Distinguished Keynote

NovoselovSir Kostya Novoselov, The University of Manchester

Materials for the Future

Written by Sophia Chen

Two-dimensional structures like graphene and hexagonal boron nitride make a versatile palette for designing next-generation materials, physicist Kostya Novoselov said in Wednesday’s keynote, titled, “Materials for the Future.”

Novoselov, now at the National University of Singapore, won the 2010 Nobel Prize in Physics for his seminal experiments characterizing the two-dimensional (2D) material graphene. Since then, graphene’s profile has risen among commercial products, both because of its desirable properties and because of its ease of production. Graphene can be found under the hood of all Ford cars, said Novoselov, where they serve noise absorption purposes. Montreal-based company ORA has made headphones with graphene for its stiffness and lightness. Huawei uses graphene films to cool their phones. Graphene is also used as an electrical resistance standard, he said.

Researchers are now pursuing new materials from stacking layers of 2D structures—not just graphene, but also boron nitride, molybdenum diselenide, and tungsten disulfide. This class of materials are broadly known as van der Waals heterostructures, as each atomically thin layer is bonded to the next via van der Waals forces. Researchers have already created LEDs with this type of structure.

A heterostructure’s properties derive from the strong interaction of many electrons between different layers. Thus, researchers can tune a heterostructure’s electronic properties by changing the order and number of layers. Researchers have found surprising materials properties from rotating one layer of atoms with respect to the other slightly. In one 2018 study, researchers created a superconductor by stacking two layers of graphene and rotating one layer by about 1.1 degrees.

Novoselov also discussed several promising future applications for two-dimensional materials. They could be used to design adaptive intelligent materials that respond to external triggers. One example might be a capsule that can open and close to deliver medicine inside the body depending on environmental conditions. Two-dimensional materials could also be used as components in a new type of computer known as neuromorphic computing, he said.

The use of two-dimensional structures could simplify the materials for our electronics. Novoselov pointed out that modern silicon-based devices use a dizzying number of elements ranging from semiconductors to metals to rare earth elements—more than those found in the human body. The increase in material complexity began around 1990, when manufacturers strived to cram more transistors on chips. Two-dimensional materials could potentially reduce the need for rare elements, as they can be oriented and stacked in many configurations to achieve a range of properties.


Symposium SB10: Micro- and Nanoengineering of Biomaterials—From Precision Medicine to Precision Agriculture and Enhanced Food Security

Joyce Wong, Boston University

Molecularly Targeted Polymerized Shell Microbubbles to Treat Abdominal Surgical Adhesions

Written by Jessalyn Low

Abdominal adhesions are common occurrences following abdominal surgeries, attributed to a disruption of the healing process. Current techniques of monitoring adhesions are, however, invasive and ironically cause more adhesions. To tackle the unmet need of non-invasive early diagnosis and monitoring of abdominal adhesions post-surgery, Wong has designed novel targeted polymerized-shell microbubbles (PSMs) as ultrasound contrast agents. These PSMs are designed with cross-linked lipid shells and targeting moieties that target fibrin, an early adhesion target. One key consideration in the design of the PSMs is the need to ensure stability against gas dissolution, while ensuring that their acoustic response and ability to oscillate is not compromised, as commercial microbubbles are generally not designed with the intention of long-term use. Wong demonstrates that these can be optimized by controlling the crosslink density of the microbubbles. Results show that the various PSM formulations exhibit consistent radii and stability over 48 hours, which is the important time frame for monitoring early adhesions. Importantly, these PSMs are not cytotoxic to mesothelial cells and when conjugated to CREKA (Cys-Arg-Glu-Lys-Ala), the PSMs could bind to fibrin. These results demonstrate great potential to advance clinical trials of adhesion prevention and treatment.


Diamond Materials for Quantum Applications

The EQ19.09/EQ03.06, joint session, on "Diamond Materials for Quantum Applications" has explored a range of concepts and experimental techniques to fabricate diamond materials of different properties for various applications. One interesting presentation in this session is the talk given by my colleague Rani Mary Joy on the fabrication of Germanium vacancy centres as a potential replacement of the more studied Nitrogen vacancy centers.

