Amazing Science

A team of engineers at the University of Colorado Boulder has designed a new class of tiny, self-propelled robots that can zip through liquid at incredible speeds -- and may one day even deliver prescription drugs to hard-to-reach places inside the human body.

MIT researchers have developed a technique for precisely controlling the arrangement and placement of nanoparticles on a material, like the silicon used for computer chips, in a way that does not damage or contaminate the surface of the material. The technique, which combines chemistry and directed assembly processes with conventional fabrication techniques, enables the efficient formation of high-resolution, nanoscale features integrated with nanoparticles for devices like sensors, lasers, and LEDs, which could boost their performance.

Transistors and other nanoscale devices are typically fabricated from the top down—materials are etched away to reach the desired arrangement of nanostructures. But creating the smallest nanostructures, which can enable the highest performance and new functionalities, requires expensive equipment and remains difficult to do at scale and with the desired resolution.

A more precise way to assemble nanoscale devices is from the bottom up. In one scheme, engineers have used chemistry to "grow" nanoparticles in solution, drop that solution onto a template, arrange the nanoparticles, and then transfer them to a surface. However, this technique also involves steep challenges.

First, thousands of nanoparticles must be arranged on the template efficiently. And transferring them to a surface typically requires a chemical glue, large pressure, or high temperatures, which could damage the surfaces and the resulting device.

The MIT researchers developed a new approach to overcome these limitations. They used the powerful forces that exist at the nanoscale to efficiently arrange particles in a desired pattern and then transfer them to a surface without any chemicals or high pressures, and at lower temperatures. Because the surface material remains pristine, these nanoscale structures can be incorporated into components for electronic and optical devices, where even minuscule imperfections can hamper performance.

"This approach allows you, through engineering of forces, to place the nanoparticles, despite their very small size, in deterministic arrangements with single-particle resolution and on diverse surfaces, to create libraries of nanoscale building blocks that can have very unique properties, whether it is their light-matter interactions, electronic properties, mechanical performance, etc.," says Farnaz Niroui, the EE Landsman Career Development Assistant Professor of Electrical Engineering and Computer Science (EECS) at MIT. "By integrating these building blocks with other nanostructures and materials we can then achieve devices with unique functionalities that would not be readily feasible to make if we were to use the conventional top-down fabrication strategies alone."

Constructing a tiny robot from DNA and using it to study cell processes invisible to the naked eye. You would be forgiven for thinking it is science fiction, but it is in fact the subject of serious research by scientists from Inserm, CNRS and Université de Montpellier at the Structural Biology Center in Montpellier. This highly innovative "nano-robot" should enable closer study of the mechanical forces applied at microscopic levels, which are crucial for many biological and pathological processes. It is described in a new study published in Nature Communications.

All cells are subject to mechanical forces exerted on a microscopic scale, triggering biological signals essential to many cell processes involved in the normal functioning of our body or in the development of diseases. For example, the feeling of touch is partly conditional on the application of mechanical forces on specific cell receptors (the discovery of which was this year rewarded by the Nobel Prize in Physiology or Medicine). In addition to touch, these receptors that are sensitive to mechanical forces (known as mechanoreceptors) enable the regulation of other key biological processes such as blood vessel constriction, pain perception, breathing or even the detection of sound waves in the ear, etc.

The dysfunction of this cellular mechanosensitivity is involved in many diseases -- for example, cancer: cancer cells migrate within the body by sounding and constantly adapting to the mechanical properties of their microenvironment. Such adaptation is only possible because specific forces are detected by mechanoreceptors that transmit the information to the cell cytoskeleton.

At present, our knowledge of these molecular mechanisms involved in cell mechanosensitivity is still very limited. Several technologies are already available to apply controlled forces and study these mechanisms, but they have a number of limitations. In particular, they are very costly and do not allow us to study several cell receptors at a time, which makes their use very time-consuming if we want to collect a lot of data.

Mathematical simulations show the new approach may offer faster, cheaper, and more accurate detection, including identifying new variants.

A novel approach to testing for the presence of the virus that causes Covid-19 may lead to tests that are faster, less expensive, and potentially less prone to erroneous results than existing detection methods. Though the work, based on quantum effects, is still theoretical, these detectors could potentially be adapted to detect virtually any virus, the researchers say.

The new approach is described in a paper published on December 16, 2021, in the journal Nano Letters, by Changhao Li, an MIT doctoral student; Paola Cappellaro, a professor of nuclear science and engineering and of physics; and Rouholla Soleyman and Mohammad Kohandel of the University of Waterloo.

