Researchers find thermal limits of advanced nanomaterials

Boron nitride nanotube material in a crucible for heating at Florida State University's High-Performance Materials Institute.
Photo Credit: Mark Wallheiser/FAMU-FSU Engineering

A team of FAMU-FSU College of Engineering researchers at the High-Performance Materials Institute is exploring the thermal limits of advanced nanomaterials, work that could have a direct impact on medicine delivery systems, electronics, space travel and other applications.

The research team, led by Assistant Professor in Industrial and Manufacturing Engineering Rebekah Sweat, completed the first-ever study on how purified boron nitride nanotubes remain stable in extreme temperatures in inert environments.

Their work was published in the journal Applied Nano Materials.

Boron nitride nanotubes, or BNNTs, are stronger and more resistant to high temperatures than carbon nanotubes. Like their carbon cousins, they are structures measured by the nanometer — a length equal to one-billionth of a meter.

Packaged DNA: MLU researchers develop new method to promote bone growth

Image Credit: Sangharsh Lohakare

DNA can help to stimulate bone healing in a localized and targeted manner, for example after a complicated fracture or after severe tissue loss following surgery. This has been demonstrated by researchers at Martin Luther University Halle-Wittenberg (MLU), the University of Leipzig, the University of Aveiro (Portugal) and the Fraunhofer Institute for Microstructure of Materials and Systems IMWS in Halle. They have developed a new process in which they coat implant materials with a gene-activated biomaterial that induces stem cells to produce bone tissue. Their findings were published in the renowned journal Advanced Healthcare Materials.

Bones are a fascinating example of the body’s ability to regenerate. They are able to regain full functionality - even after a fracture - thanks to their ability to form new, resilient tissue at the fracture site. "However, when it comes to complicated fractures or major tissue loss, even a bone’s self-healing power is insufficient," explains Professor Thomas Groth, head of the Biomedical Materials research group at MLU’s Institute of Pharmacy. "In such cases, implants are needed to stabilize the bone, replace parts of joints, or bridge larger defects with degradable materials." The success of such implants depends largely on how well they are incorporated into the bone. Increased efforts have been made in recent years to support this process by coating implants with bioactive materials to activate bone cells and mesenchymal stem cells. 

Molecular machines could treat fungal infections

Schematic representation of the mechanisms by which light-activated molecular machines kill fungi. Molecular machines bind to fungal mitochondria, decreasing adenosine triphosphate (ATP) production and impairing the function of energy-dependent transporters that control the movement of ions, such as calcium. This leads to the influx of water, which causes the organelles to swell and eventually the cells to burst.
Image Credit: Tour Group/Rice University

That stubborn athlete’s foot infection an estimated 70% of people get at some point in their life could become much easier to get rid of thanks to nanoscale drills activated by visible light.

Proven effective against antibiotic-resistant infectious bacteria and cancer cells, the molecular machines developed by Rice University chemist James Tour and collaborators are just as good at combating infectious fungi, according to a new study published in Advanced Science.

Based on the work of Nobel laureate Bernard Feringa, the Tour group’s molecular machines are nanoscale compounds whose paddlelike chain of atoms moves in a single direction when exposed to visible light. This causes a drilling motion that allows the machines to bore into the surface of cells, killing them.

New type of solar cell is being tested in space

Magnus Borgström Professor, Solid State Physics Lund University
Photo Credit: Lund University

Physics researchers at Lund University in Sweden recently succeeded in constructing small solar radiation-collecting antennas – nanowires – using three different materials that are a better match for the solar spectrum compared with today’s silicon solar cells. As the nanowires are light and require little material per unit of area, they are now to be installed for tests on satellites, which are powered by solar cells and where efficiency, in combination with low weight, is the most important factor. The new solar cells were sent into space a few days ago.

A group of nanoengineering researchers at Lund University working on solar cells made a breakthrough last year when they succeeded in building photovoltaic nanowires with three different band gaps. This, in other words, means that one and the same nanowire consists of three different materials that react to different parts of solar light. The results have been published in Materials Today Energy and subsequently in more detail in Nano Research.

“The big challenge was to get the current to transfer between the materials. It took more than ten years, but it worked in the end,” says Magnus Borgström, professor of solid-state physics, who wrote the articles with the then doctoral student Lukas Hrachowina.

Targeting cancer with a multidrug nanoparticle

MIT chemists designed a bottlebrush-shaped nanoparticle that can be loaded with multiple drugs, in ratios that can be easily controlled.
Illustration Credit: Courtesy of the researchers. Edited by MIT News.

