TL;DR
- Carbon nanotubes woven into thread-like fibers and sewn into fabrics become a thermoelectric generator that can turn heat from the sun or other sources into other forms of energy.
- Researchers recently completed a study that has the potential to improve cancer treatment for colorectal cancer and melanoma by using nanotechnology to deliver chemotherapy in a way that makes it more effective against aggressive tumors.
- Physicists from the University of Southampton and ETH ZĂźrich have reached a new threshold of light-matter coupling at the nanoscale.
- Researchers are developing novel asthma therapeutics using gene-silencing nanocapsules in a bid to help patients who arenât benefiting from existing treatments.
- A research team has recently synthesized a chemo-enzymatic nanostructure that can selectively synthesize one enantiomer while acting as an artificial organelle in the cell.
- âGrowingâ electronic components directly onto a semiconductor block avoid messy, noisy oxidation scattering that slows and impedes electronic operation. A new study shows that the resulting high-mobility components are ideal candidates for high-frequency, ultra-small electronic devices, quantum dots, and qubit applications in quantum computing.
- Researchers have developed a novel method for imaging vibrations and movements of atoms in catalysts. The new method makes it possible to identify and locate the individual atoms in the nanoparticle, even if they are vibrating and moving.
- Membrane electrode assembly is the core part of proton exchange membrane fuel cells (PEMFCs). However, the high consumption of platinum and poor durability of carbon-supported platinum nanoparticles (Pt/C) in the conventional cathode prohibit the large-scale commercialization of fuel cell vehicles. Recently, a group of scientists designed a highly durable biomimetic nanotrough electrode for PEMFCs.
- Although some people say that baldness is the ânew sexy,â for those losing their hair, it can be distressing. An array of over-the-counter remedies are available, but most of them donât focus on the primary causes: oxidative stress and insufficient circulation. Now, researchers have designed a preliminary microneedle patch containing cerium nanoparticles to combat both problems, regrowing hair in a mouse model faster than a leading treatment.
- Developing better nanopore technology.
- And more!
Nanotech Market
Nanotechnology deals with the ability to see, understand, measure, predict, produce or control matter at 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 potential to design risk-free and effective immunization strategies. In the post COVID-19 period, 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.
Latest News & Researches
Macroscopic weavable fibers of carbon nanotubes with giant thermoelectric power factor
by Natsumi Komatsu, Yota Ichinose, Oliver S. Dewey, Lauren W. Taylor, Mitchell A. Trafford, Yohei Yomogida, Geoff Wehmeyer, Matteo Pasquali, Kazuhiro Yanagi, Junichiro Kono in Nature Communications
Invisibly small carbon nanotubes aligned as fibers and sewn into fabrics become a thermoelectric generator that can turn heat from the sun or other sources into other forms of energy.
The Rice University lab of physicist Junichiro Kono led an effort with scientists at Tokyo Metropolitan University and the Rice-based Carbon Hub to make custom nanotube fibers and test their potential for large-scale applications.
Their small-scale experiments led to a fiber-enhanced, flexible cotton fabric that turned heat energy into enough electrical energy to power an LED. With further development, they say such materials could become building blocks for fiber and textile electronics and energy harvesting.
The same nanotube fibers could also be used as heat sinks to actively cool sensitive electronics with high efficiency.
The effect seems simple: If one side of a thermoelectric material is hotter than the other, it produces usable energy. The heat can come from the sun or other devices like the hotplates used in the fabric experiment. Conversely, adding energy can prompt the material to cool the hotter side.
Until now, no macroscopic assemblies of nanomaterials have displayed the necessary âgiant power factor,â about 14 milliwatts per meter kelvin squared, that the Rice researchers measured in carbon nanotube fibers.
âThe power factor tells you how much power density you can get out of a material upon certain temperature difference and temperature gradient,â said Rice graduate student Natsumi Komatsu, lead author of the paper. She noted a materialâs power factor is a combined effect from its electrical conductivity and whatâs known as the Seebeck coefficient, a measure of its ability to translate thermal differences into electricity.
âThe ultrahigh electrical conductivity of this fiber was one of the key attributes,â Komatsu said.
The source of this superpower also relates to tuning the nanotubesâ inherent Fermi energy, a property that determines electrochemical potential. The researchers were able to control the Fermi energy by chemically doping the nanotubes made into fibers by the Rice lab of co-author and chemical and biomolecular engineer Matteo Pasquali, allowing them to tune the fibersâ electronic properties.
