3D Bioprinted Heart Provides New Tool For Surgeons (Bioengineering / Engineering)

Professor of Biomedical Engineering Adam Feinberg and his team have created the first full-size 3D bioprinted human heart model using their Freeform Reversible Embedding of Suspended Hydrogels (FRESH) technique. Showcased in a recent video by American Chemical Society and created from MRI data using a specially built 3D printer, the model mimics the elasticity of cardiac tissue and sutures realistically. This milestone represents the culmination of two years of research, holding both immediate promise for surgeons and clinicians, as well as long term implications for the future of bioengineered organ research.

A 3D bioprinted heart model developed by Adam Feinberg and his team. ©Carnegie Mellon University College of Engineering

The FRESH technique of 3D bioprinting was invented in Feinberg’s lab to fill an unfilled demand for 3D printed soft polymers, which lack the rigidity to stand unsupported as in a normal print. FRESH 3D printing uses a needle to inject bioink into a bath of soft hydrogel, which supports the object as it prints. Once finished, a simple application of heat causes the hydrogel to melt away, leaving only the 3D bioprinted object.

While Feinberg’s lab has proven both the versatility and the fidelity of the FRESH technique, the major obstacle to achieving this milestone was printing a human heart at full scale. This necessitated the building of a new 3D printer custom made to hold a gel support bath large enough to print at the desired size, as well as minor software changes to maintain the speed and fidelity of the print.

A needle prints the alginate into a hydrogel bath, which is later melted away to leave the finished model. ©Carnegie Mellon University College of Engineering

Major hospitals often have facilities for 3D printing models of a patient’s body to help surgeons educate patients and plan for the actual procedure, however these tissues and organs can only be modeled in hard plastic or rubber. Feinberg’s team’s heart is made from a soft natural polymer called alginate, giving it properties similar to real cardiac tissue. For surgeons, this enables the creation of models that can cut, suture, and be manipulated in ways similar to a real heart. Feinberg’s immediate goal is to begin working with surgeons and clinicians to fine tune their technique and ensure it’s ready for the hospital setting.

“We can now build a model that not only allows for visual planning, but allows for physical practice,” says Feinberg. “The surgeon can manipulate it and have it actually respond like real tissue, so that when they get into the operating site they’ve got an additional layer of realistic practice in that setting.”

Modeling incorporates imaging data into the final 3D printed object. ©Carnegie Mellon University College of Engineering

This paper represents another important marker on the long path to bioengineering a functional human organ. Soft, biocompatible scaffolds like that created by Feinberg’s group may one day provide the structure onto which cells adhere and form an organ system, placing biomedicine one step closer to the ability to repair or replace full human organs.

“While major hurdles still exist in bioprinting a full-sized functional human heart, we are proud to help establish its foundational groundwork using the FRESH platform while showing immediate applications for realistic surgical simulation,” added Eman Mirdamadi, lead author on the publication.

Published in ACS Biomaterials Science and Engineering, the paper was co-authored by Feinberg’s students Joshua W. Tashman, Daniel J. Shiwarski, Rachelle N. Palchesko, and former student Eman Mirdamadi.

References: Eman Mirdamadi, Joshua W. Tashman, Daniel J. Shiwarski, Rachelle N. Palchesko, and Adam W. Feinberg, “FRESH 3D Bioprinting a Full-Size Model of the Human Heart”, ACS Biomater. Sci. Eng. 2020, 6, 11, 6453–6459. https://doi.org/10.1021/acsbiomaterials.0c01133

Provided by Carnegie Mellon University

Unraveling A Mystery Surrounding Embryonic Cells (Medicine)

Neural crest study results could boost stem cell therapies.

Last year, researchers at the University of California, Riverside, identified the early origins of neural crest cells — embryonic cells in vertebrates that travel throughout the body and generate many cell types — in chick embryos. Now the researchers have used a human model to figure out when neural crest cells acquire distinctive molecular and functional attributes.

Maneeshi S. Prasad is an assistant project scientist at UC Riverside. ©Garcia-Castro lab, UC Riverside.

The study, published in Stem Cell Research, provides new insight into the formation of neural crest cells and outlines transient prospective stages in their development. It also shows the neural crest lineage is distinct from pluripotent stem cells.

