Yale U: A new material to unearth mysteries of magnetic fields ~ Helping to Understand ‘Pole Flipping’



Credit: Yale UniversityJourneying to the center of the Earth, a la Jules Verne, won’t be happening anytime soon. A new material made from a liquid metal and magnetic particles, however, could make it much easier for researchers to recreate the powerful forces at the planet’s core.




“We can potentially reproduce some of the phenomena seen in planets and stars with this material,” said Eric Brown, assistant professor of mechanical engineering and materials science at Yale and senior author of a study published Jan. 30 in the journal Physical Review Fluids.

The new material is made from an alloy of indium and gallium (eGaIn) with various particles suspended within it. When flowing, its ability to generate or modify magnetic fields is up to five times greater than that of pure liquid metal. 

That, along with a significant increase in electrical conductivity, means researchers can use the material to study the effects of magnetohydrodynamics (MHD)—the magnetic properties of conductive fluids usually only observable in the cores of planets and stars.

One challenge of suspending particles in liquid metals is that the air oxidizes the skin of the metals, keeping particles on the surface. The researchers got around this by submerging the liquid metal in an acid solution, which removes and prevents oxidation.

“We managed to suspend almost anything we wanted—steel, zinc, nickel, iron—basically anything with a conductivity higher than that of the eGaIn,” said Florian Carle, a postdoctoral associate in Yale’s Department of Mechanical Engineering & Materials Science, and lead author of the paper.

The discovery could hold benefits for geophysics, astrophysics, and other fields that explore the dynamics of the Earth’s magnetic field, which is generated by the liquid metal flowing in the core. 

This magnetic field creates an electrical current inside the Earth and blocks radiation from space. Considering the wide range of the material’s potential applications, the researchers developed a detailed protocol to ensure that other labs could reproduce their results.

One potential use of the material is studying magnetic pole flips, when the Earth’s north and south poles reverse. It doesn’t happen often—on average, flips occur once every few hundred thousand years—but the effects of the geomagnetic switch can be devastating by temporarily lifting the barrier that shields radiation from space. 

Some scientists believe these flips have caused a number of species extinctions on Earth.

With the material, Carle said, researchers can “create a smaller Earth” and explore these phenomena and potentially make better predictions about pole reversals and other effects of the magnetic field. 

Attempts to recreate the Earth’s magnetic field have been attempted in other labs, but with limited success. Most involve the use of highly explosive liquid sodium, which requires very large models.

“People have tried these big flow chambers as large as three meters across, filled with liquid sodium and spinning around like a miniature Earth,” said Brown.

With the material that the Yale researchers have developed, scientists can potentially create models as small as 20 square centimeters to recreate the phenomena of magnetic fields. 
Besides being much easier to work with, the material allows users to tune its viscosity and levels of magnetism to better fit their own research and applications.

“So they might see results that you couldn’t get with liquid sodium, or even observe completely different MHD phenomena,” said Carle.

Because these effects can be created on such a small scale, the material could also lead to the creation of new devices. “You can imagine people coming up with applications that use these MHD phenomena in lab and industrial settings,” Brown said.

Provided by: Yale University

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Stanford University: Researchers Make Wires That Are Just Three Atoms Wide


 

diamondoid-penny-fullresResearchers at Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory have discovered a way to use diamondoids — the smallest possible bits of diamond — to self-assemble atoms, LEGO-style, into the thinnest possible electrical wires, just three atoms wide.

 

Scientists at Stanford University and the US Department of Energy’s SLAC National Accelerator Laboratory have discovered a way to use diamondoids – the smallest possible bits of diamond – to assemble atoms into the thinnest possible electrical wires, just three atoms wide.

By grabbing various types of atoms and putting them together building-block style, the new technique could potentially be used to build tiny wires for a wide range of applications, including fabrics that generate electricity, optoelectronic devices that employ both electricity and light, and superconducting materials that conduct electricity without any loss. The scientists reported their results in Nature Materials.

The animation above shows molecular building blocks joining the tip of a growing nanowire. Each block consists of a diamondoid – the smallest possible bit of diamond – attached to sulfur and copper atoms (yellow and brown spheres). Like LEGO blocks, they only fit together in certain ways that are determined by their size and shape. The copper and sulfur atoms form a conductive wire in the middle, and the diamondoids form an insulating outer shell.

