as researchers developed simple nanorobots that can be propelled through blood to clear out bacteria and toxins.

Blood.

Image credits Mate Marschalko / Flickr.

A team of engineers from the University of California San Diego has developed a class of ultrasound-powered robots that can scrub blood clean of bacteria and the toxins they produce. While still simple, the proof-of-concept nanobots could pave the way towards safe and rapid methods of decontaminating biological fluids — even in the bodies of living patients.

Bling medicine

The team builds their nanorobots out of gold nanowires coated with platelet and red blood cell membranes. This hybrid membrane is what gives the nanites the ability to clear out biological contaminants. The platelet membrane binds to pathogens such as the antibiotic-resistant strain of Staphylococcus aureus, MRSA, while the red blood cell membranes can absorb and neutralize toxins produced by bacteria.

The gold nanobody is what lets the researchers move the bots around. The metal responds to ultrasound, giving the team the means to power them through the bloodstream without the use of engines or fuel. The bots need to be mobile in order to more efficiently mix with a fluid sample, speeding up the process of detoxification.

The nanobots were created using processes pioneered by the teams of Joseph Wang and Liangfang Zhang, professors in the Department of NanoEngineering at the UC San Diego Jacobs School of Engineering. Wang’s team designed and built the nanobots and the means of ultrasound-powered propulsion, while Zhang’s team developed the process used to coat these in natural cell membranes.

“By integrating natural cell coatings onto synthetic nanomachines, we can impart new capabilities on tiny robots such as removal of pathogens and toxins from the body and from other matrices,” said Wang.

“This is a proof-of-concept platform for diverse therapeutic and biodetoxification applications.”

Furthermore, the natural membranes prevent the nanobots from being ‘biofouled’ — a process by which proteins cake onto the surface of a foreign body, which would prevent the nanobots from functioning. The hybrid membranes were created from natural membranes, separated in one piece from platelets and red blood cells. These were then blasted with high-frequency sound waves, causing them to fuse together.

Nanobot.

The nanobot binding to and isolating a pathogen.
Image credits Fernández de Ávila et al., 2018, Science Robotics.

The robots’ bodies were constructed by then applying these membranes to gold nanowires through chemical means.

The finished devices are roughly 25 times smaller than the width of a hair, the team writes. Ultrasound waves can propel them up to 35 micrometers per second in blood. They were successful in cleaning blood samples contaminated with MRSA and associated toxins — after 5 minutes of being injected, the levels of bacteria and toxins were three times lower in treated samples than untreated samples.

If you’re like me and dream all starry-eyed about the day we’ll treat ourselves with nanobots, this research might make you feel quite happy inside. However, this work is at a very early stage. It’s also focused on something different — the team notes that, while their current nanobots can be used to treat MRSA in blood samples, they aim to have a device that can detoxify all kinds of biological fluids.

We still have a ways to go until then. For the near future, the team hopes to test their devices in live animal models, and to devise a way of creating the robot bodies out of biodegradable materials instead of gold.

The paper “Hybrid biomembrane–functionalized nanorobots for concurrent removal of pathogenic bacteria and toxins” has been published in the journal Science Robotics.

Proteins can be kept active outside of a cell for the first time– and used to degrade toxic chemicals

Proteins usually cannot work outside of a cell, but this ability would allow us to do many cool and useful things with them, such as catalyzing reactions and replicating DNA. Scientists from the University of California, Berkeley have managed to keep proteins proteins active and working outside of a cell, using synthetic structures. As proof of what their new method is capable of, the researchers created mats that are able to soak up and degrade chemical pollution.

Proteins need a very specific type of environment to function properly. Usually, when they are taken out the cell, they fall apart and are useless. The key to make proteins work outside of a cell is to combine them with synthetic materials that mimic a cell-like environment and help them to fold into a specific structure.

To create synthetic polymers that keep proteins in the right shape, the lab members of Ting Xu, a Berkeley professor in the Department of Materials Science and Engineering and the Department of Chemistry, looked at the structures of protein sequences and surfaces. They wanted to create something that would be able to support the protein so that it could be in the right structure and function normally.

The white circle (fiber mat) contains a stable protein that can break down a toxic chemical. Image credits: Christopher DelRe and Charley Huang.

“Proteins have very well-defined statistical pattern, so if you can mimic that pattern, then you can marry the synthetic and natural systems, which allows us to make these materials,” Xu said.

The end result of these analyses was the creation of random heteropolymers (RHPs). They contain four connected types of monomers; their chemical properties were designed to interact with proteins of interest. They mimic an unstructured natural protein and enable protein membrane folding and activity. Many molecular simulations were run to make sure that these structures would act the way that they were intended.

