Artificial synapses made from Zinc-Oxide nanowires – ideal candidate for use in building bioinspired “neuromorphic” processors


Image captured by an electron microscope of a single nanowire memristor (highlighted in colour to distinguish it from other nanowires in the background image). Blue: silver electrode, orange: nanowire, yellow: platinum electrode. Blue bubbles are dispersed over the nanowire. They are made up of silver ions and form a bridge between the electrodes which increases the resistance. Credit: Forschungszentrum Jülich

Scientists from Jülich together with colleagues from Aachen and Turin have produced a memristive element made from nanowires that functions in much the same way as a biological nerve cell.

The component is able to save and process information, as well as receive numerous signals in parallel. The resistive switching cell made from oxide crystal nanowires is thus an ideal candidate for use in building bioinspired “neuromorphic” processors, able to take over the diverse functions of biological synapses and neurons.

Computers have learned a lot in recent years. Thanks to rapid progress in artificial intelligence they are now able to drive cars, translate texts, defeat world champions at chess, and much more besides.
In doing so, one of the greatest challenges lies in the attempt to artificially reproduce the signal processing in the human brain.
In , data are stored and processed to a high degree in parallel. Traditional computers, on the other hand, rapidly work through tasks in succession and clearly distinguish between the storing and processing of information.
As a rule, neural networks can only be simulated in a very cumbersome and inefficient way using conventional hardware.

Systems with neuromorphic chips that imitate the way the  works offer significant advantages. These types of computers work in a decentralised way, having at their disposal a multitude of processors, which, like neurons in the brain, are connected to each other by networks. If a processor breaks down, another can take over its function.

What is more, just like in the brain, where practice leads to improved signal transfer, a bioinspired processor should have the capacity to learn.

“With today’s semiconductor technology, these functions are to some extent already achievable. These systems are, however, suitable for particular applications and require a lot of space and energy,” says Dr. Ilia Valov from Forschungszentrum Jülich. “Our nanowire devices made from zinc oxide crystals can inherently process and even store information, and are extremely small and energy efficient.”

For years, memristive cells have been ascribed the best chances of taking over the function of neurons and synapses in bioinspired computers. They alter their electrical resistance depending on the intensity and direction of the electric current flowing through them.

In contrast to conventional transistors, their last resistance value remains intact even when the electric current is switched off. Memristors are thus fundamentally capable of learning.

In order to create these properties, scientists at Forschungszentrum Jülich and RWTH Aachen University used a single zinc oxide nanowire, produced by their colleagues from the polytechnic university in Turin. Measuring approximately one 10,000th of a millimeter in size, this type of nanowire is over 1,000 times thinner than a human hair. The resulting memristive component not only takes up a tiny amount of space, but is also able to switch much faster than flash memory.

Nanowires offer promising novel physical properties compared to other solids and are used among other things in the development of new types of solar cells, sensors, batteries and computer chips. Their manufacture is comparatively simple. Nanowires result from the evaporation deposition of specified materials onto a suitable substrate, where they practically grow of their own accord.

In order to create a functioning cell, both ends of the nanowire must be attached to suitable metals, in this case platinum and silver. The metals function as electrodes, and in addition, release ions triggered by an appropriate electric current. The metal ions are able to spread over the surface of the wire and build a bridge to alter its conductivity.

Components made from single are, however, still too isolated to be of practical use in chips. Consequently, the next step being planned by the Jülich and Turin researchers is to produce and study a memristive element, composed of a larger, relatively easy to generate group of several hundred nanowires offering more exciting functionalities.

More information: Gianluca Milano et al, Self-limited single nanowire systems combining all-in-one memristive and neuromorphic functionalities, Nature Communications (2018).  DOI: 10.1038/s41467-018-07330-7

Provided by Forschungszentrum Juelich

Explore further: Scientists create a prototype neural network based on memristors

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Nano-textiles: The Fabric of the Future


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When you think of futuristic clothing, you probably imagine lots of metallics, holographic accents, and textures. In fact, the sci-fi imagery that springs to mind is coming back into fashion, as evidenced by some recent runway trends (Below: Figure 1).

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Figure 1. An amalgam of different futuristic looks that graced the runway in early 2017 (image by Cristina Cifuentes)

While we can’t say for certain what the fashion of the future will look like, many of us hope that clothing a few years from now will have some greatly enhanced function, making use of science to create cleaner, safer textiles. One way to achieve these goals is to use nanotechnology to do things like kill bacteria or remove dirt.

Nanotechnology in the clothing industry is not a new phenomenon. Beginning in the mid-2000s, many clothing companies started incorporating silver nanoparticles into their products. Silver nanoparticles are antimicrobial, which means they kill the bacteria that cause bad odors. By including these nanoparticles in fabric to prevent odor, the resulting clothes need to be washed less frequently. These nano-infused items range from socks to t-shirts and are still popular today.1 To learn more about the environmental implications of silver-nanoparticle impregnated fabric, visit our previous blog post here.

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Figure 2. Nanosilver is being incorporated into clothing items like socks to prevent odor by killing odor-causing bacteria (adapted from images by Theivasanthi and Scott Bauer)

There is a lot more new technology beyond antimicrobial nanoparticles coming from the field of nano-fabrics. Other desirable clothing characteristics that could be achieved with nanotechnology include self-cleaning fabrics, water-repelling textiles, and clothing that can reduce odors by chemically changing the compounds that cause bad odor.2 These innovations would take advantage of nano- specific properties, particularly the high surface area per volume ratio of nano-sized materials that increase the exposure of active surfaces to the surrounding environment.

Some of these more futuristic-sounding features are already in development. Recently, fabrics coated with silver and copper nanomaterials were produced that can degrade organic matter, such as food and dirt, upon exposure to the sun. These nanomaterials absorb visible light, producing high energy “hot” electrons that can break down surrounding organic matter. The nano features are helpful because the increased surface area of silver or copper metal drastically increases surface-exposed sites that can form the “hot” electrons to help break down food and dirt.2,3 Incorporating these nanomaterials could thus help create clothes that clean themselves!

