NT/ Revolutionary nanodrones enable targeted cancer treatment
Nanotechnology & nanomaterials biweekly vol.46, 26th December — 9th January
TL;DR
- A groundbreaking study has unveiled a remarkable breakthrough in cancer treatment. The research team has successfully developed unprecedented “NK cell-engaging nanodrones” capable of selectively targeting and eliminating cancer cells, offering a potential solution for intractable types of cancers.
- Perovskite nanosheets show distinctive characteristics with significant applications in science and technology. In a recent study, researchers achieved enhanced signal amplification in CsPbBr3 perovskite nanosheets with a unique waveguide pattern, which enhanced both gain and thermal stability. These advancements carry wide-ranging implications for laser, sensor, and solar cell applications, and can potentially influence areas like environmental monitoring, industrial processes, and healthcare.
- Researchers have used artificial intelligence to solve a difficult problem in crystal science. Seeking to understand why crystals develop tiny defects called dislocations, the researchers discovered unique defects that look like staircases. This discovery helps to better understand the defects in crystals that reduce the efficiency of complex polycrystalline materials used in our everyday electronic devices.
- The integration of mechanical memory in the form of springs has for hundreds of years proven to be a key enabling technology for mechanical devices (like clocks), achieving advanced functionality through complex autonomous movements. In our times, the integration of springs in silicon-based microtechnology has opened the world of planar mass-producible mechatronic devices from which we all benefit, via air-bag sensors for example.
- A research team has developed a novel high-performance photoelectrode by constructing a zinc oxide nanopagoda array with a unique shape on a transparent electrode and applying silver nanoparticles to its surface.
- Physics is filled with mysteries. To find a few worth exploring, look no further than an ice cube. At room temperature, of course, the cube will melt before your eyes. But even far below freezing, ice can shift in barely perceptible ways that scientists are still trying to understand. Using imaging tools researchers have detected a phenomenon known as premelting at temperatures far lower than those previously observed.
- When electrons move within a molecule or semiconductor, this occurs on unimaginably short time scales. A Swedish-German team has now made significant progress towards a better understanding of these ultrafast processes: The researchers were able to track the dynamics of electrons released from the surface of zinc oxide crystals using laser pulses with spatial resolution in the nanometer range and at previously unattained temporal resolution.
- Peptide nanotubes are tubular-shaped structures formed by the controlled stacking of cyclic peptide components. These hollow biomaterials show inner and outer faces, allowing control over their properties. Researchers from the Center for Research in Biological Chemistry and Molecular Materials (CiQUS) presented a novel kind of cyclic peptide that, when light-irradiated, induces the formation or desegregation of nanotubes on demand.
- A team of researchers has discovered a new method for the manufacture of metal nanocatalysts that is more sustainable and economical.
- Researchers, in a recent publication in Nature Nanotechnology, have demonstrated that controllable springs can be integrated at arbitrary chosen locations within soft three-dimensional structures using confocal photolithographic manufacturing (with nanoscale precision) of a novel magnetically active material in the form of a photoresist impregnated with customizable densities of magnetic nanoparticles.
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 an 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
Protein cage nanoparticle-based NK cell-engaging nanodrones (NKeNDs) effectively recruit NK cells to target tumor sites and suppress tumor growth
by Seong Guk Park, Hyo Jeong Kim, Hyun Bin Lee, Soomin Eom, Heejin Jun, Yeongim Jang, Sung Ho Park, Sebyung Kang in Nano Today
A groundbreaking study led by Professor Sebyung Kang and Professor Sung Ho Park in the Department of Biological Sciences at UNIST has unveiled a remarkable breakthrough in cancer treatment. The research team has successfully developed unprecedented “NK cell-engaging nanodrones” capable of selectively targeting and eliminating cancer cells, offering a potential solution for intractable types of cancers.
The innate lymphoid cells known as natural killer (NK) cells play a vital role in the body’s immune response against cancer.
Numerous efforts have been made to harness the power of NK cells to develop effective cancer therapies.
Now, the research team has designed and fabricated exceptional NK cell-engaging nanodrones, referred to as NKeNDs, using AaLS protein cage nanoparticles.
These groundbreaking NKeNDs simultaneously display cancer-targeting ligands, such as HER2Afb or EGFRAfb, and NK cell-recruiting ligands, aCD16Nb, on the surface of the AaLS through the SpyCatcher/SpyTag protein ligation system.