As if this result wasn’t ground-breaking enough, the researchers tested out a practical application of using proteins outside of cells—to degrade pollution. They created a mat out of their RHPs and a useful protein called organophosphorus hydrolase (OPH), which can degrade the toxic compounds found in insecticides and chemical warfare agents. They used this combination to create mats that were used to soak up and degrade an insecticide from water in a few minutes.

The pesticide has been successfully degraded by the RHP-protein fiber mat! Image credits: Christopher DelRe and Charley Huang.

“Our study indicated that the approach should be applicable to other enzymes,” Xu said. “This may make it possible to have a portable chemistry lab in different materials.”

The results have been published today in the journal Science. Scientists have been trying to achieve protein function outside of a cell for years. Now, biochemical reactions can be created easily, opening up a whole new field of possibilities.

Journal reference: “Random heteropolymers preserve protein function in foreign environments” Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aao0335

Back to black– graphene-based hair dyes provide permanent color without damaging hair

If you’ve ever dyed your hair, you know that it can make the strands brittle and damaged. A materials scientist at Northwestern University, Jiaxing Huang, has a trendy (at the least in the world of science and research) solution to this problem. It involves the super material graphene, which is incredible light, strong, and conductible. The graphene-based dye coats, rather than penetrates, hair, reducing the amount of damaged caused when making the leap from blond to black.

Most hair dyes in use today are quite aggressive in penetrating the hair cuticle. This quality allows the dye to get inside the strand of hair and stay there, so that the hair color is permanent.

“Your hair is covered in these cuticle scales like the scales of a fish, and people have to use ammonia or organic amines to lift the scales and allow dye molecules to get inside a lot quicker,” says senior author Jiaxing Huang, a materials scientist at Northwestern University.

Lifting the cuticle makes the strands of hair more brittle and prone to breakage. It’s made even worse by the use of hydrogen peroxide, which is used to bleach the natural hair pigment and initiate the reaction inside the hair strand between the colorants necessary to create the final dye.

Blond hair before (left) and after (right) being dyed by a graphene-based dye (structural model of graphene shown on the right). Image credits: Chong Luo.

The graphene-based dye coats the strand rather than going inside of it. It can be applied by spraying, brushing, and drying it on the hair. It doesn’t contain organic solvents or toxic chemicals.

“However, the obvious problem of coating-based dyes is that they tend to wash out very easily,” says Huang.

Huang and his research team created a graphene-based dye that made platinum blond hair jet black, and it stayed that way for 30 washes—the minimum number that a dye needs to be labelled as “permanent”.

Although this may seem a frivolous use of graphene, the properties of graphene are well suited to this purpose. The material is made of thin, flexible sheets which makes it good at covering uneven surfaces. These sheets keep out water well, which is ideal for keeping the color between washes. The material is conductive and is being researched for all sorts of electronic applications. This property is useful for a dye, because it could prevent hat hair by dissipating static electricity. The graphene flakes are large enough that the skin won’t absorb them like it does other dyes.

When rubbed with a sheet of plastic, untreated hairs (left) and hairs dyed with a commercial permanent black hair dye (middle) both are static-y, while graphene-dyed hairs remain smooth (right). Image credits: Chong Luo.

The graphene dye isn’t just a one trick pony—it doesn’t need to be just black. Its precursor, graphene oxide, is light brown and can be darkened with heat or chemicals to a range of different colors. This dye could potentially cover the spectrum of hair colors from light brown to black. They can even be used to create an “ombre” look by applying heat or chemicals in different proportions down the hair (rather humorously, there is an entire section in the scientific paper dedicated to this topic). Most of the world’s population has dark to black hair, so these dyes could be useful to dye gray hairs.

Graphene is naturally black so it is perfect for making those difficult-to-create dark shades. In other applications, the black colour of graphene isn’t desirable, but here it is an advantage because lasting dark hair colors are otherwise hard to create. The graphene used here doesn’t need to be top quality like for other uses, such as electronics, so lower quality materials could be used for this purpose rather than discarded.The study has been published in the Journal Chem. There you have it — using cutting edge science to give hair color an upgrade.

 

Luo et al. 2018. “Multifunctional Graphene Hair Dye”, Chem, http://www.cell.com/chem/fulltext/S2451-9294(18)30082-2

Researchers develop nanospears that can transport DNA to cells with pinpoint accuracy

Researchers have recently developed remote-controlled, needle-like nanospears capable of piercing membrane walls and delivering DNA into selected cells. This new technology allows biological materials to be transported throughout the body with pinpoint accuracy, thus making gene alteration a simpler and more effective procedure.

Genetically modified cells are now used in stem cell and cancer research, but the production of such cells is rather costly and inefficient, often including viruses, harsh chemical reagents or external electrical fields.