Existing tests for the SARS-CoV-2 virus include rapid tests that detect specific viral proteins, and polymerase chain reaction (PCR) tests that take several hours to process. Neither of these tests can quantify the amount of virus present with high accuracy. Even the gold-standard PCR tests might have false-negative rates of more than 25 percent. In contrast, the team’s analysis shows the new test could have false negative rates below 1 percent. The test could also be sensitive enough to detect just a few hundred strands of the viral RNA, within just a second.

Micro-sized cameras have great potential to spot problems in the human body and enable sensing for super-small robots, but past approaches captured fuzzy, distorted images with limited fields of view.

Now, researchers at Princeton University and the University of Washington have overcome these obstacles with an ultracompact camera the size of a coarse grain of salt. The new system can produce crisp, full-color images on par with a conventional compound camera lens 500,000 times larger in volume, the researchers reported in a paper published Nov. 29 in Nature Communications.

Enabled by a joint design of the camera's hardware and computational processing, the system could enable minimally invasive endoscopy with medical robots to diagnose and treat diseases, and improve imaging for other robots with size and weight constraints. Arrays of thousands of such cameras could be used for full-scene sensing, turning surfaces into cameras.

While a traditional camera uses a series of curved glass or plastic lenses to bend light rays into focus, the new optical system relies on a technology called a metasurface, which can be produced much like a computer chip. Just half a millimeter wide, the metasurface is studded with 1.6 million cylindrical posts, each roughly the size of the human immunodeficiency virus (HIV).

Each post has a unique geometry, and functions like an optical antenna. Varying the design of each post is necessary to correctly shape the entire optical wavefront. With the help of machine learning-based algorithms, the posts' interactions with light combine to produce the highest-quality images and widest field of view for a full-color metasurface camera developed to date.

A key innovation in the camera's creation was the integrated design of the optical surface and the signal processing algorithms that produce the image. This boosted the camera's performance in natural light conditions, in contrast to previous metasurface cameras that required the pure laser light of a laboratory or other ideal conditions to produce high-quality images, said Felix Heide, the study's senior author and an assistant professor of computer science at Princeton.

Inspired by nature, researchers at the Pacific Northwest National Laboratory (PNNL), along with collaborators from Washington State University, created a novel material capable of capturing light energy. This material provides a highly efficient artificial light-harvesting system with potential applications in photovoltaics and bioimaging.

The research provides a foundation for overcoming the difficult challenges involved in the creation of hierarchical functional organic-inorganic hybrid materials. Nature provides beautiful examples of hierarchically structured hybrid materials such as bones and teeth. These materials typically showcase a precise atomic arrangement that allows them to achieve many exceptional properties, such as increased strength and toughness.

PNNL materials scientist Chun-Long Chen, corresponding author of this study, and his collaborators created a new material that reflects the structural and functional complexity of natural hybrid materials. This material combines the programmability of a protein-like synthetic molecule with the complexity of a silicate-based nanocluster to create a new class of highly robust nanocrystals. They then programmed this 2D hybrid material to create a highly efficient artificial light-harvesting system.

“The sun is the most important energy source we have,” said Chen. “We wanted to see if we could program our hybrid nanocrystals to harvest light energy—much like natural plants and photosynthetic bacteria can—while achieving a high robustness and processibility seen in synthetic systems.” The results of this study were published May 14, 2021, in Science Advances. 

Researchers reporting in ACS’ Nano Letters have transformed copper nanowires into metal foams that could be used in facemasks and air filtration systems. The foams filter efficiently, decontaminate easily for reuse and are recyclable.

The ongoing COVID-19 pandemic highlights the severe health risks posed by deep submicrometer-sized airborne viruses and particulates in the spread of infectious diseases. There is an urgent need for the development of efficient, durable, and reusable filters for this size range. Scientists now report the realization of efficient particulate filters using nanowire-based low-density metal foams which combine extremely large surface areas with excellent mechanical properties. The metal foams exhibit outstanding filtration efficiencies (>96.6%) in the PM0.3 regime, with the potential for further improvement. Their mechanical stability, light weight, chemical and radiation resistance, ease of cleaning and reuse, and recyclability further make such metal foams promising filters for combating COVID-19 and other types of airborne particulates.

Researchers at Children's Hospital of Philadelphia and the School of Engineering and Applied Science at the University of Pennsylvania have identified ionizable lipid nanoparticles that could be used to deliver mRNA as part of fetal therapy. The proof-of-concept study, published today in Science Advances, engineered and screened a number of lipid nanoparticle formulations for targeting mouse fetal organs and has laid the groundwork for testing potential therapies to treat genetic diseases before birth.