The dual ligand-displaying NKeNDs, named HER2 @NKeND and EGFR@NKeND, have demonstrated the ability to selectively bind to HER2-overexpressing SK-OV-3 cells and EGFR-overexpressing MDA-MB-468 cells, respectively, as well as human NK cells.
The physical engagement of human NK cells with the target cancer cells mediated by the NKeNDs activates the NK cells, enabling them to effectively eliminate the target cancer cells in vitro.
Remarkably, in SK-OV-3 tumor-bearing mice, the administration of HER2 @NKeNDs along with human PBMCs facilitates the infiltration of activated human NK cells into the tumor sites.
As a result, tumor growth is significantly suppressed without causing noticeable side effects.
This study showcases a novel approach to developing cancer-specific NK cell engagers by utilizing protein cage nanoparticles and recombinant cancer cell binders.
It offers tremendous potential for the selective treatment of previously intractable types of cancers.
Professor Kang Se-byung expressed his excitement about the study, stating, “This research presents new possibilities for immune treatment through NK cell delivery nanodrones, overcoming challenges such as the movement and survival of NK cells. We aim to provide new opportunities for customized treatments that selectively address various types of cancer through further research, including cancer-specific immune cell induction.”
Gain enhancement of perovskite nanosheets by a patterned waveguide: excitation and temperature dependence of gain saturation
by Inhong Kim, Ga Eul Choi, Ming Mei, Min Woo Kim, Minju Kim, Young Woo Kwon, Tae-In Jeong, Seungchul Kim, Suck Won Hong, Kwangseuk Kyhm, Robert A. Taylor in Light: Science & Applications
Perovskite nanosheets show distinctive characteristics with significant applications in science and technology. In a recent study, researchers from Korea and UK achieved enhanced signal amplification in CsPbBr3 perovskite nanosheets with a unique waveguide pattern, which enhanced both gain and thermal stability. These advancements carry wide-ranging implications for laser, sensor, and solar cell applications, and can potentially influence areas like environmental monitoring, industrial processes, and healthcare.
Perovskite materials are still attracting a lot of interest in solar cell applications. Now, the nanostructures of perovskite materials are being considered as a new laser medium.
Over the years, light amplification in perovskite quantum dots has been reported, but most of the works present inadequate quantitative analysis. To assess the light amplification ability, “gain coefficient” is necessary, whereby the essential characteristic of a laser medium is revealed.
An efficient laser medium is one that has a large gain.
Scientists have been exploring ways to boost this gain. Now, in a recent study, a team of researchers, led by Professor Kwangseuk Kyhm from the Department of Optics & Mechatronics at Pusan National University in Korea, has managed to enhance signal amplification in perovskite nanosheets of CsPbBr3 with a unique waveguide pattern.
Perovskite nanosheets are two-dimensional structures arranged in sheet-like configurations on the nanoscale and possess characteristics that make them valuable for various applications.
Their achievement overcomes the shortcomings of CsPbBr3 quantum dots, whose gain is inherently limited due to the Auger process, which essentially shortens the decay time for population inversion (a state in which more members of the system are in higher, excited states than in lower, unexcited energy states). Prof.
Kyhm explains: “Perovskite nanosheets can be a new laser medium, and this work has demonstrated that light amplification can be achieved based on tiny perovskite nanosheets that are synthesized chemically.”
The researchers also proposed a new gain analysis of “gain contour” to overcome the limit of earlier gain analysis.
While the old method provides a gain spectrum, it is unable to analyze the gain saturation for long optical stripe lengths.
Because the “gain contour” illustrates the variation of the gain with respect to spectrum energy and optical stripe length, it is very convenient to analyze the local gain variation along spectrum energy and optical stripe length.
The researchers also studied the excitation and temperature dependence of the gain contour and the patterned waveguide, based on polyurethane-acrylate, which boosted both the gain and thermal stability of perovskite nanosheets.
This enhancement was attributed to improved optical confinement and heat dissipation, which was facilitated by the two-dimensional center-of-mass confined excitons and localized states arising from the inhomogeneous sheet thickness and the defect states.