While the fibers they tested were cut into centimeter lengths, Komatsu said thereâs no reason devices canât make use of the excellent nanotube fibers from the Pasquali lab that are spooled in continuous lengths. âNo matter where you measure them, they have the same very high electrical conductivity,â she said. âThe piece I measured was small only because my setup isnât capable of measuring 50 meters of fiber.â
Pasquali is director of the Carbon Hub, which promotes expanding the development of carbon materials and hydrogen in a way that also fundamentally changes how the world uses fossil hydrocarbons.
âCarbon nanotube fibers have been on a steady growth path and are proving advantageous in more and more applications,â he said. âRather than wasting carbon by burning it into carbon dioxide, we can fix it as useful materials that have further environmental benefits in electricity generation and transportation.â
Whether the new research leads to a solar panel you can throw in the washing machine remains to be seen, but Kono agreed the technology has great and varied potential.
âNanotubes have been around for 30 years, and scientifically, a lot is known,â he said. âBut in order to make real-world devices, we need macroscopically ordered or crystalline assemblies. Those are the types of nanotube samples that Matteoâs group and my group can make, and there are many, many possibilities for applications.â
Co-authors of the paper are Rice graduate students Oliver Dewey, Lauren Taylor and Mitchell Trafford and Geoff Wehmeyer, an assistant professor of mechanical engineering; and Yota Ichinose, Professor Yohei Yomogida, and Professor Kazuhiro Yanagi of Tokyo Metropolitan University.
Kono is the Karl F. Hasselmann Professor in Engineering and a professor of electrical and computer engineering, of physics and astronomy and of materials science and nanoengineering. Pasquali is the A.J. Hartsook Professor of Chemical and Biomolecular Engineering and a professor of chemistry and of materials science and nanoengineering.
Immunogenic camptothesome nanovesicles comprising sphingomyelin-derived camptothecin bilayers for safe and synergistic cancer immunochemotherapy
by Zhiren Wang, Nicholas Little, Jiawei Chen, Kevin Tyler Lambesis, Kimberly Thi Le, Weiguo Han, Aaron James Scott, Jianqin Lu in Nature Nanotechnology
University of Arizona Health Sciences researchers recently completed a study that has the potential to improve cancer treatment for colorectal cancer and melanoma by using nanotechnology to deliver chemotherapy in a way that makes it more effective against aggressive tumors.
âIâve always been interested in harnessing the intrinsic immunity to fight against cancer,â said Jianqin Lu, BPharm, PhD, assistant professor of pharmaceutics and pharmacokinetics in the UArizona College of Pharmacyâs Department of Pharmacology and Toxicology and associate member of the UArizona Cancer Center. âTo do this in a safe and effective way, nanotechnology comes into play because of its ability to improve drug movement and therapeutic efficacy, as well as the potential to reduce systemic toxicities. My hope is that these innovative nanotherapeutics and therapeutic regimens eventually will help cancer patients combat cancers more effectively and safely.â
Immunotherapies help boost the immune systemâs ability to fight off cancer cells. Immune checkpoints are regulators of the immune system, which are pivotal in preventing the body from attacking healthy cells indiscriminately. Some types of cancer circumvent these checkpoints, allowing cancerous cells to avoid detection and continue to spread. Immune checkpoint blockade (ICB) is a newer therapy that can essentially ârelease the brakesâ on the immune system and help the body fight back.
ICB therapies are effective for some types of cancer, but they donât work for every patient. For example, only approximately 4% of patients with colorectal cancer, the second leading cause of cancer-related deaths in U.S., will respond to ICB therapy, Dr. Lu said.
Recent research has focused on ways to enhance the power of ICB therapies by combining them with chemotherapeutic agents such as camptothecin. Though camptothecin is potent, it is also unstable, has poor solubility in water and can have serious side effects for healthy cells.
Dr. Lu and the research team created the first nanotherapeutic platform of its kind to overcome these hurdles. Using a nanotechnology delivery method, researchers enhanced camptothecinâs ability to synergize with ICB therapies, making them more effective against aggressive tumors.