In the past, researchers used sharp-tipped nanoparticles stuck to surfaces in order to deliver molecules to cells, but removing the altered cells from the nanoparticle-coated surface was difficult. Other techniques involved self-propelled nanoparticles, but controlling them was not easy. In addition, mobile nanoparticles can generate toxic byproducts.

A team of scientists from the University of California, Los Angeles, wanted to make the process more efficient, so they developed biocompatible nanospears that can accurately transport biological material via an external magnetic field. In this way, cells are safe from damage and the use of chemical propellants is no longer necessary.

Authors Steven J. Jonas, Paul S. Weiss, Xiaobin Xu and colleagues fabricated nanospears using templates made of polystyrene beads. They put the beads on a silicon structure and etched them down into a sharp spear shape. After the beads’ removal, they coated the resulting silicon spears with thin layers of nickel and functionalized gold, so that biomolecules, such as DNA, could attach.

Next, the team scraped the nanospears from the silicon. Thanks to the magnetic nickel layer, scientists could accurately control the particles’ movements and orientation. Then, researchers tested their invention in a lab dish, where the nanospears had to deliver DNA to brain cancer cells. The cancerous cells were altered so that they would express a green fluorescent protein.

Researchers were pleased with the results: more than 90% of the cells remained viable, and more than 80% exhibited green fluorescence. The results also showed that this method was less harmful and more effective than other non-viral ones. The authors believe that this technique might lead to new ways to prepare vast numbers of cells for the coordinated manufacture of gene therapies.

The paper was published today in the journal ACS Nano.

Graphene labels can be burned into food and clothing–and used as electronics or sensors

Scientists at Rice University have converted common materials, such as food, cloth, and paper, into graphene with a special laser. Graphene is conductive so electronics can be embedded into almost any substance, in any pattern. This means that you could have a graphene label on an apple that is a bar-code or a sensor that tells you where the apple came from and if it is safe to eat, and you could still eat the label.

A graphene “tag” on a piece of toast. Image credits: Jeff Fitlow/Rice University.

Graphene is viewed as one of the most important recent discoveries. It is a material made of single atomic sheets of graphite and has a two-dimensional structure which makes it easy to stack and still keep super thin. It is extremely strong, light, stiff, thin, almost transparent, and really good at conducting electricity and heat. Therefore, it has tremendous potential for electronics.

The real advance that the researchers at Rice University made is to make graphene out of any substance. Previously, it was only possible to make graphene from certain polymers. The graphene is not printed or stuck on the organic materials used, it is actually a part of the material. The researchers used a defocused laser so that it first turns the object’s surface into amorphous carbon and then, after subsequent laser passes, into graphene. Defocusing the laser made the beam wider so a target could be lased multiple times in one raster time. This allowed the process to be quicker and more precise.

“This is not ink,” Rice lab of chemist James Tour said, “This is taking the material itself and converting it into graphene.”

“Very often, we don’t see the advantage of something until we make it available,” Tour said. “Perhaps all food will have a tiny RFID tag that gives you information about where it’s been, how long it’s been stored, its country and city of origin and the path it took to get to your table.”

Theoretically, anything with a high enough carbon content can be turned into graphene. All of the materials converted have lignin, which appears to a carbon precursor that makes it easier to convert to graphene. For example, cork, coconut shells, and potato skins have a high lignin content. Additionally to food, an interesting application could be in wearable electronics. Perhaps in the near future, you could have a jacket with built-in heating or exercise clothing with a sensor that measures heart rate.

Journal reference: Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food, ACS Nano (2018). pubs.acs.org/doi/10.1021/acsnano.7b08539

 

 

 

 

New, revolutionary metalens focuses entire visible spectrum into a single point

The Harvard-produced lens could usher in a new age of cameras and augmented reality.

The next generation of cameras might be powered by nanotechnology.

From the gargantuan telescopes built to study the universe to the ever smaller cameras inside your smartphones, lenses have come a long way. They’ve reached incredibly high performance at lower and lower costs, but researchers want to take them to the next level. A team from Harvard has developed a metalens — a flat surface that uses nanostructures to focus light — capable of concentrating the entire visible spectrum onto a single spot.

Metalenses aren’t exactly a new thing. They’ve been around for quite a while, but until now, they’ve struggled to focus a broad spectrum of light, addressing only some of the light wavelengths. This is the first time researchers managed to focus the entire spectrum — and in high resolution. This raises exciting possibilities.

“Metalenses have advantages over traditional lenses,” says Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the research. “Metalenses are thin, easy to fabricate and cost effective. This breakthrough extends those advantages across the whole visible range of light. This is the next big step.”