The implementation of such a patterned waveguide is promising for efficient and controlled signal amplification and can contribute to the development of more reliable and versatile devices based on perovskite nanosheets, including lasers, sensors, and solar cells.
In addition, it could also impact industries related to encryption and decryption of information, neuromorphic computing, and visible light communication.
Furthermore, enhanced amplification and increased efficiencies can help perovskite solar cells compete better with traditional silicon-based solar cells.
The study is also poised to significantly influence optics and photonics. The insights gained can help optimize laser operation, enhance signal transmission in optical communication, and improve sensitivity in photodetectors. This, in turn, could allow devices to operate more reliably.
In the long term, when intense light is needed at the nanoscale, perovskite nanosheets can be combined with other nanostructures, allowing the amplified light to serve as an optical probe.
However, the successful application of perovskite nanosheets in diverse areas, including consumer products like smartphones and lighting, would depend on overcoming challenges related to their stability, scalability, and toxicity.
“So far, perovskite quantum dots have been studied for lasers, but such zero-dimensional structures have fundamental limits. In this regard, our work suggests that the two-dimensional structure of perovskite nanosheets can be an alternative solution,” concludes Prof. Kyhm.
Multicrystalline Informatics Applied to Multicrystalline Silicon for Unraveling the Microscopic Root Cause of Dislocation Generation
by Kenta Yamakoshi, Yutaka Ohno, Kentaro Kutsukake, Takuto Kojima, Tatsuya Yokoi, Hideto Yoshida, Hiroyuki Tanaka, Xin Liu, Hiroaki Kudo, Noritaka Usami in Advanced Materials
Researchers at Nagoya University in Japan have used artificial intelligence to discover a new method for understanding small defects called dislocations in polycrystalline materials, materials widely used in information equipment, solar cells, and electronic devices, that can reduce the efficiency of such devices. The findings were published in the journal Advanced Materials.
Integration method of various data developed in this study. Mc-Si ingots were fabricated and various imaging techniques were applied to the cut-out wafers. Then, the 3D mc-Si structure was reconstructed by applying image processing to the obtained optical images. The stresses inside the ingot during crystal growth were analyzed from the simulations, and the theory of dislocation cluster generation was discussed by comparing the calculated results with the experimental results.
Almost every device that we use in our modern lives has a polycrystal component. From your smartphone to your computer to the metals and ceramics in your car. Despite this, polycrystalline materials are tough to utilize because of their complex structures. Along with their composition, the performance of a polycrystalline material is affected by its complex microstructure, dislocations, and impurities.
A major problem for using polycrystals in industry is the formation of tiny crystal defects caused by stress and temperature changes. These are known as dislocations and can disrupt the regular arrangement of atoms in the lattice, affecting electrical conduction and overall performance.
To reduce the chances of failure in devices that use polycrystalline materials, it is important to understand the formation of these dislocations.
A team of researchers at Nagoya University, led by Professor Noritaka Usami and including Lecturer Tatsuya Yokoi and Associate Professor Hiroaki Kudo and collaborators, used a new AI to analyze image data of a material widely used in solar panels, called polycrystalline silicon.
The AI created a 3D model in virtual space, helping the team to identify the areas where dislocation clusters were affecting the material’s performance. After identifying the areas of the dislocation clusters, the researchers used electron microscopy and theoretical calculations to understand how these areas formed. They revealed stress distribution in the crystal lattice and found staircase-like structures at the boundaries between the crystal grains. These structures appear to cause dislocations during crystal growth.
“We found a special nanostructure in the crystals associated with dislocations in polycrystalline structures,” Usami said.
Along with its practical implications, this study may have important implications for the science of crystal growth and deformation as well.
The Haasen-Alexander-Sumino (HAS) model is an influential theoretical framework used to understand the behavior of dislocations in materials.
But Usami believes that they have discovered dislocations that the Haasen-Alexander-Sumino model missed.
Another surprise was to follow soon after, as when the team calculated the arrangement of the atoms in these structures, they found unexpectedly large tensile bond strains along the edge of the staircase-like structures that triggered dislocation generation.
As explained by Usami, “As experts who have been studying this for years, we were amazed and excited to finally see proof of the presence of dislocations in these structures. It suggests that we can control the formation of dislocation clusters by controlling the direction in which the boundary spreads.”