âTo render a more effective ICB therapy, we have developed a nanotherapeutic platform that can switch the tumors from âimmune-coldâ to âimmune-hot,ââ said Dr. Lu, who is also a member of the BIO5 Institute and the Southwest Environmental Health Sciences Center. âAs a result, this nanotherapeutic platform was able to increase the effectiveness of the ICB therapy to eradicate a large portion of early-stage colorectal cancer tumors while concurrently activating the bodyâs memory immunity, preventing tumor recurrence.â
The team attached camptothecin to sphingomyelin, a naturally occuring lipid found on the surface of cells. The combination of the two molecules into a nanovesicle called camptothesome stabilized camptothecin, improving its efficacy and diminishing systemic toxicities. The nanotech delivery method also improved the tumor uptake of the camptothesome in a rodent model, where it deeply penetrated the tumour with efficient release of the chemotherapy.
Dr. Lu and the research team then created a way to load an immune checkpoint inhibitor targeting one of the key checkpoints, indoleamine 2,3-dioxygenase (IDO1), inside of the camptothesomes. When combined with inhibitors targeting other immune checkpoints known as PD-L1 and PD-1, this nanotherapeutic strategy eliminated a significant portion of clinically difficult-to-treat late-stage metastatic colorectal cancer and melanoma tumors, paving the pathway for further studies.
Polaritonic nonlocality in lightâmatter interaction
by Shima Rajabali, Erika Cortese, Mattias Beck, Simone De Liberato, JĂŠrĂ´me Faist, Giacomo Scalari in Nature Photonics
Physicists from the University of Southampton and ETH ZĂźrich have reached a new threshold of light-matter coupling at the nanoscale.
The international research, combined theoretical and experimental findings to establish a fundamental limitation of our ability to confine and exploit light.
The collaboration focussed on photonic nano-antennas fabricated in ever reducing sizes on the top of a two-dimensional electron gas. The setup is commonly used in laboratories all over the world to explore the effect of intense electromagnetic coupling, taking advantage of the antennasâ ability to trap and focus light close to electrons.
Professor Simone De Liberato, Director of the Quantum Theory and Technology group at the University of Southampton, says: âThe fabrication of photonic resonators able to focus light in extremely small volumes is proving a key technology which is presently enabling advances in fields as different as material science, optoelectronics, chemistry, quantum technologies, and many others.
âIn particular, the focussed light can be made to interact extremely strongly with matter, making electromagnetism non-perturbative. Light can then be used to modify the properties of the materials it interacts with, thus becoming a powerful tool for material science. Light can be effectively woven into novel materials.â
Scientists discovered that light could no longer be confined in the system below a critical dimension, of the order of 250nm in the sample under study, when the experiment started exciting propagating plasmons. This caused waves of electrons to move away from the resonator and spill the energy of the photon.
Experiments performed in the group of Professors JĂŠrĂ´me Faist and Giacomo Scalari at ETH ZĂźrich had obtained results that could not be interpreted with state-of-the-art understanding of light-matter coupling. The physicists approached Southamptonâs School of Physics and Astronomy, where researchers led theoretical analysis and built a novel theory able to quantitatively reproduce the results.
Professor De Liberato believes the newfound limits could yet be exceeded by future experiments, unlocking dramatic technological advances that hinge on ultra-confined electromagnetic fields.
âIt has been said that proofs of impossibility are only proofs of a lack of imagination,â he explains. âThis is not the first time that a âfundamental limitâ on how tightly we can focus light has been discovered. The most famous is the Abbe diffraction limit, from 19th century German physicist Ernst Abbe, which says light canât be confined in a volume smaller than a cubic wavelength. Nanophotonics is a very active and successful field of research that is studying different ways to break out of Abbe limit. I think the next step will be to use some ingenuity and look for novel ways to confine light, bypassing both Abbe limit and the one we have just discovered.â
A GATA3 Targeting Nucleic Acid Nanocapsule for In Vivo Gene Regulation in Asthma
by Tyler D. Gavitt, Alyssa K. Hartmann, Shraddha S. Sawant, Arlind B. Mara, Steven M. Szczepanek, Jessica L. Rouge in ACS Nano
Steroid-based inhalers deliver life-saving medication for millions of asthma sufferers, providing relief and the ability to simply breathe. Unfortunately, inhalers do not work for all patients, and with rates on the rise for a disease that leads to hundreds of thousands of deaths world-wide each year, new asthma treatments and strategies are needed.
