Tag Archives: nanotechnology

The swarm is near: get ready for the flying microbots

Imagine a swarm of insect-sized robots capable of recording criminals for the authorities undetected or searching for survivors caught in the ruins of unstable buildings. Researchers worldwide have been quietly working toward this but have been unable to power these miniature machines — until now.

A 0.16 g microscale robot that is powered by a muscle-like soft actuator. Credit: Ren et al (2022).

Engineers from MIT have developed powerful micro-drones that can zip around with bug-like agility, which could eventually perform these tasks. Their paper in the journal Advanced Materials describes a new form of synthetic muscle (known as an actuator) that converts energy sources into motion to power these devices and enable them to move around. Their new fabrication technique produces artificial muscles, which dramatically extend the lifespan of the microbot while increasing its performance and the amount it can carry.  

In an interview with Tech Xplore, Dr. Kevin Chen, senior author of the paper, explained that they have big plans for this type of robot:

“Our group has a long-term vision of creating a swarm of insect-like robots that can perform complex tasks such as assisted pollination and collective search-and-rescue. Since three years ago, we have been working on developing aerial robots that are driven by muscle-like soft actuators.”

Soft artificial muscles contract like the real thing

Your run-of-the-mill drone uses rigid actuators to fly as these can supply more voltage or power to make them move, but robots on this miniature scale couldn’t carry such a heavy power supply. So-called ‘soft’ actuators are a far better solution as they’re far lighter than their rigid counterparts.

In their previous research, the team engineered microbots that could perform acrobatic movements mid-air and quickly recover after colliding with objects. But despite these promising results, the soft actuators underpinning these systems required more electricity than could be supplied, meaning an external power supply had to be used to propel the devices.

“To fly without wires, the soft actuator needs to operate at a lower voltage,” Chen explained. “Therefore, the main goal of our recent study was to reduce the operating voltage.”

In this case, the device would need a soft actuator with a large surface area to produce enough power. However, it would also need to be lightweight so a micromachine could lift it.

To achieve this, the group elected for soft dielectric elastomer actuators (DEAs) made from layers of a flexible, rubber-like solid known as an elastomer whose polymer chains are held together by relatively weak bonds – permitting it to stretch under stress.

The DEAs used in the study consists of a long piece of elastomer that is only 10 micrometers thick (roughly the same diameter as a red blood cell) sandwiched between a pair of electrodes. These, in turn, are wound into a 20-layered ‘tootsie roll’ to expand the surface area and create a ‘power-dense’ muscle that deforms when a current is applied, similar to how human and animal muscles contract. In this case, the contraction causes the microbot’s wings to flap rapidly.

A microbot that acts and senses like an insect

A microscale soft robot lands on a flower. Credit: Ren et al (2022).

The result is an artificial muscle that forms the compact body of a robust microrobot that can carry nearly three times its weight (despite weighing less than one-quarter of a penny). Most notably, it can operate with 75% lower voltage than other versions while carrying 80% more payload.

They also demonstrated a 20-second hovering flight, which Chen says is the longest recorded by a sub-gram robot with the actuator still working smoothly after 2 million cycles – far outpacing the lifespan of other models.

“This small actuator oscillates 400 times every second, and its motion drives a pair of flapping wings, which generate lift force and allow the robot to fly,” Chen said. “Compared to other small flying robots, our soft robot has the unique advantage of being robust and agile. It can collide with obstacles during flight and recover and it can make a 360 degree turn within 0.16 seconds.”

The DEA-based design introduced by the team could soon pave the way for microbots that work using untethered batteries. For example, it could inspire the creation of functional robots that blend into our environment and everyday lives, including those that mimic dragonflies or hummingbirds.

The researchers add:

“We further demonstrated open-loop takeoff, passively stable ascending flight, and closed-loop hovering flights in these robots. Not only are they resilient against collisions with nearby obstacles, they can also sense these impact events. This work shows soft robots can be agile, robust, and controllable, which are important for developing next generation of soft robots for diverse applications such as environmental exploration and manipulation.”