In her talk, titled " Investigation of Germanium-Vacancy Colour Centre Formation in Nanocrystalline CVD Diamond", Joy discussed the potential and challenges of creating Germanium vacancy centres within nanocrystalline diamond films. She used commercially available Germanium substrates as the source of Germanium in the diamond layer, grown using chemical vapor deposition.  One of the main obstacles in the fabrication process, she explained, is the proximity of the melting point of germanium to the deposition temperature of diamond. Adhesion of the diamond layer to the Germanium substrate is another problem that is caused by the absence of a carbide layer at the interface between the two materials, as Joy explains. That has led her to make use of free standing diamond films in which she was able to detect low concentrations of Germanium. Once the incorporation of Germanium into the diamond layer was confirmed, additional tests were carried out, by Joy and her colleagues, to improve the distribution of the Germanium vacancies across the diamond film. One of the findings in this study was that a lower methane concentration, in the deposition process of diamond, has led to better crystalline quality. 

This session was a great learning moment for me to know a bit more about NV and GeV centres and their applications.  

 


Symposium SB05: Antimicrobial Materials Against Coronaviruses and Other Nosocomial Pathogens

Anthony Galante, University of Pittsburgh

Superhemophobic and Antivirofouling Coating for Mechanically Durable and Wash-Stable Medical Textiles

Written by Jessalyn Low

The development of fluid-repellent textiles in the medical field such as masks and gowns are highly favorable to reduce the spread of infectious diseases. In this presentation, Galante presents the development of a self-cleaning surface on nonwoven polypropylene (PP) with the ability to repel various liquids. This is achieved by coating polytetrafluoroethylene (PTFE) nanoparticles, which have low surface energy, onto the surface of the PP textiles. As such, the treated surfaces are superhydrophobic and superhemophobic with high static contact angle, thus allowing the surface to repel liquids. This was found to significantly reduce the attachment of proteins and viruses. In addition, the surface roughness of the treated textiles ensured that the surfaces remain durable after harsh abrasion, where static contact angle was found to remain stable even after abrasion of the surface.


Symposium SB10: Micro- and Nanoengineering of Biomaterials—From Precision Medicine to Precision Agriculture and Enhanced Food Security

Adam Behrens, Mori

Silk Fibroin as an Edible Food Coating

Written by Jessalyn Low

Over one third of food is wasted every year. To enhance food resilience, one potential approach would be finding ways to improve food packaging and increase their shelf life. In this presentation, Behrens presents the idea of using silk fibroin as a material for edible food coating that has great potential in slowing down food spoilage and making food more resilient. Silk fibroin is a highly favorable material due to properties such as its self-assembly properties which create strong barrier properties, as well as film-forming properties which allow for coating on a diverse range of substrates. In particular, silk crystallinity is an integral factor that improves the moisture barrier of silk, while influencing other properties such as mechanical strength and water resistance. This crystallinity can be controlled accordingly using heat and solvent treatments. The silk fibroin coating has shown immense potential to improve shelf life across a wide range of food, ranging from avocadoes, to cereal and fish. In leafy greens, the silk coating provided a barrier effect on leaves, thus reducing respiration rate and a 25% improvement in shelf life. This highlights the potential of using silk fibroin as an edible food coating to build the resilience of our food systems.


Symposium SB05: Antimicrobial Materials Against Coronaviruses and Other Nosocomial Pathogens

Jinju Chen, Newcastle University

Covalently Attached Liquid-Like Solid Surfaces Prevent Biofilm Formation

Written by Jessalyn Low

Infections caused by biofilms are highly detrimental, associated with a high mortality rate as well as healthcare costs. As such, there is a critical need for the development of antimicrobial technologies. Taking inspiration from slippery surfaces found in nature like pitcher plants, lubricant-based surfaces can inhibit bacterial attachment. However, this is limited by the loss of lubricant over time with repeated use. In this presentation, Chen presents the idea of developing liquid-like solid surfaces to tackle this issue. Here, Slippery Omniphobic Covalently Attached Liquid-like (SOCAL) surface was developed, where uncrosslinked PDMS which behaves like a liquid is being covalently bonded to the surface. This slippery surface prevents biofilm formation as the bacteria is unable to anchor to the solid surface underneath and can be easily detached from the surface with low force. When validated against two clinically relevant bacteria strains, Staphylococcus (S.) aureus and Pseudomonas (P.) aeruginosa in static and dynamic conditions, the SOCAL surface showed enhanced antibiofilm efficiency as compared to non-coated controls. This opens up opportunities for the development of antibacterial surfaces in medical devices and implants.