The neural crest is an important embryonic cell population in the developing embryo that generates cells such as neurons, glia, and melanocytes, along with cells that make up bone and cartilage. Its improper development is linked to a wide range of pathologies, from craniofacial malformations such as palate clefts to aggressive cancers such as melanoma and neuroblastoma.

“Defining the molecular signature required for the formation of the neural crest better equips us to understand human neural crest related pathologies and develop diagnostic and therapeutic efforts,” said lead study author Maneeshi S. Prasad, an assistant project scientist in the lab of Martin I. Garcia-Castro, an associate professor of biomedical sciences at the UC Riverside School of Medicine. “The knowledge of the precise time and molecular signals involved, when exactly the neural crest acquires the potential to form jaw and tooth cells, for example, will enable scientists to replicate and modulate their potential in stem cell therapies designed to aid regenerative craniofacial repair approaches, among many others.”

The study used a robust human model of neural crest formation to demonstrate a fast transition from the pluripotent stem cell state to the neural crest precursor state. According to this model, a sequential loss of pluripotency markers occurs during the pluripotent stem cell state as cells transition to neural crest cells.

“We address the precise timing when pluripotent stem cells diverge toward the neural crest cell lineage by exploring the distinctive molecular and functional attributes of early neural crest cells — something that had never been established,” Prasad said. “We also identified unique molecular signatures during the transition stages of neural crest formation from pluripotent stem cells.”

Martin I. Garcia-Castro is an associate professor of biomedical sciences at UC Riverside. ©School of Medicine, UC Riverside.

The researchers provide a high-resolution temporal map of gene expression and epigenetic changes with well-defined stages of neural crest formation they say should be a valuable resource for scientists identifying and studying the role of various genes involved in human neural crest formation.

Neural crest cells have been thought to originate in the ectoderm, one of the three germ layers formed in the earliest stages of embryonic development, but their capacity to form derivatives, such as bone- and tooth-forming cells, are in conflict with fundamental concepts in developmental and stem cell biology.

Garcia-Castro noted the study also establishes a novel in vitro specification test to determine the differentiation capacity of specified neural crest cells into other germ layers such as mesoderm and endoderm cell types. The specification test involves exposing the potentially specified cells to precise level of signals that stimulate the formation of other germ layers such as mesoderm and endoderm from pluripotent embryonic stem cells.

“Our work demonstrates that neural crest cells depart from the pluripotent stem cell state soon after the activation of Wnt signaling, an ancient and evolutionarily conserved pathway that regulates crucial aspects of the cell,” he said. “Importantly, using our novel specification test we found that prospective neural crest cells lose the mesodermal and endodermal potential characteristic of pluripotent stem cells just hours upon their induction.”

Garcia-Castro and Prasad were joined in the research by postdoctoral fellow Rebekah M. Charney and undergraduate researcher Lipsa J. Patel.

The research was funded by the National Institutes of Health.

The title of the research paper is “Distinct molecular profile and restricted stem cell potential defines the prospective human cranial neural crest from embryonic stem cell state.”

Provided by University of California

The Gut Microbiota Forms A Molecule That Can Contribute To Diabetes Progression (Medicine)

It is the bacterial changes in the gut that increase the levels of imidazole propionate, the molecule that makes the body’s cells resistant to insulin in type 2 diabetes. This result emerges from a European study, MetaCardis.

©Gettyimages

The gut and its bacteria are considered important in many diseases and several studies have shown that the gut microbiota affects the breakdown of several different parts of our diet. In previous research on gut microbiota and type 2 diabetes, the focus has often been on butyric acid-producing dietary fibers and their possible effects on blood sugar regulation and insulin resistance.

In previous research led by Fredrik Bäckhed, Professor of molecular medicine at the University of Gothenburg, demonstrated that diabetes can be linked to a changes in the composition of intestinal bacteria, which increases the production of molecules that may contribute to the disease.

His group has shown that the altered intestinal microbiota leads to altered metabolism of the amino acid histidine, which in turn leads to increased production of imidazole propionate, the molecule that prevents the blood sugar lowering effects of insulin.