And while they’re thrilled about producing workable flying microbots, they hope to reduce the DEA thickness to only 1 micrometer, which would open the door to many more applications for these insect-sized robots.

Source: MIT

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.

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.

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.

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.

SRT coated fabric self-heals. From left, fabric with hole, wet fabric and patch in a drop of water, self-healed fabric. Image: Demirel Lab / Penn State

Self-healing textiles means you don’t have to throw away your torn jeans — just add water

SRT coated fabric self-heals.  From left, fabric with hole, wet fabric and patch in a drop of water, self-healed fabric. Image: Demirel Lab / Penn State

SRT coated fabric self-heals. From left, fabric with hole, wet fabric and patch in a drop of water, self-healed fabric. Image: Demirel Lab / Penn State

Penn State scientists made a coating that allows conventional textiles used in everyday clothing to patch themselves up. Derived from squid ring teeth, the coating can turn virtually any fabric into a self-healing one. Simply adding water is enough to kick start the repairing process.

Nano research has already revealed the potential of self-cleaning clothes, and now a new study reveals the potential for similar technology in suits that can be used to protect soldiers from chemical or biological attacks.

“Fashion designers use natural fibers made of proteins like wool or silk that are expensive and they are not self-healing,” said Melik Demirel, professor of engineering science and mechanics at Penn State University and senior author of the study. “We were looking for a way to make fabrics self-healing using conventional textiles. So we came up with this coating technology.”

In order to create the unique self-healing textile, the team takes the material to be coated and immerses it in a series of liquids, creating layers of material that ultimately form the self-healing, polyelectrolyte coating. These coatings are composed of both positively and negatively charged polymers – in the case of the current study the polymers resemble those in squid teeth ring proteins.

When the coating needs to be healed, it can be placed in a safe solvent – such as water – under ambient conditions, where it will then repair itself. Essentially, you could repair torn jeans simply by throwing them in the washing machine.

Enzymes that protect against toxins can be integrated into the coating during the laying process and for this research the team decided to use urease. However, during commercial use, the type of enzyme would depend on the target chemical.

“If you need to use enzymes for biological or chemical effects, you can have an encapsulated enzyme with self-healing properties degrade the toxin before it reaches the skin,” Demirel said.

Self-healing film could coat garments and protect farmers from harmful chemicals such as organophosphates, which are used as herbicides and insecticides as well as nerve agents against soldiers. These chemicals can be lethal if enough are absorbed through the skin. A film that contains a specific enzyme that breaks down organophosphates would protect individuals from these toxic materials.

Journal Reference: SELF-HEALING TEXTILE: ENZYME ENCAPSULATED LAYER-BY-LAYER STRUCTURAL PROTEINS. 15 July 2016. 10.1021/acsami.6b05232

Remote-controlled microrobots could be the future of medicine

One of the primary goals in the modern medical field is to create microrobots that can enter the human body and replace invasive and complicated surgery procedures. These robots could optimize the field of medicine by giving scientists and doctors the ability to deliver drugs at specific locations and perform precise operations.

Image credit Pixabay

Image credit Pixabay

Along with researchers from the Swiss Federal Institute of Technology in Zurich (ETHZ), scientists from the Ecole Polytechnique Fédérale de Lausanne (EPFL) have created such devices. The team created soft, flexible and motor-less microrobots that mimic the Trypanosoma brucei bacterium. The unique devices are composed of biocompatible hydrogel and magnetic nanoparticles that give them their unique shape and allow them to move and swim in the presence of an electromagnetic field.

The team begins the manufacturing process by placing nanoparticles inside layers of a biocompatible hydrogel. Afterwards, they apply an electromagnetic field, which results in the orientation of the nanoparticles at different regions of the robot.

Polymerization follows in order to “solidify” the composition of the hydrogel and the robot is then placed in water, where it folds into a unique shape that is dependent on the orientation of the nanoparticles inside of the gel. The final form represents the 3D architecture of the microrobot.