“What we have shown here is that we can make tiny, conductive wires of the smallest possible size that essentially assemble themselves,” said Hao Yan, a Stanford postdoctoral researcher and lead author of the paper. “The process is a simple, one-pot synthesis. You dump the ingredients together and you can get results in half an hour. It’s almost as if the diamondoids know where they want to go.”

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Fuzzy white clusters of nanowires on a lab bench, with a penny for scale.
Image Source – Hao Yan/SIMES; photo by SLAC National Accelerator Laboratory
In the image above, assembled with the help of diamondoids, the microscopic nanowires can be seen with the naked eye because the strong mutual attraction between their diamondoid shells makes them clump together, in this case by the millions. Also, at top right, is an image made with a scanning electron microscope shows nanowire clusters magnified 10,000 times.

 

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There are other methods to get materials to self-assemble, but this is the first one shown to make a nanowire with a solid, crystalline core that has good electronic properties, said study co-author Nicholas Melosh, an associate professor at SLAC and Stanford and investigator with SIMES, the Stanford Institute for Materials and Energy Sciences at SLAC.

Over the past decade, a SIMES research program led by Melosh and SLAC/Stanford Professor Zhi-Xun Shen has found a number of potential uses for the little diamonds, including improving electron microscope images and making tiny electronic gadgets.

The needle-like wires have a semiconducting core – a combination of copper and sulfur known as a chalcogenide – surrounded by the attached diamondoids, which form an insulating shell.

The wires minuscule size is important, Melosh said, because a material that exists in just one or two dimensions – as atomic-scale dots, wires or sheets – can have very different, extraordinary properties compared to the same material made in bulk. The new method allows researchers to assemble those materials with atom-by-atom precision and control.

“You can imagine weaving those into fabrics to generate energy,” Melosh said. “This method gives us a versatile toolkit where we can tinker with a number of ingredients and experimental conditions to create new materials with finely tuned electronic properties and interesting physics.”

 

 

 

Nanotechnology is Changing EVERYTHING … Health Care, Clean Energy, Clean Water, Quantum Computing …


 

 

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“Science is not only the disciple of Reason, but also one of Romance and Passion ~ Stephen B. Hawking

 

 

Nanotechnology is so small it’s measured in billionths of meters, and it is revolutionizing every aspect of our lives … 

The past 70 years have seen the way we live and work transformed by two tiny inventions. The electronic transistor and the microchip are what make all modern electronics possible, and since their development in the 1940s they have been getting smaller. Today, one chip can contain as many as 5 billion transistors. If cars had followed the same development pathway, we would now be able to drive them at 300,000 mph and they would cost just $6.00 (US) each.AmorChem Nanotechnology-300x200

But to keep this progress going we need to be able to create circuits on the extremely small, nanometer scale. A nanometer (nm) is one billionth of a meter and so this kind of engineering involves manipulating individual atoms. We can do this, for example, by firing a beam of electrons at a material, or by vaporizing it and depositing the resulting gaseous atoms layer by layer onto a base.

The real challenge is using such techniques reliably to manufacture working nanoscale devices. The physical properties of matter, such as its melting point, electrical conductivity and chemical reactivity, become very different at the nanoscale, so shrinking a device can affect its performance. If we can master this technology, however, then we have the opportunity to improve not just electronics but all sorts of areas of modern life.

Doctors inside your body

Wearable fitness technology means we can monitor our health by strapping gadgets to ourselves. There are even prototype electronic tattoos that can sense our vital signs. But by scaling down this technology, we could go further by implanting or injecting tiny sensors inside our bodies. This would capture much more detailed information with less hassle to the patient, enabling doctors to personalize their treatment.

The possibilities are endless, ranging from monitoring inflammation and post-surgery recovery to more exotic applications whereby electronic devices actually interfere with our body’s signals for controlling organ function. Although these technologies might sound like a thing of the far future, multi-billion healthcare firms such as GlaxoSmithKline are already working on ways to develop so-called “electroceuticals”.