An article published in the journal Nature Communications now confirms the initial findings in a large European study with 1,990 subjects, which shows that patients with type 2 diabetes from Denmark, France and Germany also had increased levels of imidazole propionate in their blood.

“Our study clearly shows that imidazole propionate is elevated in type 2 diabetes in other populations as well” says Fredrik Bäckhed, and continues:

“The study also shows that the levels of imidazole propionate are elevated even before the diabetes diagnosis is established, in so-called prediabetes. This may indicate that imidazole propionate may contribute to disease progression.”

The altered gut microbiota observed in people with type 2 diabetes has fewer species than normal glucose tolerant individuals, which is also linked to other diseases. The researchers speculate that this leads to an altered metabolism of the amino acid histidine.

The EU-funded research collaboration MetaCardis has been led by Karine Clément, Professor of Nutrition at Sorbonne University and Assistance Publique Hôpitaux de Paris, a direction of an INSERM group in Paris.

“Interestingly enough, our findings suggest that it is the altered intestinal microbiota rather than the histidine intake in the diet that affects the levels of imidazole propionate”. She continuous:

“An unhealthy diet also associates with increased imidazole propionate in individuals with type 2 diabetes”.

One problem with research on microbiota and various diseases has been limited reproducibility. By studying the products that the bacteria produce, the metabolites, one focuses on the function of the bacteria rather than on the exact species in the intestine. Fredrik Bäckhed:

“The collaboration gave us unique opportunities to confirm preliminary findings that imidazole propionate can be linked to type 2 diabetes. Here we had the opportunity to analyze almost 2,000 samples and can thus determine that elevated levels of imidazole propionate can be linked to type 2 diabetes. As the levels are elevated even in prediabetes, imidazole propionate may also cause the disease in some cases, he says.

References: http://dx.doi.org/10.1038/s41467-020-19589-w

Provided by University of Gotherburg

Dentists From RUDN University Found a Reason For Early Deterioration of Dental Implants (Dentistry / Medicine)

A team of dentists from RUDN University confirmed that a change in the dominant side of chewing is a reason for the early deterioration of dental implants. Such a change makes it more difficult for a patient to get accustomed to an implant and can lead to bone tissue abnormalities. The discovery can help dentists plan the recovery process after implantation surgeries. The results of the study were published in the European Journal of Dentistry.

A team of dentists from RUDN University confirmed that a change in the dominant side of chewing is a reason for the early deterioration of dental implants. Such a change makes it more difficult for a patient to get accustomed to an implant and can lead to bone tissue abnormalities. The discovery can help dentists plan the recovery process after implantation surgeries. ©RUDN University

Every year, around 2 mln dental implants with fixed dentures attached to them are installed all over the world. An implant is an effective way to restore a deformed or lost tooth without negatively affecting a patient’s quality of life. Modern-day dental implants, usually made of titanium, are durable and quick to take in the bone tissue of a jaw. The only issue with them is their early deterioration in 4-5% of patients. Such deterioration is caused by microdamage that occurs when the load on the implant is calculated incorrectly before the surgery. Excessive load affects the junction between the metal and the bone, letting the bacteria in under the implant and causing inflammation. A team of dentists from RUDN University suggested that additional load on the implant might occur when a patient changes the dominant side of chewing in the first months after the surgery.

Most people don’t chew symmetrically on both sides of the jaw but have a dominant side that accounts for up to 75% of chewing movements. However, such a side can be changed, for example, because of a sore tooth. It usually takes a patient 3 to 4 months to get accustomed to a dental implant and during this time the type of chewing and the load on the teeth can change. As a result, after the surgery, a patient can switch to a different side of chewing, and load calculations from before the surgery can become invalid. Until recently, the effect of this dramatic change in chewing habits on the state of dential implants remained understudied.

The team monitored the course of rehabilitation of 64 patients with dental implants. The participants of the study were adults with implants installed only on one side of the jaw. Surgeries on both sides of the jaw were not included in the study as they would not allow for measuring the effect of dominant chewing side change. The team took X-ray images of the participants’ teeth, measured the strength of their chewing muscles, and in some cases took CT images of the jaws. All these operations were conducted once before the surgery and twice within a year after it. To analyze the results of the treatment, the team asked the participants to fill in questionnaires.

