NT/ Using sound waves to image nanostructures
Nanotechnology & nanomaterials biweekly vol.38, 24th July — 8th August
TL;DR
- The potential of ultrafast forms of transmission electron microscopy to measure sound waves in nanostructures has been demonstrated by three RIKEN physicists. This could help realize a high-resolution imaging method that uses ultrahigh-frequency sound waves to image structures that are nanometers in size.
- In a recently published paper, researchers demonstrated how adding molybdenum to a nickel-cobalt phosphide catalyst and synthesizing it with a gradient hydrothermal process, in which the catalyst is heated to 100 degrees, 150 degrees, and then 180 degrees Celsius over 10 hours, creating a unique microstructure that improved the performance of the catalyst, resulting in hydrogen production that could be more applicable to large-scale hydrogen production.
- Junctions between the two different materials, single-wall carbon nanotubes (SWCNTs) and perovskite (CsPbBr3) quantum dots (QDs) — a mechanically stable and easily customized photovoltaic material that creates an electrical current from sunlight when paired with another material, such as SWCNTs — form semiconductor heterojunctions that work exceptionally well as a photodetector. Recent research suggests that increasing the diameter of SWCNTs in SWCNT/perovskite QD heterojunctions improves the optoelectronic, or ability to convert light to electricity, the performance of the heterojunction between the two materials.
- Emerging nanotechnology (based on a “twisted” state of light) promises to make it easier to identify the chemical composition of impurities and their geometrical shape in samples of air, liquid, and live tissue. An international team of scientists led by physicists at the University of Bath is contributing toward this technology, which may pave the way to new environmental monitoring methods and advanced medicines. Their work is published in the journal Advanced Materials.
- Rather than being solely detrimental, cracks in the positive electrode of lithium-ion batteries reduce battery charge time, research done at the University of Michigan shows.
- Silver cluster-assembled materials (SCAMs) are emerging light-emitting materials with molecular designability and unique properties. However, due to their dissimilar structural architecture in different solvents, their widespread application remains limited. Now, researchers have developed two new SCAMs that exhibit excellent fluorescence and high sensitivity to Fe3+ ions in aqueous solutions, indicating their potential for environmental monitoring and assessment.
- Scientists are developing an approach to enhance multifunctionality and structural properties simultaneously by embedding patterned nanostructures in composite materials, which could result in more efficient energy systems enhancing everyday life.
- QUT researchers have developed a new approach for designing molecular ON-OFF switches based on proteins which can be used in a multitude of biotechnological, biomedical, and bioengineering applications.
- Researchers at the University of Basel and Lund University have generated superconducting pair states of electrons on several segments of a nanowire, separated by grown barriers. Depending on the height of the barriers, these pair states can be coupled and fused.
- In-cell engineering can be a powerful tool for synthesizing functional protein crystals with promising catalytic properties. Using genetically modified bacteria as an environmentally friendly synthesis platform, the researchers produced hybrid solid catalysts for artificial photosynthesis. These catalysts exhibit high activity, stability, and durability, highlighting the potential of the proposed innovative approach.
Nanotech Market
Nanotechnology deals with the ability to see, understand, measure, predict, produce or control matter at the nanoscale (below 100 nanometers). The realm of nanotechnology lies between 0.1 and 100 nanometers, wherein a nanometer is defined as one-thousandth of a micron. As a versatile technology with widespread applications in a wide range of end-use sectors, nanotechnology is currently facing a mixed bag of challenges and opportunities as the COVID-19 pandemic continues to spread across the globe. With the world fighting its biggest public health crisis in history, nanotechnology healthcare applications are storming into the spotlight led by the focus on nano intervention in terms of designing effective ways to identify, diagnose, treat and eliminate the spread of COVID-19 infections. Their role as nanocarriers has the potential to design risk-free and effective immunization strategies. In the post-COVID-19 period, the use of nanotechnology solutions in the production of a multitude of devices & products will continue to grow.
Amid the COVID-19 crisis, the global market for Nanotechnology estimated at US$42.2 Billion in the year 2020, is projected to reach a revised size of US$70.7 Billion by 2026, growing at a CAGR of 9.2% over the analysis period. Nanocomposites, one of the segments analyzed in the report, is projected to record a 8.7% CAGR and reach US$35.4 Billion by the end of the analysis period. After a thorough analysis of the business implications of the pandemic and its induced economic crisis, growth in the Nanomaterials segment is readjusted to a revised 10.1% CAGR for the next 7-year period.
Global nanotechnology market to reach US $126.8 billion by the year 2027. Amid the COVID-19 crisis, the global market for Nanotechnology is estimated at US $54.2 billion in the year 2020, and is projected to reach a revised size of US $126 billion.