After the final step of the manufacturing process, these microrobots can be exposed to an electromagnetic field to make them swim or to heat to cause them to change shape and unfold. Ultimately, the final product – which possesses a bacterium-like flagellum – mirrors the T. brucei bacterium that is responsible for causing sleeping sickness.

“We show that both a bacterium’s body and its flagellum play an important role in its movement,” said Selman Sakar of the EPFL and co-author of the study. “Our new production method lets us test an array of shapes and combinations to obtain the best motion capability for a given task. Our research also provides valuable insight into how bacteria move inside the human body and adapt to changes in their microenvironment.”

Much more research is still needed until these microrobots are ready to traverse the human body to determine any potential side effects, but the promise and benefits that they could bring to the field of medicine is immense.

Journal Reference: Soft micromachines with programmable motility and morphology. 25 July 2016. 10.1038/ncomms12263

Nano-probes sniff out cancer using their nucleic acids

Fighting cancer with nanotechnology seems to be the theme of the day, as researchers from Wake Forest Baptist Medical Center develop new technology that could detect the disease early on. Their miniaturized probes can check a sample for nucleic acids belonging to any known pathogen or malign cells.

In the new technique, nanotechnology is used to determine whether a specific target nucleic acid sequence exists within a mixture, and to quantify it if it does through a simple electronic signature.

DNA Molecule display at Oxford University. Image via flikr @ allispossible.org.uk

DNA Molecule display at Oxford University.
Image via flikr @ allispossible.org.uk

“If the sequence you are looking for is there, it forms a double helix with a probe we provide and you see a clear signal. If the sequence isn’t there, then there isn’t any signal. By simply counting the number of signals, you can determine how much of the target is around,” says Adam R. Hall, Ph.D., assistant professor of biomedical engineering and lead author of the study.

While there are countless nucleic acids that we know of, they’re all built using the same blocks. Like words and letters, these acids are made of simple bases strewn together. They can range in size from a few to a few millions, but their order is set by their function. The Wake Forest researchers are basing their findings on this assumption that cell and tissue activity can be predicted solely by nucleic acids.

One type of nucleic acids, known as microRNAs, usually about 20 bases long, has caught the team’s interest as they could be used to screen for conditions like cancer.

“Scientists have studied microRNA biomarkers for years, but one problem has been accurate detection because they are so short, many technologies have real difficulty identifying them,” Hall adds.

The team first demonstrated that their technology could target a specific sequence of nucleic acids, and then applied their technique to one particular microRNA (mi-R155) known to indicate lung cancer in humans. Their probes were able to pick up on the tiny amounts of microRNAs in their patient’s bloodstream.

The Wake forest team now plans to test their technology on clinical samples of tissue, blood or urine. After they find out how to get the best results from their probes, they hope it will help detect virtually any pathogen known today.

“We envision this as a potential first-line, noninvasive diagnostic to detect anything from cancer to the Ebola virus,” Hall concludes

“Although we are certainly at the early stages of the technology, eventually we could perform the test using a few drops of blood from a simple finger prick.”

The full paper, titled “Sequence-Specific Recognition of MicroRNAs and Other Short Nucleic Acids with Solid-State Nanopores,” has been published online in the journal Nano Letters

The Hagfish produces a 12 nanometer wide, 15 centimeter long thread it clamps into a single cell

Winegard et al, 2014.

When it feels threatened, the hagfish produces a slime which is only 12 nanometers wide, but 15 centimeters long – 10,000,000 times longer than it is wide. It’s not clear exactly what this slime is made of (likely a sugar modification), but its purpose is to make the hagfish slippery and possibly clog the gills of a predator. The thread is clamped into a single cell. To make thing even more interesting, the threat can withstand pressures of gigapascals, much like spider silk or steel.

Hagfish are remarkable creatures. They are living fossils, remaining virtually unchanged in the past 300 million years. They are jawless and are the only known living animals that have a skull but no vertebral column. They are so strange that biologists still aren’t sure where to classify them in the tree of life.

Hagfish. Image credits: Wikipedia.