"This is an important first step in identifying nonviral mediated approaches for delivering cutting-edge therapies before birth," said co-senior author William H. Peranteau, MD, an attending surgeon in the Division of General, Thoracic and Fetal Surgery and the Adzick-McCausland Distinguished Chair in Fetal and Pediatric Surgery at CHOP. "These lipid nanoparticles may provide a platform for in utero mRNA delivery, which would be used in therapies like fetal protein replacement and gene editing."

Recent advances in DNA sequencing technology and prenatal diagnostics have made it possible to diagnose many genetic diseases before birth. Some of these diseases are treated by protein or enzyme replacement therapies after birth, but by then, some of the damaging effects of the disease have taken hold. Thus, applying therapies while the patient is still in the womb has the potential to be more effective for some conditions. The small fetal size allows for maximal therapeutic dosing, and the immature fetal immune system may be more tolerant of replacement therapy.

Of the potential vehicles for introducing therapeutic protein replacement, mRNA is distinct from other nucleic acids, such as DNA, because it does not need to enter the nucleus and can use the body's own machinery to produce the desired proteins. Currently, the common methods of nucleic acid delivery include viral vectors and nonviral approaches. Although viral vectors may be well-suited to gene therapy, they come with the potential risk of unwanted integration of the transgene or parts of the viral vector in the recipient genome. Thus, there is an important need to develop safe and effective nonviral nucleic acid delivery technologies to treat prenatal diseases.

MIT engineers designed a tiny “brain-on-a-chip” from tens of thousands of artificial brain synapses known as memristors — silicon-based components that mimic the information-transmitting synapses in the human brain.

The researchers borrowed from principles of metallurgy to fabricate each memristor from alloys of silver and copper, along with silicon. When they ran the chip through several visual tasks, the chip was able to “remember” stored images and reproduce them many times over, in versions that were crisper and cleaner compared with existing memristor designs made with unalloyed elements.

Their results, published today in the journal Nature Nanotechnology, demonstrate a promising new memristor design for neuromorphic devices — electronics that are based on a new type of circuit that processes information in a way that mimics the brain’s neural architecture. Such brain-inspired circuits could be built into small, portable devices, and would carry out complex computational tasks that only today’s supercomputers can handle.

“So far, artificial synapse networks exist as software. We’re trying to build real neural network hardware for portable artificial intelligence systems,” says Jeehwan Kim, associate professor of mechanical engineering at MIT. “Imagine connecting a neuromorphic device to a camera on your car, and having it recognize lights and objects and make a decision immediately, without having to connect to the internet. We hope to use energy-efficient memristors to do those tasks on-site, in real-time.”

Researchers from the University of Cambridge used a numerical experiment to determine the limits of matt structural color – a phenomenon which is responsible for some of the most intense colors in nature – and found that it extends only as far as blue and green in the visible spectrum. The results, published in PNAS, could be useful in the development of non-toxic paints or coatings with intense color that never fades.

Structural color, which is seen in some bird feathers, butterfly wings or insects, is not caused by pigments or dyes, but internal structure alone. The appearance of the color, whether matt or iridescent, will depending on how the structures are arranged at the nanoscale.

Ordered, or crystalline, structures result in iridescent colors, which change when viewed from different angles. Disordered, or correlated, structures result in angle-independent matt colors, which look the same from any viewing angle. Since structural color does not fade, these angle-independent matt colors would be highly useful for applications such as paints or coatings, where metallic effects are not wanted. “In addition to their intensity and resistance to fading, a matt paint which uses structural color would also be far more environmentally-friendly, as toxic dyes and pigments would not be needed,” said first author Gianni Jacucci from Cambridge’s Department of Chemistry. “However, we first need to understand what the limitations are for recreating these types of colors before any commercial applications are possible.”

“Most of the examples of structural color in nature are iridescent – so far, examples of naturally-occurring matt structural color only exist in blue or green hues,” said co-author Lukas Schertel. “When we’ve tried to artificially recreate matt structural color for reds or oranges, we end up with a poor-quality result, both in terms of saturation and color purity.”

The researchers, who are based in the lab of Dr Silvia Vignolini, used numerical modeling to determine the limitations of creating saturated, pure and matt red structural color. The researchers modeled the optical response and color appearance of nanostructures, as found in the natural world. They found that saturated, matt structural colors cannot be recreated in the red region of the visible spectrum, which might explain the absence of these hues in natural systems.

“Because of the complex interplay between single scattering and multiple scattering, and contributions from correlated scattering, we found that in addition to red, yellow and orange can also hardly be reached,” said Vignolini. Despite the apparent limitations of structural color, the researchers say these can be overcome by using other kinds of nanostructures, such as network structures or multi-layered hierarchical structures, although these systems are not fully understood yet.