Latest News & Research
Characterizing an Optically Induced Sub-micrometer Gigahertz Acoustic Wave in a Silicon Thin Plate
by Asuka Nakamura et al in Nano Letters
The potential of ultrafast forms of transmission electron microscopy to measure sound waves in nanostructures has been demonstrated by three RIKEN physicists. This could help realize a high-resolution imaging method that uses ultrahigh-frequency sound waves to image structures that are nanometers in size.
Ultrasound is routinely used in clinics and hospitals to image internal organs and babies in the womb. The sound waves used are usually a few millimeters in wavelength, so they can image structures down to that level.
While such a resolution is fine for medical imaging, physicists would like to use sound waves to image structures in materials that are a few nanometers in size.
“If we can use sound waves that have wavelengths of about 100 nanometers or so, we can use them for inspecting materials, such as finding defects,” explains Asuka Nakamura of the RIKEN Center for Emergent Matter Science (CEMS). “But the sensitivity to small defects really depends on the wavelength.”
This requires generating and detecting sound waves that have much smaller wavelengths (and hence higher frequencies). Creating such high-frequency sound waves is relatively easy — ultrashort laser pulses have been used to generate them in metals and semiconductors for several decades. But detecting them is much more challenging since it requires developing detectors capable of achieving a resolution of nanometers in space and picoseconds in time.
Now, Nakamura, along with CEM colleagues Takahiro Shimojima and Kyoko Ishizaka, has demonstrated the potential of a special type of electron microscope for imaging such ultrahigh-frequency sound waves. The research is published in the journal Nano Letters.
Specifically, they used an ultrafast transmission electron microscope (UTEM) to detect sound waves generated by a 200-nanometer hole in the center of an ultrathin silicon plate. A UTEM uses two laser beams with a slight delay between them (see figure above). One beam illuminates the sample, while the other generates an ultrashort pulse of electrons in the microscope. This setup enables very short timescales to be resolved.
When the trio simulated the waves theoretically and compared the simulations with experimentally obtained images, they found good agreement.
The quality of the images exceeded the team’s expectations, allowing them to perform Fourier-transform analysis — a commonly used mathematical analytic technique — on the images.
“Before performing these experiments, we didn’t intend to characterize the sound waves,” says Nakamura. “But after taking the data, we noticed they were very beautiful, and we could apply Fourier transformation. That was surprising for me.”
The researchers now intend to investigate ultrafast structural and magnetic dynamics in solids induced by such nanometric sound waves using UTEM.
Highly efficient and stable electrocatalyst for hydrogen evolution by molybdenum doped Ni-Co phosphide nanoneedles at high current density
by Chengyu Huang et al in Nano Research
The low-cost, efficient production of hydrogen is an important step toward developing alternative, clean energy sources. Electrochemical water splitting, which splits water into its hydrogen and oxygen elements using an electrocatalyst, is a viable option for producing hydrogen. Conventionally, catalysts have been based on costly elements such as platinum, which makes it difficult to apply this technology on a widespread, commercial scale.
In a recently published paper, researchers demonstrated how adding molybdenum to a nickel-cobalt phosphide catalyst and synthesizing it with a gradient hydrothermal process, in which the catalyst is heated to 100 degrees, 150 degrees, and then 180 degrees Celsius over 10 hours, creating a unique microstructure that improved the performance of the catalyst, resulting in hydrogen production that could be more applicable to large-scale hydrogen production.
“The innovative combination of gradient hydrothermal and phosphidation processes forms a microsphere structure,” said Yufeng Zhao, a professor at the College of Sciences & Institute for Sustainable Energy at Shanghai University in Shanghai, China.
“These nanoparticles with a diameter of approximately 5 to 10 nanometers form nanoneedles, which subsequently self-assemble into a spherical structure. The nanoneedles offer abundant active sites for efficient electron transfer and the presence of small-sized particles and micro-scale roughness enhances the release of hydrogen bubbles.”
To create this unique microstructure, researchers employed a technique called element doping. Element doping is the intentional addition of impurities to a catalyst to improve its activity. In this study, molybdenum (Mo) was added to the bimetallic nickel-cobalt (Ni-Co) phosphide (P).
Ni-Co phosphides already have exceptional electrocatalytic performance because of the way the cobalt and nickel ions interact. After adding the molybdenum and then using a gradient hydrothermal process, the Mo-doped Ni-CoP was deposited onto a nickel foam. After this process, the unique microstructure of nanoneedles formed on the phosphide.
“Trace molybdenum doping optimizes the electronic structure and increases the number of electroactive sites,” said Zhao.