In a way, creating such a lens is like building a maze for light. Different wavelengths travel at different speeds; red moves the fastest, with violet being the slowest. At macroscopic scales (say, if you were using a prism for light diffraction), this difference is not noticeable. But if you go down to the nanoscale, it becomes evident, leading to so-called chromatic aberrations. Conventional lenses bypass this by having a curved surface, but metalenses need to take a different approach. This is where the innovation takes place. The team from the School of Engineering and Applied Sciences (SEAS) at Harvard used tiny arrays of titanium dioxide nano-sized fins to fix chromatic aberrations.

An artist’s conception of incoming light being focused on a single point by a metalens. Image credits: Jared Sisler/Harvard SEAS.

Previous research had shown that this is possible in theory, but this is the first time a practical solution was designed, and it was no easy feat.

“One of the biggest challenges in designing an achromatic broadband lens is making sure that the outgoing wavelengths from all the different points of the metalens arrive at the focal point at the same time,” said Wei Ting Chen, a postdoctoral fellow at SEAS and first author of the paper.

“By combining two nanofins into one element, we can tune the speed of light in the nanostructured material, to ensure that all wavelengths in the visible are focused in the same spot, using a single metalens. This dramatically reduces thickness and design complexity compared to composite standard achromatic lenses.”

Through this approach, they were able to focus all the colors of the rainbow onto a single point — in other words, they were able to image “normal” white light, using a lens thousands of times thinner than what we’re used to.

“Using our achromatic lens, we are able to perform high quality, white light imaging. This brings us one step closer to the goal of incorporating them into common optical devices such as cameras,” said Alexander Zhu, co-author of the study.

The potential for practical applications is practically limitless, not only in photography but also in emerging technologies such as virtual or augmented reality. But while this does bring researchers one step closer to developing smaller, better lenses for your camera or smartphone, there’s still a long way to go before the technology will reach consumers. The first step is achieving the same results in macro-scale lenses. Chen and Zhu say that they plan on scaling up the lens to about 1 cm (0.39 in) in diameter, which would make it suitable for real-world applications. It will undoubtedly take them at least a few years to reach that goal, but if they can do it, we’re in for quite a treat.

Journal Reference: Wei Ting Chen et al. A broadband achromatic metalens for focusing and imaging in the visible. doi:10.1038/s41565-017-0034-6.

Scientists turn DNA into virtually any 3D shape imaginable

Scientists have made a significant advancement in shaping DNA — they can now twist and turn the building blocks of life into just about any shape. In order to demonstrate their technique, they have shaped DNA into doughnuts, cubes, a teddy bear, and even the Mona Lisa.

New DNA origami techniques can build virus-size objects of virtually any shape. Image credits: Wyss Institute.

Scientists have long desired to make shapes out of DNA. The field of research emerged in the 1980s, but things really took off in 2006, with the advent of a technique called DNA origami. As the name implies, it involves transforming DNA into a multitude of shapes, similar to the traditional Japanese technique of origami. The process starts with a long strand placed on a scaffold with the desired sequence of nucleotides, dubbed A, C, G, and T. Then, patches of the scaffold are matched with complementary strands of DNA called staples, which latch on to their desired target. In 2012, a different technique emerged — one which didn’t use scaffolds or large strands of DNA, but rather small strands that fit together like LEGO pieces.

Both techniques became wildly popular with various research groups. Scientists started to coat DNA objects with plastics, metals, and other materials to make electronic devices, electronics, and even computer components. But there was always a limitation: the size of conventional DNA objects has been limited to about 100 nanometers. There was just no way to make them bigger without becoming floppier or unstable in the process. Well, not anymore.

New DNA origami techniques can make far larger objects, such as this dodecahedron composed of 1.8 million DNA bases. Image credits: K. Wagenbauer et al, Nature, Vol. 551, 2017.

Groups in Germany, Massachusetts, and California all report that they’ve made dramatic breakthroughs in DNA origami, creating rigid modules with preprogrammed shapes that can assemble with other copies to build specific shapes — and they have a variety of shapes to prove it.

A German team, led by Hendrik Dietz, a biophysicist at the Technical University of Munich, created a miniature doughnut about 300 nanometers across. A Massachusetts team led by Peng Yin, a systems biologist at Harvard University’s Wyss Institute in Boston, created complex structures with both blocks and holes. With this technique, they developed cut-out shapes like an hourglass and a teddy bear. The third group led by Lulu Qian, a biochemist at the California Institute of Technology in Pasadena, developed origami-based pixels that appear in different shades when viewed through an atomic microscope. Taken together, these structures represent a new age for DNA origami.

Furthermore, it’s only a matter of time before things get even more complex. Yin’s group actually had to stop making more complex shape sbecause they ran out of money. Synthesizing the DNA comes at the exorbitant price of $100,000 per gram. However, Dietz and his collaborators believe they could dramatically lower the price by coaxing viruses to replicate the strands inside bacterial hosts.

“Now, there are so many ways to be creative with these tools,” Yin concludes.