Sensors, sensors, everywhere

These sensors rely on newly-invented nanomaterials and manufacturing techniques to make them smaller, more complex and more energy efficient. For example, sensors with very fine features can now be printed in large quantities on flexible rolls of plastic at low cost. This opens up the possibility of placing sensors at lots of points over critical infrastructure to constantly check that everything is running correctly. Bridges, aircraft and even nuclear power plants could benefit.

Read More: Nanotechnology cancer treatment tested with ‘astounding’ results

 

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Self-healing structures

If cracks do appear then nanotechnology could play a further role. Changing the structure of materials at the nanoscale can give them some amazing properties – by giving them a texture that repels water, for example. In the future, nanotechnology coatings or additives will even have the potential to allow materials to “heal” when damaged or worn. For example, dispersing nanoparticles throughout a material means that they can migrate to fill in any cracks that appear. This could produce self-healing materials for everything from aircraft cockpits to microelectronics, preventing small fractures from turning into large, more problematic cracks.

Making big data possible

All these sensors will produce more information than we’ve ever had to deal with before – so we’ll need the technology to process it and spot the patterns that will alert us to problems. The same will be true if we want to use the “big data” from traffic sensors to help manage congestion and prevent accidents, or prevent crime by using statistics to more effectively allocate police resources.

Here, nanotechnology is helping to create ultra-dense memory that will allow us to store this wealth of data. But it’s also providing the inspiration for ultra-efficient algorithms for processing, encrypting and communicating data without compromising its reliability. Nature has several examples of big-data processes efficiently being performed in real-time by tiny structures, such as the parts of the eye and ear that turn external signals into information for the brain.

Computer architectures inspired by the brain could also use energy more efficiently and so would struggle less with excess heat – one of the key problems with shrinking electronic devices further.

Renewable Energy Pix

Also Read: Can nanotechnology solve the energy crisis?   …

The late Richard Smalley, often considered to be one of the fathers of nanotechnology following his Nobel Prize-winning work on fullerenes, had a keen interest in energy. In many presentations he would ask the audience to call out what they considered to be the most pressing issues facing humanity. The answers were often similar to those identified in the World Economic Forum’s Global Risks Report, including persistent worries such as disease, clean water, poverty, inequality and access to resources. Smalley would then rearrange the list to put energy at the top and proceed to explain how a happy, healthy world of 9 billion could be achieved if we could only fix the problem of providing cheap and abundant clean energy.

 

Tackling climate change

The fight against climate change means we need new ways to generate and use electricity, and nanotechnology is already playing a role. It has helped create batteries that can store more energy for electric cars and has enabled solar panels to convert more sunlight into electricity.

The common trick in both applications is to use nanotexturing or nanomaterials (for example nanowires or carbon nanotubes) that turn a flat surface into a three-dimensional one with a much greater surface area. This means that there is more space for the reactions that enable energy storage or generation to take place, so the devices operate more efficiently

In the future, nanotechnology could also enable objects to harvest energy from their environment. New nano-materials and concepts are currently being developed that show potential for producing energy from movement, light, variations in temperature, glucose and other sources with high conversion efficiency.

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MIT: Seeking sustainable solutions through Nanotechnology – Engineer’s designs may help purify water, diagnose disease in remote regions of world.

 

 

Graphene Quantum Dots: Introduction and Market News


 

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What are quantum dots?

Quantum dots, or QDs, are semiconductor nanoparticles or nanocrystals, usually in the range of 2-10 nanometers (10-50 atoms) in size. Their small size and high surface-to-volume ratio affects their optical and electronic properties and makes them different from larger particles made of the same materials. Quantum dots confine the motion of conduction band electrons, valence band holes, or excitons (bound pairs of conduction band electrons and valence band holes) in all three spatial directions. Quantum dots are also sometimes referred to as ‘artificial atoms’, a term that emphasizes that they are a single object with bound, discrete electronic states, similarly to naturally occurring atoms or molecules.