The current global health threat by the novel coronavirus disease 2019 (COVID-19) requires an urgent deployment of advanced therapeutic options being widely available. The role of nanotechnology is highly relevant to counter this viral nano enemy. Nano intervention is discussed in terms of designing effective nanocarriers to counter the conventional limitations of antiviral and biological therapeutics. This strategy directs the safe and effective delivery of available therapeutic options using engineered nanocarriers, blocking the initial interactions of viral spike glycoprotein with host cell surface receptors, and disruption of virion construction. Controlling and eliminating the spread and reoccurrence of this pandemic demands a safe and effective vaccine strategy. Nanocarriers have potential to design risk-free and effective immunization strategies for severe acute respiratory syndrome coronavirus 2 vaccine candidates such as protein constructs and nucleic acids. Ongoing nanotechnology-based therapeutic and prophylactic strategies to fight against this pandemic, outlining key areas, are being discussed.

Researchers at the Dutch Advanced Research Center for Nanolithography (ARCNL) and Vrije Universiteit Amsterdam (VU), developed an advanced microscope capable of super-resolution microscopy through an ultra-thin fiber. 

Up until now, it was generally the case that the higher the resolution of a microscope, the larger the device needed to be, making it virtually impossible to look inside the human body in real-time. Although some methods that enable researchers to look inside living animals already exist, their resolution is very limited, and it takes a long time to generate an acceptable image. 

With the use of smart signal processing, the researchers are able to beat the theoretical limits of resolution and speed. With this newly developed compact setup, scientists are finally able to, for example, look inside the brain in real-time and high resolution, using an ultra-thin fiber. Because the method does not require any unique fluorescent labeling, it is promising for both medical uses and characterization of 3D structures in nano-lithography! 

A newly discovered technique, reported in the journal Nanoscale, offers a low-cost way to enhance the effectiveness of existing drugs. "If you take sand and heat it to 500 degrees Celsius, nothing changes," said Bradley Smith, the Emil T. Hofman Professor of Science at the University of Notre Dame. So Smith, who is also the director of Notre Dame's Integrated Imaging Facility, was puzzled when Canjia Zhai and Cassandra Shaffer, two doctoral students in the Department of Chemistry and Biochemistry who were working in his lab, discovered they had changed the structure of particles of silica—the main component of sand—at 80 degrees Celsius, a temperature similar to that of a cup of coffee.

The discovery happened by accident. The particles were microscopically small—a thousandth the diameter of a human hair. But like their larger counterparts marked "silica gel" in packages attached to new articles of clothing, these particles were porous and could retain a chemical. In this case, that chemical was a blue dye used to detect tumors in mice. The new dye, which had been developed in Smith's lab, was taking a long time to enter the narrow pores in the particles. So, to make the molecules move more quickly, Shaffer and Zhai warmed the mixture to just under boiling and left it overnight. When they returned the next day, they could see that the particles had turned blue.

To confirm that the dye had fully infused, Shaffer and Zhai enlisted the help of Tatyana Orlova and Maksym Zhukovskyi, microscopy experts at the Notre Dame Integrated Imaging Facility. Orlova and Zhukovskyi produced high-resolution electron microscopy images that showed that not only had the dye infused, the silica particles themselves had changed shape. The original particles were solitary spheres lightly dotted with pores like the skin of an orange. The new structures were spherical and were composed of smaller dye-filled globules. They also had small openings here and there that revealed a hollow core inside. The overall unit resembled a hollow raspberry. After the surprise of the initial discovery came a number of practical questions. What other chemicals could the researchers load into similar raspberry-shaped particles? And, most importantly, would those chemicals remain active even after their surrounding structures had changed shape?

Fellow doctoral student Jordan Chasteen took up these questions, repeating the process using a cancer drug. After a series of tests, he confirmed that the cancer drug loaded into the particles was still active and capable of killing cancer cells. This discovery offers a new tool for making existing drugs more effective, Smith said. "What we have now is a way to go through the whole catalog of amine-containing drugs, and by following the simple steps we have discovered, we can create new versions of existing drugs that could be more effective or have fewer unwanted side effects," he said. Smith and his students have found that subtle changes in the loading procedure allow them to vary the thickness of the particles, offering a whole host of new options to fine-tune the particles to release drugs at different rates. The new particle's unique structure may also make it possible to load it with more than one ingredient—for example, a drug in the outer layer and a dye inside the "raspberry"—to enhance researchers' ability to observe the way drugs release. In addition, the new particle, Smith says, also sheds light on a little-understood biological phenomenon known as biomineralization.