Nanotechnology can also be harnessed to produce water-repelling, or hydrophobic, materials. This application draws its inspiration from nature: many plants have foliage that is hydrophobic because of nano-scale structures on the leaves. You can observe water-repelling plant leaves on a dewy summer morning. Water droplets on a leaf tend to ball up into spheres instead of being absorbed into the surface (Figure 3). This phenomenon is called the “lotus effect” because it is especially potent for the leaves of the lotus plant.

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Figure 3.The Lotus Effect in action (image by Sweetaholic)

The hydrophobicity of the lotus leaf also makes it self-cleaning; dirt that initially sticks to the leaf surface is often washed away by beads of water that roll off the plant due to its hydrophobicity (Figure 4).4 After studying the physical structure of lotus leaves, researchers understand that their superhydrophobic nature is partially due to the presence of nanostructures, which create a rough surface that repels water.4

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Figure 4. Nanopatterned surfaces can exploit the Lotus effect, causing them to be hydrophobic enough for water droplets to ball up and roll off the fabric surface, removing dirt particles in their path (image by William Thielicke)

Researchers are working to exploit the lotus effect to create artificial superhydrophobic fabrics. Imagine how convenient it would be if rain was completely repelled by your umbrella, to the point that you could wrap it up when you get inside- no having to shake it off or leave it open to dry! New nanofabrics can do just this because they contain patterned nano-silicone spikes. Silicone is naturally water resistant, and the use of nano-sized patterns makes the material even more hydrophobic. When a water droplet comes into contact with the surface of these materials, it balls up and slides off instead of being absorbed.5

Nanotechnology can also be used to chemically target and eliminate odor-causing molecules. Whereas the silver nanoparticles mentioned earlier prevent odor formation by killing bacteria, a second generation of odor-busting nanoparticles work by chemically targeting and modifying stinky compounds. Whereas things like fabric or room sprays merely mask odor, fabrics modified with these new nanomaterials could break down the source of the odor, making them better and more efficient at deodorizing. One group of researchers found that copper coated silica nanoparticles were effective at eliminating odor arising from ethyl mercaptan, which is a stinky chemical typically added to petroleum gas (which is odorless) to enable us to smell gas leaks. Interacting with the copper-silica nanoparticles modifies the ethyl mercaptan molecules and binds them to the surface of the particles, so there is less ethyl mercaptan left to smell bad.6 This second generation of odor-reducing nanoparticles may be more environmentally sound than antimicrobial silver, because the mechanism of odor elimination is targeted towards specific compounds as opposed to general bacterial toxicity.

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Figure 5. Microscopy image showing copper clusters (arrow) on the surface of a silica nanoparticle. These nanoparticles were used to modify and bind to stinky ethyl mercaptan, greatly reducing odor. (image adapted from Singh et al. 2010,6 with permission from the American Chemical Society)

So, will nano-fabrics be the future of clothing, enabling us to all have self-cleaning, water-resistant clothes that we only have to wash a few times a year? Only time will tell. The field of nano-fabrics is still very much in its infancy and it still faces some challenges. For example, washing clothes that contain antimicrobial silver releases nanoparticles into the waste water, giving them a limited effective lifetime as the nanomaterial washes out. Perhaps more important is the potential environmental risk of this nanoparticle release into the environment, which has incited continued debate and controversy, as metal nanoparticles can dissolve into toxic ions when exposed to environmental conditions.7,8 Newer nanofabric technologies may carry their own concerns, which have not yet been thoroughly studied. However, the potential benefits of nano-enhanced fabrics makes their use worth exploration. And with continued scientific advancement that will allow us to address environmental concerns, this sector of nanotechnology can only continue to grow.


EDUCATIONAL RESOURCES


REFERENCES

  1. Soutter, W. Nanotechnology in Clothing. AZO Nano, 2012.   https://www.azonano.com/article.aspx?ArticleID=3129.
  2. Osborne, H. Self-cleaning clothes edge closer as scientists create textile cleansed of dirt by sunlight. International Business Times, 2016.    https://www.ibtimes.co.uk/self-cleaning-clothes-edge-closer-scientists-create-textile-cleansed-dirt-by-sunlight-1551240.
  3. Anderson, S. R.; Mohammadtaheri, M.; Kumar, D.; O’Mullane, A. P.; Field, M. R.; Ramanathan, R.; Bansal, V. Adv. Mater. Interfaces 20163(6), 1–8. DOI: 10.1002/admi.201500632.
  4. Nanowerk. Nanotechnology solutions for self-cleaning, dirt and water-repellent coatings. 2011.   https://www.nanowerk.com/spotlight/spotid=19644.php.
  5. Evans, J. Nanotech clothing fabric ‘never gets wet.’ New Scientist, 2008 https://www.newscientist.com/article/dn16126-nanotech-clothing-fabric-never-gets-wet/.
  6. Singh, A.; Krishna, V.; Angerhofer, A.; Do, B.; MacDonald, G.; Moudgil, B. Langmuir 201026(20), 15837–15844. doi: 10.1021/la100793u
  7. Mole, B. News Brief: Wash removes nano germ-killers https://www.sciencenewsforstudents.org/article/news-brief-wash-removes-nano-germ-killers.
  8. American Chemical Society. The impact of anti-odor clothing on the environment (press release) 2016.   https://www.acs.org/content/acs/en/pressroom/presspacs/2016/acs-presspac-april-13-2016/the-impact-of-anti-odor-clothing-on-the-environment.html.