“By extracting and analyzing the nanoscale regions through polycrystalline materials informatics, which combines experiment, theory, and AI, we made this clarification of phenomena in complex polycrystalline materials possible for the first time,” Usami continued. “This research illuminates the path towards establishing universal guidelines for high-performance materials and is expected to contribute to the creation of innovative polycrystalline materials. The potential impact of this research extends beyond solar cells to everything from ceramics to semiconductors. Polycrystalline materials are widely used in society, and the improved performance of these materials has the potential to revolutionize society.”
3D nanofabricated soft microrobots with super-compliant picoforce springs as onboard sensors and actuators
by Haifeng Xu, Song Wu, Yuan Liu, Xiaopu Wang, Artem K. Efremov, Lei Wang, John S. McCaskill, Mariana Medina-Sánchez, Oliver G. Schmidt in Nature Nanotechnology
The integration of mechanical memory in the form of springs has for hundreds of years proven to be a key enabling technology for mechanical devices (like clocks), achieving advanced functionality through complex autonomous movements. In our times, the integration of springs in silicon-based microtechnology has opened the world of planar mass-producible mechatronic devices from which we all benefit, via air-bag sensors for example. For a new generation of minimally and even non-invasive biomedical applications however, mobile devices that can safely interact mechanically with cells must be achieved at much smaller scales (10 microns) and with much softer forces (pico Newton scale i. e. lifting weights less than one millionth of a mg) and in customized three-dimensional shapes.
Researchers at the Chemnitz University of Technology, the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences and the Leibniz IFW Dresden, in a recent publication in Nature Nanotechnology, have now demonstrated that controllable springs can be integrated at arbitrary chosen locations within soft three-dimensional structures using confocal photolithographic manufacturing (with nanoscale precision) of a novel magnetically active material in the form of a photoresist impregnated with customizable densities of magnetic nanoparticles.
These “picosprings” have remarkably large and tuneable compliancy and can be controlled remotely through magnetic fields (even deep within the human body) allowing articulated motion in microrobots as well as micromanipulations well beyond the state of the art.
Moreover, the extension of the picosprings can also be used visually to measure forces, for example propulsion or grasping forces, in interaction with other objects like cells.
For example, these picosprings have been used to measure the locomotive propulsion force of sperm cells.
The publication showcases these capabilities by demonstrating several microbots (including a micropenguin) containing picosprings at multiple locations that can do these tasks at cellular scales: propel themselves, grasp and release cells and measure the minute forces needed to do this safely.
Dr. Haifeng Yu, first author of the study and group leader at the Chinese Academy of Sciences in Shenzhen (China), says: “Programmable elasticity at the micrometer scale offers a feasible strategy for producing 3D devices and finely structured ‘micro-surgeons’ capable of performing complex medical tasks.”
Dr. Mariana Medina-Sanchez, group leader at the Leibniz IFW and BCUBE- TU Dresden, co-author and co-supervisor of this work, adds: “These picospring-based micromachines with programmable elasticity and magnetism, crafted through monolithic fabrication, open numerous possibilities for localized force sensing and actuation in low Reynolds number environments. This versatility underscores their significance across a spectrum of biomedical applications.”
Prof. Oliver Schmidt, who is last author of the paper and supervised this work, sees this as another important step in the transition towards life-ready soft and smart modular microrobotics.
“Remotely controlled microdevices using magnetic fields form a particularly promising technology for non-invasive medical applications — and now this extends to mechanical mechanisms inside these remote microdevices,” says Schmidt. “Being able to incorporate designer springs will also add a new tool to the growing capability at TU Chemnitz towards microelectronic morphogenesis and artificial life,” adds Prof.
Ag nanoparticles decorated ZnO nanopagodas for Photoelectrochemical application
by Marwa Mohamed Abouelela et al in Electrochemistry Communications
A research team consisting of members of the Egyptian Petroleum Research Institute and the Functional Materials Engineering Laboratory at the Toyohashi University of Technology, has developed a novel high-performance photoelectrode by constructing a zinc oxide nanopagoda array with a unique shape on a transparent electrode and applying silver nanoparticles to its surface.
The zinc oxide nanopagoda is characterized by having many step structures, as it comprises stacks of differently-sized hexagonal prisms. In addition, it exhibits very few crystal defects and excellent electron conductivity. By decorating its surface with silver nanoparticles, the zinc oxide nanopagoda array photoelectrode gains visible light absorption properties, enabling it to function under sunlight irradiation.