Treating cancer with combinations of drugs can be more effective than using a single drug. However, figuring out the optimal combination of drugs, and making sure that all of the drugs reach the right place, can be challenging.

To help address those challenges, MIT chemists have designed a bottlebrush-shaped nanoparticle that can be loaded with multiple drugs, in ratios that can be easily controlled. Using these particles, the researchers were able to calculate and then deliver the optimal ratio of three cancer drugs used to treat multiple myeloma.

“There’s a lot of interest in finding synergistic combination therapies for cancer, meaning that they leverage some underlying mechanism of the cancer cell that allows them to kill more effectively, but oftentimes we don’t know what that right ratio will be,” says Jeremiah Johnson, an MIT professor of chemistry and one of the senior authors of the study.

Scientists Suggest New Approach to Targeted Treatment of Bacterial Infections

Photo Source: Ural Federal University

It is based on the nanosystem with polyoxometalate

Chemists from the Ural Federal University have proposed a new approach to targeted treatment of affected areas of the human body, in particular, bacterial infections. It is based on a nanosystem, the core of which is polyoxometalate (containing molybdenum and iron). A broad-spectrum antibiotic, tetracycline, is attached to the surface of the polyoxometalate. This approach makes it possible to fight bacteria more effectively by targeting them. The results of the study are published in the journal Inorganics.

"The polyoxometalate ion is a charged nanoparticle that can be used as a base. It is very small - 2.5 nanometers. This allows it to easily penetrate cells and the walls of blood vessels. Drugs and additional substances (vector molecules) can be "planted" on it to help the system reach a specific affected organ. In this case, the drug is distributed less throughout the rest of the body. This reduces side effects, especially of highly toxic drugs," explains Margarita Tonkushina, a Researcher at the Section of Chemical Material Science and the Laboratory of Functional Design of Nanoclusters of Polyoxometalates at UrFU.

New method for designing tiny 3D materials could make fuel cells more efficient

Authors of the study Professor Richard Tilley and Dr Lucy Gloag.
Photo Credit: UNSW Sydney / Courtesy of the researchers 

Researchers have developed an innovative technique for creating nanoscale materials with unique chemical and physical properties.

Scientists from UNSW Sydney have demonstrated a novel technique for creating tiny 3D materials that could eventually make fuel cells like hydrogen batteries cheaper and more sustainable.

In the study published in Science Advances, researchers from the School of Chemistry at UNSW Science show it’s possible to sequentially ‘grow’ interconnected hierarchical structures in 3D at the nanoscale which have unique chemical and physical properties to support energy conversion reactions.

In chemistry, hierarchical structures are configurations of units like molecules within an organization of other units that themselves may be ordered. Similar phenomena can be seen in the natural world, like in flower petals and tree branches. But where these structures have extraordinary potential is at a level beyond the visibility of the human eye – at the nanoscale.

Highly accurate test for common respiratory viruses uses DNA as ‘bait’

Doctor examining a patient
Photo Credit: Thirdman

The test uses DNA ‘nanobait’ to detect the most common respiratory viruses – including influenza, rhinovirus, RSV and COVID-19 – at the same time. In comparison, PCR (polymerase chain reaction) tests, while highly specific and highly accurate, can only test for a single virus at a time and take several hours to return a result.

While many common respiratory viruses have similar symptoms, they require different treatments. By testing for multiple viruses at once, the researchers say their test will ensure patients get the right treatment quickly and could also reduce the unwarranted use of antibiotics.

In addition, the tests can be used in any setting, and can be easily modified to detect different bacteria and viruses, including potential new variants of SARS-CoV-2, the virus which causes COVID-19. The results are reported in the journal Nature Nanotechnology.

The winter cold, flu and RSV season has arrived in the northern hemisphere, and healthcare workers must make quick decisions about treatment when patients show up in their hospital or clinic.

Scientists Have Figured Out How to Use Silicone to Protect against Radiation

Scientists plan to investigate a broader set of materials that can attenuate radiation.
Photo Credit: Anastasia Farafontova

An international team of scientists has developed a material that can be used in the future as radiation protection against gamma radiation, in particular, it can be used to create radiation protection for Nuclear Power Station workers. The new material is based on silicone using zinc oxide nano powder additions. The results of research on the new material and its properties have been published in the journal Optical Materials. Physicists from Russia (Ural Federal University), Jordan, and Turkey took part in the work.