Penn State – 3D Imaging Technique Unlocks Properties of Perovskite Crystals – Applications for Perovskite Solar Cells


A reconstruction of a perovskite crystal (CaTiO3) grown on a similar perovskite substrate (NdGaO3) showing electron density and oxygen octahedral tilt. (insert) Artist’s conception of the interface between substrate and film. Credit: Yakun Yuan/Penn State

A team of materials scientists from Penn State, Cornell and Argonne National Laboratory have, for the first time, visualized the 3D atomic and electron density structure of the most complex perovskite crystal structure system decoded to date.

Perovskites are minerals that are of interest as electrical insulators, semiconductors, metals or superconductors, depending on the arrangement of their atoms and electrons.

Perovskite crystals have an unusual grouping of oxygen atoms that form an octahedron, an eight-sided polygon. This arrangement of oxygen atoms acts like a cage that can hold a large number of the elemental atoms in the periodic table. Additionally, other atoms can be fixed to the corners of a cube outside of the cage at precise locations to alter the material’s properties, for instance in changing a metal into an insulator, or a non-magnet into a ferromagnet.

In their current work, the team grew the very first discovered perovskite crystal, called calcium titanate, on top of a series of other perovskite crystal substrates with similar but slightly different oxygen cages at their surfaces. Because the thin film perovskite on top wants to conform to the structure of the thicker substrate, it contorts its cages in a process known as tilt epitaxy.

The researchers found this tilt epitaxy of calcium titanate caused a very ordinary material to take on the property of ferroelectricity, a spontaneous polarization, and to remain ferroelectric up to 900 Kelvin, around three times hotter than room temperature. They were also able to visualize the three-dimensional electron density distribution in calcium titanate thin film for the first time.

“We have been able to see atoms for quite some time, but not map them and their electron distribution in space in a crystal in three dimensions,” said Venkat Gopalan, professor of materials science and physics, Penn State. “If we can see not just where atomic nuclei are located in space, but also how their electron clouds are shared, that will tell us basically everything we need to know about the material in order to infer its properties.”

That was the challenge the team set for itself over five years ago when Gopalan gave his student and lead author of a new report in Nature Communications, Yakun Yuan, the project.

Based on a rarely used x-ray visualization technique called COBRA, for coherent Bragg rod analysis, originally developed by a group in Israel, Yuan figured out how to expand and modify the technique to analyze one of the most complicated, least symmetrical material systems studied to date: the strained three-dimensional perovskite crystal with octahedral tilts in all directions, grown on another equally complex crystal structure.

“To reveal 3D structural details at the atomic level, we had to collect extensive datasets using the most brilliant synchrotron X-ray source available at Argonne National Labs and carefully analyze them with the COBRA analysis code modified for accommodating the complexity of such low symmetry,” said Yakun Yuan.

Gopalan went on to explain that very few perovskite oxygen cages are perfectly aligned throughout the material. Some rotate counterclockwise in one layer of atoms and clockwise in the next. Some cages are squeezed out of shape or tilt in directions that are in or out of plane to the substrate surface.

From the interface of a film with the substrate it is grown on, all the way to its surface, each atomic layer may have unique changes in their structure and pattern.  All of these distortions make a difference in the material properties, which they can predict using a computational technique called density functional theory (DFT).

“The predictions from the DFT calculations provide insights that complement the experimental data and help explain the way that material properties change with the alignment or tilting of the perovskite oxygen cages,” said Prof. Susan Sinnott, whose group performed the theoretical calculations.

The team also validated their advanced COBRA technique against multiple images of their material using the powerful Titan transmission electron microscope in the Materials Research Institute at Penn State.  Since the electron microscopes image extremely thin electron transparent samples in a 2-dimensional projection, not all of the 3-dimensional image could be captured even with the best microscope available today and with multiple sample orientations.

Why Perovskite Solar Cells Are So Efficient

This is an area where 3-dimensional imaging by the COBRA technique outperformed the electron microscopy in such complex structures.

The researchers believe their COBRA technique is applicable to the study of many other three-dimensional low-symmetry atomic crystals.

Additional authors on “Three-dimensional atomic scale electron density reconstruction of octahedral tilt epitaxy in functionals perovskites” are Yanfu Lu, a Ph.D. student in Sinnott’s group, Greg Stone, Gopalan’s former postdoctoral scholar, Ke Wang, a staff scientist in Penn State’s Materials Research Institute, Darrell Schlom and his Ph.D. student Charles Brooks, Cornell University, and Hua Zhou, staff scientist, Argonne National Laboratory.

img_0885-1Penn State University

Funding was provided by the National Science Foundation with additional support provided through the Department of Energy and the Penn State 2D Crystal Consortium, a NSF Materials Innovation Platform, and the Penn State institute for CyberScience.

Contact Venkat Gopalan at vxg8@psu.edu or Hua Zhou at hzhou@aps.anl.gov.

MIT – Nanoparticles Deliver Potential Arthritis Treatment and could Prevent Cartilage Breakdown – Potential to Heal Tissue Damaged by Osteoarthritis


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Six days after treatment with IGF-1 carried by dendrimer nanoparticles (blue), the particles have penetrated through the cartilage of the knee joint. Image: Brett Geiger and Jeff Wyckof

Courtesy of MIT News

Injectable material made of nanoscale particles can deliver arthritis drugs throughout cartilage.

Osteoarthritis, a disease that causes severe joint pain, affects more than 20 million people in the United States. Some drug treatments can help alleviate the pain, but there are no treatments that can reverse or slow the cartilage breakdown associated with the disease.

In an advance that could improve the treatment options available for osteoarthritis, MIT engineers have designed a new material that can administer drugs directly to the cartilage. The material can penetrate deep into the cartilage, delivering drugs that could potentially heal damaged tissue.

“This is a way to get directly to the cells that are experiencing the damage, and introduce different kinds of therapeutics that might change their behavior,” says Paula Hammond, head of MIT’s Department of Chemical Engineering, a member of MIT’s Koch Institute for Integrative Cancer Research, and the senior author of the study.