The technique isn’t just about creating pretty DNA shapes. Someday, this approach could lead to a novel generation of electronics, photonics, nanoscale machines, and possibly disease detection, Robert F. Service writes for Science. The prospect of using DNA origami to detect cancer biomarkers and other biological targets could open exciting avenues for research and help revolutionize cancer detection.

Journal References:

  1. Klaus F. Wagenbauer, Christian Sigl & Hendrik Dietz. Gigadalton-scale shape-programmable DNA assemblies. doi:10.1038/nature24651.
  2. Grigory Tikhomirov, Philip Petersen & Lulu Qian. Fractal assembly of micrometre-scale DNA origami arrays with arbitrary patternsdoi:10.1038/nature24655.
  3. Luvena L. Ong et al. Programmable self-assembly of three-dimensional nanostructures from 10,000 unique componentsdoi:10.1038/nature24648.
  4. Florian Praetorius et al. Biotechnological mass production of DNA origami. doi:10.1038/nature24650.

How butterflies have such a beautiful colour

Butterflies are some of the most exquisitely patterned and coloured creatures in the world. The colours all start with the scales on their wings. The scales contain crystals called gyroids that are made of chitin, the substance that is also in insect exoskeletons. These structures are complex and just a few nanometers large — so extremely tiny. Nanotechnology, creating tiny structures for industry, also creates such small-scale structures. They are important in areas such as medicine, electronics, and space travel. However, the nanostructures on butterfly wings are way more complex than anything that can be man-made. A group of researchers examined how the crystals develop on a butterfly’s wing for potential uses in industry.

The small Hairstreak. Image credits: Wilts et al., 2017.

The study that is published in Science Advances set out to discover how these crystals that give butterflies their magnificent colour form. It isn’t yet possible to study a butterfly’s wing while it’s developing, so the researchers examined the scales of a grown butterfly under extreme magnification. The subject? The small Hairstreak butterfly Thecla opisena from Mexico. The upper side is jet-black with blue patches while the lower side is green with a small red patch on the bottom edge of the wing. However, if you zoom into the bright green wing it’s actually not all green. The cover scales are bright green while the background is an orange-red colour. The cover scales themselves are not completely green but are made up of several domains that don’t overlap.

A close-up of one wing scale wing; it has a red background with green domains on top. Image credits: Wilts et al., 2017.

Each scale contains structured nanocrystals that interestingly, were spatially separated and loosely connected to the lower surface of the wing. On the wing, the crystals were arranged in lines, and at the beginning of the line the crystals were really small but as you progress further down the line, the crystals get larger. Perhaps, the scales form this way and are constantly growing on the wing. They seem to be developmental stages frozen in time and show the process of how these crystal form. The way that the scales develop is likely that the casing forms first and then the internal gyroid structure follows.

How the crystals develop over time. Image credits: Wilts et al., 2017.

We do need to keep in mind that this is just one butterfly out of more than 140,000 species. However, it is likely, according to the authors, that this way of development can be generalised to most wing scales and that all butterflies get their colour in a similar way. They could be very useful for nanotechnological applications, such as light-guiding technology because they can manipulate light in arbitrary directions. It is interesting to see how the natural world inspires technological advances.

Journal reference: Wilts, B.D. et al., 2017. Butterfly gyroid nanostructures as a time-frozen glimpse of intracellular membrane development, Science Advances.

By adding fibers, scientists have turned a soft gel into a material tougher than many metals. Credit: Hokkaido Uni.

Adding fibers to hydrogel, a soft material mostly made of water, makes it 5 times tougher than steel

By adding fibers, scientists have turned a soft gel into a material tougher than many metals. Credit: Hokkaido Uni.

By adding fibers, scientists have turned a soft gel into a material tougher than many metals. Credit: Hokkaido Uni.

Hydrogels are made of a network of polymer chains that are hydrophilic. For this reason, this material can absorb up to 90% of its weight in water making the hydrogel highly flexible, mimicking natural tissue. On the flipside, hydrogels aren’t very strong. However, Japanese researchers from Hokkaido University have found a way to make very strong hydrogels by introducing fibers into their composition without compromising too much flexibility. The fiber-reinforced hydrogels are five times tougher than steels according to tests ran in the lab.

Due to its properties, hydrogel is used for medical purposes in tissue engineering as well as sustained-release of drug delivery system or rectal diagnoses. It also has the potential to become a very useful structural material if only it could be coaxed to be stronger for long-term use.

The Japanese team led by Dr. Jian Ping Gong looked at the problem and decided to go with a time-honored approach: just mix and match with some other material to create a composite material that has all of the desired properties. For instance, mud is mushy but add some straw to it and leave it to bask in the sun for a while and you have some pretty functional solid bricks. It’s how people used to make their homes for thousands of years.