The Mo-doped Ni-CoP catalyst was tested for reliability, stability, and performance. Its density remained nearly constant after 100 hours and its structure was well-maintained, thanks in part to the unique structure of the nanoneedles, which prevent the catalyst from collapsing as hydrogen accumulates. Calculations also showed that the phosphide catalyst was exceptionally efficient.
Looking ahead, researchers hope to test the performance of the reaction in different solutions, such as acidic and neutral solutions. Future studies will also look at alternatives to nickel foam, such as titanium mesh, that can operate across the pH range.
“In future work, we recommend exploring the application of the catalyst in the oxidation-assisted hydrogen production of small molecules, such as urea. This approach would reduce the overpotential of water electrolysis and mitigate environmental pollution caused by urea wastewater,” said Zhao.
Diameter-dependent photoelectric performances of semiconducting carbon nanotubes/perovskite heterojunctions
by Yayang Yu et al in Nano Research
Junctions between the two different materials, single-wall carbon nanotubes (SWCNTs) and perovskite (CsPbBr3) quantum dots (QDs) — a mechanically stable and easily customized photovoltaic material that creates an electrical current from sunlight when paired with another material, such as SWCNTs — form semiconductor heterojunctions that work exceptionally well as a photodetector. Recent research suggests that increasing the diameter of SWCNTs in SWCNT/perovskite QD heterojunctions improves the optoelectronic, or ability to convert light to electricity, performance of the heterojunction between the two materials.
A team of scientists systematically tested the performance effects of varying diameters of SWCNTs, a single layer of carbon atoms that form a hexagonal lattice rolled into a seamless cylinder, with different band gaps, or the amount of energy required for an electron to conduct electric current, in heterojunction films with perovskite QDs.
Their study indicated that increasing the diameter of SWCNTs improved the responsivity, detectivity, and response time of this type of heterojunction film. This effect may be mediated by the enhanced separation and transport of photogenerated excitons, an energy-carrying, neutrally charged electron that combines with a positive electron-hole, in the film.
“The alignment between the band gaps of SWCNTs and QDs determines the separation of the photogenerated excitons at the heterogeneous interfaces, while different diameter SWCNTs show different carrier capacity and mobility,” said Huaping Liu, the principal investigator of the study and professor at the Institute of Physics at the Chinese Academy of Sciences in Beijing, China.
“These characteristics determine the photoelectronic performance of SWCNTs/perovskite QDs heterojunction films, making it… important to systematically study the diameter effect of different band gap SWCNTs on the photodetection performance of these films.”
The team investigated the differences in photodetector performance for SWCNT diameters between 1.0 and 1.4 nm. Characteristics of each diameter were assessed by exposing the SWCNT/perovskite QD films to 410 nm light at differing intensities and measuring the current-voltage curves of each film. This data could then be used to determine the photocurrent, photoresponsivity and detectivity at each nanotube diameter.
The band gap of SWCNTs is roughly inversely proportional to the diameter of the nanotube. When SWCNT diameter was increased from 1.0 nm to 1.4 nm, the research team observed an increase in responsivity by about one order of magnitude, a 5-fold increase in detectivity and a 4-fold increase in response speed. The larger-diameter SWCNTs measured in the study improved carrier capacity and mobility to enhance film performance.
“The great improvement in the photoelectric performances in films with larger-diameter SWCNTs is attributed to increasing built-in electric fields at the heterojunction interface of s-SWCNTs semiconducting SWCNTs/QDs…, which drives the separation of hole carriers from photogenerated excitons to s-SWCNTs and rapid transport in SWCNT films,” said Liu.
Next-generation photodetectors made from SWCNTs and QDs are necessary to reduce material cost, energy consumption and fragility of these types of detectors in future electronics. Interestingly, SWCNT monolayer films alone are very inefficient at detecting light, and perovskite QD films are prone to low carrier mobility, responsivity and detectivity. In contrast, perovskite quantum dot films, when paired with SWCNT monolayers, improve optical absorption as a thin, bilayer film with enhanced responsivity.
Results from this study will help other scientists in the design and fabrication of new high-performance photodetectors required for optical communications, wearable technologies and other applications in medicine and artificial intelligence. Liu’s team plans to utilize these experimental findings specifically in the design of optimized photodetectors for use in highly sensitive artificial vision systems.
Dense Arrays of Nanohelices: Raman Scattering from Achiral Molecules Reveals the Near‐Field Enhancements at Chiral Metasurfaces
by Robin R. Jones et al in Advanced Materials
Using conventional testing techniques, it can be challenging — sometimes impossible — to detect harmful contaminants such as nano-plastics, air pollutants and microbes in living organisms and natural materials. These contaminants are sometimes found in such tiny quantities that tests are unable to reliably pick them up. This may soon change, however. Emerging nanotechnology (based on a “twisted” state of light) promises to make it easier to identify the chemical composition of impurities and their geometrical shape in samples of air, liquid, and live tissue.