"We have found that amine-containing drugs have certain chemical attributes that speed up the degradation and reforming process in silica, and we think that it is similar to what goes on in nature," he said. Smith mentions as an example diatoms, a kind of microscopic plankton, and their delicate glass-like shells formed from silica. "These microorganisms have mechanisms that allow them to take sand and remodel it into their shells," he says. "And they clearly do it at relatively low temperature using organic molecules. What we have discovered is potentially some of the chemistry behind that process."

For the first time, physicists have observed novel quantum effects in a topological insulator at room temperature. This breakthrough, published as the cover article of the October issue of Nature Materials, came when Princeton scientists explored a topological material based on the element bismuth.

The scientists have used topological insulators to demonstrate quantum effects for more than a decade, but this experiment is the first time these effects have been observed at room temperature. Typically, inducing and observing quantum states in topological insulators requires temperatures around absolute zero, which is equal to -459 degrees Fahrenheit (or -273 degrees Celsius).

This finding opens up a new range of possibilities for the development of efficient quantum technologies, such as spin-based electronics, which may potentially replace many current electronic systems for higher energy efficiency.

In recent years, the study of topological states of matter has attracted considerable attention among physicists and engineers and is presently the focus of much international interest and research. This area of study combines quantum physics with topology—a branch of theoretical mathematics that explores geometric properties that can be deformed but not intrinsically changed.

"The novel topological properties of matter have emerged as one of the most sought-after treasures in modern physics, both from a fundamental physics point of view and for finding potential applications in next-generation quantum engineering and nanotechnologies," said M. Zahid Hasan, the Eugene Higgins Professor of Physics at Princeton University, who led the research.

Tiny fragments of DNA combined with fluorescent probes can be used to take temperature at the nanoscale.

Scientists from the University of Montreal, Canada have developed the world’s smallest programmable thermometer, known as Nano-thermometer from DNA. This could recast nanotechnology. Scientists made this Nano-thermometer from actual DNA. This new device is nearly about 20,000 thousand times tinier as compared to human hair.

This new device is made from getting inspiration of “heated DNA always unfolds at a specific temperature”. It can be used in different sectors like Physics, Chemistry and atomic & molecular levels and engineering. This technology has become as a solution to the problem of checking temperature changes in nano-technology. Currently, these devices are so big for doing such things.

A scientist has cultivated DNA structure which can fold and unfold at a certain temperature. They got this idea from natural minute thermometers. Alexis Valle Belisle, Professor at University of Montreal said, “In recent years, biochemists also discovered that biomolecules such as proteins and RNA (Ribonucleic Acid, an important molecule with long chains of nucleotides, like DNA) are employed as Nano-thermometers in living organism and report temperature variation by folding or unfolding.”

Researchers are making some slight adjustment to the product so that it can be combined with new electronic devices. In the field of Science and Technology, this device allows the researcher to answer other problematical questions which have been gone unanswered for years. Were the questions like, can human body runs hotter than 37 degrees Celsius on the natural scale? Or what if naturally occurring Nanomachines overheat when operating at a high rate?

Arnaud Desrosiers, one of the researchers from the team, said, “By adding optical reporters to these DNA structures, we can, therefore, create 5nm wide thermometer that produces an easily detectable signal as a function of temperature.”

Some key feature of this Nano-thermometer:

• It is 5 nanometres wide in the size which is 20,000 times smaller than a human hair.
• It is reversible, robust and efficient.
• It has different applications in different sectors like, in various nanotechnology fields: cell imaging, nano-fluidics, Nano-medicine, Nano-electronics, nano-material, and artificial biology.
• It is used to create super strong structures, repairing cells and help Nano-computing to become more efficient.

Forget expensive antibody-based COVID diagnostics and long waits for test results. An innovative new approach developed by scientists and engineers at MIT leverages the power of nanotechnology to detect traces of the coronavirus in patient samples. The results are ready in around five minutes. 

The emergence of these and similar technologies herald the next wave in biorecognition platforms, opening up exciting possibilities in the realms of health technologies and therapeutics. As the pandemic drags on, vaccine rollouts continue across many parts of the globe. However, experts predict that diagnostic technologies will continue to be a cornerstone of public health responses to the COVID-19 crisis. For example, with travel, large social events, and workplaces opening up again, we will need cost-effective screening tools to keep our communities safe.

With that objective in mind, the team turned to a nanotechnology method of creating carbon nanotubes cocooned in polymer fibers. The target molecules (in this case SARS-CoV-2 proteins) stick to this network of fibers and alter the fluorescent readout generated when a laser shines on the nanotubes. 

This sensor setup is known as Corona Phase Molecular Recognition or CoPhMoRe. It boasts speed, precision, and compatibility with saliva samples without the cost and development lag times of traditional antibody-based tests. The nanotechnology powering this test had been in development long before the pandemic began. However, the innovators designed it such that it can be rapidly adapted to detect a novel viral target; their COVID test took under two weeks to set up.