Researchers have known for quite a while that hagfish can exude copious quantities of a milky and fibrous slime or mucus from some 100 glands or invaginations running along its flanks, but until now, no one has studied in detail the characteristics of this slime – and the results were surprising. They were curios as to how they secrete the microfibrous slime, which expands into up to 20 litres (5¼ gallons) of gelatinous and sticky goo when combined with water, and how is it that they don’t get themselves tangled into it. Using electron microscopy they found how the thread doesn’t get tangled: it is coiled up in a conical “skein” in 15-20 layers, inside a highly specialized cell – a gland thread cell (GTC).

The method they used is called Focused Ion Beam Scanning Electron Microscopy or (FIB-SEM); they used it to scan a fully matured GTC. The technology’s main advantage is that it allows researchers to make visual slices of the interior of the GTC, which they can then reconstruct to create a 3D representation. This research doesn’t only reveal an extraordinary biological mechanism, but it can also pave the way for a new generation of nanofibers.

Industrial attempts to create strong, long lasting and cheap fibers have generally failed. Harvesting silk from the silk worm in bulk has been done with success for thousands of years, but the silk isn’t strong enough. Harvesting spider silk is not feasible on an industrial scale because it is not possible to generate a sufficient production volume (although some are working to develop this technology). It’s not clear if hagfish fibers can be the solution to this, but it does definitely paint an interesting perspective.

Journal Reference: Timothy Winegard,Julia Herr,Carlos Mena,Betty Lee,Ivo Dinov,Deborah Bird,Mark Bernards Jr,Sam Hobel,Blaire Van Valkenburgh,Arthur Toga& Douglas Fudge. Coiling and maturation of a high-performance fibre in hagfish slime gland thread cells. Nature Communications 5, Article number: 3534 doi:10.1038/ncomms4534

Watching Nanoscale Fluids Flow

Nanoscale nanofluids flowing.

Nanofluids, fluids containing nanometer-sized particles, show immense potential for future engineering. Even water flowing through nanotubes flows much faster than traditional mechanics says it should be possible. Now, researchers have found a way to directly image nanofluids.

Researchers at Caltech have applied a new imaging technique called four-dimensional (4D) electron microscopy to the nanofluid dynamics problem. The technique was invented at Caltech, and basically involves a stream of ultra-fast-moving electrons bombarding a sample in a carefully timed manner. Each electron scatters off a sample, providing a still image that lasts about a millionth of a billionth of a second. They are able to make millions and millions of these scatters, and stitch together the images – creating the result you see below.

Ahmed Zewail, the Linus Pauling Professor of Chemistry and professor of physics, and Ulrich Lorenz, a postdoctoral scholar in chemistry, the authors of the paper, used single laser pulses to melt the lead cores of individual zinc oxide nanotubes. Then, they observed how the hot pressurized liquid moved within the tubes.

“These observations are particularly significant because visualizing the behavior of fluids at the nanoscale is essential to our understanding of how materials and biological channels effectively transport liquids,” says Zewail. In 1999, Zewail won the Nobel Prize for his development of femtosecond chemistry.

Scientific Reference: Lorenz, Ulrich J. and Zewail, Ahmed H. (2014) Observing liquid flow in nanotubes by 4D electron microscopy. Science, 344 (6191). pp. 1496-1500. ISSN 0036-8075.

Nanoparticles make turkey eggs microbe-resistant

Credits: JJ Harrison.

Australian brush turkeys incubate their eggs in places most animals would stay clear of: moist piles of rotting vegetation. There are some advantages to this approach, most notably that the heat released by the microbes keeps the eggs warm but those same microbes can also get through eggshells and kill the embryos. However, even though the risks are apparently huge, only 9% of eggs laid by Australian brush turkeys (Alectura lathami) are infected.

Researchers now believe they know why this happens: the shells are covered in a layer of nanometre-sized spheres of calcium phosphate, which makes them repel water and harder to crack.  The results are extremely promising, with potential applications in antimicrobial coatings for plastics and other surfaces.