Likewise, the researchers added glass fiber fabric to polyampholyte (PA) hydrogels that contained high levels of water. Though the fibers were no bigger than 10μm in diameter, slightly thinner than the human hair, the resulting composite material proved to be bendable and very strong at the same time.

Scanning Electron Microscopy (SEM) images of the fiber-reinforced hydrogels. The polymer matrix (arrows) filled the interstitial space in the fiber bundles and connected the neighboring fibers. (Huang Y. et al., Advanced Functional Materials, January 16, 2017)

Scanning Electron Microscopy (SEM) images of the fiber-reinforced hydrogels. The polymer matrix (arrows) filled the interstitial space in the fiber bundles and connected the neighboring fibers. (Huang Y. et al., Advanced Functional Materials, January 16, 2017)

Lab tests show the fiver-reinforced hydrogels are 25 times tougher than glass fiber fabric and 100 times tougher than unaltered hydrogels. That makes it 5 times tougher than carbon steel. The researchers measured the energy required to destroy them when assessing the materials’ strength.

It’s not certain yet but the Japanese researchers think this high toughness is due to an increase in dynamic ionic bonds between the fiber and hydrogels, as well as within the gels themselves.

The manufacturing process is quite simple — you only have to immerse the fabric in PA precursor solutions for polymerization — and should prove scalable.

“The fiber-reinforced hydrogels, with a 40 percent water level, are environmentally friendly,” Gong said in a statement. “The material has multiple potential applications because of its reliability, durability and flexibility. For example, in addition to fashion and manufacturing uses, it could be used as artificial ligaments and tendons, which are subject to strong load-bearing tensions.”

The same process, reported in the journal Advanced Functional Materials should be able to make other polymers tougher, like rubber.

Plants embedded with electronics can detect explosives, dopamine, and a slew of other chemicals. Credit: Juan Pablo Giraldo / MIT

Spinach doped with carbon nanotubes turns into explosive detector

Plants embedded with electronics can detect explosives, dopamine, and a slew of other chemicals. Credit: Juan Pablo Giraldo / MIT

Plants embedded with electronics can detect explosives, dopamine, and a slew of other chemicals. Credit: Juan Pablo Giraldo / MIT

Popeye’s favorite superfood was turned into an explosive detector after researchers at MIT enhanced the plant’s natural sensing abilities with nanotechnology. When explosive molecules bind to the plant’s leaves, these emit a telltale infrared signal that can be read with cheap equipment — even a smartphone with the right camera. This is one of the first demonstrations of “plant nanobionics” — engineering electronics inside plants — something that we’ll hear about more often in the near future because of the immense potential this technology has for detecting virtually anything: explosives, CO2, droughts, even neurotransmitters like dopamine. The possibilities could be endless.

Borg plants

Previously, in 2014, the team led by Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT, worked with a common lab plant called Arabidopsis thaliana. Back then, they also showcased plant nanobionics technology by using nanoparticles to enhance photosynthesis, but this time they wanted to use spinach because it’s so common and ubiquitous. Seeing how it worked with spinach, it should work with right about any plant, the researchers reckon.

Strano and colleagues first developed carbon nanotubes — a tube-shaped material, made of carbon, having a diameter measuring on the nanometer scale — which can sense a wide range of molecules, including TNT, sarin nerve gas or hydrogen peroxide.

Using a technique known as vascular infusion, the researchers applied a solution of these nanoparticles to the underside of the spinach’s leaves. This allows the plant to detect nitroaromatics, which are often used in landmines and other explosives. When one of these chemicals binds to the tubes, it alters their fluorescence.

Another set of carbon nanotubes was embedded in the plant which emits a constant fluorescent signal. This serves as a reference to compare the explosive-detection fluorescent signal against a background and drastically speeds up detection. If there are any explosives in groundwater, for instance, the spinach bomb detector can draw them in under 10 minutes, as reported in Nature Materials.

Diagram of the plant-nanotech sensing setup. Credit:  Juan Pablo Giraldo / MIT

Diagram of the plant-nanotech sensing setup. Credit: Juan Pablo Giraldo / MIT

To read the signal, a laser is shone onto the leaf prompting the leaves to emit near-infrared fluorescent light. Then, a small infrared camera connected to a cheap computer, like a $35 Raspberry Pi, can be used to monitor the signals. A smartphone whose infrared filter from the camera is removed can also be used with accuracy.

“This is a novel demonstration of how we have overcome the plant/human communication barrier,” says Strano.

Plants are already one of the best sensors in the world. If you ever thought plants are good listeners, you’re not far from the truth as they continuously monitor the air, soil, moisture, and water — otherwise, they couldn’t adapt to the slightest weather and climate fluctuations, perishing.