An international team of scientists led by physicists at the University of Bath is contributing toward this technology, which may pave the way to new environmental monitoring methods and advanced medicines. Their work is published in the journal Advanced Materials.
The emerging chemical-detection technique is based on a light-matter interaction known as the Raman effect. The Raman effect occurs when a material that is illuminated at a certain color of light scatters and changes the light into a multitude of slightly different colors. It essentially produces a mini-rainbow that is dependent on how atoms within materials vibrate.
Measuring the colors of the Raman rainbow reveals individual atomic bonds because molecular bonds have distinct vibrational patterns. Each bond within a material produces its own unique color change from that of the illumination. Altogether, the colors in the Raman rainbow serve to detect, analyze and monitor the chemical composition (chemical bonds) of complex molecules, such as those found within mixtures of environmental pollutants.
“The Raman effect serves to detect pesticides, pharmaceuticals, antibiotics, heavy metals, pathogens and bacteria. It’s also used for analyzing individual atmospheric aerosols that impact human health and the climate,” said Dr. Robin Jones from the Department of Physics at Bath, who is the first-author of the study.
Expanding, co-author Professor Liwu Zhang from the Department of Environmental Science at Fudan University in China said, “Aquatic pollutants, even in trace amounts, can accumulate in living organisms through the biological chain. This poses a threat to human health, animal welfare and wildlife. Generally, it is really hard to know exactly what the chemical composition of complex mixtures are.”
Professor Ventsislav Valev from Bath, who led the study, added:
“Understanding complex, potentially harmful pollutants in the environment is necessary, so that we can learn how to break them down into harmless components. But it is not all about what atoms they are made of. The way the atoms are arranged matters a lot — it can be decisive for how molecules act, especially within living organisms.
“Our work aims to develop new ways in which the Raman effect can tell us about the way atoms are arranged in space and now we have taken an important technological step using tiny helix shaped antennas made of gold.”
The Raman effect is very weak — only one out of 1,000,000 photons (light particles) undergo the color change. In order to enhance it, scientists use miniature antennas fabricated at the nanoscale that channel the incident light into the molecules. Often these antennas are made of precious metals and their design is limited by nanofabrication capabilities.
The team at Bath used the smallest helical antennas ever employed: their length is 700 times smaller than the thickness of a human hair and the width of the antennas is 2,800 times smaller. These antennas were made from gold by scientists in the team of Professor Peer Fischer at the University of Stuttgart in Germany.
“Our measurements show these helical antennas help to get a lot of Raman rainbow photons out of molecules,” said Dr. Jones. “But more importantly, the helical shape enhances the difference between two types of light that are often used to probe the geometry of molecules. These are known as circularly polarized light.
“Circularly polarized light can be left-handed or right-handed and our helices can, basically, handshake with light. And because we can make the helices twist to the left or to the right, the handshake with light that we devised can be both with left or right hands.”
“While such handshakes have been observed before, the key advance here is that we demonstrate for the first time that it is felt by molecules, as it affects their Raman rainbow. This is an important step that will allow us to distinguish efficiently and reliably between left- and right-handed molecules, first in the lab and then in the environment.”
In order to demonstrate that the new handshaking between light and antennas could be transmitted to molecules, the researchers made use of molecules — crystal violet — that are unable to ‘handshake’ with light by themselves. Yet these molecules behaved as if they could perform this function, expressing the ‘handshaking’ ability of gold nanohelices to which they were attached.
“Another important aspect of our work here is that we worked with two industrial partners,” said Professor Valev. “VSParticle produce standard nanomaterials for measuring Raman light. Having common standards is really important for researchers around the world to be able to compare results.”
He added:
“Our industrial partner Renishaw PLC is a world-leading manufacturer of Raman spectroscopy and microscopy equipment. Such partnerships are essential, so that new technology can move out of the labs and into the real-world, where the environmental challenges are.”
Building on this work, the team is now working on developing more advanced forms of Raman technologies.
Direct measurements of size-independent lithium diffusion and reaction times in individual polycrystalline battery particles
by Jinhong Min, Lindsay M. Gubow, Riley J. Hargrave, Jason B. Siegel, Yiyang Li in Energy & Environmental Science
Rather than being solely detrimental, cracks in the positive electrode of lithium-ion batteries reduce battery charge time, research done at the University of Michigan shows.
This runs counter to the view of many electric vehicle manufacturers, who try to minimize cracking because it decreases battery longevity.