40 patients (62.5%) reported changes in the dominant side of chewing after the surgery. According to the dentists, this might have happened because the patients returned to the chewing patterns they had been used to earlier, before losing a tooth. Having compared this group with the rest of the patients that reported no changes in their chewing habits, the team found out that a change of the dominant side of chewing leads to more bone tissue formation pathologies. In 4 patients with changed chewing habits, the first signs of issue deterioration around the implant were visible in X-ray images. As for the second group, these signs were identified in only one participant. Six months after the surgery the patients that changed their dominant side of chewing felt 22% less adapted to the implants than the patients with no changes in their chewing patterns.

“A change in the dominant side of chewing is an important factor in one’s adaptation to dental implants. According to our study, it can also be the reason for pathological processes, eventually leading to the loss of an implant. Dentists need to be aware of the prevalence of such changes, consider them when developing postsurgical rehabilitation plants, and look for their signs during regular checkups,” said Prof. Igor Voronov, MD, from the Department of Orthopedic Dentistry, RUDN University.

References: http://dx.doi.org/10.1055/s-0040-1715551

Provided by RUDN University

New Technique Seamlessly Converts Ammonia to Green Hydrogen (Chemistry)

New technique seamlessly converts ammonia to green hydrogen.

Northwestern University researchers have developed a highly effective, environmentally friendly method for converting ammonia into hydrogen. Outlined in a recent publication in the journal Joule, the new technique is a major step forward for enabling a zero-pollution, hydrogen-fueled economy.

©Northwestern University

The idea of using ammonia as a carrier for hydrogen delivery has gained traction in recent years because ammonia is much easier to liquify than hydrogen and is therefore much easier to store and transport. Northwestern’s technological breakthrough overcomes several existing barriers to the production of clean hydrogen from ammonia.

“The bane for hydrogen fuel cells has been the lack of delivery infrastructure,” said Sossina Haile, lead author of the study. “It’s difficult and expensive to transport hydrogen, but an extensive ammonia delivery system already exists. There are pipelines for it. We deliver lots of ammonia all over the world for fertilizer. If you give us ammonia, the electrochemical systems we developed can convert that ammonia to fuel-cell-ready, clean hydrogen on-site at any scale.”

Haile is Walter P. Murphy Professor of materials science and engineering at Northwestern’s McCormick School of Engineering with additional appointments in applied physics and chemistry. She also is co-director at the University-wide Institute for Sustainability and Energy at Northwestern.

In the study, Haile and her research team report they are able to conduct the ammonia-to-hydrogen conversion using renewable electricity instead of fossil-fueled thermal energy because the process functions at much lower temperatures than traditional methods (250 degrees Celsius as opposed to 500 to 600 degrees Celsius). Second, the new technique generates pure hydrogen that does not need to be separated from any unreacted ammonia or other products. Third, the process is efficient because all of the electrical current supplied to the device directly produces hydrogen, without any loss to parasitic reactions. As an added advantage, because the hydrogen produced is pure, it can be directly pressurized for high-density storage by simply ramping up the electrical power.

To accomplish the conversion, the researchers built a unique electrochemical cell with a proton-conducting membrane and integrated it with an ammonia-splitting catalyst.

“The ammonia first encounters the catalyst that splits it into nitrogen and hydrogen,” Haile said. “That hydrogen gets immediately converted into protons, which are then electrically driven across the proton-conducting membrane in our electrochemical cell. By continually pulling off the hydrogen, we drive the reaction to go further than it would otherwise. This is known as Le Chatelier’s principle. By removing one of the products of the ammonia-splitting reaction–namely the hydrogen–we push the reaction forward, beyond what the ammonia-splitting catalyst can do alone.”

The hydrogen generated from the ammonia splitting then can be used in a fuel cell. Like batteries, fuel cells produce electric power by converting energy produced by chemical reactions. Unlike batteries, fuel cells can produce electricity as long as fuel is supplied, never losing their charge. Hydrogen is a clean fuel that, when consumed in a fuel cell, produces water as its only byproduct. This stands in contrast with fossil fuels, which produce climate-changing greenhouse gases such as carbon dioxide, methane and nitrous oxide.