A team of UConn researchers â including Assistant Professor of Chemistry in the College of Liberal Arts and Sciences Jessica Rouge and Associate Professor of Pathobiology in the College of Agriculture, Health, and Natural Resources Steven Szczepanek â are collaborating to develop novel asthma therapeutics using gene-silencing nanocapsules in a bid to help patients who arenât benefiting from existing treatments.
âWhen treating asthma, many people think of small molecule anti-inflammatory medications as the way to go, but there are plenty of patients who have asthma who do not respond to corticosteroids,â says Rouge. âThereâs an unmet need for creating different therapeutics that can suppress asthma for this group of people.â
Rougeâs research group, including co-authors Ph.D. student Shraddha Sawant and Alyssa Hartmann â20 Ph.D., designs nanomaterials and targeted therapeutics that deliver gene silencing messages to cells. This paper details a nucleic acid nanocapsule (NAN) designed to selectively deliver an enzyme, called a DNAzyme, to silence a component of the immune response, called GATA-3, that leads to the over-expression of immune components that play a significant role in allergic asthma attacks.
Szczepanek explains there are different types of asthma, and this technology is designed to treat allergic asthma specifically, which constitutes about 50% of cases in adults and 90% in children. GATA-3-based treatments are already showing promise in clinical trials, and Rouge says that by pairing the sequence with nanotechnology, they hope to provide more efficient means of delivery and treatment straight to the source of inflammation.
âWhen using nanomaterials, we try to administer the therapy in a way that could allow us to use less materials to get a bigger effect,â Rouge says.
Their system is based on surfactants that assemble into micelles, similar to tiny bubbles, and occurs in a stepwise process, resulting in each being around 60 nanometers in size.
âFirst, we synthesize something called a surfactant, itâs much like soap and essentially forms a nanoscale bubble. Then we modify the surface chemistry of this bubble so it can conjugate or connect to DNA. The next step, and whatâs unique to our lab, is we use enzymes to build the next piece to attach the DNA sequence that essentially cleaves mRNA encoding GATA-3,â Rouge says.
The nanocaspules were then characterized and checked if they could cleave the nucleic acid target cell lines in vitro and the results were promising.
âWe showed these gene-silencing sequences were effectively delivered using our formulation and we saw that they knocked down the gene target of interest. That was an exciting first step,â says Rouge.
Rouge brought the data to Szczepanek to see if his research group, including co-authors and graduate students Tyler Gavitt â21 Ph.D. and Arlind Mara â21 Ph.D., who study respiratory pathogens and disease pathology, would be interested in collaborating on the next steps of research to see how technology performed in vivo and if it could be of clinical relevance.
Having studied asthma as part of his post-doctoral research, and with his lab equipped for taking the next steps, Szczepanek says the collaboration was a natural fit.
âI thought this gene silencing technology was a fantastic application for an asthma therapeutic.â
The researchers tested the GATA-3 DNAzyme-NAN efficacy in an allergic asthma mouse model sensitive to house dust mites. The results showed the lungs of mice treated with the NANs had less inflammatory damage compared to the untreated control group. The treatment also reduced the presence of inflammatory immune cells, called eosinophils, which contribute to airway obstruction.
âNot only did we see a substantial reduction of asthma phenotypes in our mouse model, but we tested the GATA-3 DNAzyme-NANs in human white blood cells and saw both uptake of the nanoparticles and knock-down of expression of the gene of interest. This combination of data makes me really hopeful about the translational potential of the nanoparticles for human health,â says Szczepanek.
Rouge points out another important detail: âGenerally speaking, when putting nanoparticles in our lungs, you might think they could cause inflammation. However, we were really excited that at doses we used, the nanocarrier alone didnât cause inflammation.â
âI believe our unique nanoconstruct holds great promise in the field of oligonucleotide delivery,â says Sawant. âI am happy to be a part of this collaborative research as it marks the beginning of the development of the NAN as an effective in vivo nanocarrier.â
Rouge says the next step is to hopefully get NIH funding to continue the research: âWe want to figure out, Where do these nanocapsules go? We need to do a biodistribution study and other logical next steps, like pharmacokinetics and determining how long these therapeutics last in an organism.â
The researchers were recently awarded a patent for the nanocapsule formulation, and they hope to commercialize it. Szczepanek explains the team envisions that, eventually, the technology could be delivered to the patient via an inhaler, like current asthma medications are and, depending on exactly how it is formulated, that it could target active inflammation or act as a prophylactic measure. Rouge adds that this technology has the potential to be customizable.