“Plants are very good analytical chemists,” Strano says. “They have an extensive root network in the soil, are constantly sampling groundwater, and have a way to self-power the transport of that water up into the leaves.”

Besides explosive detection, the MIT lab also engineered spinach plants that read dopamine, which can influence plant root growth. They’re also working on other sensors which can track chemicals plants use to convey information within their own tissues.

“Plants are very environmentally responsive,” Strano says. “They know that there is going to be a drought long before we do. They can detect small changes in the properties of soil and water potential. If we tap into those chemical signaling pathways, there is a wealth of information to access.”

Largest database of crystal surfaces and shapes can help researchers design better materials

Crystal lovers rejoice – researchers have created the largest database of elemental crystal surfaces and shapes to date.

There is an incredibly large variety of crystals in nature. When you add in the ones humans designed themselves, the possibilities are simply staggering. Dubbed Crystallium, this new open-source database can go a long way towards helping researchers design new materials – especially where crystal surface orientation

“This work is an important starting point for studying the material surfaces and interfaces, where many novel properties can be found. We’ve developed a new resource that can be used to better understand surface science and find better materials for surface-driven technologies,” said Shyue Ping Ong, a nanoengineering professor at UC San Diego and senior author of the study.

Crystals found in rocks typically range in size from a fraction of a millimetre to several centimetres across, although exceptionally large crystals are occasionally found. But this database is less about geology and more about material design. Size is not often important when trying to use crystals to design materials but the other geometrical parameters are. For instance, fuel cell performance is significantly influenced by molecules of hydrogen and oxygen reacting on the surface of metal catalysts. The orientation of the building blocks of that surface is key here. Similarly, the interfaces between the electrodes and electrolyte in a rechargeable lithium-ion battery can increase or reduce the battery’s performance. This is where the database steps in – it makes this kind of information much more accessible to everyone.

“Researchers can use this database to figure out which elements or materials are more likely to be viable catalysts for processes like ammonia production or making hydrogen gas from water,” said Richard Tran, a nanoengineering PhD student in Ong’s Materials Virtual Lab and the study’s first author. Tran did this work while he was an undergraduate at UC San Diego.

The surface resistance is particularly important in such cases. Surface energy describes the stability of a surface, it’s basically a measure of the excess energy of atoms on the surface relative to those in the bulk material. The surface resistance is always important for designing nanoparticles and catalysts.

At this point, you might think this is a trivial task. After all, what’s so special in publishing a crystal database?

Well, in the past, researchers have experimentally measured the surface energies elements in their crystal. This is a complex process which traditionally involves melting the crystal, measuring the resulting liquid’s surface tension at the melting temperature, then extrapolating that value back to room temperature – and all this must be done on a perfectly smooth surface, which is pretty difficult to obtain. Some crystals had already been measured this way, but the problem is that the results were averaged values and thus lacked the specific resolution that is necessary for design, Ong said. Furthermore, the surface energy is not a simple number, because it depends on the crystal’s orientation

“A crystal is a regular arrangement of atoms. When you cut a crystal in different places and at different angles, you expose different facets with unique arrangements of atoms,” explained Ong, who teaches the Crystallography of Materials course at UC San Diego.

There was no place with such information for all elemental crystals, so Ong and his team developed sophisticated automated workflows to calculate surface energies virtually, using the open-source Python Materials Genomics library and FireWorks workflow codes of the Materials Project. Their virtual laboratory setup was excellent, thanks to the powerful supercomputers at the San Diego Supercomputer Center and the National Energy Research Scientific Computing Center. It simulates the experiments with accuracy, offering all the required information without any hassle.

“This is one of the areas where the ‘virtual laboratory’ can create the most value–by allowing us to precisely control the models and conditions in a way that is extremely difficult to do in experiments.”

At the moment, the database covers only chemical elements, but the team is already working on expanding it to multi-element compounds like alloys, which are made of two or more different metals, and binary oxides, which are made of oxygen and one other element.

Stanford researchers develop the coolest clothes – literally

Stanford engineers have developed cheap, low-cost textiles that can cool your body much more efficiently than existing clothes.

The clothes can make you feel cooler than wearing nothing at all. Photo by AhmetSelcuk.

Naturally, a logical application for this technology would be in hot climates, especially where air conditioning is not available. But even when air conditioning is available, the cooling clothes could help save a lot of energy. Detailing their work in Science, the researchers explain:

“If you can cool the person rather than the building where they work or live, that will save energy,” said Yi Cui, an associate professor of materials science and engineering at Stanford and of photon science at SLAC National Accelerator Laboratory.

There are two mechanisms through which the material cools the body. The first one is not innovative, and is something that already exists in some fabrics: it lets perspiration evaporate through the material. But the second mechanism is indeed revolutionary: it allows heat that the body emits as infrared radiation to pass through the plastic textile. This means that the wearer feels almost 4 degrees Fahrenheit cooler than if they wore cotton clothing.