It’s generally pretty tough for microbes to crack through eggs. Most eggs have a tough barrier for pathogens to crack, and even if they do breach the eggs’ defenses, they are met with antimicrobial enzyme called lysozymes, found in the whites of bird eggs. But brush-turkey eggs have just as many lysosomes as chicken eggs, and more interestingly, their eggs are 1.5 times thinner than those of chickens – so how is it that their eggs are more resistant to infections?

The key difference is the ability to repel water. While chicken eggs absorb some of the water, brush-turkey eggs repel it. Since most microbes are usually transmitted into eggs by moisture, they are basically rejected by this hydrophobic layer.

“The lotus leaf is considered the most hydrophobic material in nature,” says first author Liliana D’Alba, a behavioural ecologist at the University of Akron, Ohio. “These eggshells are pretty close to that, to being super-hydrophobic.”

 This hydrophobic layer also works as a mechanical defense, aside for the biological protection it offers. The properties of this layer are achieved through calcium phosphate nanospheres, which are pretty uncommon in birds. Understanding how these nanospheres work could help to create better antimicrobial coatings for use on a wide range of materials, and ultimately to many more applications in biomedicine.
“Hydrophobic nanoparticles on the surface of medical devices could change the way bacteria adhere or form biofilms,” says Matthew Shawkey, an evolutionary biologist at the University of Akron.

DNA nanobots deliver drugs in living cockroaches – it’s a computer, inside a cockroach

The future is here. Nano-sized entities made of DNA that are able to perform the same kind of logic operations as a silicon-based computer have been introduced into a living animal.

Artistic depiction of nanobots. Via ProTV.

It’s every Science Fiction fan’s dream come true. The tiny DNA computers are called origami robots, because they work by folding and unfolding strands of DNA; they travel around the insect’s body and interact with each other, as well as the insect’s cells. When they unfold just like a complex origami, they dispense the drugs which they carry.

“DNA nanorobots could potentially carry out complex programs that could one day be used to diagnose or treat diseases with unprecedented sophistication,” says Daniel Levner, a bioengineer at the Wyss Institute at Harvard University.

DNA computing sounds like science fiction, but it’s not exactly a novelty – it’s been researched and developed for over a decade now. DNA computing is a form of computing which uses DNA, biochemistry and molecular biology just like you would use a traditional silicon microprocessor. DNA also has a remarkable property which makes it even more useful for this kind of technique, as it unravels into two complementary strands when it meets a certain protein, making it ideal for delivering substances inside a body. When the molecule opens up, it “delivers the package”.

DNA computing nanobots with the same computing power as an 80s computer injected into cockroaches. Simply mindblowing! Image credits: Daly and Newton/Getty Images.

Researchers injected different nanobots into cockroaches, labeling them with different fluorescent markers so they can follow and analyze how robot combinations affect where substances are delivered. The accuracy of this technique is similar to that of a computer system.

“This is the first time that biological therapy has been able to match how a computer processor works,” says co-author Ido Bachelet of the Institute of Nanotechnology and Advanced Materials at Bar Ilan University. Unlike electronic devices, which are suitable for our watches, our cars or phones, we can use these robots in life domains, like a living cockroach,” says Ángel Goñi Moreno of the National Center for Biotechnology in Madrid, Spain. “This opens the door for environmental or health applications.”

DNA has already been used for storing large amounts of information and circuits for amplifying chemical signals, but when you compare these achievements with the origami robots, they are not that impressive. The number of the nanobots which were successfully used and their impressive accuracy are extremely promising.

 “The higher the number of robots present, the more complex the decisions and actions that can be achieved. If you reach a certain threshold of capability, you can perform any kind of computation. In this case, we have gone past that threshold,” he says.

The team believes they will soon be able to scale up the computing power up to that of an 8-bit computer, equivalent to a computer from the 80s – it may not seem that impressive at a first glance, but remember, this is a computer made from DNA, which serves a very unique purpose, so it’s actually more than enough.