âThe major theme is that different people respond differently to diseases in general, so there is the potential for personalized medicine. We are looking toward a paradigm shift because if you know the genetics of somebody in terms of the intensity or overexpression of a particular gene or if it is upregulated, we could treat it or at least depress it.â
Silica JarâwithâLid as ChemoâEnzymatic NanoâCompartment for Enantioselective Synthesis inside Living Cells
by Seonock Kim, Nitee Kumari, Jongwon Lim, Sateesh Dubbu, Amit Kumar, In Su Lee in Angewandte Chemie International Edition
As COVID-19 vaccinations are well underway, people await a return to normal life. However, fears also grow due to unforeseen side effects like rare thrombosis. In the body, life is maintained by the movement of substances or energy. Chemical reactions are regulated by the presence of organelles or core structures of cells that accommodate specific enzymes or cofactors. A nanoreactor with both the activity of a synthetic catalyst, such as an artificial organelle that mimics a cell, and the properties of an enzyme creates a platform for selectively synthesizing natural enantiomeric bioactive molecules that can respond to pathogens â such as drugs â in the body. However, until now, a nanoreactor with the functions of both a synthetic catalyst and an enzyme for such a platform has not been reported.
To this, a research team at POSTECH has recently synthesized a chemo-enzymatic nanostructure that can selectively synthesize one enantiomer while acting like an artificial organelle in the cell.
A research team led by Professor In Su Lee, Research Professor Amit Kumar, and Ph.D. candidate Seonock Kim of POSTECHâs Department of Chemistry has succeeded in designing a silica nanostructure (SiJAR) as an artificial organelle for selective synthesis of enantiomers in cells.
The first consideration in designing nanostructures for intracellular applications is to stably co-localize and maintain the reactive surface of catalytic nanocrystals while protecting the enzyme from inactivation. Until now, the catalysis of nature-inspired hollow nanostructures accommodating catalytic nanocrystals or enzymes, or both, has only been experimentally proven and has not been demonstrated in living organisms. This is because microporous closed nanostructures restrict the entry and co-localization of catalytic nanocrystals and large-size biomolecules.
The research team synthesized round jar-shaped SiJARs with chemo-responsive metal-silicate lids by modifying the chemical composition of a section in the reactor using spatiotemporal-controlled thermal conversion chemistry. Due to the divided configuration of SiJAR, different catalytic noble metals (Pt, Pd, Ru) were selectively modified on the lid-section by galvanic reactions. Subsequently, the lid was opened under mild acidic conditions or an intracellular environment, creating a wide-passage into the shell while shifting the residual metal catalyst of the lid inwards. This open structure accommodates large enzymes, thus facilitating encapsulation.
The nanoreactor synthesized in this study is composed of silica with high biocompatibility and by protecting catalytic nanocrystals or large biomolecules in an open-mouth silica-compartment, it performed asymmetric aldol reaction with high enantioselectivity via an enzyme-metal co-operative transition state stabilization. In addition, the researchers confirmed that it functions as an artificial catalytic organelle by stably performing the reaction inside living cells.
The hybrid chemoenzymatic nanodevice, customizable through this sophisticated solid-state conversion strategy, has a structure and function similar to that of intracellular organelles, and can be utilized for synthesizing active therapeutics and bioimaging probes locally inside cells to be suitable for use in next generation bioimaging and treatment.
âWith the results of this research using the unique Nanospace-Confined Chemical Reactions (NCCR), we look forward to developing the technology that artificially regulates cell functions,â commented Professor In Su Lee who led the study.
Probing atom dynamics of excited Co-Mo-S nanocrystals in 3D
by Fu-Rong Chen, Dirk Van Dyck, Christian Kisielowski, Lars P. Hansen, Bastian Barton, Stig Helveg in Nature Communications
A group of leading electron microscopy and catalysis researchers have in recent years been working to determine the three-dimensional arrangements of atoms in nanoparticle catalysts in chemical processes. Their work has combined experimental measurements with mathematical modelling.
The result is a new method that makes it possible to identify and locate the individual atoms in the nanoparticle, even if they are vibrating and moving.