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Image: Grapehene Quantum Dots 

Many types of quantum dot are fluorescent – they emit light of specific frequencies if electricity or light is applied to them. These frequencies can be tuned by changing the dots’ size, shape and material, opening the door to diverse applications. Generally speaking, smaller dots appear blue while larger ones tend to be more red. Specific colors also vary depending on the exact composition of the QD.
Applications

Thanks to their highly tunable properties, QDs are attracting interest from various application developers and researchers. Among these potential applications are displays, transistors, solar cells, diode lasers, quantum computing, and medical imaging. Additionally, their small size enables QDs to be suspended in solution, which leads to possible uses in inkjet printing and spin-coating. These processing techniques may result in less-expensive and less time consuming methods of semiconductor fabrication. Quantum dots are considered especially suitable for optical applications, thanks to their ability to emit diverse colors, coupled with their high efficiencies, longer lifetimes and high extinction coefficient.

 

Their small size also means that electrons do not have to travel as far as with larger particles, thus electronic devices can operate faster. Examples of applications that take advantage of these electronic properties include transistors, solar cells, quantum computing, and more. QDs can greatly improve LED screens, offering them higher peak brightness, better colour accuracy, higher color saturation and more. QDs are also very interesting for use in biomedical applications, since their small size allows them to travel in the body, thus making them suitable for applications like medical imaging, biosensors, etc.
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What is graphene?

 

Graphene is a material made of carbon atoms that are bonded together in a repeating pattern of hexagons. Graphene is so thin that it is considered two dimensional. Graphene’s flat honeycomb pattern gives it many extraordinary characteristics, such as being the strongest material in the world, as well as one of the lightest, most conductive and transparent. Graphene has endless potential applications, in almost every industry (like electronics, medicine, aviation and much more).

 

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Graphene structure photo
The single layers of carbon atoms provide the basis for many other materials. Graphite, like the substance found in pencil lead, is formed by stacked graphene. Carbon nanotubes are made of rolled graphene and are used in many emerging applications from sports gear to biomedicine.

 

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Graphene quantum dots

The term graphene quantum dots (GQDs) is usually used to describe miniscule fragments, limited in size, or domains, of single-layer to tens of layers of graphene. GQDs often possess properties like low toxicity, stable photoluminescence, chemical stability and pronounced quantum confinement effect, which make them attractive for biological, opto-electronics, energy and environmental applications.

 

tour-gqds-iii-1206_coal-5-webPhoto: Dr. James M. Tour: Rice University: 

The synthesis of graphene quantum structures, such as graphene quantum dots, has become a popular topic in recent years. While graphene usually does not have a bandgap – which is a problem for many applications – graphene quantum dots do contain a bandgap due to quantum confinement and edge effects, and that bandgap modifies graphene’s carrier behaviors and can lead to versatile applications in optoelectronics. GQDs were also found to have four quantum states at a given energy level, unlike semiconductor quantum dots, which have only two. These additional quantum states, according to researchers, could make GQDs beneficial for quantum computing.
Additional properties of GQDs such as high transparency and high surface area have been proposed for energy and display applications. Because of the large surface area, electrodes using GQDs are applied for capacitors and batteries. Various techniques have been developed to produce GQDs. Top-down methods include solution chemical, microwave, and ultrasonic methods. Bottom-up methods include hydrothermal and electrochemical methods.

 

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Graphene Quantum Dots in the News

Dotz Nano secures first order of graphene quantum dots:

In January 2017, Dotz Nano, a nanotechnology company focused on the development, manufacture and commercialization of graphene quantum dots (GQDs), signed a marketing agreement with Strem Chemicals, a manufacturer and distributor of specialty chemicals headquartered in the U.S.

Strem Chemicals will aim to facilitate sales of Dotz’s GQDs to academic, industrial and government research and development laboratories, as well as commercial businesses using GQDs for research purposes.

 
Fuji Pigment announces graphene and carbon QD manufacturing process:

In April 2016, Fuji Pigment announced the development of a large-scale manufacturing process for carbon and graphene quantum dots (QDs). Fuji Pigment stated that its toxic-metal-free QDs exhibit a high light-emitting quantum efficiency and stability comparable to the toxic metal-based quantum dots.

 
Samsung developed graphene quantum dots based flash memory devices:

In June 2014, researchers from Samsung Electronics (and Korea’s Kyung Hee University) developed flash devices based on graphene quantum dots (GQDs). The performance of such a device is promising, with an electron density that is comparable to semiconductor and metal nanocrystal based memories. Those flash memory can also be made flexible and transparent.