The obvious benefits would be cancer treatments, because these must be cell-specific and one of the main problems with current treatments is the lack of cell-targeting. However, the main problem here is that any such treatment has to somehow overcome the immune response delivered by the host. Basically, your immune system will sense the nanobots as a foreign body, and try to fight them. But scientists believe they can overcome even that problem – Bachelet is confident that the team can enhance the robots’ stability so that they can survive in mammals.

“There is no reason why preliminary trials on humans can’t start within five years,” he says.

 

Professor Zhang Li shows enlarged images of his team's medical microbots that are being tested. Photo: Nora Tam

Microbots no larger than a human cell set to carry more payload drugs

Professor Zhang Li shows enlarged images of his team's medical microbots that are being tested. Photo: Nora Tam

Professor Zhang Li shows enlarged images of his team’s medical microbots that are being tested. Photo: Nora Tam

Researchers at the Chinese University of Hong Kong have developed a new type of microbots approximately the size of a human cell that can carry more targeted drugs than other such options. These can be guided wirelessly through magnetic field manipulation. The Chinese designed microbots as well as other micro or nano-scale alternatives  are meant to funnel key substances for non-invasive treatments that otherwise today can only be performed using risky surgery.

Resembling a cage, the microbots are 100 microns long and 40 wide, and are small enough to be injected into the body without leaving a wound. The mirobots are coated with a thin layer of nickel which makes them magnetic and thus can be guided by a magnetic field. The key innovation here is that these micro-containers are larger than other alternatives and can carry more drugs making treatments more effective.

The truck of microbots

“A microbot is like a vehicle that ships drugs directly to the affected area. And I want to design a truck, not a car,” said Zhang Li, assistant professor in the university’s mechanical engineering department. He has been working on microbot technology for seven years.

By modifying the shape of other drug-delivery bots, Zhang and colleagues reached a design capable of carrying more drugs. Preliminary tests show these are indeed biocompatible after the team cultivated human kidney cells in the microbot model. These cells grew and even interacted with the model. So far, the researchers are testing their microbots with mice and rabbits, but Zhang warns that we might be decades away from seeing this work implemented with humans. Safety is a huge concern, and it’s enough for a few or even one of these cage-like bots to stray away from its target destination to become a health hazard.

“Tracking the microbot is a huge challenge. It will be very dangerous if we lose track of the model after injecting it into a human body,” Zhang said.

[NOW READ] Nanorobots made out of DNA seek and kill cancer cells

Creating the smallest Mona Lisa – just 30 microns across

Mona Lisa is probably the most well known picture in the world – it’s been painted thousands of times, inspired countless artists, and her enigmatic smile still puzzles researchers and artists alike; but never before has it been painted on such a small canvas.

Picture source

Picture source

Demonstrating a very potent nanotechnique, researchers have made a miniature Mona Lisa that stretches 30 microns across – about a third of the width of a human hair. The team from Georgia Tech created the molecular masterpiece using an atomic force microscope and a process which they have called ThermoChemical NanoLithography, or TCNL for short.

Thermochemical nanolithography (TCNL) employs heated nano-size tips to create heat which activates chemical reactions to change the functionality of a nanoscale surface  or obtain new nanostructures. It’s not a novel technique, being used for the first time in 2007, also at Georgia Tech.

The pixels of the “Mini Lisa” each measure 125-nanometer , and they are basically a confined set of chemical reactions. By controlling the amount of heat which goes into the molecules, researchers influenced the shade of grey of every ‘pixel’ – making this extremely small work of art a brilliant demonstration of TCNL’s ability to make variations in molecular concentrations on this extremely small scale. This has the potential to be applied in nanoscale manufacturing.

“We envision TCNL will be capable of patterning gradients of other physical or chemical properties, such as conductivity of graphene,” study researcher Jennifer Curtis said in a statement. “This technique should enable a wide range of previously inaccessible experiments and applications in fields as diverse as nanoelectronics, optoelectronics and bioengineering.”

This is not the first time the Mona Lisa has been used in science – earlier this year, NASA beamed the famous image to the Moon, using a very powerful laser.

The findings were detailed in the Journal Langmuir.