Until now, atoms in nanoparticles have been expected to be static during observations. But the researchersâ analyses of 3D atomic-scale images demonstrated that the original expectation is not sufficient. Instead, the researchers revealed a dynamic behavior of the atoms using a new analytical method.
In their work, the researchers have chosen to use a well-known catalytic nanoparticle material, namely molybdenum disulfide. Since the atomic structure of the material is well-known, it provided a good basis for interpreting the research groupâs 3D atomic-resolved images compiled using the unique TEAM 0.5 electron microscope at Lawrence Berkeley National Laboratory, which offers the highest picometre-scale resolution in the world.
The mathematical model makes it possible to identify the individual atoms in the nanoparticle, even if they are moving. The model measures both the intensity and width of the atoms in the images.
âUntil now, determining which atom we are observing has been challenging due to blurring caused by the oscillations of the atoms. However, by factoring in the oscillations, we can more accurately identify, for example, the location of individual sulphur or molybdenum atoms,â says Professor Stig Helveg, DTU Physics, who is part of the research group.
The new model also makes it possible to correct alterations of the nanoparticles in the form of oscillations resulting from the illumination of energetic electrons in the electron microscope. It will thus make it possible to focus on the chemical information hidden in the images atom by atom â and this is the essense of the research.
The researchers hope that the new groundbreaking model will find use by other researchers within their field. The model will also provide a basis for the work of Stig Helvegâs new basic research centre at DTU, VISION.
Here, the focus will be on going one step beyond by combining the atomic-resolved images with measurements of the catalytic properties of the nanoparticles. The knowledge produced will contribute to the development of nanoparticles for catalytic processes as part of the transition to sustainable energy.
Free-standing and ionomer-free 3D platinum nanotrough fiber network electrode for proton exchange membrane fuel cells
by Manman Qi et al . in Applied Catalysis B: Environmental
Membrane electrode assembly is the core part of proton exchange membrane fuel cells (PEMFCs). However, the high consumption of platinum and poor durability of carbon supported platinum nanoparticles (Pt/C) in the conventional cathode prohibit the large-scale commercialization of fuel cell vehicles. Recently, a group led by Prof. Shao Zhigang and Hou Ming from the Dalian Institute of Chemical Physics (DICP) of the Chinese Academy of Sciences (CAS), in collaboration with Prof. Wu Gang from the State University of New York at Buffalo, designed a highly-durable biomimetic nanotrough electrode for PEMFCs. The electrode is a nanotrough-like catalyst layer (NTCL) with low Pt loading and enhanced durability.
The researchers adopted a facile template-assisted method to construct the nanotrough catalyst layer by electrospinning and magnetron sputtering.
They observed the water in-situ formed on the Pt nanotrough electrode and conventional Pt/C electrode by the environmental scanning electron microscopy (ESEM), which verified a similar water repelling mechanism of the Pt nanotrough electrode with gramineous plants.
The Pt nanotrough catalyst layer realized effective water management due to the biomimetic architecture and anisotropic surface.
âWe achieved a peak power density of 22.26 W mgPt-1 with a platinum loading of 42 Îźg cm-2 in the cathode, which was 1.27-fold higher than the conventional Pt/C electrode,â said Prof. HOU.
Furthermore, they achieved ultrahigh durability in the accelerated stress tests. âThis may be attributed to a self-healing mechanism that involves Pt dissolution and re-deposition,â said Prof. SHAO.
High electron mobility and low noise quantum point contacts in an ultra-shallow all-epitaxial metal gate GaAs/AlxGa1âxAs heterostructure
by Y. Ashlea Alava, D. Q. Wang, C. Chen, D. A. Ritchie, O. Klochan, A. R. Hamilton in Applied Physics Letters
âGrowingâ electronic components directly onto a semiconductor block avoids messy, noisy oxidation scattering that slows and impedes electronic operation.
A UNSW study out this month shows that the resulting high-mobility components are ideal candidates for high-frequency, ultra-small electronic devices, quantum dots, and for qubit applications in quantum computing.
Making computers faster requires ever-smaller transistors, with these electronic components now only a handful of nanometres in size. (There are around 12 billion transistors in the postage-stamp sized central chip of modern smartphones.)
However, in even smaller devices, the channel that the electrons flow through has to be very close to the interface between the semiconductor and the metallic gate used to turn the transistor on and off. Unavoidable surface oxidation and other surface contaminants cause unwanted scattering of electrons flowing through the channel, and also lead to instabilities and noise that are particularly problematic for quantum devices.