According to the researchers, this is a significant step-up from first-generation COVID tests and has the potential to become the next gold standard in SARS-CoV-2 diagnostics. “It is a unique feature of this type of molecular recognition scheme that rapid design and testing is possible, unhindered by the development time and supply chain requirements of a conventional antibody or enzymatic receptor,” said a researcher involved in the study, Sooyeon Cho. 

To really appreciate what a team of researchers led by Maksym Kovalenko and Maryna Bodnarchuk has achieved, it is best to start with something mundane: Crystals of table salt are familiar to anyone who has ever had to spice up an overtly bland lunch. Sodium chloride -- NaCl in chemical terms -- is the name of the helpful chemical; it consists of positively charged sodium ions (Na+) and negatively charged chloride ions (Cl-). You can imagine the ions as beads that strongly attract each other forming densely packed and rigid crystals like the ones we can see in a saltshaker. Many naturally occurring minerals consist of ions -- positive metal ions and negative ions, which arrange themselves into different crystal structures depending on their relative sizes. In addition, there are structures such as diamond and silicon: These crystals consist of only one kind of atoms -- carbon in the case of diamond -, but, similar to minerals, the atoms are also held together by strong bonding forces.

What if all strong bonding forces between atoms could be eliminated? In the realm of atoms, with all the quantum mechanics at play, this would not yield a molecule or a solid-state matter, at least at ambient conditions. "But modern chemistry can produce alternative building blocks that can indeed have vastly different interactions than those between atoms," says Maksym Kovalenko, Empa researcher and professor of chemistry at ETH Zurich. "They can be as hard as billiard balls in a sense that they sense each other only when colliding. Or they can be softer on the surfaces, like tennis balls. Moreover, they can be built in many different shapes: not just spheres, but also cubes or other polyhedra, or more anisotropic entities." Such building blocks are made of hundreds or thousands of atoms and are known as inorganic nanocrystals. Kovalenko's team of chemists at Empa and ETH is able to synthesize them in large quantities with a high degree of uniformity. Kovalenko and Bodnarchuk, and some of their colleagues the world over, have been working for about 20 years now with these kinds of building blocks. The scientists call them "Lego materials" because they form long-range ordered dense lattices known as superlattices. It had long been speculated that mixing different kinds of nanocrystals would allow the engineering of completely new supramolecular structures.

The electronic, optical or magnetic properties of such multicomponent assemblies would be expected to be a mélange of the properties of the individual components. In the early years, the work had focused on mixing spheres of different sizes, resulting in dozens of various superlattices with packing structures that mimic common crystal structures, such as table salt -- albeit with crystal unit cells ten- to 100-times larger. With their latest article in "Nature," the team led by Kovalenko and Bodnarchuk now managed to expand the knowledge a great deal further: They set out to study a mixture of different shapes -- spheres and cubes to start with. This seemingly simple deviation from the mainstream immediately led to vastly different observations. Moreover, the chosen cubes, namely colloidal cesium lead halide perovskite nanocrystals, are known as some of the brightest light emitters developed to date, ever since their invention by the same team six years ago. The superlattices the researchers obtained are not only peculiar as far as their structure is concerned, but also with respect to some of their properties. In particular, they exhibit superfluorescence -- that is, the light is irradiated in a collective manner and much faster than the same nanocrystals can accomplish in their conventional state, embedded in a liquid or a powder.

Someday, scientists believe, tiny DNA-based robots and other nanodevices will deliver medicine inside our bodies, detect the presence of deadly pathogens, and help manufacture increasingly smaller electronics. Researchers took a big step toward that future by developing a new tool that can design much more complex DNA robots and nanodevices than were ever possible before in a fraction of the time.

In a paper published on April 19, 2021 in the journal Nature Materials, researchers from The Ohio State University -- led by former engineering doctoral student Chao-Min Huang -- unveiled new software they call MagicDNA. The software helps researchers design ways to take tiny strands of DNA and combine them into complex structures with parts like rotors and hinges that can move and complete a variety of tasks, including drug delivery.

Researchers have been doing this for a number of years with slower tools with tedious manual steps, said Carlos Castro, co-author of the study and associate professor of mechanical and aerospace engineering at Ohio State. "But now, nanodevices that may have taken us several days to design before now take us just a few minutes," Castro said. And now researchers can make much more complex -- and useful -- nanodevices.