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Read More: Graphene ‘artificial atom’ opens door to quantum computing

The world’s fastest mode of transport could soon be here 



Believe the Hyperloop … passengers could soon hurtle between Asia and Europe at 760 mph Image: REUTERS/Steve Marcus

Imagine if it only took a day for products to travel over land from China to Germany.
It could soon be a reality, if Russia goes ahead with a plan to introduce a new fast-speed pipeline called the Hyperloop. 
Much as oil and gas travel through pipes, cargo and passengers may soon find themselves shooting through pneumatic tubes at speeds of up to 760 miles per hour.

Tech entrepreneur Elon Musk once envisioned a tube transportation project that could move passengers and cargo from San Francisco to Los Angeles in 30 minutes. 
Two companies – Hyperloop One (formerly Hyperloop Technologies) and Hyperloop Transportation Technologies (HTT) – are now exploring Musk’s idea with a view to building the first transport-ready tube by 2020. 

According to the chief executive officer of Hyperloop One, feasibility studies have been launched not only in Russia but also in the United Arab Emirates, Finland, the United Kingdom and the United States.

Hyperloop One has joined forces with the city of Moscow and Summa Group, a local investment and construction conglomerate, to bring the vacuum tube to Russia.
       

So what are the benefits?




Air transportation is fast but costly, so most cargo is shipped by sea. To travel by sea between Asia and Europe can take around 30 days – and that’s without considering overland transport to and from the ports. Rail transportation takes nearly half that.

The southern rail route between China and Russia is 6,213 miles long and takes 12 days, while an 8,077-mile northern rail route through Russia takes 16 days. Can the Hyperloop ultimately provide the quickest transportation option, at affordable cost?

Construction costs are important to consider. Building and operating a Hyperloop is estimated to be in a similar range as building and operating high-speed rail infrastructure and trains. 

The construction cost for high-speed rail lines, such as the Haikou-Sanya line in China and Madrid-Albacete line in Spain, come in at about US$15 million a mile.

U of Michigan: New metamaterial can switch from hard to soft—and back again



Topological transitions of a deformed kagome lattice by uniform soft twisting. Credit: Nature Communications (2017). DOI: 10.1038/ncomms14201

When a material is made, you typically cannot change whether that material is hard or soft. But a group of University of Michigan researchers have developed a new way to design a “metamaterial” that allows the material to switch between being hard and soft without damaging or altering the material itself.

 

Metamaterials are man-made materials that get their properties—in this case, whether a material is hard or soft—from the way the material is constructed rather than the material that constructs it. This allows researchers to manipulate a metamaterial’s structure in order to make the material exhibit a certain property.

In the group’s study, published in the journal Nature Communications, the U-M researchers discovered a way to compose a metamaterial that can be easily manipulated to increase the stiffness of its surface by orders of magnitude—the difference between rubber and steel.

Since these properties are “topologically protected,” meaning that the material’s properties come from its total structure, they’re easily maintained even as the material shifts repeatedly between its hard and soft states.

“The novel aspect of this metamaterial is that its surface can change between hard and soft,” said Xiaoming Mao, assistant professor of physics. “Usually, it’s hard to change the stiffness of a traditional material. It’s either hard or soft after the material is made.”

For example, a dental filling cannot be changed after the dentist has set the filling without causing stress, either by drilling or grinding, to the original filling. A guitar string cannot be tightened without putting stress on the string itself, according to Mao.

Mao says the way an object comes in contact with the edge of the metamaterial changes the geometry of the material’s structure, and therefore how the material responds to stress at the edge. But metamaterial’s topological protection allows the inside of the metamaterial remains damage free.

The material could one day be used to build cars or rocket launch systems. In cars, the material could help absorb impacts from a crash.

“When you’re driving a car, you want the car to be stiff and to support a load,” Mao said. “During a collision, you want components to become softer to absorb the energy from the collision and protect the passenger in the car.”

The researchers also suggest the material could be used to make bicycle tires that could self-adjust to ride more easily on soft surfaces such as sand, or to make damage-resistant, reusable rockets.