âIn the new work we create transistors in which an ultra-thin metal gate is grown as part of the semiconductor crystal, preventing problems associated with oxidation of the semiconductor surface,â says lead author Yonatan Ashlea Alava.
âWe have demonstrated that this new design dramatically reduces unwanted effects from surface imperfections, and show that nanoscale quantum point contacts exhibit significantly lower noise than devices fabricated using conventional approaches,â says Yonatan, who is a FLEET PhD student.
âThis new all single-crystal design will be ideal for making ultra-small electronic devices, quantum dots, and for qubit applications,â comments group leader Prof Alex Hamilton at UNSW.
Semiconductor devices are a staple of modern-day electronics. Field-effect transistors (FETs) are one of the building blocks of consumer electronics, computers and telecommunication devices.
High electron-mobility transistors (HEMTs) are field-effect transistors that combine two semiconductors with different bandgap (ie, they are âheterostructuresâ) and are widely used for high-power, high-frequency applications such as cell phones, radar, radio and satellite communications.
These devices are optimised to have high conductivity (in comparison to conventional MOSFET devices) to provide lower device noise and enable higher frequency operations. Improving electron conduction within these devices should directly improve device performance in critical applications.
The quest to make increasingly smaller electronic devices demands the conducting channel in HEMTs to be in close proximity to the surface of the device. The challenging part, which has troubled many researchers over the years, has its roots in simple electron transport theory:
When electrons travel in solids, the electrostatic force due to unavoidable impurities/charge in the environment causes the electron trajectory to deviate from the original path: the so-called âelectron scatteringâ process. The more scattering events, the more difficult it is for electrons to travel in the solid, and thus the lower the conductivity.
The surface of semiconductors often has high levels of unwanted charge trapped by the unsatisfied chemical bonds- or âdanglingâ bonds â of the surface atoms. This surface charge causes scattering of electrons in the channel and reduces the device conductivity. As a consequence, when the conducting channel is brought close to the surface, the performance/conductivity of the HEMT plunges rapidly.
Additionally, surface charge creates local potential fluctuations which, apart from lowering the conductivity, result in charge-noise in sensitive devices such as quantum point contacts and quantum dots.
Collaborating with wafer growers at Cambridge University, the team at UNSW Sydney showed that the problem associated with surface charge can be eliminated by growing an epitaxial aluminium gate before removing the wafer from the growth chamber.
âWe confirmed the performance improvement via characterisation measurements in the lab at UNSW,â says co-author Dr Daisy Wang.
The team compared shallow HEMTs fabricated on two wafers with nearly-identical structures and growth conditions â one with an epitaxial aluminium gate, and a second with an ex-situ metal gate deposited on an aluminium oxide dielectric.
They characterised the devices using low-temperature transport measurements and showed the epitaxial gate design greatly reduced surface-charge scattering, with up to 2.5Ă increase in conductivity.
They also showed that the epitaxial aluminium gate can be patterned to make nanostructures. A quantum-point contact fabricated using the proposed structure showed robust and reproducible 1D conductance quantisation, with extremely low charge noise.
The high conductivity in ultra-shallow wafers, and the compatibility of the structure with reproducible nano-device fabrication, suggests that MBE-grown aluminium gated wafers are ideal candidates for making ultra-small electronic devices, quantum dots, and for qubit applications.
Understanding Electrical Conduction and Nanopore Formation During Controlled Breakdown
by Jasper P. Fried et al. in Small
At the simplest of levels, nanopores are (nanometre-sized) holes in an insulating membrane. The hole allows ions to pass through the membrane when a voltage is applied, resulting in a measurable current. When a molecule passes through a nanopore it causes a change in the current, this can be used to characterize and even identify individual molecules. Nanopores are extremely powerful single-molecule biosensing devices and can be used to detect and sequence DNA, RNA, and even proteins. Recently, it has been used in the SARS-CoV-2 virus sequencing.
Solid-state nanopores are an extremely versatile type of nanopore formed in ultrathin membranes (less than 50 nanometres), made from materials such as silicon nitride (SiNx). Solid-state nanopores can be created with a range of diameters and can withstand a multitude of conditions. One of the most appealing techniques with which to fabricate nanopores is Controlled Breakdown (CBD). This technique is quick, reduces fabrication costs, does not require specialized equipment, and can be automated.