"Previously, we could build devices with up to about six individual components and connect them with joints and hinges and try to make them execute complex motions," said study co-author Hai-Jun Su, professor of mechanical and aerospace engineering at Ohio State. "With this software, it is not hard to make robots or other devices with upwards of 20 components that are much easier to control. It is a huge step in our ability to design nanodevices that can perform the complex actions that we want them to do."

The software has a variety of advantages that will help scientists design better, more helpful nanodevices and -- researchers hope -- shorten the time before they are in everyday use. One advantage is that it allows researchers to carry out the entire design truly in 3D. Earlier design tools only allowed creation in 2D, forcing researchers to map their creations into 3D. That meant designers couldn't make their devices too complex.

The software also allows designers to build DNA structures "bottom up" or "top down." In "bottom up" design, researchers take individual strands of DNA and decide how to organize them into the structure they want, which allows fine control over local device structure and properties. But they can also take a "top down" approach where they decide how their overall device needs to be shaped geometrically and then automate how the DNA strands are put together. Combining the two allows for increasing complexity of the overall geometry while maintaining precise control over individual component properties, Castro said.

Another key element of the software is that it allows simulations of how designed DNA devices would move and operate in the real world. "As you make these structures more complex, it is difficult to predict exactly what they are going to look like and how they are going to behave," Castro said. "It is critical to be able to simulate how our devices will actually operate. Otherwise, we waste a lot of time."

As a demonstration of the software's ability, co-author Anjelica Kucinic, a doctoral student in chemical and biomolecular engineering at Ohio State, led the researchers in making and characterizing many nanostructures designed by the software. Some of the devices they created included robot arms with claws that can pick up smaller items, and a hundred nanometer-sized structure that looks like an airplane. The "airplane", however, is about 1,000 times smaller than the width of a human hair!

The ability to make more complex nanodevices means that they can do more useful things and even carry out multiple tasks with one device, Castro said.

Researchers develop first intravenous medication that can cross the blood-brain barrier in mice and treat malignant brain tumors.

Researchers from the University of Michigan report they have developed a new synthetic protein nanoparticle capable of passing through the nearly impermeable blood-brain barrier (BBB) in mice that could deliver cancer-killing drugs directly to malignant brain tumors. Their findings, “Systemic brain tumor delivery of synthetic protein nanoparticles for glioblastoma therapy,” is published in the journal Nature Communications and led by Joerg Lahann, PhD, the Wolfgang Pauli collegiate professor of chemical engineering, and Maria Castro, PhD, the R.C. Schneider collegiate professor of neurosurgery.

“Inspired by the capacity of natural proteins and viral particulates to cross the BBB, we engineered a synthetic protein nanoparticle (SPNP) based on polymerized human serum albumin (HSA) equipped with the cell-penetrating peptide iRGD,” the researchers wrote.

The BBB comprises a layer of endothelial cells that line the blood vessels in the brain, which allows only select types of molecules to pass from the bloodstream into the fluid surrounding the neurons and other cells of the brain. The BBB prevents the transfer of most small-molecule drugs and macromolecules, such as peptides, proteins, and gene-based drugs, which has limited the treatment of CNS diseases, such as neurodegenerative disorders, brain tumors, brain infections, and stroke. Although the blood-brain barrier is considered “leaky” in the core part of glioblastomas (GBMs), the efficient passage of cancer therapeutics, including small molecules and antibodies are still prevented.

Glioblastoma is one of the most common, deadly, and difficult-to-treat adult brain tumors. Surgical removal of the tumor, followed by radiotherapy, and temozolomide (TMZ) administration, is the current treatment modality, but this regimen only improves overall patient survival. The current median survival (MS) for patients with glioblastoma is around 18 months; the average five-year survival rate is below 5%.

Engineers at Duke University have demonstrated a dual-mode heating and cooling device for building climate control that, if widely deployed in the U.S., could cut HVAC energy use by nearly 20 percent. The invention uses a combination of mechanics and materials science to either harness or expel certain wavelengths of light. Depending on conditions, rollers move a sheet back and forth to expose either heat-trapping materials on one half or cooling materials on the other. Specially designed at the nanoscale, one material absorbs the sun's energy and traps existing heat, while the other reflects light and allows heat to escape through the Earth's atmosphere and into space.

"I think we are the first to demonstrate a reversible thermal contact, which allows us to switch between the two modes for heating or cooling," said Po-Chun Hsu, assistant professor of mechanical engineering and materials science at Duke and leader of the team. "This allows the material to be movable while still maintaining a good thermal contact with the building to either bring heat in or let heat out."

The results appeared online November 30, in the journal Nature Communications.

While digital technology is extremely good at solving certain problems, it often struggles with tasks that the human brain excels at. In a new study, scientists have leveraged brain-inspired connectivity between artificial neurons to solve a real-world problem of identifying mutations of a new viral species.