MRS Award Recipients—Lightning Talks and Panel Discussion

Written by Sophia Chen

At each conference, MRS invites award recipients to deliver a short talk about their research. This year’s speakers presented topics ranging from quantum theoretical simulation to more environmentally sustainable cement. The panel was moderated by MRS Awards Committee chair Suveen Mathaudhu of the University of California, Riverside.

Emily Carter of the University of California, Los Angeles, presented about theoretical research for predicting materials properties, particularly for carbon mitigation purposes. She uses theoretical methods to identify catalysts for recycling carbon dioxide into chemical feedstocks or to devise carbon sequestration methods.

These applications involve electron transfer and electronic excited states, both of which are not well described by density functional theory, the primary theoretical framework for modeling quantum processes, says Carter. Instead, she studies embedded correlated wavefunction (ECW) theory. In one study, she found that ECW described carbon dioxide reduction on a copper electrode more accurately than density functional theory.

Yury Gogotsi of Drexel University presented research on a class of two-dimensional materials known as MXenes (pronounced “max-eens”) for energy storage. The basic unit of these materials is a transition metal bonded to a carbon or nitrogen. To tune the material’s properties, you can swap out the atoms exposed at the material’s surface.

Gogotsi says MXenes could be suitable for many different applications. It has already outperformed all other known materials for electromagnetic interference shielding, he said. In addition, MXenes can be used for antennas and communications. It can also be knitted into fabrics for wearable electronics.

Susan Bernal Lopez of the University of Leeds presented her research on more environmentally sustainable concrete. Concrete is the most widely used material in the world after water, and making it produces a significant amount of carbon dioxide. Bernal is studying how to reduce CO2 during production.

In one case, she is looking into a class of materials known as alkali-activated cement to replace Portland cement, the glue that keeps concrete together. Alkali-activated cement can be made by combining an aluminosilicate source, such as volcanic ash or byproducts from coal combustion, with an alkali source. Alkali-activated cement would produce half or less of the hundreds of kilograms of carbon dioxide that Portland cement produces.

Bernal’s group is working to characterize alkali-activated cement. She has studied how impurities affected the performance of the cement. She has also studied the evolution of pores within paste after mixing for identifying strategies to make concrete more durable.

Stafford Sheehan, chief technology officer of Air Company, presented his company’s efforts to convert carbon dioxide into alcohol-containing products. These products range from vodka and hand sanitizer to aviation fuel and fragrances. The company operates three facilities: a catalyst lab for optimizing catalysts in New Jersey, a pilot facility for testing reactions, and a production facility that operates 24 hours a day, seven days a week.

Air Company is working to scale up their production, said Sheehan. They have operated a system that can handle one tonne of carbon dioxide per day. Now, they are striving to scale up to 500 tons per day by 2024 and eventually 10,000 tons per day by 2027.

Dasha Nelidova, a postdoctoral researcher at the Institute Molecular Clinical Ophthalmology Basel, presented a sensor that attaches to a retina that could help restore visual function in vision-impaired humans.

The sensor makes cells sensitive to near-infrared light. The system achieves this by combining nanotechnology with optogenetics, a technique to control cell activity with light. Gold nanorods serve as antennas, converting near-infrared light into local heat. This heat then opens up an ion channel known as a TRP channel attached to the nanorods to drive photocurrents through the retina. When she tested the sensor in blind mice, the mice were able to perform simple behavioral tasks. She aims for her system to help those with age-related macular degeneration or retinitis pigmentosa, two leading causes of blindness worldwide.