In a study in rats, the researchers showed that delivering an experimental drug called insulin-like growth factor 1 (IGF-1) with this new material prevented cartilage breakdown much more effectively than injecting the drug into the joint on its own.

Brett Geiger, an MIT graduate student, is the lead author of the paper, which appears in the Nov. 28 issue of Science Translational Medicine. Other authors are Sheryl Wang, an MIT graduate student, Robert Padera, an associate professor of pathology at Brigham and Women’s Hospital, and Alan Grodzinsky, an MIT professor of biological engineering.

Better delivery

Osteoarthritis is a progressive disease that can be caused by a traumatic injury such as tearing a ligament; it can also result from gradual wearing down of cartilage as people age. A smooth connective tissue that protects the joints, cartilage is produced by cells called chondrocytes but is not easily replaced once it is damaged.

Previous studies have shown that IGF-1 can help regenerate cartilage in animals. However, many osteoarthritis drugs that showed promise in animal studies have not performed well in clinical trials.

The MIT team suspected that this was because the drugs were cleared from the joint before they could reach the deep layer of chondrocytes that they were intended to target. To overcome that, they set out to design a material that could penetrate all the way through the cartilage.

The sphere-shaped molecule they came up with contains many branched structures called dendrimers that branch from a central core. The molecule has a positive charge at the tip of each of its branches, which helps it bind to the negatively charged cartilage. Some of those charges can be replaced with a short flexible, water-loving polymer, known as PEG, that can swing around on the surface and partially cover the positive charge. Molecules of IGF-1 are also attached to the surface.

When these particles are injected into a joint, they coat the surface of the cartilage and then begin diffusing through it. This is easier for them to do than it is for free IGF-1 because the spheres’ positive charges allow them to bind to cartilage and prevent them from being washed away. The charged molecules do not adhere permanently, however. Thanks to the flexible PEG chains on the surface that cover and uncover charge as they move, the molecules can briefly detach from cartilage, enabling them to move deeper into the tissue.

“We found an optimal charge range so that the material can both bind the tissue and unbind for further diffusion, and not be so strong that it just gets stuck at the surface,” Geiger says.

Once the particles reach the chondrocytes, the IGF-1 molecules bind to receptors on the cell surfaces and stimulate the cells to start producing proteoglycans, the building blocks of cartilage and other connective tissues. The IGF-1 also promotes cell growth and prevents cell death.

Joint repair

When the researchers injected the particles into the knee joints of rats, they found that the material had a half-life of about four days, which is 10 times longer than IGF-1 injected on its own. The drug concentration in the joints remained high enough to have a therapeutic effect for about 30 days. If this holds true for humans, patients could benefit greatly from joint injections — which can only be given monthly or biweekly — the researchers say.

In the animal studies, the researchers found that cartilage in injured joints treated with the nanoparticle-drug combination was far less damaged than cartilage in untreated joints or joints treated with IGF-1 alone. The joints also showed reductions in joint inflammation and bone spur formation.

“This is an important proof-of-concept that builds on the recent advances in the identification of anabolic growth factors with clinical promise (such as IGF-1), with promising disease-modifying results in a clinically relevant model. Delivery of growth factors using nanoparticles in a manner that sustains and improves treatments for osteoarthritis is a significant step for nanomedicines,” says Kannan Rangaramanujam, a professor of ophthalmology and co-director of the Center for Nanomedicine at Johns Hopkins School of Medicine, who was not involved in the research.

Cartilage in rat joints is about 100 microns thick, but the researchers also showed that their particles could penetrate chunks of cartilage up to 1 millimeter — the thickness of cartilage in a human joint.

“That is a very hard thing to do. Drugs typically will get cleared before they are able to move through much of the cartilage,” Geiger says. “When you start to think about translating this technology from studies in rats to larger animals and someday humans, the ability of this technology to succeed depends on its ability to work in thicker cartilage.”

The researchers began developing this material as a way to treat osteoarthritis that arises after traumatic injury, but they believe it could also be adapted to treat age-related osteoarthritis. They now plan to explore the possibility of delivering different types of drugs, such as other growth factors, drugs that block inflammatory cytokines, and nucleic acids such as DNA and RNA.

The research was funded by the Department of Defense Congressionally Funded Medical Research Program and a National Science Foundation fellowship.

MIT – Measuring cancer cell “fitness” reveals drug susceptibility and the potential to treat non-responsive cancer cells


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MIT engineers have designed a system that can repeatedly measure cancer cells as they flow through an array of mass sensors. Once the cells reach the end, they are collected for RNA-sequencing. Image courtesy of the researchers.

Courtesy of MIT News

Together, cell growth rate and gene expression shed light on why some tumor cells survive treatment.

 

By studying both the physical and genomic features of cancer cells, MIT researchers have come up with a new way to investigate why some cancer cells survive drug treatment while others succumb.

Their new approach, which combines measurements of cell mass and growth rate with analysis of a cell’s gene expression, could be used to reveal new drug targets that would make cancer treatment more effective. Exploiting these targets could help knock out the defenses that cells use to overcome the original drug treatment, the researchers say.

In a paper appearing in the Nov. 28 issue of the journal Genome Biology, the researchers identified a growth signaling pathway that is active in glioblastoma cells that are resistant to an experimental type of drug known as an MDM2 inhibitor.

“By measuring a cell’s mass and growth rate immediately prior to single-cell RNA-sequencing, we can now use a cell’s ‘fitness’ to classify it as responsive or nonresponsive to a drug, and to relate this to underlying molecular pathways,” says Alex K. Shalek, the Pfizer-Laubach Career Development Assistant Professor of Chemistry, a member of MIT’s Institute for Medical Engineering and Science (IMES), an extramural member of the Koch Institute for Integrative Cancer Research, and an associate member of the Ragon and Broad Institutes.