Photoelectrochemical water splitting using sunlight is expected to be used as a technology to produce clean energy in the form of hydrogen. As key materials for this technology, photoelectrodes must have low overpotential against water splitting reactions, in addition to high solar absorption and charge transfer efficiencies.
For practical applicability, this technology cannot use rare metals as primary materials, and the fabrication process must be industrialized; however, materials that satisfy these requirements have not yet been developed.
Accordingly, the research team solely focused on the zinc oxide nanopagoda array, as such arrays are inexpensive to produce, feature high electron conductivity, and are not vulnerable to raw material depletion. Initially, zinc oxide nanopagoda arrays were considered difficult to fabricate with good reproducibility.
Led by Marwa Abouelela — a third-year doctoral student who is also the lead author of the paper published in Electrochemistry Communications — the team first optimized the synthesis process to ensure high reproducibility. When the photoelectrochemical properties of the obtained photoelectrode were evaluated, a relatively large photocurrent was observed to emerge under pseudo-sunlight irradiation.
In addition to the high charge transfer efficiency associated with low defect density and high surface chemical reaction activity in many steps, an electromagnetic field analysis has revealed that the nanopagoda’s unique nanostructure can efficiently capture ultraviolet rays contained in the incident light.
To ensure the effective utilization of visible light, which accounts for 55% of sunlight, the research team further improved the photoelectrochemical properties by decorating the zinc oxide nanopagoda surface with silver nanoparticles that exhibit localized surface plasmon resonance, increasing the photocurrent by approximately 1.5-fold.
The action spectrum of the photocurrent value indicates that this improvement is primarily attributed to the hot electron transfer caused by visible light absorption by the localized surface plasmon resonance of silver nanoparticles. By optimizing the application of silver nanoparticles, it became possible to only improve the photoelectrochemical properties while preventing adverse effects on the properties of the nanopagoda itself.
Associate Professor Go Kawamura, one of the corresponding authors, said, “Zinc oxide nanopagodas were considered for application only to electron gun emitters, utilizing their high charge transfer efficiency. However, because the structure has many steps, our initial idea was that it is highly active against surface chemical reactions and may be suitable for catalyzing photoelectrochemical reactions.”
“Having succeeded in fabricating the nanopagoda, we aimed to improve the efficiency of sunlight utilization by applying silver nanoparticles that exhibit localized surface plasmon resonance, and evaluated the effect by electromagnetic field analysis; however, it was found that the zinc oxide nanopagoda captures incident light, especially ultraviolet rays, into its interior. Although this was completely unexpected, it was a fortunate discovery, as this property contributes to the improvement of photoelectrochemical properties.”
Currently, Marwa and students of the same laboratory are leading an investigation into the effect of precise structural control of zinc oxide nanopagodas, as well as surface decoration with other materials, on the photoelectrochemical properties of said pagodas. Because zinc oxide is prone to photocorrosion, it cannot withstand long-term sunlight irradiation by itself, leading us to focus on improving durability via surface decoration.
Upon achieving both high photoelectrochemical properties and durability, the team plans to carry out water splitting hydrogen production in a real environment (decomposition of river water or seawater by sunlight).
Surface premelting of ice far below the triple point
by Yulin Lin et al in Proceedings of the National Academy of Science
Physics is filled with mysteries. To find a few worth exploring, look no further than an ice cube. At room temperature, of course, the cube will melt before your eyes. But even far below freezing, ice can shift in barely perceptible ways that scientists are still trying to understand. Using imaging tools at the U.S. Department of Energy’s (DOE) Argonne National Laboratory, researchers have detected a phenomenon known as premelting at temperatures far lower than those previously observed.
Premelting is the reason that a patch of ice can be slippery even on a frigid, clear day. Though the spot is frozen, some part at the surface is wet, an idea first posited by Michael Faraday in the mid-1800s. The idea of a premelted, liquid-like layer on ice opens up other longstanding questions about how water transforms from liquid to solid to vapor — and how, under certain conditions, it can be all three at once.
In the recent study, scientists examined ice crystals formed below minus 200 degrees Fahrenheit. The team used Argonne’s Center for Nanoscale Materials (CNM), a DOE Office of Science user facility, to grow and observe the ice nanocrystals, which measured only 10 millionths of a meter across.