Haile predicts that the new technology could be especially transformative in the transportation sector. In 2018, the movement of people and goods by cars, trucks, trains, ships, airplanes and other vehicles accounted for 28% of greenhouse gas emissions in the U.S.–more than any other economic sector according to the Environmental Protection Agency.

“Battery-powered vehicles are great, but there’s certainly a question of range and material supply,” Haile said. “Converting ammonia to hydrogen on-site and in a distributed way would allow you to drive into a fueling station and get pressurized hydrogen for your car. There’s also a growing interest for hydrogen fuel cells for the aviation industry because batteries are so heavy.”

Haile and her team have made major advances in the area of fuel cells over the years. As a next step in their work, they are exploring new methods to produce ammonia in an environmentally friendly way.

References: Dae-Kwang Lim, Austin B. Plymill, Haemin Paik, Xin Qian, Strahinja Zecevic, Calum R.I. Chisholm, Sossina M. Haile, “Solid Acid Electrochemical Cell for the Production of Hydrogen from Ammonia”, Joule, Volume 4, Issue 11, 2020, Pages 2338-2347, ISSN 2542-4351,
https://doi.org/10.1016/j.joule.2020.10.006
(http://www.sciencedirect.com/science/article/pii/S2542435120304955)

Provided by Northwestern University

UIC Researchers Describe Fundamental Processes Behind Movement of Magnetic Particles (Engineering)

The motion of magnetic particles as they pass through a magnetic field is called magnetophoresis. Until now, not much was known about the factors influencing these particles and their movement. Now, researchers from the University of Illinois Chicago describe several fundamental processes associated with the motion of magnetic particles through fluids as they are pulled by a magnetic field.

Pictured is an infinity ring formed by magnetic nanoparticles in response to the magnetic field. The center of the infinity ring represents the ballistic transport where nanoparticles are accumulated, whereas the lighter shade of the ring shows the diffusive transport where nanoparticles are free and diffusing away. This very fundamental process of magnetophoresis is central to various biomedical applications and it also has been protecting the Earth by deflecting the charged particles in the magnetosphere. UIC researchers have developed a predictive model to understand and control magnetophoresis. ©Ayankola Ayansiji and Meenesh Singh

Their findings are reported in the journal Proceedings of the National Academy of Sciences.

Understanding more about the motion of magnetic particles as they pass through a magnetic field has numerous applications, including drug delivery, biosensors, molecular imaging, and catalysis. For example, magnetic nanoparticles loaded with drugs can be delivered to discrete spots in the body after they are injected into the bloodstream or cerebrospinal fluid using magnets. This process currently is used in some forms of chemotherapy for the treatment of cancer.

“We need to know more about how magnetic particles move so we can better predict how fast they move, how many will reach their targets and when and what factors influence their behaviors as they move through various fluids,” said Meenesh Singh, UIC assistant professor of chemical engineering at the College of Engineering and corresponding author on the paper.

Meenesh and colleagues found that four major factors influence the motion of magnetic particles: the difference between the magnetic properties of the particles and the solution they are moving through, the gradient of the magnetic field, the magnetic interactions between particles or how much they stick together, and the interaction of electrical charges on particles with the magnetic field.

“We can build on this new knowledge to increase the specificity by which magnetic nanoparticles reach desired target tissues in the central nervous system,” said Andreas Linninger, UIC professor of bioengineering at the College of Engineering and first author on the paper.

Based on these findings, the researchers created a mathematical formula with all these factors included. Using real-world data, they populated their model and were able to accurately predict the speed and location of particles in real systems.

“By using our model, physicians and researchers will be better able to design magnetic nanoparticles to deliver drugs or other molecules and do so much more accurately,” Meenesh said. “This model can also predict the motion of charged magnetic particles in various applications, including the deflection of charged particles in earth’s magnetosphere.”

The research described in this paper, which was co-authored by UIC’s Ayankola Ayansiji and Anish Dighe, was funded by the National Science Foundation (CBET-1706921).