"Gamma radiation is widespread in the health care, food and aerospace industries. Excessive exposure can be harmful to human health. Gamma radiation is now attenuated or absorbed using lead, concrete, lead-oxide, tungsten, or tin-based materials. These protective materials are not always convenient to use as protection against gamma rays. In addition, they are expensive, too heavy and highly toxic to humans and the environment. This is why it is important to find new materials and optimize their composition for radiation protection, which will ensure human and environmental safety," says Oleg Tashlykov, Associate Professor at the Department of Nuclear Power Plants and Renewable Energy Sources at UrFU.

Princeton chemists create quantum dots at room temp using lab-designed protein

Nature uses 20 canonical amino acids as building blocks to make proteins, combining their sequences to create complex molecules that perform biological functions.

But what happens with the sequences not selected by nature? And what possibilities lie in constructing entirely new sequences to make novel, or de novo, proteins bearing little resemblance to anything in nature?

That’s the terrain where Michael Hecht, professor of chemistry, works with his research group. And recently, their curiosity for designing their own sequences paid off.

They discovered the first known de novo (newly created) protein that catalyzes, or drives, the synthesis of quantum dots. Quantum dots are fluorescent nanocrystals used in electronic applications from LED screens to solar panels.

Their work opens the door to making nanomaterials in a more sustainable way by demonstrating that protein sequences not derived from nature can be used to synthesize functional materials — with pronounced benefits to the environment.

Say Hello to the Toughest Material on Earth

Microscopy-generated images showing the path of a fracture and accompanying crystal structure deformation in the CrCoNi alloy at nanometer scale during stress testing at 20 kelvin (-424 F). The fracture is propagating from left to right.
Image Credit: Robert Ritchie/Berkeley Lab

Scientists have measured the highest toughness ever recorded, of any material, while investigating a metallic alloy made of chromium, cobalt, and nickel (CrCoNi). Not only is the metal extremely ductile – which, in materials science, means highly malleable – and impressively strong (meaning it resists permanent deformation), its strength and ductility improve as it gets colder. This runs counter to most other materials in existence.

The team, led by researchers from Lawrence Berkeley National Laboratory (Berkeley Lab) and Oak Ridge National Laboratory, published a study describing their record-breaking findings in Science. “When you design structural materials, you want them to be strong but also ductile and resistant to fracture,” said project co-lead Easo George, the Governor’s Chair for Advanced Alloy Theory and Development at ORNL and the University of Tennessee. “Typically, it’s a compromise between these properties. But this material is both, and instead of becoming brittle at low temperatures, it gets tougher.”

CrCoNi is a subset of a class of metals called high entropy alloys (HEAs). All the alloys in use today contain a high proportion of one element with lower amounts of additional elements added, but HEAs are made of an equal mix of each constituent element. These balanced atomic recipes appear to bestow some of these materials with an extraordinarily high combination of strength and ductility when stressed, which together make up what is termed “toughness.” HEAs have been a hot area of research since they were first developed about 20 years ago, but the technology required to push the materials to their limits in extreme tests was not available until recently.

Unexpected speed-dependent friction

Surprisingly, the friction between the tip of an atomic force microscope and the Moiré superstructures depends on the speed at which the tip is moved across the surface.
Illustration Credit: Department of Physics and Scixel

Due to their low-friction properties, materials consisting of single atomic layers are of great interest for applications where the aim is to reduce friction — such as hard disks or moving components for satellites or space telescopes. One such example is graphene, which consists of a single layer of carbon atoms in a honeycomb arrangement and is being examined with a view to potential use as a lubricating layer. Indeed, previous studies have shown that a graphene ribbon can be moved across a gold surface with almost no friction.

Surprising results with a rough surface

If graphene is applied to a platinum surface, it has a significant impact on the measurable friction forces. Now, physicists from the University of Basel and Tel Aviv University have reported in the journal Nano Letters that, in this instance, the friction depends on the speed at which the tip of an atomic force microscope (*AFM) is moved across the surface. This finding is surprising because friction does not depend on speed according to Coulomb’s law, which applies in the macro world.

Positively charged nanomaterials treat obesity anywhere you want

Illustration of depot-specific targeting of fat by cationic nanomaterials
Illustration Credit: Nicoletta Barolini/Columbia University

Researchers have long been working on how to treat obesity, a serious condition that can lead to hypertension, diabetes, chronic inflammation, and cardiovascular diseases. Studies have also revealed a strong correlation of obesity and cancer--recent data show that smoking, drinking alcohol, and obesity are the biggest contributors to cancer worldwide.