Besides what the study reveals about the nature of water at subfreezing temperatures, it demonstrates a method for examining sensitive samples in molecular detail: low-dose, high-resolution transmission electron microscopy (TEM). TEM directs a stream of electrons, which are subatomic particles, at an object. A detector creates an image by picking up how the electrons scatter off the object.
“Some materials are beam-sensitive. When you use an electron beam to image them, they can be changed or destroyed,” said Jianguo Wen, Argonne materials scientist and a lead author on the paper. One example of an electron beam sensitive material is electrolytes, which exchange charged particles in batteries.” Being able to study them in fine detail without disrupting their structure could help in the development of better batteries.
But to start, researchers are experimenting with the low-dose TEM technique on frozen water.
After all, water is cheap and abundant. More than that, Wen said, “Ice is very challenging to image, because it is so unstable under the high-energy electron beam. If we successfully demonstrate this technique on ice, imaging other beam-sensitive materials will be a piece of cake.”
The low-dose technique combines the CNM’s aberration-corrected TEM with a specialized direct electron detection camera. The system is extremely efficient at capturing information from each and every electron that hits a sample, so it is possible to get a high-resolution image using fewer electrons, thus inflicting less damage on the target than a conventional TEM approach.
The low level of electron exposure makes it possible to capture something as delicate as an ice crystal in situ, or in its environment. The research team used liquid nitrogen to grow the ice crystals on carbon nanotubes at 130 degrees Kelvin, or minus 226 degrees Fahrenheit.
Previous studies had observed premelting close to water’s triple point. At the triple point, the temperature is just a hair above freezing and the pressure is low enough that ice, liquid and water vapor can exist at once. At temperatures and pressures below triple point, ice sublimates directly into water vapor.
The “rules” of water’s behavior are often neatly summed up in a simple phase diagram that maps out water’s varying states across different combinations of temperature and pressure.
“But the real world is much more complex than this simple phase diagram,” said Tao Zhou, Argonne materials scientist and another corresponding author of the paper. “We showed that premelting can happen far down on the curve, though we cannot explain why.”
In a video captured during the experiment, two separate nanocrystals can be seen dissolving into each other as the ice is warmed under constant pressure to 150 degrees Kelvin, or minus 190 degrees Fahrenheit. Though still well below freezing, the ice formed a quasi-liquid-like layer. This ultraviscous water is not accounted for among the simple lines of the phase diagram, where water goes directly from ice to vapor.
The study raises intriguing questions that could be explored in future work. What is the exact nature of the liquid-like layer the researchers saw? What would happen if the pressure is raised, along with the temperature? And does this technique pave the way toward a glimpse of “no-man’s land,” the state where super-cooled water suddenly crystallizes from liquid into ice? The centuries-long scientific inquiry into water’s many states continues.
Time‐Resolved Photoemission Electron Microscopy on a ZnO Surface Using an Extreme Ultraviolet Attosecond Pulse Pair
by Jan Vogelsang et al in Advanced Physics Research
When electrons move within a molecule or semiconductor, this occurs on unimaginably short time scales. A Swedish-German team, including Dr. Jan Vogelsang from the University of Oldenburg, has now made significant progress towards a better understanding of these ultrafast processes: The researchers were able to track the dynamics of electrons released from the surface of zinc oxide crystals using laser pulses with spatial resolution in the nanometer range and at previously unattained temporal resolution.
With these experiments, the team demonstrated the applicability of a method that could be used to understand better the behavior of electrons in nanomaterials and new types of solar cells, among other applications. Researchers from Lund University, including Professor Dr. Anne L’Huillier, one of last year’s three Nobel laureates in physics, were involved in the study published in the journal Advanced Physics Research.
In their experiments, the research team combined a special type of electron microscopy known as photoemission electron microscopy (PEEM) with attosecond physics technology. The scientists use extremely short-duration light pulses to excite electrons and record their subsequent behavior.
“The process is much like a flash capturing a fast movement in photography,” Vogelsang explained. An attosecond is incredibly short — just a billionth of a billionth of a second.