“Many companies are interested in making ‘million-mile’ batteries using particles that do not crack. Unfortunately, if the cracks are removed, the battery particles won’t be able to charge quickly without the extra surface area from those cracks,” said Yiyang Li, assistant professor of materials science and engineering and corresponding author of the study published in Energy and Environmental Sciences.
“On a road trip, we don’t want to wait five hours for a car to charge. We want to charge within 15 or 30 minutes.”
The team believes the findings apply to more than half of all electric vehicle batteries, in which the positive electrode — or cathode — is composed of trillions of microscopic particles made of either lithium nickel manganese cobalt oxide or lithium nickel cobalt aluminum oxide. Theoretically, the speed at which the cathode charges comes down to the particles’ surface-to-volume ratio. Smaller particles should charge faster than larger particles because they have a higher surface area relative to volume, so the lithium ions have shorter distances to diffuse through them.
However, conventional methods couldn’t directly measure the charging properties of individual cathode particles, only the average for all the particles that make up the battery’s cathode. That limitation means the widely accepted relationship between charging speed and cathode particle size was merely an assumption.
“We find that the cathode particles are cracked and have more active surfaces to take in lithium ions — not just on their outer surface, but inside the particle cracks,” said Jinhong Min, a doctoral student in materials science and engineering working in Li’s lab. “Battery scientists know that the cracking occurs but have not measured how such cracking affects the charging speed.”
Measuring the charging speed of individual cathode particles was key to discovering the upside to cracking cathodes, which Li and Min accomplished by inserting the particles into a device that is typically used by neuroscientists to study how individual brain cells transmit electrical signals.
“Back when I was in graduate school, a colleague studying neuroscience showed me these arrays that they used to study individual neurons. I wondered if we can also use them to study battery particles, which are similar in size to neurons,” Li said.
Each array is a custom-designed, 2-by-2 centimeter chip with up to 100 microelectrodes. After scattering some cathode particles in the center of the chip, Min moved single particles onto their own electrodes on the array using a needle around 70 times thinner than a human hair. Once the particles were in place, Min could simultaneously charge and discharge up to four individual particles at a time on the array and measured 21 particles in this particular study.
The experiment revealed that the cathode particles’ charging speeds did not depend on their size. Li and Min think that the most likely explanation for this unexpected behavior is that larger particles actually behave like a collection of smaller particles when they crack. Another possibility is that the lithium ions move very quickly in the grain boundaries — the tiny spaces between the nanoscale crystals comprising the cathode particle. Li thinks this is unlikely unless the battery’s electrolyte — the liquid medium in which the lithium ions move — penetrates these boundaries, forming cracks.
The benefits of cracked materials are important to consider when designing long-lived batteries with single-crystal particles that don’t crack. To charge quickly, these particles may need to be smaller than today’s cracking cathode particles. The alternative is to make single-crystal cathodes with different materials that can move lithium faster, but those materials could be limited by the supply of necessary metals or have lower energy densities, Li said.
Synthesis and luminescence properties of two silver cluster-assembled materials for selective Fe3+ sensing
by Jin Sakai, Sourav Biswas, Tsukasa Irie, Haruna Mabuchi, Taishu Sekine, Yoshiki Niihori, Saikat Das, Yuichi Negishi in Nanoscale
In recent years, there has been a growing interest in using silver nanoclusters (Ag NCs), nanoscale silver particles composed of tens to hundreds of atoms, across various fields like material science, chemistry, and biology. Ag NCs typically have sizes ranging from 1–3 nm. Scientists have made significant progress in creating and manipulating Ag NCs, leading to the development of silver cluster-assembled materials (SCAMs). SCAMs are light-emitting materials made up of many interconnected Ag NCs, joined together by special organic linker molecules called “ligands.” What is special about them is their molecular-level structural designability and unique photophysical properties. However, their widespread use has been limited owing to their dissimilar structural architecture when immersed in different solvents.
To address this problem, a team of researchers from Tokyo University of Science (TUS), led by Professor Yuichi Negishi and including Assistant Professor Saikat Das, recently developed two new (4.6)-connected three-dimensional luminescent SCAMs comprising an Ag12 cluster core connected by quadridentate pyridine linkers — [Ag12(StBu)6(CF3COO)6(TPEPE)6]n, denoted as TUS 1 and [Ag12(StBu)6(CF3COO)6(TPVPE)6]n, denoted as TUS 2. “We have successfully developed two silver -cluster-connected architectures with a new linkage structure, which can be applied to environmental monitoring and assessment,” explains Prof. Negishi. T
The researchers synthesized the SCAMs using the same facile reaction method with the only difference being the linker molecules. They combined [AgStBu]n and CF3COOAg in a solution of acetonitrile and ethanol. The linker molecules TPEPE = 1,1,2,2-tetrakis(4-(pyridin-4-ylethynyl)phenyl)ethene and TPVPE = 1,1,2,2-tetrakis(4-((E)-2-(pyridin-4yl)vinyl)phenyl)ethene were dissolved in separate chemicals, namely tetrahydrofuran and dichloromethane, respectively. The metal solution was then added to the linker molecule solution and left to crystallize in the dark. After one day, yellow crystals formed near the junction of the two solutions, signifying the creation of the SCAMs.