The development of fat cells, which are produced from a tiny fibroblast-like progenitor, not only activates the fat cells’ specific genes but also grows them by storing more lipids (adipocytes and adipose tissue). In fact, lipid storage is the defining function of a fat cell. But the storage of too much lipid can make fat cells unhealthy and lead to obesity.

Challenges in targeting fat cells

The ability to target fat cells and safely uncouple unhealthy fat formation from healthy fat metabolism would be the answer to many peoples’ prayers. A major challenge in obesity treatment is that fat tissue, which is not continuous in the body but is found piece by piece in “depots,” has been difficult to target in a depot-specific manner, pinpointed at the exact location.

There are two main kinds of fat: visceral fat, internal tissues that surround the stomach, liver, and intestines, and subcutaneous fat, found under the skin anywhere in the body. Visceral fat produces potbellies; subcutaneous fat can create chin jowls, arm fat, etc. To date, there has been no way to specifically treat visceral adipose tissue. And current treatments for subcutaneous fat like liposuction are invasive and destructive.

Fertilizing the Ocean to Store Carbon Dioxide

Seeding the oceans with nano-scale fertilizers could create a much-needed, substantial carbon sink.
  Illustration Credit: Stephanie King | Pacific Northwest National Laboratory

The urgent need to remove excess carbon dioxide from Earth’s environment could include enlisting some of our planet’s smallest inhabitants, according to an international research team led by Michael Hochella of the Department of Energy’s Pacific Northwest National Laboratory.

Hochella and his colleagues examined the scientific evidence for seeding the oceans with iron-rich engineered fertilizer particles near ocean plankton. The goal would be to feed phytoplankton, microscopic plants that are a key part of the ocean ecosystem, to encourage growth and carbon dioxide (CO2) uptake. The analysis article appears in the journal Nature Nanotechnology.

“The idea is to augment existing processes,” said Hochella, a Laboratory fellow at Pacific Northwest National Laboratory. “Humans have fertilized the land to grow crops for centuries. We can learn to fertilize the oceans responsibly.”

Organizing nanoparticles into pinwheel shapes offers new twist on engineered materials

Jiahui Li, left, Shan Zhou and professor Qian Chen show off an electron micrograph image of their new pinwheel lattice structure developed to help engineers build new materials with unique optical, magnetic, electronic and catalytic properties. 
Photo Credit: Fred Zwicky

Researchers have developed a new strategy to help build materials with unique optical, magnetic, electronic and catalytic properties. These pinwheel-shaped structures self-assemble from nanoparticles and exhibit a characteristic called chirality – one of nature’s strategies to build complexity into structures at all scales, from molecules to galaxies.

Nature is rich with examples of chirality – DNA, organic molecules and even human hands. In general, chirality can be seen in objects that can have more than one spatial arrangement. For example, chirality in molecules might present itself as two strings of atoms that have the same composition, but each having a “twist” to the left or right in their spatial orientations, the researchers said.

The new study, led by Qian Chen, a professor of materials science and engineering at the University of Illinois Urbana-Champaign, and Nicholas A. Kotov, a professor chemical engineering at the University of Michigan, extends chirality into lattices assembled from nanoparticle building blocks to create new metamaterials – materials designed to interact with their surroundings to perform specific functions.

The study is published in the journal Nature.

Researchers build long-sought nanoparticle structure, opening door to special properties

Theoretical physicist Alex Travesset uses computer models, equations and scientific figures to explain how nanostructures assemble.
Photo Credit: Christopher Gannon/Iowa State University.

Alex Travesset doesn’t have a shiny research lab filled with the latest instruments that probe new nanomaterials and measure their special properties.

No, his theoretical work explaining what’s happening inside those new nanomaterials is all about computer models, equations and figures. And so, when he joins a project, the Iowa State University professor of physics and astronomy who’s also affiliated with the U.S. Department of Energy’s Ames National Laboratory might contribute many dense pages showing how nanoparticles assemble.

Case in point: Travesset’s “Chiral Tetrahedra” calculations and illustrations that are part of a research paper just published by the journal Nature. Those calculations show how controlled evaporation of a solution containing tetrahedron-shaped gold nanoparticles on a solid silicon substrate can assemble into a pinwheel-shaped, two-layered structure.

It turns out the nanostructure is chiral, meaning it’s not identical to its mirror image. (The classic example is a hand and its reflection. The thumbs end up on opposite sides and so one hand can’t be superimposed on the other. That’s chirality.)

Can a new technique for capturing ‘hot’ electrons make solar cells more efficient?