Zhijie Chen, a postdoctoral researcher at Northwestern University, presented his work on a class of porous materials known as metal-organic frameworks (MOFs). These network-like structures can be made from a variety of tunable materials and are known for their large surface area.

Chen has developed several applications using MOFs. In one, he designed a highly porous MOF called NU-1500 for hydrogen storage. In another, he integrated a MOF onto fabric that breaks down deadly chemical weapons known as nerve agents. To do this, the MOF captures water from the air, and the water breaks down the nerve agents with the help of a zirconium catalyst in the MOF. The fabric is intended for military uniforms.

Carter received the Materials Theory Award for “advances in quantum mechanics theory with broad applications to materials and chemical sciences.” Endowed by Dr. Gwo-Ching Wang and Dr. Toh-Ming Lu.

Gogotsi received the MRS Medal for “contributions to advancing the understanding of processing, structure, and properties of two-dimensional carbides and nitrides (MXenes) for energy storage applications.” Endowed by Dr. Gwo-Ching Wang and Dr. Toh-Ming Lu.

Lopez (Kavli Foundation Early Career Lectureship in Materials Science) for significant novel contributions to materials science. The Kavli Foundation is dedicated to advancing science for the benefit of humanity, promoting public understanding of scientific research and supporting scientists and their work.

Sheehan (MRS Nelson “Buck” Robinson Science and Technology Award for Renewable Energy) for the development of novel sustainable solutions for the realization of renewable sources of energy. Endowed by Sophie Robinson in memory of her father, Nelson "Buck" Robinson.

Nelidova (MRS Postdoctoral Award) for “creating tunable nanogenetic near-infrared light sensors to restore vision.” Supported by the Jiang Family Foundation and MTI Corporation.

Chen (MRS Postdoctoral Award) for “his outstanding contributions to the fields of porous materials, nanochemistry, and supramolecular assembly.” Supported by the Jiang Family Foundation and MTI Corporation.


Symposium SB11: Photo/Electrical Phenomena at the Interface with Living Cells and Bacteria

Karan Bali, University of Cambridge

Using High Resolution Correlative Microscopy To Characterize Bacterial Derived Supported Lipid Bilayers

Written by Jessalyn Low

Supported lipid bilayers (SLBs) can be derived from bacterial vesicles to model bacterial membranes. These have many applications, for instance in drug screening. To characterize these SLBs optically at high precision, Bali reports the use of correlative atomic force microscopy (AFM) and structured illumination microscopy (SIM) to image the bilayers and structure of the SLBs. This technique offers much more detailed information of the molecular interactions as compared to conventional techniques like fluorescence recovery after photobleaching (FRAP). Furthermore, by expressing proteins of interest in the bacterial vesicles, it is found that AFM-SIM could achieve high precision to map the bacterial components in complex systems. With these promising results, Bali is working toward integrating the correlative AFM-SIM setup with electrical monitoring on devices. This aims to achieve highly precise screening platforms for interactions with bacterial SLBs.


Symposium EN12—Advanced Materials and Chemistries for Low-Cost and Sustainable Batteries

Esther Takeuchi, Stony Brook University

Mechanistic Investigations of Manganese and Vanadium Oxide Electrochemistry in Aqueous Zinc Batteries

Written by Chetna Madan

Establishing the intermittent renewable energy obtained from solar and wind power as the primary source of energy requires the assistance of sustainable, easily scalable, and cost-effective energy storage systems. Aqueous zinc batteries are becoming a popular option due to their high volumetric capacity, high theoretical energy density, low cost, rapid scalability, and environment-friendly processing conditions. The cathode materials as explored by Professor Takeuchi’s group include the oxides of vanadium and manganese. The effect of annealing temperature during synthesis was found to be governing the electronic and chemical behavior of the cathode catalysts as determined from the ex situ and operando x-ray absorption studies. This was indeed reflected in the electrochemical performance and charge storage mechanism of the aqueous zinc battery. In another study, it was also found by the crystallographic structure analysis that the composition of phases of the cathode catalyst gets modified after charging-discharging cycles. A thorough understanding of the key parameters that regulate the charge storage mechanism of aqueous zinc batteries provides the stepping stone for the successful wide-scale implementation of this technology.