The anti-blanket

All existing bodies in the universe give off infrared radiation, which is invisible to the human eye. To easily visualize this, think of night-vision goggles – they see the heat given away by bodies. When you put a blanket on, it doesn’t heat you directly, but it traps the heat you radiate close to you. This material does kind of the opposite, allowing most of this energy to be released.

“Forty to 60 percent of our body heat is dissipated as infrared radiation when we are sitting in an office,” said Shanhui Fan, a professor of electrical engineering who specializes in photonics, which is the study of visible and invisible light.

“But until now there has been little or no research on designing the thermal radiation characteristics of textiles.”

Stanford researchers began with a sheet of polyethylene and modified it with a series of chemical treatments, resulting in a cooling fabric. (Image credit: L.A. Cicero)

While the idea sounds fairly simple, the technology behind it is anything but. The team implemented nanotechnology, photonics, and chemistry to give polyethylene – the common, transparent plastic often used as kitchen wrap – a number of desirable characteristics. For example, they made it allow thermal radiation to pass right through it. The same goes for air and water vapor. They also made it opaque (not transparent).

But people don’t wear plastic, so they had to change it once more. To make this thin material more fabric-like, they created a three-ply version: two sheets of treated polyethylene separated by a cotton mesh for strength and thickness.

Better than wearing nothing at all

The end result was that the clothes keep you cooler than your own skin, which is quite an achievement.

“Wearing anything traps some heat and makes the skin warmer,” Fan said. “If dissipating thermal radiation were our only concern, then it would be best to wear nothing.”

When they compared it with regular cotton, it made the skin surface 3.6 F colder. This might not seem like much, but it can make a huge difference – the difference between turning the air conditioning on or leaving it off, or the difference between making a person feel comfortable or uncomfortable.

The team is now working on making different textures and colors, making it suitable for mass production. The material and the thermal treatment is quite cheap, and it could be suitable for countries in hot climates.

“If you want to make a textile, you have to be able to make huge volumes inexpensively,” Cui concluded.

Scientists count microscopic particles without a microscope

Counting microscopic particles is hard, but researchers from Russia and Australia believe they’ve found a way to make it easier.

The process - image via ITMO University.

The process – image via ITMO University.

The principle is fairly simple. A research team from ITMO University, Ioffe Institute, and Australian National University passed a laser beam through an optic material riddled with microscopic particles and then projected it onto a screen. The screen showed a characteristic pattern consisting of numerous bright spots and the number of these bright spots corresponded to exactly to the number of scattering microscopic particles in the optical material.

“The light senses heterogeneity,” says Mikhail Rybin, first author of the paper, senior researcher at the Department of Nanophotonics and Metamaterials at ITMO University.

“We found out that by looking at the pattern it is possible to determine the precise number of scatterers in the material. This helps understand not only the type of the sample lattice (square, triangular), but also establish its structure (20 to 20 particles, or 30 to 15) just by counting the light spots on the screen”.

It’s very simple but also very effective. You shine a laser beam through the material and then onto a projector. The different structure of the material will cause light to diffract, and the result will be visible on the projector.

“Depending on the shape and relative position of the scatterers, the light wave continues to propagate differently behind the sample. In other words, the structure of the sample affects the diffraction pattern, which will be projected on the screen.

Mikhail Rybin at work. Photo via ITMO University.

Mikhail Rybin at work. Photo via ITMO University.

The new method is a much more affordable option to expensive electron or atomic force microscopy and doesn’t damage the sample at all. It’s also extremely easy to use.

“Even a schoolboy can buy a laser pointer, adapt a small lens to focus the light better, fix the sample and shine a laser beam on it,” notes Mikhail Rybin. “In addition, our method makes it possible to study optical materials without changing their structure, in contrast to electron microscopy, where the sample surface has to be covered with conductive metal layer, which impairs optical properties of the sample”.

The method can be extremely useful for constructing and assessing metamaterials. They tested it for two classes of such materials: photonic crystals and metasurfaces. Photonic crystals are periodic optical nanostructures which affect the motion of photons in much the same way that ionic lattices affect electrons in solids. When light passes through one, it generates a fancy pattern on the screen behind the sample.

In the case of a metasurface – an artificial sheet material – things are a bit more complicated because the material has to be constructed in such a way that the distance between particles is significantly smaller than the wavelength of light. In fact, the difference between a photonic crystal and a metasurface depends on the wavelength of the light.

“For one wavelength, the material will act as a photonic crystal and as a metasurface for another. That is why designing such structures, we can evaluate maximum lattice period with laser,” concludes Mikhail Rybin.