Shalek and Scott Manalis, the Andrew and Erna Viterbi Professor in the MIT departments of Biological Engineering and Mechanical Engineering and a member of the Koch Institute, are the senior authors of the study. The paper’s lead author is Robert Kimmerling, a recent MIT PhD recipient.

Cancer cell analysis

About a decade ago, Manalis’ lab invented a technology that allows researchers to measure the mass of single cells. In recent years, they have adapted the device, which measures cells’ masses as they flow through tiny channels, so that it can also measure cell growth rates by repeatedly weighing the cells over short periods of time.

Last year, working with researchers at Dana-Farber Cancer Institute (DFCI), Manalis and his colleagues used this approach to test drug responses of tumor cells from patients with multiple myeloma, a type of blood cancer. After treating the cells with three different drugs, the researchers measured the cells’ growth rates and found they were correlated with the cells’ susceptibility to the treatment.

“Single-cell biophysical properties such as mass and growth rate provide early indicators of drug response, thereby offering the potential to delineate sensitive cells from resistant cells while they are still viable,” Manalis says.

In their new study, the researchers wanted to add a genomic component, which they hoped could help reveal why only certain cells are susceptible to a particular drug. “We wanted to be able to take those measurements and add on some of the biological context for why a cell is growing a certain way or behaving a certain way,” Kimmerling says.

To accomplish this, Kimmerling and Manalis teamed up with Shalek, who has extensive experience in sequencing the messenger RNA (mRNA) of individual cells. This information can provide a snapshot of which genes are being expressed in a single cell at a particular moment.

The researchers modified the cell-weighing system so that cells would be spaced evenly as they flowed through, making it easier to collect them one at a time when they exit the system. The cells are weighed several times over the course of 20 minutes to determine growth rate, and as soon as they reach the end of the channel, they are immediately captured and ruptured to release their RNA for analysis. Shalek’s lab then sequenced the RNA of each of the cells. This approach enabled the mass and growth rate of each cell to be directly linked to its gene expression.

Once they had the system working, the researchers collaborated with Keith Ligon and his lab at DFCI to analyze cancer cells derived from a patient with glioblastoma, an aggressive type of brain cancer. The researchers treated the cells with an MDM2 inhibitor, a type of drug that helps to boost the function of p53, a protein that helps cells stop tumor formation. Such drugs are now in clinical trials to treat glioblastoma. In animal studies, this drug has been effective against tumors, but the tumors often grow back later.

In this study, the researchers hoped to find out why some glioblastoma cells survive MDM2 treatment. They treated the cells, measured their growth rates about 16 hours after the treatment, and then sequenced their RNA. “Before the cells have lost viability, we can measure their mass and their growth rate to reveal drug response heterogeneity to that treatment, and then link that with their gene expression,” Kimmerling says.

Importantly, the researchers found subpopulations of cells that were not responsive to the drug. RNA sequencing revealed that in cells that were responsive, genes required for programmed cell death were turned on. Meanwhile, in cells that did not seem to be vulnerable to the drug, genes involved in mTOR, a signaling pathway involved in growth and survival, were turned up.

“What we’re excited about here is we now have this list of biological targets to look into,” Kimmerling says. “We can start to generate testable hypotheses from these gene expression signatures that are more highly expressed in the cells that continue to grow after drug treatment.”

Possible drug targets

The researchers now plan to explore the possibility of targeting some of the genes that were turned up on the non-responding cells, in hopes of developing drugs that could be used together with the original MDM2 inhibitor. They also hope to adapt this approach for other types of cancers. Some, such as blood cancers, are easier to study than solid tumors, which are more difficult to separate into single cells.

“The hope is that we’ll be able to apply this technology to any sample that can be dissociated into a single-cell population,” Kimmerling says.

Another possible application of the cell-growth measurement technology is studying tumor cells from individual patients to try to predict how they will respond to a particular drug. Kimmerling, Manalis, and others have founded a company called Travera, which has licensed the technology and hopes to develop it for patient use. The company is currently not working on the RNA sequencing aspect of the technology, but that element could also be valuable to incorporate in the future, Kimmerling says.

The research was funded by the Cancer Systems Biology Consortium U54 Research Center and the Cancer Center Support (core) Grant from the National Cancer Institute; the Searle Scholars Program; the Beckman Young Investigator Program; the National Institutes of Health, including an NIH New Innovator Award; the Pew-Stewart Scholars; and a Sloan Fellowship in Chemistry.

BIG … News from the LA Auto Show and MIT: “Rivian” unveils electric vehicles for the future – Startup founded by MIT alumnus


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One of the two models unveiled at the Los Angeles Auto Show this week, Rivian’s R1S, will sell for $65,000, according to the company. Courtesy of Rivian

Courtesy of MIT News

Rivian Automotive is showing off its first products at the Los Angeles Auto Show this week.

 

Electric vehicle startup Rivian Automotive has spent the first nine years of its existence in stealth mode working to design vehicles around what it believes are future trends in mobility, such as electrification, subscription-based ownership, and autonomy. This week the company is finally revealing what it’s been up to, dropping the curtains on its first two products, an all-electric pickup truck and SUV, at the Los Angeles Auto Show.

Rivian has garnered interest over the years for quietly securing some of the building blocks of mass production, including raising nearly $500 million in capital and purchasing a 2.6-million-square-foot manufacturing facility in Illinois that once produced 200,000 cars a year for Mitsubishi. Now Rivian says it will begin shipping its vehicles to customers in 2020.

The abrupt transition from stealth mode to large vehicle supplier is all part of the plan for Rivian founder and CEO R.J. Scaringe SM ’07 PhD ’09. Scaringe didn’t want to hype up the company until he could show something off that customers could actually drive in a reasonable amount of time.