 

More information: D. Zeb Rocklin et al. Transformable topological mechanical metamaterials, Nature Communications (2017). DOI: 10.1038/ncomms14201

Provided by: University of Michigan

Rice University: Antioxidant compounds mimic effective graphene agents, show potential for therapies 


PEG-PDI, which incorporates a compound long used as a red dye, changes to greenish-blue with the addition of potassium superoxide as it converts the superoxide to dioxygen. Adding more further quenches the reactive oxygen species superoxide, turning the solution purple. Adding hydrogen peroxide in the last step clarifies the liquid, showing that a build-up of excess hydrogen peroxide can deactivate the structure. PEG-PDI, created at Rice University, shows potential as a biological antioxidant. Credit: Tour Group/Rice University

Treated particles of graphene derived from carbon nanotubes have demonstrated remarkable potential as life-saving antioxidants, but as small as they are, something even smaller had to be created to figure out why they work so well.

 

Researchers at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston (UTHealth) and Baylor College of Medicine created single-molecule compounds that also quench damaging reactive oxygen species (ROS) but are far easier to analyze using standard scientific tools. The molecules may become the basis for new antioxidant therapies in their own right.

The research appears in the American Chemical Society journal ACS Nano.

The original compounds are hydrophilic carbon clusters functionalized with polyethylene glycol, known as PEG-HCCs and created by Rice and Baylor scientists five years ago. The particles help neutralize ROS molecules overexpressed by the body’s cells in response to an injury before they damage cells or cause mutations.

PEG-HCCs show promise for treating cancer, rebooting blood flow in the brain after traumatic injury and controlling chronic diseases.

The new particles, called PEG-PDI, consist of polyethylene glycol and perylene diimide, a compound used as a dye, the color in red car paint and in solar cells for its light-absorbing properties. Their ability to accept electrons from other molecules makes them functionally similar to PEG-HCCs.

They’re close enough to serve as an analog for experiments, according to Rice chemist James Tour, who led the study with University of Texas biochemist Ah-Lim Tsai.

The researchers wrote that the molecule is not only the first example of a small molecular analogue of PEG-HCCs, but also represents the first successful isolation of a PDI radical anion as a single crystal, which allows its structure to be captured with X-ray crystallography.

“This allows us to see the structure of these active particles,” Tour said. “We can get a view of every atom and the distances between them, and get a lot of information about how these molecules quench destructive oxidants in biological tissue.

“Lots of people get crystal structures for stable compounds, but this is a transient intermediate during a catalytic reaction,” he said. “To be able to crystallize a reactive intermediate like that is amazing.”

Antioxidant compounds mimic effective graphene agents, show potential for therapies 





The crystal structure of PEG-PDI is achieved using cobaltocene as a reducing agent and omitting solvents and hydrogen atoms for clarity. Carbon atoms are gray, nitrogens are blue, oxygens red and cobalts purple. The molecules created by scientists at Rice University, the McGovern Medical School at the University of Texas Health Science Center at Houston and Baylor College of Medicine are efficient antioxidants and help scientists understand how larger nanoparticles quench damaging reactive oxygen species in the body. Credit: Tour Group

PEG-HCCs are about 3 nanometers wide and 30 to 40 nanometers long. By comparison, much simpler PEG-PDI molecules are less than a nanometer in width and length.

 

PEG-PDI molecules are true mimics of superoxide dismutase enzymes, protective antioxidants that break down toxic superoxide radicals into harmless molecular oxygen and hydrogen peroxide. The molecules pull electrons from unstable ROS and catalyze their transformation into less-reactive species.

Testing the PEG-PDI molecules can be as simple as putting them in a solution that contains reactive oxygen species molecules like potassium superoxide and watching the solution change color. Further characterization with electron paramagnetic resonance spectroscopy was more complicated, but the fact that it’s even possible makes them powerful tools in resolving mechanistic details, the researchers said.

Tour said adding polyethylene glycol makes the molecules soluble and also increases the amount of time they remain in the bloodstream. “Without PEG, they just go right out of the system through the kidneys,” he said.

When the PEG groups are added, the molecules circulate longer and continue to catalyze reactions.

He said PEG-PDI is just as effective as PEG-HCCs if measured by weight. “Because they have so much more surface area, PEG-HCC particles probably catalyze more parallel reactions per particle,” Tour said. “But if you compare them with PEG-PDI by weight, they are quite similar in total catalytic activity.”