Creating glasses that don’t fog up

Creating glasses that don’t fog or freeze up could not only bring a world of comfort to millions of people, but it could also have a myriad of applications in cameras, microscopes, mirrors and refrigerated displays – to name just a few. While there have been many advancements in this field, so far, the main problem is that there is no systematic way of testing different coatings and materials to see how effectively they work under the pressure real-world conditions.

See things clearly

zwitter wettability]

If such a method were developed, then it would benefit the field greatly and almost certainly lead to quick advancements – and that’s exactly what a team of MIT researchers has done. Immediately afterwards, they used it to test a coating they developed, and found that it works great in preventing foggy buildups, but also in maintaining good optical properties without distortion.

This work has been detailed in a paper published in ACS Nano. The research was conducted by Michael Rubner, the TDK Professor of Polymer Materials Science and Engineering, Robert Cohen, the Raymond A. and Helen E. St. Laurent Professor of Chemical Engineering, doctoral student Hyomin Lee and recent MIT graduate Maria Alcaraz.

“When people want to tackle the fogging process, caused when microscopic water droplets condense on a cold surface and scatter light, the common way of doing it is to build a surface that’s so hydrophilic — water-loving — that the water spreads out into a sheet,” says Rubner, who is also director of MIT’s Center for Materials Science and Engineering. “So even though the water’s there, it doesn’t scatter the light.”

But this method has a big problem – if the thickness of the water layer varies considerably, then distortion occurs, and this is especially bad for systems where you want to have a clear sight of what’s going on (say cameras, for example). Also, if you have a layer of water and it’s cold enough outside, the water will freeze (doh), and that produces even more distortion.

For that purpose, what you need is a coating that holds water, but not too much water, and also that prevents it from freezing; in other words, you want both hydrophobic and hydrophilic traits in the same material – and this is exactly what the team accomplished.

Zwitter wettability

They even coined a term for this hybrid property: Zwitter wettability. Zwitter, Rubner explains, is a German word for hybrid, and is often used in chemistry for things that exhibit two opposite properties at once. The surface itself is made through a layer-by-layer technique, alternating between layers of two different polymers — poly(vinyl alcohol) and poly(acrylic acid). The magic happens on the nanoscale, but is actually quite cheap and easy to make on a large scale.

“These are common polymers,” Rubner says. “They’re well-known and cheap, but brought together in a unique way.”

They tested this new material in extreme conditions – at minus 20 degrees Celsius, in a very humid environment. Everything worked fine, and the test was successful, but there are still limitations.

The main problem is that the layer is extremely thing, and therefore very vulnerable to mechanical impacts or even cleaning. Also, it can’t hold up when exposed to big quantities of frosty water, such as say, on an airplane wing. But this still leaves us with so many possible applications: glasses, automobile windshields, refrigerator cases, etc.

Joseph Schlenoff, a professor of polymer science at Florida State University who was not involved in this work, says,

“Everyone knows how inconvenient, or even dangerous, it is to have a cold window or lens fog up when water condenses on it. The MIT group has devised a practical and effective method of combatting the fogging problem using a new ultrathin polymer film.”

Cicada wing destroys bacteria solely through its physical structure

The veined wing of the clanger cicada kills bacteria is able to destroy bacteria by its structure alone – one of the first structures ever found that can do this.

The clanger cicada is an insects that looks like something between a fly and a locust; its wings are covered with a vast hexagonal array of ‘nanopillars’ – basically blunted spikes with sizes comparable to that of bacteria. What happens is that when a bacteria settles on this surface, its cellular membrane sticks to the surface of the nanopillars and stretches into the crevices between them, where it experiences the most strain. When the stretch is powerful enough, the membrane ruptures.

Lead study author Elena Ivanova of Australia’s Swinburne University of Technology in Hawthorne, Victoria worked with a team of biophysicists to come up with an advanced nanoscale model of how this happens. She explains that the rupture is much like “the stretching of an elastic sheet of some kind, such as a latex glove. If you take hold of a piece of latex in both hands and slowly stretch it, it will become thinner at the center, [and] will begin to tear”.

cicada

To test their model, the team irradiated bacteria with microwaves to generate cells that had different levels of membrane rigidity. If the model was correct, then the more rigid bacteria would be less likely to rupture between the nanopillars. The results validated their model, but also showed that not all bacteria are destroyed – only those with soft enough membranes.