“It would’ve been easy to make statements early on and show sketches,” Scaringe says. “But we wanted to get all the pieces aligned: To build out a robust team with robust processes, get capital in place, line up key suppliers, acquire a large-scale production facility, and align it with our products. All that is done now. It’s been blood, sweat, and tears for a period of years to get in a position where we’re very comfortable showing our products.”

Designing a vehicle from the ground up has taken time, but the process has allowed Rivian to create some novel vehicles with intriguing performance specifications. The company describes its first two products, named the R1T and R1S, as high-end adventure vehicles that can be driven on- or off-road. MIT-Rivian 2

“They’re designed to be comfortable to use and invite you to get dirty,” Scaringe says. “When I say truck or SUV, you’re thinking inefficient and not particularly sophisticated. But we’ve used technology to make the traditional weaknesses of these vehicles strengths.”

Users purchasing trucks or SUVs have traditionally had to make compromises in areas like acceleration, control, and gas mileage in return for more space and towing capacity. Rivian uses an innovative design and powertrain to change that.

A high-tech transportation solution

Both the R1T and R1S will come with a hardware suite including cameras and sensors, which gives them self-driving capabilities on highways. The vehicles have a unique quad-motor setup that allows the electronic control unit to send 147 kilowatts of power to each wheel.

The fastest versions of the vehicles go from 0 to 60 miles per hour in three seconds and 0 to 100 miles per hour in less than seven seconds. Scaringe says the products’ ride and handling feel more like a sports sedan than a truck or SUV. He also says the vehicles can “go off-road better than any vehicle on the planet today” thanks to high ground clearance and wheel articulation that’s helped by a suspension system that adjusts to the environment, stiffening on the road and immediately loosening off the road.

Rivian’s battery configuration has been referred to as “skateboard architecture” because the battery pack stretches across the floor of the vehicle. The packs come in different sizes, the largest of which gives the vehicles over 400 miles in range. Rivian assembles its own battery packs, using proprietary cooling systems to achieve energy efficiency that Scaringe claims is better than anything on the EV market today.

Rivian-autonotive-governor-rauner-illinois-620x350“We’re doing all of the electronics, control systems, and battery packaging in-house,” Scaringe says. “And the digital architecture of the vehicle is a complete clean-sheet approach. So we’ve done the hardware design, the software design, the full stack development. It gives us complete control over how we move data around the vehicle and synchronize it with our cloud platform. We have a real-time sense of the health of all of our assets in the field.”

The high-tech platform comes inside two spacious vehicles that are designed to be stylish and functional. Both models include a 330-liter front trunk and a long compartment under the rear seats that Scaringe says is perfect for objects like surfboards, skis, and golf bags.

Rivian is listing the R1S at $65,000 and the R1T at $61,500 after federal tax rebates. The company is planning to release lower-priced cars in the future.

MIT past helps change the future

Scaringe studied mechanical engineering  for his master’s and PhD in the Sloan Automotive Laboratory, where he was a member of the automotive research team. He worked with some of the biggest car companies in the world in that role, and realized how difficult it would be for them to reorient around the big changes in transportation that he believed were coming.

Immediately after earning his PhD in 2009, in a year when General Motors and Chrysler would declare for bankruptcy, Scaringe founded Rivian. At a time when many people were wondering if America’s biggest car companies would make it another day, Scaringe set out to start a company that would lead the market decades into the future.

“In 2020, we’d love to have you use one of our vehicles. But in 2035, when you’re thinking about those trips to the beach or hiking, we want you to immediately think about using a Rivian,” Scaringe says. “The brand position we set up in 2020 lays the foundation for us.”

Scaringe knew fulfilling his vision would be difficult, but he believes his time at MIT helped him persevere in the face of the major challenges that come with starting something as complex and capital-intensive as a automotive company.

“MIT draws together some of the smartest minds in the world to study and work on deeply challenging problems,” Scaringe says. “That environment helps demonstrate that even the most challenging problems can be solved through the application of time and effort. … The foundation around solving complex and difficult problems is precisely what has enabled Rivian to this point.”

Now that Rivian’s first vehicles have been revealed, Scaringe hopes the company can move beyond thinking about these trends and start accelerating their arrival.

“It comes back to these big fundamental shifts in how we think of mobility,” Scaringe says. “The change in how we power our vehicles; how the vehicles are controlled and operated, going from human operation to machine operation; and because of those changes, the significant changes to how we think about the business model. Like how consumers purchase vehicles and how manufacturers make money, shifting away from the traditional asset sale model. We think it’s really important to line up the megatrends with our business strategy, and now it’s about making sure the strategy helps drive those megatrends.”

How Nanotechnology is Providing a Solution for Photovoltaic Systems


Nanotechnology-in-Solar-Energy-2

Photovoltaic (PV) systems, which harvest sustainable and clean energy from the sun, accumulate dirt or particles like dust, water and sand. This build-up leads to a reduction in the light energy reaching the solar cells and lowers their power output by up to 50%, according to some studies. Therefore, it’s crucial to keep them clean. However, the process of regular cleaning and maintenance could be costly and also waste water.

Enter the EU-funded SolarSharc project, whose highly repellent  technology will eliminate surface contamination, optimising energy efficiency and PV yield. In an interview published on the European Coatings website, David Hannan from project partner Opus Materials Technologies said developments in anti-soiling coatings are being driven by the sustainability agenda and the need for clean power. He highlighted the challenges involved in the production of solar energy and added that “dust, dirt and fouling of solar panels are major sources of inefficiency and loss in solar generation, resulting in lost generating capacity to a value in excess of EUR 40bn p.a.

In turn this causes over 100M tonnes of CO2 emission through fossil fuel generation in order to make up the shortfall.” Hannan pointed to the drawbacks of existing self-cleaning coatings, such as “a short lifetime (2-3 years), poor transparency and high cost (over €260/litre). This means that they are not usually cost-effective and are not deployed, with losses accepted as the lesser economic impact for the operation of the plant.”