Understanding the structure of PEG-PDI should allow researchers to customize the molecule for applications. “We should have a tremendous ability to modify the molecule’s structure,” he said. “We can add anything we want, exactly where we want, for specific therapies.”

The researchers said PEG-PDI may also be efficient metal- and protein-free catalysts for oxygen reduction reactions used in industry and essential to fuel cells. They are intrinsically more stable than enzymes and can function in much a wider pH range, Tsai said.

Co-author Thomas Kent, a professor of neurology at Baylor who has worked on the project from the start, noted small molecules have a better chance to get on the fast track to approval for therapy by the Food and Drug Administration than nanotube-based agents.
“A small molecule that is not derived from larger nanomaterial may have a better chance of approval to use in humans, assuming it is safe and effective,” he said.

Tour said PEG-PDI serves as a precise model for other graphene derivatives like graphene oxide and permits a more detailed study of graphene-based nanomaterials.

“Making nanomaterials smaller, from well-defined molecules, permits 150 years of synthetic chemistry methods to address the mechanistic questions within nanotechnology,” he said.

 

More information: Almaz S. Jalilov et al. Perylene Diimide as a Precise Graphene-Like Superoxide Dismutase Mimetic, ACS Nano (2017). DOI: 10.1021/acsnano.6b08211

Provided by: Rice University

Read Genesis Nanotech Online ~ Stanford team demonstrates a graphene-based thermal-to-electricity conversion technology + More News


 

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New class of materials could revolutionize biomedical, alternative energy industries: Cancer Therapies ~ Low Cost Solar Cells


poly-new-material-170125145735_1_540x360Polyarylboranes are a new class of materials that could be used in biomedical, personal computer and alternative energy applications. Credit: Mark Lee

Polyhedral boranes, or clusters of boron atoms bound to hydrogen atoms, are transforming the biomedical industry. These humanmade materials have become the basis for the creation of cancer therapies, enhanced drug delivery and new contrast agents needed for radioimaging and diagnosis. Now, a researcher at the University of Missouri has discovered an entirely new class of materials based on boranes that might have widespread potential applications, including improved diagnostic tools for cancer and other diseases as well as low-cost solar energy cells.

Mark Lee Jr., an assistant professor of chemistry in the MU College of Arts and Science, discovered the new class of hybrid nanomolecules by combining boranes with carbon and hydrogen. Boranes are chemically stable and have been tested at extreme heat of up to 900 degrees Celsius or 1,652 degrees Fahrenheit. It is the thermodynamic stability these molecules exhibit that make them non-toxic and attractive to the biomedical, personal computer and alternative energy industries.

“Despite their stability, we discovered that boranes react with aromatic hydrocarbons at mildly elevated temperatures, replacing many of the hydrogen atoms with rings of carbon,” Lee said. “Polyhedral boranes are incredibly inert, and it is their reaction with aromatic hydrocarbons like benzene that will make them more useful.”

Lee also showed that the attached hydrocarbons communicate with the borane core.

“The result is that these new materials are highly fluorescent in solution,” Lee said. “Fluorescence can be used in applications such as bio-imaging agents and organic light-emitting diodes like those in phones or television screens. Solar cells and other alternative energy sources also use fluorescence, so there are many practical uses for these new materials.”

Lee’s discovery is based on decades of research. Lee’s doctoral advisor, M. Frederick Hawthorne, MU Curators Distinguished Professor of Chemistry and Radiology, discovered several of these boron clusters as early as 1959. In the past, boranes have been used for medical imaging, drug delivery, neutron-based treatments for cancer and rheumatoid arthritis, catalysis and molecular motors. Borane researchers also have created a specific type of nanoparticle that selectively targets cancer cells.

“When these molecules were discovered years ago we never could have imagined that they would lead to so many advancements in biomedicine,” Lee said. “Now, my group is expanding on the scope of this new chemistry to examine the possibilities. These new materials, called ‘polyarylboranes,’ are much broader than we imagined, and now my students are systematically exploring the use of these new clusters.”


Story Source:

Materials provided by University of Missouri-Columbia. Note: Content may be edited for style and length.