Provided by University of Illinois at Chicago

Small Finlets On Owl Feathers Point The Way To Less Aircraft Noise (Engineering)

Collaboration between between City, University of London and RWTH Aachen University researchers reveals how these micro-structures enable silent flight.

A recent research study conducted by City, University of London’s Professor Christoph Bruecker and his team has revealed how micro-structured finlets on owl feathers enable silent flight and may show the way forward in reducing aircraft noise in future.

Owl wingspan. ©Courtesy Professor Hermann Wagner

Professor Bruecker is City’s Royal Academy of Engineering Research Chair in Nature-Inspired Sensing and Flow Control for Sustainable Transport and Sir Richard Olver BAE Systems Chair for Aeronautical Engineering.

His team have published their discoveries in the Institute of Physics journal, Bioinspiration and Biomimetics in a paper titled ‘Flow turning effect and laminar control by the 3D curvature of leading edge serrations from owl wing’.

Their research outlines their translation of the detailed 3D geometry data of typical owl feather examples provided by Professor Hermann Wagner at RWTH Aachen University (Germany) into a biomimetic aerofoil to study the aerodynamic effect on the special filaments at the leading edge of the feathers.

The results show that these structures work as arrays of finlets which coherently turn the flow direction near the aerodynamic wall and keep the flow for longer and with greater stability, avoiding turbulence.

The City research team was inspired by the complex 3D geometry of the extensions along the front of the owl’s feathers – reconstructed by Professor Wagner and his team in previous studies using high-resolution micro-CT scans.

After being transferred into a digital shape model, the flow simulations around those structures (using computational fluid dynamics) clearly indicated the aerodynamic function of these extensions as finlets, which turn the flow direction in a coherent way.

Owl serration feather image. ©Professor Christoph Bruecker

This effect is known to stabilize the flow over a swept wing aerofoil, typical for owls while flapping their wings and gliding.

Using flow studies in a water tunnel, Professor Bruecker, also proved the flow-turning hypothesis in experiments with an enlarged finlet model.

His team was surprised that instead of producing vortices, the finlets act as thin guide vanes due to their special 3D curvature. The regular array of such finlets over the wing span therefore turns the flow direction near the wall in a smooth and coherent manner.

The team plans to use a technical realisation of such a swept wing aerofoil pattern in an anechoic wind-tunnel for further acoustic tests. The outcome of this research will prove to be important for future laminar wing design and has the potential to reduce aircraft noise.

References: Muthukumar Muthuramalingam, Edward Talboys, Hermann Wagner and Christoph Bruecker, “Flow turning effect and laminar control by the 3D curvature of leading edge serrations from owl wing”, IOPscience, 2020. https://iopscience.iop.org/article/10.1088/1748-3190/abc6b4/pdf

Provided by City University London

A DNA-based Nanogel For Targeted Chemotherapy (Medicine / Chemistry)

Current chemotherapy regimens slow cancer progression and save lives, but these powerful drugs affect both healthy and cancerous cells. Now, researchers reporting in ACS’ Nano Letters have designed DNA-based nanogels that only break down and release their chemotherapeutic contents within cancer cells, minimizing the impacts on normal ones and potentially eliminating painful and uncomfortable side effects.

A DNA-based nanogel (shown above) is broken down in cancer cells to release chemotherapy drugs. ©Adapted from Nano Letters 2020, DOI: 10.1021/acs.nanolet.0c03671

Once ingested or injected, chemotherapy medications move throughout the body, indiscriminately affecting healthy cells along with those that are responsible for disease. Since many of these drugs are toxic to all cells, the desired tumor shrinkage can be accompanied by undesirable side effects, such as hair loss, gastrointestinal issues and fatigue. Nanogels made of DNA are one way that these drugs could be delivered, but they would still enter all cells. Tianhu Li, Teck-Peng Loh and colleagues reasoned that biomarkers — proteins or other components that are present in differing amounts in cancer cells and their healthy counterparts — could play a role in breaking down a nanogel, causing it to release its contents only in those that are cancerous. A biomarker called FEN1, a repair enzyme that cuts certain types of DNA, is present in larger amounts in cancer cells compared with healthy ones. The researchers wanted to see whether they could design a DNA nanogel that would specifically be degraded in cancer cells by FEN1.