Clean me Sign

Improved Efficiency

According to the project website, SolarSharc’s nanoparticle structure provides “high transparency, improving generating efficiency by 4 % and improving aesthetic quality for architectural applications. Silica chemistry is non-hazardous and permits scaleable manufacture.” In addition to being durable and self-cleaning, SolarSharc is “anti-reflective, resistant to high temperatures and offers outstanding weather resistance.” Thanks to its anti-reflective properties, SolarSharc “leads to an improvement in transmittance to enable over 93 % of all available light to reach the PV semiconductor.”

The inorganic-organic hybrid coating of SolarSharc is only a few microns thick, as explained on the project website. “Based on a silica (glass) network chemically bound to non-stick organic groups Solar Sharc [coating] readily repels water and water-borne contamination. Rather than wetting the surface, water droplets form beads on the coating and readily roll-off at low angles.” It also states that solid contamination, such as dust and sand, is “easily removed by the action of wind or by the use of minimum amounts of water.”

The markets targeted by the  are utility-scale solar and the rapidly growing building-integrated photovoltaics (BIPV). Project partners hope to commercialise the SolarSharc coating and new self-cleaning BIPV modules “from the current TRL6 [technology readiness level 6] prototype to operational demonstration (TRL9) in BIPV, certification, commercialisation and supply chain measures to deliver rapid growth,” as stated on CORDIS.

 Explore further: Self-cleaning solar panel coating optimizes energy collection, reduces costs

 

Researchers Develop a universal DNA Nano-signature for early cancer detection – University of Queensland


Killer T cells surround cancer cell. Credit: NIH

Researchers from the University of Queensland’s Australian Institute for Bioengineering and Nanotechnology (AIBN) have discovered a unique nano-scaled DNA signature that appears to be common to all cancers.

Based on this discovery, the team has developed a  that enables  to be quickly and easily detected from any tissue type, e.g. blood or biopsy.

The study, which was supported by a grant from the National Breast Cancer Foundation and is published in the journal Nature Communications, reveals new insight about how epigenetic reprogramming in cancer regulates the physical and chemical properties of DNA and could lead to an entirely new approach to point-of-care diagnostics.

“Because cancer is an extremely complicated and variable disease, it has been difficult to find a simple signature common to all cancers, yet distinct from healthy ,” explains AIBN researcher Dr. Abu Sina.

To address this, Dr. Sina and Dr. Laura Carrascosa, who are working with Professor Matt Trau at AIBN, focussed on something called circulating free DNA.

Like healthy cells,  are always in the process of dying and renewing. When they die, they essentially explode and release their cargo, including DNA, which then circulates.

“There’s been a big hunt to find whether there is some distinct DNA signature that is just in the cancer and not in the rest of the body,” says Dr. Carrascosa.

So they examined epigenetic patterns on the genomes of cancer cells and healthy cells. In other words, they looked for patterns of molecules, called methyl groups, which decorate the DNA. These methyl groups are important to cell function because they serve as signals that control which genes are turned on and off at any given time.

In healthy cells, these methyl groups are spread out across the genome. However, the AIBN team discovered that the genome of a cancer cell is essentially barren except for intense clusters of methyl groups at very specific locations.

This unique signature—which they dubbed the cancer “methylscape”, for methylation landscape—appeared in every type of breast cancer they examined and appeared in other forms of cancer, too, including prostate cancer, colorectal cancer and lymphoma.

“Virtually every piece of cancerous DNA we examined had this highly predictable pattern,” says Professor Trau.

He says that if you think of a cell as a hard-drive, then the new findings suggest that cancer needs certain genetic programmes or apps in order to run.

“It seems to be a general feature for all cancer,” he says. “It’s a startling discovery.”

They also discovered that, when placed in solution, those intense clusters of  cause cancer DNA fragments to fold up into three-dimensional nanostructures that really like to stick to gold.

Taking advantage of this, the researchers designed an assay which uses gold nanoparticles that instantly change colour depending on whether or not these 3-D nanostructures of cancer DNA are present.

“This happens in one drop of fluid,” says Trau. “You can detect it by eye, it’s as simple as that.”

The technology has also been adapted for electrochemical systems, which allows inexpensive and portable detection that could eventually be performed using a mobile phone.

So far they’ve tested the new technology on 200 samples across different types of human cancers, and . In some cases, the accuracy of cancer detection runs as high as 90%.

“It works for tissue derived genomic DNA and blood derived circulating free DNA,” says Sina. “This new discovery could be a game-changer in the field of point of care cancer diagnostics.” It’s not perfect yet, but it’s a promising start and will only get better with time, says the team.

“We certainly don’t know yet whether it’s the Holy Grail or not for all cancer diagnostics,” says Trau, “but it looks really interesting as an incredibly simple universal marker of cancer, and as a very accessible and inexpensive technology that does not require complicated lab based equipment like DNA sequencing.”

More information: Abu Ali Ibn Sina et al, Epigenetically reprogrammed methylation landscape drives the DNA self-assembly and serves as a universal cancer biomarker, Nature Communications(2018).  DOI: 10.1038/s41467-018-07214-w

Provided by University of Queensland

Explore further: New cancer monitoring technology worth its weight in gold

Graphene Could Revolutionize the Development of Wearable Electronic Devices


 

graphenehydr

Thanks to the application of the wonder material graphene, the quest for producing durable, affordable, and mass-produced “smart textiles” has been given a new push.

Headed by Professor Monica Craciun from the University of Exeter Engineering department, an international group of researchers has developed a novel method for producing fully electronic fibers that can be integrated into the production of day-to-day clothing.