The team conducted various tests to examine the structure of the SCAMs. They found that TUS 1 had a rod-shaped structure, while TUS 2 had a block-shaped structure. They also tested the chemical stability of the materials by immersing them in different solvents, and found that their crystal structure remained unchanged, highlighting their exceptional stability. Additionally, due to their exceptional fluorescence properties with a quantum yield of up to 9.7% and stability in water, the team investigated the potential of SCAMs for detecting metal ions in aqueous solutions.
To their delight, both SCAMs were highly sensitive to Fe3+ ions, which effectively quenched their fluorescence at room temperature, indicating the presence of Fe3+ ions. The detection limits of Fe3+ ions were 0.05 and 0.86 nM L-1 for TUS 1 and TUS 2, respectively, comparable to the standard values. Furthermore, both SCAMs were highly selective towards Fe3+ and were not affected by other common metal ions.
These results suggest a potential application of SCAMs in environmental monitoring, particularly in detecting Fe3+ ions in water.
“The ability to link silver clusters via various linkage modes can enable a bottom-up fabrication of materials with various physicochemical properties. Further developments nanotechnology can thus allow us to fabricate materials and devices on a smaller scale, which is expected to lead to higher functionalities in materials and devices,” speculates Prof. Negishi.
Multifunctionality through Embedding Patterned Nanostructures in High‐Performance Composites
by Ozge Kaynan, Ehsan Hosseini, Mohammad Zakertabrizi, Emile Motta De Castro, Lisa M. Pérez, Dorrin Jarrahbashi, Amir Asadi in Advanced Materials
Dr. Amir Asadi, an assistant professor in the Department of Engineering Technology and Industrial Distribution at Texas A&M University, is making groundbreaking strides in the field of composite materials. His research explores embedding patterned nanostructures composed of multiple materials into high-performance composites to achieve the desired multifunctionality without sacrificing any other properties. This could lead to advancements in various fields, including electronics, energy storage, transportation and consumer products.
Asadi’s work has significant implications, as it addresses the challenge of simultaneously enhancing two properties — multifunctionality and structural integrity — in composite materials, which consist of at least two materials with different properties. By incorporating patterned nanostructures, he aims to overcome the trade-off typically observed between these properties, eliminating the need to sacrifice one to improve the other in current manufacturing methods.
He explains:
“Currently, manufacturing materials with concurrently maximized functionality and structural performance is considered paradoxical. For example, increasing electrical conductivity often reduces strength or vice versa; increasing strength usually decreases fracture toughness.”
However, Asadi draws inspiration from natural structures, such as the elephant trunk, which possesses seemingly incompatible properties and functionality.
“Natural structures with properties considered incompatible in today’s engineering already exist, such as an elephant trunk that is concurrently stiff and strong but also flexible and delicate to handle small vegetables while having communication and sensing functionalities, all arising from its muscular hydrostats architecture.”
The research team used a unique method to adjust how much a material absorbs water or repels it, known as the amphiphilicity degree, in multiple nanomaterials. Using these materials, they created and combined specific patterns called ring and disk patterns, which govern the final properties of composite materials. To do this, they used a precise spray system with carbon dioxide (CO2) to deposit the patterns on the surface of carbon fibers. This allowed them to control the size of the droplets, the patterns on a microscopic scale and the materials’ interactions, ultimately achieving the desired properties. In this study, water droplets delivered the nanomaterials to the surface of carbon fibers using the spray system.
“We developed a new spray technique, referred to as supercritical-CO2 assisted atomization, which leverages the properties of supercritical CO2 and its high dissolution in water that can create several small droplets inside a suspension composed of water and nanomaterials,” said Dr. Dorrin Jarrahbashi, co-author of the group’s journal article, “Multifunctionality Through Embedding Patterned Nanostructures in High-Performance Composites.”
“Unlike conventional approaches in which materials with desired intrinsic properties are integrated to add functionality, this research introduces the concept of integrating nanopatterns and shows that different patterns from the same material will lead to different properties in macroscale composites,” Asadi said. “If concurrent enhancement of functionality and structural properties is the goal, patterns can be combined and synergistically enhance all desired properties.”