Further study of the cicada’s wing is needed before its physical-defence properties can be mimicked in man-made materials, but doctors are already rubbing their hands, because if this can be replicated, it could be very useful (say) in hospitals and rooms which you want to keep as bacteria-free as possible.

“This would provide a passive bacteria-killing surface,” she says, adding that it “does not require active agents like detergents, which are often environmentally harmful”.

Stealth nanoparticles sneak past immune system’s defences

Most of the time, when you’re sick, you want to deliver drugs and imaging agents to diseased cells or tumours where they’re needed most – that’s a problem researchers have solved quite a while ago, we can get particles pretty much wherever we want to. The thing is, most of the time, these agents are stopped by your immune system, which of course, can’t recognize them, and therefore, treats them as enemies.

Credits: Diego Pantano

Credits: Diego Pantano

Researchers at the University of Pennsylvania in Philadelphia have now found a way to stop macrophages (specialized cells that attack foreign substances, infectious microbes and cancer cells through destruction and ingestion) from destroying drug-bearing nanoparticles. They have created a peptide that sneaks drug-bearing nanobeads past the ever-vigilant immune system.

They have developed membrane protein called CD47, which is recognized by macrophages as being safe, and let it pass through. Basically, they give the drug-bearing a badge which your body’s security system recognizes as safe. Biophysicist Dennis Discher, who led the work, says that he was inspired when he saw another group’s work describing the structure of CD47:

“I saw a minimal part of CD47 we could take out and make,” he says. This was the part of CD47 that attaches to a macrophage receptor protein, allowing the macrophage to let the protein, and its cargo, into the cell the macrophage is guarding. The work of Discher and his team is published today in Science.

Neil Barclay of the University of Oxford, UK worked on the project that inspired Discher, and he was quite interested in the results:

“It’s neat,” he says of Discher’s research. “It’s a new way of trying to get the immune system to prevent phagocytosis of drugs or particles.”

While these are merely the early stages of the research, Discher is confident:

“We want to make this accessible and reproducible,” he says.

Via Nature

New nanotechnology will enable earlier cancer diagnosis

Finding ways to diagnose cancer earlier could potentially save millions of lives, improving the chances of survival for many patients. This is why researchers have developed nanoparticles which amplify tumor signals, making them much easier to detect.

Nanotech to the rescue

The new technology was developed by researchers from MIT and it makes biomarker detection much easier; a biomarker, which is short for biological marker is a characteristic that is objectively measured and evaluated as an indicator of normal biological processes – in this case, for detecting tumors. The team was led by Sangeeta Bhatia and they have developed nanoparticles that can find a tumor, and when they do, produce thousands of biomarkers, which can then be easily detected in the patient’s urine.

According to them, the biomarker amplification could also be used to monitor disease progression and responsiveness to treatment, explains Bhatia, the John and Dorothy Wilson Professor of Health Sciences and Technology and Electrical Engineering and Computer Science at MIT.

“There’s a desperate search for biomarkers, for early detection or disease prognosis, or looking at how the body responds to therapy,” says Bhatia, who is also a member of MIT’s David H. Koch Institute for Integrative Cancer Research.

Amplying signals

Cancer cells produce many proteins that are not typically produced by healthy cells. However, the main problem in detecting the disease is that most often, the proteins are so diluted in the blood stream that it’s really hard to pinpoint. A recent study from Stanford University researchers found that even using the best existing biomarkers for ovarian cancer, and the best technology to detect them, it would take 8-10 years to detect an ovarian tumor.

“The cell is making biomarkers, but it has limited production capacity,” Bhatia says. “That’s when we had this ‘aha’ moment: What if you could deliver something that could amplify that signal?”

The research was funded by the National Institutes of Health and the Kathy and Curt Marble Cancer. Research Fund.

Via MIT