In the September issue of the journal Nature, scientists from Texas A&M University, Hewlett Packard Labs and Stanford University have described a new nanodevice that acts almost identically to a brain cell. Furthermore, they have shown that these synthetic brain cells can be joined together to form intricate networks that can then solve problems in a brain-like manner.

"This is the first study where we have been able to emulate a neuron with just a single nanoscale device, which would otherwise need hundreds of transistors," said Dr. R. Stanley Williams, senior author on the study and professor in the Department of Electrical and Computer Engineering. "We have also been able to successfully use networks of our artificial neurons to solve toy versions of a real-world problem that is computationally intense even for the most sophisticated digital technologies."

In particular, the researchers have demonstrated proof of concept that their brain-inspired system can identify possible mutations in a virus, which is highly relevant for ensuring the efficacy of vaccines and medications for strains exhibiting genetic diversity.

Over the past decades, digital technologies have become smaller and faster largely because of the advancements in transistor technology. However, these critical circuit components are fast approaching their limit of how small they can be built, initiating a global effort to find a new type of technology that can supplement, if not replace, transistors.

In addition to this "scaling-down" problem, transistor-based digital technologies have other well-known challenges. For example, they struggle at finding optimal solutions when presented with large sets of data. "Let's take a familiar example of finding the shortest route from your office to your home. If you have to make a single stop, it's a fairly easy problem to solve. But if for some reason you need to make 15 stops in between, you have 43 billion routes to choose from," said Dr. Suhas Kumar, lead author on the study and researcher at Hewlett Packard Labs. "This is now an optimization problem, and current computers are rather inept at solving it."

Kumar added that another arduous task for digital machines is pattern recognition, such as identifying a face as the same regardless of viewpoint or recognizing a familiar voice buried within a din of sounds. But tasks that can send digital machines into a computational tizzy are ones at which the brain excels. In fact, brains are not just quick at recognition and optimization problems, but they also consume far less energy than digital systems. Hence, by mimicking how the brain solves these types of tasks, Williams said brain-inspired or neuromorphic systems could potentially overcome some of the computational hurdles faced by current digital technologies.

To build the fundamental building block of the brain or a neuron, the researchers assembled a synthetic nanoscale device consisting of layers of different inorganic materials, each with a unique function. However, they said the real magic happens in the thin layer made of the compound niobium dioxide.

When a small voltage is applied to this region, its temperature begins to increase. But when the temperature reaches a critical value, niobium dioxide undergoes a quick change in personality, turning from an insulator to a conductor. But as it begins to conduct electric currents, its temperature drops and niobium dioxide switches back to being an insulator.

These back-and-forth transitions enable the synthetic devices to generate a pulse of electrical current that closely resembles the profile of electrical spikes, or action potentials, produced by biological neurons. Further, by changing the voltage across their synthetic neurons, the researchers reproduced a rich range of neuronal behaviors observed in the brain, such as sustained, burst and chaotic firing of electrical spikes. "Capturing the dynamical behavior of neurons is a key goal for brain-inspired computers," said Kumar. "Altogether, we were able to recreate around 15 types of neuronal firing profiles, all using a single electrical component and at much lower energies compared to transistor-based circuits."

A team from Osaka City University, in collaboration with other international partners, has demonstrated a reliable and precise microscope-based thermometer that works in live, microscopic animals based on quantum technology, specifically, detecting temperature-dependent properties of quantum spins in fluorescent nanodiamonds.

The research is published in Science Advances.

A unique nanoparticle to deliver a localized cancer treatment inhibits tumor growth in mice, according to a team of Penn State researchers.

The nanoparticles, developed by Daniel Hayes, associate professor of biomedical engineering, have a specific chemistry that allows a microRNA (miRNA) to attach to it. A miRNA is a molecule that when paired to a messenger RNA (mRNA) prevents it from operating. In this case, it prohibits the mRNA in a cancer cell from creating proteins, which are essential for that cancer cell to survive.

In their study, the researchers delivered nanoparticles to the cancer cells of mice through an IV. Once the nanoparticles built up in the cancerous area, they used a specific wavelength of light to separate the miRNA from the nanoparticles. The miRNA then pairs with a mRNA in the cancer cell, causing the mRNA to stop making proteins. Eventually, the cancer cell dies.

Their paper is published on June 22, 2020 in the journal Biomaterials. "This delivery method gives you temporal and spatial specificity," said Adam Glick, professor of molecular toxicology and carcinogenesis. "Instead of having systemic delivery of a miRNA and the associated side effects, you are able to deliver the miRNA to a specific area of tissue at a specific time by exposing it to light."