There are various benefits of Asadi’s approach. It offers a practical, scalable, economically viable method for creating nanostructured materials and components with tunable properties. The use of diverse materials and precise control over architecture at multiple-length scales enhances the versatility and customization potential of the composites.
Development of epistatic YES and AND protein logic gates and their assembly into signalling cascades
by Zhong Guo, Oleh Smutok, Cagla Ergun Ayva, Patricia Walden, Jake Parker, Jason Whitfield, Claudia E. Vickers, Jacobus P. J. Ungerer, Evgeny Katz, Kirill Alexandrov in Nature Nanotechnology
QUT researchers have developed a new approach for designing molecular ON-OFF switches based on proteins which can be used in a multitude of biotechnological, biomedical and bioengineering applications.
The research team demonstrated that this novel approach allows them to design and build faster and more accurate diagnostic tests for detecting diseases, monitoring water quality and detecting environmental pollutants.
Professor Kirill Alexandrov, of the QUT School of Biology and Environmental Science, lead scientist on the CSIRO-QUT Synthetic Biology Alliance and a researcher with the ARC Centre of Excellence in Synthetic Biology, said that the new technique published in the scientific journal Nature Nanotechnology demonstrated that protein switches could be engineered in a predictable way.
Professor Alexandrov said currently available ‘point of care’ diagnostic tests which provided immediate results, such as blood glucose, pregnancy, and COVID test kits, used protein-sensing systems to detect the presence of sugar, pregnancy hormones, and COVID proteins.
“These, however, represent only a tiny fraction of what is needed in patient-focused healthcare model,” Professor Alexandrov said. “However, developing new sensing systems is a challenging and time-consuming trial-and-error process. The new ‘protein nano-switch’ method can massively accelerate development of similar diagnostics by decreasing the time and increasing the success rate. It uses proteins modified to behave like ON/OFF switches in response to specific targets. The advantage of our approach is that the system is modular, similar to building with Lego bricks, so you can replace parts easily to target something else — another drug or a medical biomarker, for example.”
Professor Alexandrov said the method offered the possibility of building many different diagnostic and analytic tests, with a wide range of possible applications including diagnostics in human and animal health, testing kits for water contamination, and detecting rare earth metals in samples to direct mining efforts.
The multidisciplinary research team included scientists from QUT and the ARC Centre of Excellence in Synthetic Biology, consisting of lead researcher Professor Kirill Alexandrov, Dr Zhong Guo, Cagla Ergun Ayva, Patricia Walden and Adjunct Professor Claudia Vickers.
The QUT team collaborated with leading electrochemists Evgeny Katz and Oleh Smutok from Clarkson University, in New York, and chemical pathologist Dr Jacobus Ungerer from Queensland Health.
To demonstrate the technology, the team focused on a cancer chemotherapy drug that is toxic and requires constant measurement to ensure patient welfare.
“Too little of the drug won’t kill the cancer, but too much could kill the patient,” Professor Alexandrov said.
The sensor the team designed for the drug uses a colour change to identify and quantify the drug.
Professor Alexandrov said the next step was the for the sensor to be tested in Queensland Health laboratories for approval for use in clinical setting.
“It’s really exciting, because it’s the first time an artificially designed protein biosensor may be actually suitable for a real-life diagnostic application” Professor Alexandrov said.
Dr Ungerer said the protein-engineering technology developed by the research team provided a novel means to create laboratory tests.
“This has the potential to improve and expand laboratory testing, which will result in substantial health and economic benefits,” Dr Ungerer said.
Dr Guo said these advancements were made possible by an international and interdisciplinary team and excellent teamwork.
Professor Alexandrov said that the next step was to take this approach and standardise and scale it, to then start building more sophisticated sub-systems. He said there are two future directions for the work.
“One is to develop computer models that allow us to design and build the switches even more rapidly and precisely,” he said. “The other is to demonstrate the scale and potential of the technology by building many switches for different diagnostic applications.”
Professor Alexandrov said the team were currently modifying existing proteins, but in the future, they could use the same principles to develop components that did not exist and would be designed from scratch.
“The new technique provides scientists unprecedented control over construction of protein-based sensing systems,” he said.
Intermediate states in Andreev bound state fusion
by Christian Jünger et al in Communications Physics
Researchers at the University of Basel and Lund University have generated superconducting pair states of electrons on several segments of a nanowire, separated by grown barriers. Depending on the height of the barriers, these pair states can be coupled and fused.
The results were published in Communications Physics and provide important insights for the development of new quantum states.
In a superconductor, electrons form a kind of pair that results in new material properties such as dissipationless currents. If a semiconducting material is brought into contact with a superconductor, the electrons of a semiconductor can also enter into similar pair states known as Andreev bound states (ABSs).