The development of the current generation of wearable electronics involves fixing devices to fabrics, which could make them extremely rigid and prone to malfunctioning. However, in the latest study, the electronic devices are embedded in the material’s fabric, and this is done by coating electronic fibers with durable and lightweight components that will enable showing images directly on the fabric.

According to the scientists, the discovery could transform the development of wearable electronic devices for applications in many different day-to-day applications, and also medical diagnostics and health monitoring, like blood pressure and heart rates.

The international collaborative study has been reported in the scientific journal Flexible Electronics. Experts from the Centre for Graphene Science at the University of Exeter, CenTexBel in Belgium, and the Universities of Aveiro and Lisbon in Portugal took part in the study.

For truly wearable electronic devices to be achieved, it is vital that the components are able to be incorporated within the material, and not simply added to it.

Monica Craciun, Professor and Study Co-Author, Engineering Department, University of Exeter.

 

 

Graphene is only one-atom thick, which makes it the thinnest substance with the ability to conduct electricity. It is also one of the strongest known materials and quite flexible. In recent years, the race has been on for engineers and scientists to adapt graphene for applications in wearable electronic devices.

The latest study applied existing polypropylene fibers—often employed in an array of commercial applications in the textile sector—to fix the novel, graphene-based electronic fibers to develop light-emitting and touch-sensor devices.

The innovative method means that the fabrics will be capable of integrating truly wearable displays but without the requirement for electrodes—wires of extra materials.

The incorporation of electronic devices on fabrics is something that scientists have tried to produce for a number of years, and is a truly game-changing advancement for modern technology.

Saverio Russo, Professor and Study Co-Author, Physics Department, University of Exeter.

The key to this new technique is that the textile fibres are flexible, comfortable and light, while being durable enough to cope with the demands of modern life.

Dr Ana Neves, Study Co-Author, Engineering Department, University of Exeter.

Earlier in 2015, an international group of researchers, including Dr Ana Neves, Professor Russo, and Professor Craciun from the University of Exeter, had developed a novel method to integrate flexible, transparent graphene electrodes into fibers often associated with the textile sector.

graphene-supercapacitor

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RMIT – Study unlocks full potential of graphene ‘supermaterial’


Drs. Esrafilzadeh and Jalili working on 3D-printed graphene mesh in the lab.
Credit: RMIT University

New research reveals why the “supermaterial” graphene has not transformed electronics as promised, and shows how to double its performance and finally harness its extraordinary potential.

Graphene is the strongest material ever tested. It’s also flexible, transparent and conducts heat and electricity 10 times better than copper.

After graphene research won the Nobel Prize for Physics in 2010 it was hailed as a transformative material for flexible electronics, more powerful computer chips and solar panels, water filters and bio-sensors. But performance has been mixed and industry adoption slow.

Now a study published in Nature Communications identifies silicon contamination as the root cause of disappointing results and details how to produce higher performing, pure graphene.

The RMIT University team led by Dr Dorna Esrafilzadeh and Dr Rouhollah Ali Jalili inspected commercially-available graphene samples, atom by atom, with a state-of-art scanning transition electron microscope.

“We found high levels of silicon contamination in commercially available graphene, with massive impacts on the material’s performance,” Esrafilzadeh said.

Testing showed that silicon present in natural graphite, the raw material used to make graphene, was not being fully removed when processed.

“We believe this contamination is at the heart of many seemingly inconsistent reports on the properties of graphene and perhaps many other atomically thin two-dimensional (2D) materials ,” Esrafilzadeh said.

Graphene has not become the next big thing because of silicon impurities holding it back, RMIT researchers have said.

Graphene was billed as being transformative, but has so far failed to make a significant commercial impact, as have some similar 2D nanomaterials. Now we know why it has not been performing as promised, and what needs to be done to harness its full potential.”

The testing not only identified these impurities but also demonstrated the major influence they have on performance, with contaminated material performing up to 50% worse when tested as electrodes.

“This level of inconsistency may have stymied the emergence of major industry applications for graphene-based systems.

But it’s also preventing the development of regulatory frameworks governing the implementation of such layered nanomaterials, which are destined to become the backbone of next-generation devices,” she said.

The two-dimensional property of graphene sheeting, which is only one atom thick, makes it ideal for electricity storage and new sensor technologies that rely on high surface area.

This study reveals how that 2D property is also graphene’s Achilles’ heel, by making it so vulnerable to surface contamination, and underscores how important high purity graphite is for the production of more pure graphene.

Using pure graphene, researchers demonstrated how the material performed extraordinarily well when used to build a supercapacitator, a kind of super battery.

When tested, the device’s capacity to hold electrical charge was massive. In fact, it was the biggest capacity so far recorded for graphene and within sight of the material’s predicted theoretical capacity.

In collaboration with RMIT’s Centre for Advanced Materials and Industrial Chemistry, the team then used pure graphene to build a versatile humidity sensor with the highest sensitivity and the lowest limit of detection ever reported.

These findings constitute a vital milestone for the complete understanding of atomically thin two-dimensional materials and their successful integration within high performance commercial devices.

“We hope this research will help to unlock the exciting potential of these materials.”

Story Source:

Materials provided by RMIT University. Note: Content may be edited for style and length.


Journal Reference:

  1. Rouhollah Jalili, Dorna Esrafilzadeh, Seyed Hamed Aboutalebi, Ylias M. Sabri, Ahmad E. Kandjani, Suresh K. Bhargava, Enrico Della Gaspera, Thomas R. Gengenbach, Ashley Walker, Yunfeng Chao, Caiyun Wang, Hossein Alimadadi, David R. G. Mitchell, David L. Officer, Douglas R. MacFarlane, Gordon G. Wallace. Silicon as a ubiquitous contaminant in graphene derivatives with significant impact on device performance. Nature Communications, 2018; 9 (1) DOI: 10.1038/s41467-018-07396-3