As the team reports, similar experiments had so far failed to attain the temporal accuracy required to track the electrons’ motion. The tiny elementary particles whizz around much faster than the larger and heavier atomic nuclei. In the present study, however, the scientists combined the two technologically demanding techniques, photoemission electron microscopy, and attosecond microscopy, without compromising either the spatial or temporal resolution.
“We have now finally reached the point where we can use attosecond pulses to investigate in detail the interaction of light and matter at the atomic level and in nanostructures,” said Vogelsang.
One factor that made this progress possible was using a light source that generates a particularly high quantity of attosecond flashes per second — in this case, 200,000 light pulses per second. Each flash released, on average, one electron from the surface of the crystal, allowing the researchers to study their behavior without them influencing each other.
“The more pulses per second you generate, the easier it is to extract a small measurement signal from a dataset,” explained the physicist.
Anne L’Huillier’s laboratory at Lund University (Sweden), where the experiments for the present study were carried out, is one of the few research laboratories worldwide with the technological equipment required for such experiments.
Vogelsang, a postdoctoral researcher at Lund University from 2017 to 2020, is currently setting up a similar experimental laboratory at the University of Oldenburg. In the future, the two teams plan to continue their investigations and explore the behavior of electrons in various materials and nanostructures.
Photo-assembling cyclic peptides for dynamic light-driven peptide nanotubes
by Marcos Vilela-Picos et al in Chem
Peptide nanotubes are tubular-shaped structures formed by the controlled stacking of cyclic peptide components. These hollow biomaterials show inner and outer faces, allowing control over their properties. Led by Juan R. Granja, researchers from the Center for Research in Biological Chemistry and Molecular Materials (CiQUS) presented a novel kind of cyclic peptide that, when light-irradiated, induces the formation or desegregation of nanotubes on demand.
The peptide switches from a folded to a flat conformation at the appropriate wavelength. When the planar conformation is adopted, the peptide rings assemble to form tubular-shaped structures, whereas in the folded arrangement, the peptides remain unassembled.
A mesh of microtubules provides structure and shape to cells and is key to performing their functions and dividing. One of the main challenges in cell biology is to emulate this fiber in order to construct an artificial cytoskeleton. To this end, Prof. Granja’s group has been studying the properties of peptide nanotubes for years to create these synthetic meshes and thus control the molecular mechanisms underlying these biological processes.
However, a simple model to simulate this vital component of cells requires the formation/disassembly process to occur with precise spatiotemporal control under physiological conditions, something that was not possible with peptide nanotubes at the time.
Using light as an external stimulus, in this work, CiQUS researchers synthesized the nanotubes inside water droplets under neutral conditions, thus simulating the physiological media present in the cell.
Fibers formed rapidly on the contour of the water-in-oil droplets and induced their fusion. According to the authors, when the nanotubes are located at the interface, they provide the droplets with the ability to fuse with each other, a mechanism of great interest to simulate cell phagocytosis or explore new drug delivery systems.
Microwave-Driven Exsolution of Ni Nanoparticles in A-Site Deficient Perovskites
by Andrés López-García et al in ACS Nano
A team of researchers from the ITACA Institute of the Universitat Politècnica de València (UPV) and the Research Institute of Chemical Technology, a joint center of the Spanish National Research Council (CSIC) and the UPV, has discovered a new method for the manufacture of metal nanocatalysts that is more sustainable and economical.
With great potential in the industrial sector, the method would contribute to the decarbonization of industry. The work has been published in the journal ACS Nano.
This new method is based on the exsolution process activated by microwave radiation. Exsolution is a method of generating metallic nanoparticles on the surface of ceramic materials.
“At elevated temperatures and in a reducing atmosphere (usually hydrogen), metal atoms migrate from the structure of the material to its surface, forming metal nanoparticles anchored to the surface. This anchoring significantly increases the strength and stability of these nanoparticles, which positively impacts the efficiency of these catalysts,” explains Beatriz García Baños, a researcher in the Microwave Area of the ITACA Institute at the UPV.
In the study, the UPV and CSIC researchers have shown that thanks to microwave radiation, this process can be carried out at more moderate temperatures and without the need to use reducing atmospheres.
“In this way, active nickel nanocatalysts can be produced in a more energy-efficient exsolution process. These catalysts have been proven to be active and stable for the reaction of CO production from CO2, obtaining a product of industrial interest and contributing to the decarbonization of the sector,” says Alfonso Juan Carrillo Del Teso, researcher of the Energy Conversion and Storage Group of the ITQ.