Such states that form on individual, long, thin crystals — so-called nanowires — have become the focus of increasing research for several years, as they might be particularly good information carriers.
Researchers in the team of Professor Christian Schönenberger and Dr. Andreas Baumgartner from the Department of Physics and Swiss Nanoscience Institute at the University of Basel and colleagues from Lund University have now succeeded in generating such pair states on three segments of a nanowire, which are separated by barriers grown in the crystal. The scientists are able to manipulate the height of the barriers using an electrical voltage.
“We can identify the respective states by characteristics in the electrical current,” explains first author of the publication, Dr. Christian Jünger. If the barriers are large, then individual, independent Andreev bound states form on the two segments near a superconductor.
Analogous to the one-electron states in natural atoms in chemistry, these can be regarded as Andreev atoms. When the barriers between the segments are reduced, the ABSs become coupled, forming states often called Andreev molecules.
When the researchers lower the barriers almost completely, pair states are created that extend across the entire nanowire and conduct electrical current without dissipation — a phenomenon known as the Josephson effect.
“This corresponds to a fusion of the original Andreev bound states into Andreev helium — similar to fused hydrogen atoms,” says Dr. Andreas Baumgartner.
In future experiments, researchers will investigate this fusion process with a similar type of pair states, so-called Majorana bound states, and thus take an important step toward application for quantum computers.
In-Cell Engineering of Protein Crystals into Hybrid Solid Catalysts for Artificial Photosynthesis
by Tiezheng Pan, Basudev Maity, Satoshi Abe, Taiki Morita, Takafumi Ueno in Nano Letters
In-cell engineering can be a powerful tool for synthesizing functional protein crystals with promising catalytic properties, show researchers at Tokyo Tech. Using genetically modified bacteria as an environmentally friendly synthesis platform, the researchers produced hybrid solid catalysts for artificial photosynthesis. These catalysts exhibit high activity, stability, and durability, highlighting the potential of the proposed innovative approach.
Protein crystals, like regular crystals, are well-ordered molecular structures with diverse properties and a huge potential for customization. They can assemble naturally from materials found within cells, which not only greatly reduces the synthesis costs but also lessens their environmental impact.
Although protein crystals are promising as catalysts because they can host various functional molecules, current techniques only enable the attachment of small molecules and simple proteins. Thus, it is imperative to find ways to produce protein crystals bearing both natural enzymes and synthetic functional molecules to tap their full potential for enzyme immobilization.
Against this backdrop, a team of researchers from Tokyo Institute of Technology (Tokyo Tech) led by Professor Takafumi Ueno has developed an innovative strategy to produce hybrid solid catalysts based on protein crystals. Their approach combines in-cell engineering and a simple in vitro process to produce catalysts for artificial photosynthesis.
The building block of the hybrid catalyst is a protein monomer derived from a virus that infects the Bombyx mori silkworm. The researchers introduced the gene that codes for this protein into Escherichia coli bacteria, where the produced monomers formed trimers that, in turn, spontaneously assembled into stable polyhedra crystals (PhCs) by binding to each other through their N-terminal α-helix (H1). Additionally, the researchers introduced a modified version of the formate dehydrogenase (FDH) gene from a species of yeast into the E. coli genome. This gene caused the bacteria to produce FDH enzymes with H1 terminals, leading to the formation of hybrid H1-FDH@PhC crystals within the cells.
The team extracted the hybrid crystals out of the E. coli bacteria through sonication and gradient centrifugation, and soaked them in a solution containing an artificial photosensitizer called eosin Y (EY). As a result, the protein monomers, which had been genetically modified such that their central channel could host an eosin Y molecule, facilitated the stable binding of EY to the hybrid crystal in large quantities.
Through this ingenious process, the team managed to produce highly active, recyclable, and thermally stable EY·H1-FDH@PhC catalysts that can convert carbon dioxide (CO2) into formate (HCOO−) upon exposure to light, mimicking photosynthesis. In addition, they maintained 94.4% of their catalytic activity after immobilization compared to that of the free enzyme.
“The conversion efficiency of the proposed hybrid crystal was an order of magnitude higher than that of previously reported compounds for enzymatic artificial photosynthesis based on FDH,” highlights Prof. Ueno. “Moreover, the hybrid PhC remained in the solid protein assembly state after enduring both in vivo and in vitro engineering processes, demonstrating the remarkable crystallizing capacity and strong plasticity of PhCs as encapsulating scaffolds.”
Overall, this study showcases the potential of bioengineering in facilitating the synthesis of complex functional materials.
“The combination of in vivo and in vitro techniques for the encapsulation of protein crystals will likely provide an effective and environmentally friendly strategy for research in the areas of nanomaterials and artificial photosynthesis,” concludes Prof. Ueno.
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