To make DNA nanogels, the researchers used special DNA structures that FEN1 could recognize and cut. With cell-free systems, the researchers observed that the DNA-based nanogels were broken down by FEN1 but not by other DNA repair enzymes or compounds. When live cells were incubated with the DNA-based nanogels, healthy ones did not have enough FEN1 to break them down, but cancer cells did. When the chemotherapeutic drugs doxorubicin and vinorelbine were incorporated into the nanogel, human breast cancer cells died at higher rates than normal, healthy breast cells. These findings indicate DNA-based nanogels can introduce drugs into cancer cells with a high specificity, reducing the risk of side effects. The researchers say that the nanogels also could be used as probes for the biomarker enzyme, helping physicians more directly diagnose cancer compared with current methods.

References: Hao Zhang, Sai Ba, Jasmine Yiqin Lee, Jianping Xie, Teck-Peng Loh, and Tianhu Li, “Cancer Biomarker-Triggered Disintegrable DNA Nanogels for Intelligent Drug Delivery”, Nano Lett. 2020, 20, 11, 8399–8407. https://pubs.acs.org/doi/10.1021/acs.nanolett.0c03671 https://dx.doi.org/doi:10.1021/acs.nanolett.0c03671

Provided by American Chemical Society

Scientists Develop a Magnetic Switch With Lower Energy Consumption (Electrical Engineering)

Magnetic materials are ubiquitous in modern society, present in nearly all the technological devices we use every day. In particular, personal electronics like smartphones/watches, tablets, and desktop computers all rely on magnetic material to store information. Information in modern devices is stored in long chains of 1’s and 0’s, in the binary number system used as the language of computers.

Schematic representation of the magnetic switch
©UAB

« If you imagine a bar magnet, the same that many of us played with as a kid (and perhaps still do), you may recall that they were labeled with a “north” side and a “south” side (or had two different colors on each end). If two magnets were brought next to each other, the same sides would repel, and the opposite sides would attract – two distinct halves which can be easily identified. In this way, a “1” and a “0” can be assigned to a magnet’s orientation, so that a long chain of magnets can be arranged in a computer to store data », explains ICREA researcher at the UAB Jordi Sort, one of the research coordinators.

Currently, changing the orientation of a magnet (essentially writing or rewriting data) in electronics has relied on using current, the same current needed to power the outlets in your house and charge your phone. But therein lies a problem: when you run current through a material, the material heats up. This heat is a form of energy that is lost to the environment, essentially wasted. The demand to store more and more data increases each year, and necessitates creating smaller and smaller devices, which exponentially worsens this heating effect, leading to huge energy losses. It is no surprise, then, that government and private research has turned to developing new, energy-efficient materials and technologies to solve this issue.

One possible solution to this problem is to use magnetic materials which can rely on voltage to reorient magnetic material, studied in a field of research called voltage-controlled magnetism, using voltage in place of current to significantly reduce the energy needed to alter the magnetic orientation. There are several approaches, but a promising and popular research branch in the field explores magneto-ionics, where non-magnetic atoms are moved in and out of a magnetic material using voltage, and so altering its magnetic properties.

A recent collaborative study between the UAB, Georgetown University, HZDR Dresden, CNM’s Madrid and Barcelona, University of Grenoble, and ICN2, and published in the journal Nature Communications has shown that it is possible to switch magnetism ON and OFF in metals containing nitrogen (that is, to generate or remove all magnetic features of this material) with voltage. One simple analogy would be that we are able to increase or completely remove the strength with which a magnet attracts to, for example, the door of a fridge, simply by connecting it to a battery and applying a certain voltage polarity. In this project, cobalt-nitride is shown to be non-magnetic on its own, but when nitrogen is removed with voltage, it forms a cobalt-rich structure which is magnetic (and vice versa). This process is shown to be repeatable and durable, suggesting that such a system is a promising means to write and store data in a cyclable manner. Interestingly, it is also shown to require less energy and it is faster than systems using alternative non-magnetic atoms, such as oxygen, elevating the possible energy savings.

References: http://dx.doi.org/10.1038/s41467-020-19758-x

Provided by UAB