A scanning tunnelling microscope is used to study the dynamics of hot electrons through single molecule manipulation.
Photo Credit: Adrian Hooper

A new way of extracting quantitative information from state-of-the-art single molecule experiments has been developed by physicists at the University of Bath. Using this quantitative information, the researchers will be able to probe the ultra-fast physics of ‘hot’ electrons on surfaces – the same physics that governs and limits the efficacy of silicon-based solar cells.

Solar cells work by converting light into electrons, whose energy can be collected and harvested. A hot solar cell is a novel type of cell that converts sunlight to electricity more efficiently than conventional solar cells. However, the efficiency of this process is limited by the creation of energetic, or ‘hot’, electrons that are extremely short lived and lose most of their energy to their surrounding within the first few femtoseconds of their creation (1 femtosecond equals 1/1,000,000,000,000,000 of a second).

The ultra-short lifetime of hot electrons and the corresponding short distance they can travel mean probing and influencing the properties of hot electrons is experimentally challenging. To date, there have been a few techniques capable of circumventing these challenges, but none has proven capable of spatial resolution – meaning, they can’t tell us about the crucial connection between a material’s atomic structure and the dynamics of hot electrons within that material.

Lab discovery leads UAH researchers to a simple, cost-effective electricity generator

Dr. Moonhyung Jang, left, operates the generator to light an LED display as Dr. Gang Wang looks on in the Adaptive Structures Laboratory. 
Photo Credit: Michael Mercier | University of Alabama in Huntsville

A bit of laboratory serendipity led University of Alabama in Huntsville (UAH) researchers to a simple mechanical way to generate electricity to operate electronic devices, says a paper they have published in the journal ACS Omega.

Triboelectric nanogenerators use multiple layers of different materials to generate electricity when pressed. While testing a triboelectric nanogenerator in the Adaptive Structures Laboratory of Dr. Gang Wang at UAH, a part of the University of Alabama System, postdoctoral research assistant Dr. Moonhyung Jang observed something unusual.

“During a finger-tapping test performed by Dr. Jang, a Scotch tape was introduced on the top to prevent electric shock,” says Dr. Wang, an associate professor of mechanical and aerospace engineering and the project’s principal investigator.

“An unexpectedly high voltage was observed. After a careful investigation, we figured out that the tape layer is the reason to cause this,” Dr. Wang says. “This led to our invention that introduces tacky materials to improve the performance of triboelectric generators.”

New carbon nanotube-based foam promises superior protection against concussions

Postdoctoral research associate Komal Chawla studies the architected vertically aligned carbon nanotube foam in the lab.
Photo Credit: Joel Hallberg

Developed by University of Wisconsin–Madison engineers, a lightweight, ultra-shock-absorbing foam could vastly improve helmets designed to protect people from strong blows.

The new material exhibits 18 times higher specific energy absorption than the foam currently used in U.S. military combat helmet liners, as well as having much greater strength and stiffness, which could allow it to provide improved impact protection.

Physical forces from an impact can inflict trauma in the brain, causing a concussion. But helmet materials that are better at absorbing and dissipating this kinetic energy before it reaches the brain could help mitigate, or even prevent, concussions and other traumatic brain injuries.

The researchers’ industry partner, helmet manufacturer Team Wendy, is experimenting with the new material in a helmet liner prototype to investigate its performance in real-world scenarios.

“This new material holds tremendous potential for energy absorption and thus impact mitigation, which in turn should significantly lower the likelihood of brain injury,” says Ramathasan Thevamaran, a UW–Madison professor of engineering physics who led the research.

The team detailed its advance in a paper recently published online in the journal Extreme Mechanics Letters.

New nanoscale 3D printing material could offer better structural protection for satellites, drones, and microelectronics

A tiny but strong Stanford logo was made using nanoscale 3D printing.
Image credit: John Kulikowski

Engineers have designed a new material for nanoscale 3D printing that is able to absorb twice as much energy as other similarly dense materials and could be used to create better lightweight protective lattices.

Science fiction envisions rapid 3D printing processes that can quickly create new objects out of any number of materials. But in reality, 3D printing is still limited in the properties and types of materials that are available for use, especially when printing at very small scales.

Researchers at Stanford have developed a new material for printing at the nanoscale – creating structures that are a fraction of the width of a human hair – and used it to print minuscule lattices that are both strong and light. In a paper published in Science, the researchers demonstrated that the new material is able to absorb twice as much energy than other 3D-printed materials of a comparable density. In the future, their invention could be used to create better lightweight protection for fragile pieces of satellites, drones, and microelectronics.