Journal Reference:

  1. Mark W. Lee. Catalyst-Free Polyhydroboration of Dodecaborate Yields Highly Photoluminescent Ionic Polyarylated Clusters. Angewandte Chemie, 2017; 129 (1): 144 DOI: 10.1002/ange.201608249

New sensors can detect single protein molecules: Modified carbon nanotubes could be used to track protein production by individual cells.


mit-protein-detection_0MIT chemical engineers have developed arrays of carbon nanotube sensors that can detect single protein molecules as they are secreted from cells. Courtesy of the researchers

For the first time, MIT engineers have designed sensors that can detect single protein molecules as they are secreted by cells or even a single cell.

These sensors, which consist of chemically modified carbon nanotubes, could help scientists with any application that requires detecting very small amounts of protein, such as tracking viral infection, monitoring cells’ manufacturing of useful proteins, or revealing food contamination, the researchers say.

“We hope to use sensor arrays like this to look for the ‘needle in a haystack,’” says Michael Strano, the Carbon P. Dubbs Professor of Chemical Engineering at MIT. “These arrays represent the most sensitive molecular sensing platforms that we have available to us technologically. You can functionalize them so you can see the stochastic fluctuations of single molecules binding to them.”

Strano is the senior author of a Jan. 23 Nature Nanotechnology paper describing the new sensors. The paper’s lead author is Markita Landry, a former MIT postdoc who is now an assistant professor at the University of California at Berkeley.

Other MIT authors are research scientist Hiroki Ando, former graduate student Allen Chen, postdocs Jicong Cao and Juyao Dong, and associate professor of electrical engineering and computer science Timothy Lu. Vishal Kottadiel of Harvard University and Linda Chio and Darwin Yang of the University of California at Berkeley are also authors.

No detection limit

Strano’s lab has previously developed sensors that can detect many types of molecules, all based on modifications of carbon nanotubes — hollow, nanometer-thick cylinders made of carbon that naturally fluoresce when exposed to laser light. To turn the nanotubes into sensors, Strano’s lab coats them with DNA, proteins, or other molecules that can bind to a specific target. When the target is bound, the nanotubes’ fluorescence changes in a measurable way.

In this case, the researchers used chains of DNA called aptamers to coat the carbon nanotubes. Previous efforts to use DNA aptamers have been stymied because of the difficulty of getting the aptamer to stick to the nanotube while maintaining the configuration it needs to bind to its target.

Landry overcame this challenge by adding a “spacer” sequence between the section of the aptamer that attaches to the nanotube and the section that binds to the target, allowing each region the freedom to perform its own function. The researchers successfully demonstrated sensors for a signaling protein called RAP1 and a viral protein called HIV1 integrase, and they believe the approach should work for many other proteins.

To monitor protein production of single cells, the researchers set up an array of the sensors on a microscope slide. When a single bacterial, human, or yeast cell is placed on the array, the sensors can detect whenever the cell secretes a molecule of the target protein.

“Nanosensor arrays like this have no detection limit,” Strano says. “They can see down to single molecules.”

However, there is a tradeoff — the fewer molecules there are, the longer it takes to sense them. As the molecule becomes more scarce, detection can take an infinite amount of time, Strano says.

“The new study by Strano and co-workers proposes an exciting new approach to detect proteins down to the single molecule level,” says Robert Hurt, a professor of engineering at Brown University who was not involved in the research. “The work pushes the forefront in single-protein detection and may allow researchers to see important, real-time molecular events at the single-cell level, such as protein release during cell division.”

Useful tools

The sensor arrays could be useful for many different applications, the researchers say.

“This platform will open a new path to detect trace amounts of proteins secreted by microorganisms,” Dong says. “It will advance biological research [on] the generation of signal molecules, as well as the biopharmaceutical industry’s [efforts to monitor] microorganism health and product quality.”

In the pharmaceutical realm, these sensors could be used to test cells engineered to help treat disease. Many researchers are now working on an approach where doctors would remove a patient’s own cells, engineer them to express a therapeutic protein, and place them back in the patient.

“We think these nanosensor arrays are going to be useful tools for measuring these precious cells and making sure that they’re performing the way that you want them to,” Strano says.

He says researchers could also use the arrays to study viral infection, neurotransmitter function, and a phenomenon called quorum sensing, which allows bacteria to communicate with each other to coordinate their gene expression.