CBD is a technique in which an electric field is applied across the membrane to induce a current. At some point, a spike in the current is observed, signifying pore formation. The voltage is then quickly reduced to ensure the fabrication of a single, small nanopore.
The mechanisms underlying this process have not been fully elucidated thus an international team involving ITQB NOVA decided to further investigate how electrical conduction through the membrane occurs during breakdown, namely how oxidation and reduction reactions (also called redox reactions, they imply electron loss or gain, respectively) influence the process. To do this, the team created three devices in which the electric field is applied to the membrane (a silicon-rich SiNx membrane) in different ways: via metal electrodes on both sides of the membrane; via electrolyte solutions on both sides of the membrane; and via a mixed device with a metal electrode on one side and an electrolyte solution on the other.
Results showed that redox reactions must occur at the membrane-electrolyte interface, whilst the metal electrodes circumvent this need. The team also demonstrated that, because of this phenomenon, nanopore fabrication could be localized to certain regions by performing CBD with metal microelectrodes on the membrane surface. Finally, by varying the content of silicon in the membrane, the investigators demonstrated that conduction and nanopore formation is highly dependent on the membrane material since it limits the electrical current in the membrane.
âControlling the location of nanopores has been of interest to us for a number of yearsâ, says James Yates. Pedro Sousa adds that âour findings suggest that CBD can be used to integrate pores with complementary micro or nanostructures, such as tunneling electrodes or field-effect sensors, across a range of different membrane materials.â
These devices may then be used for the detection of specific molecules, such as proteins, DNA, or antibodies, and applied to a wide array of scenarios, including pandemic surveillance or food safety.
Ceria Nanozyme-Integrated Microneedles Reshape the Perifollicular Microenvironment for Androgenetic Alopecia Treatment
by Anran Yuan, Fan Xia, Qiong Bian, Haibin Wu, Yueting Gu, Tao Wang, Ruxuan Wang, Lingling Huang, Qiaoling Huang, Yuefeng Rao, Daishun Ling, Fangyuan Li, Jianqing Gao in ACS Nano
Although some people say that baldness is the ânew sexy,â for those losing their hair, it can be distressing. An array of over-the-counter remedies are available, but most of them donât focus on the primary causes: oxidative stress and insufficient circulation. Now, researchers reporting in ACS Nano have designed a preliminary microneedle patch containing cerium nanoparticles to combat both problems, regrowing hair in a mouse model faster than a leading treatment.
The most common hair loss condition is called androgenic alopecia, also known as male- or female- pattern baldness. Hair loss is permanent for people with the condition because there arenât enough blood vessels surrounding the follicles to deliver nutrients, cytokines and other essential molecules. In addition, an accumulation of reactive oxygen species in the scalp can trigger the untimely death of the cells that form and grow new hair. Previously, Fangyuan Li, Jianqing Gao and colleagues determined that cerium-containing nanoparticles can mimic enzymes that remove excess reactive oxygen species, which reduced oxidative stress in liver injuries, wounds and Alzheimerâs disease. However, these nanoparticles cannot cross the outermost layer of skin. So, the researchers wanted to design a minimally invasive way to deliver cerium-containing nanoparticles near hair roots deep under the skin to promote hair regrowth.
As a first step, the researchers coated cerium nanoparticles with a biodegradable polyethylene glycol-lipid compound. Then they made the dissolvable microneedle patch by pouring a mixture of hyaluronic acid â a substance that is naturally abundant in human skin â and cerium-containing nanoparticles into a mold. The team tested control patches and the cerium-containing ones on male mice with bald spots formed by a hair removal cream. Both applications stimulated the formation of new blood vessels around the miceâs hair follicles. However, those treated with the nanoparticle patch showed faster signs of hair undergoing a transition in the root, such as earlier skin pigmentation and higher levels of a compound found only at the onset of new hair development. These mice also had fewer oxidative stress compounds in their skin. Finally, the researchers found that the cerium-containing microneedle patches resulted in faster mouse hair regrowth with similar coverage, density, and diameter compared with leading topical treatment and could be applied less frequently. Microneedle patches that introduce cerium nanoparticles into the skin are a promising strategy to reverse balding for androgenetic alopecia patients, the researchers say.
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