The exsolution process demonstrated in nickel nanoparticles has been carried out at temperatures of about 400ºC and exposure times of a few seconds, whereas the conventional exsolution procedure in these materials occurs at temperatures of 900ºC, with times of about 10 hours. In addition, this technology allows exsolution to be performed without using hydrogen.
“For all these reasons, we improve the sustainability of the process. Moreover, by obtaining the catalysts at milder temperatures and shorter exposure times, we reduce the costs of the process, which is also influenced by not having to use hydrogen as a reducing gas,” adds Beatriz García Baños.
The process developed by the UPV and CSIC team is primarily intended for high-temperature catalytic procedures for storing and converting renewable energy. It could also be applied to biogas reforming reactions for the production of synthesis gas (precursor of liquid fuels), CO2 hydrogenation reactions applicable to Power-to-X systems, and functionalizing electrodes for fuel cells and/or high-temperature electrolyzer.
3D nanofabricated soft microrobots with super-compliant picoforce springs as onboard sensors and actuators
by Haifeng Xu et al in Nature Nanotechnology
Researchers at the Chemnitz University of Technology, the Shenzhen Institute of Advanced Technology of the Chinese Academy of Sciences and the Leibniz IFW Dresden, in a recent publication in Nature Nanotechnology, have demonstrated that controllable springs can be integrated at arbitrary chosen locations within soft three-dimensional structures using confocal photolithographic manufacturing (with nanoscale precision) of a novel magnetically active material in the form of a photoresist impregnated with customizable densities of magnetic nanoparticles.
The integration of mechanical memory in the form of springs has for hundreds of years proven to be a key enabling technology for mechanical devices (such as clocks), achieving advanced functionality through complex autonomous movements. Currently, the integration of springs in silicon-based microtechnology has opened the world of planar mass-producible mechatronic devices from which we all benefit, via air-bag sensors for example.
For a new generation of minimally and even non-invasive biomedical applications however, mobile devices that can safely interact mechanically with cells must be achieved at much smaller scales (10 microns) and with much softer forces (pico Newton scale, i.e., lifting weights less than one millionth of a mg) and in customized three-dimensional shapes.
These “picosprings” have a remarkably large and tunable compliancy and can be controlled remotely through magnetic fields (even deep within the human body) allowing articulated motion in microrobots as well as micromanipulations well beyond the state of the art.
Moreover, the extension of the picosprings can also be used visually to measure forces, for example propulsion or grasping forces, in interaction with other objects like cells. For example, these picosprings have been used to measure the locomotive propulsion force of sperm cells.
The publication showcases these capabilities by demonstrating several microbots (including a micropenguin) containing picosprings at multiple locations that can do these tasks at cellular scales: propel themselves, grasp and release cells and measure the minute forces needed to do this safely.
“Micropenguin” with picospring flippers swimming through fluid. Credit: Jacob Müller
Dr. Haifeng Yu, first author of the study and group leader at the Chinese Academy of Sciences in Shenzhen (China), says, “Programmable elasticity at the micrometer scale offers a feasible strategy for producing 3D devices and finely structured ‘micro-surgeons’ capable of performing complex medical tasks.”
Dr. Mariana Medina-Sanchez, group leader at the Leibniz IFW and BCUBE- TU Dresden, co-author and co-supervisor of this work, adds, “These picospring-based micromachines with programmable elasticity and magnetism, crafted through monolithic fabrication, open numerous possibilities for localized force sensing and actuation in low Reynolds number environments. This versatility underscores their significance across a spectrum of biomedical applications.”
Prof. Oliver Schmidt, who is last author of the paper and supervised this work, sees this as another important step in the transition toward life-ready soft and smart modular microrobotics.
“Remotely controlled microdevices using magnetic fields form a particularly promising technology for non-invasive medical applications — and now this extends to mechanical mechanisms inside these remote microdevices,” says Schmidt.
“Being able to incorporate designer springs will also add a new tool to the growing capability at TU Chemnitz towards microelectronic morphogenesis and artificial life,” adds Prof. John McCaskill, co-author of the study, member of the Research Center MAIN, and founding director of the European Center for Living Technology.
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