News from the NNI Community - Research Advances Funded by Agencies Participating in the NNI

Researchers from the University of Illinois at Urbana-Champaign have discovered a new type of nanoparticle, palladium hydride, which contains palladium and hydrogen. Palladium hydride nanoparticles are typically structured symmetrically, looking like a cube with palladium atoms posted at each corner and centered on all six cubic faces. In contrast, the new nanoparticle’s structure is presumably the least symmetrical of all crystal systems. To create this unusual nanoparticle, the researchers added electrons to a solution containing palladium ions and water, and the electrons' negative charge pulled positive hydrogen ions from the water molecules, allowing the hydrogen ions to bond with the palladium ions. 

Scientists from Washington State University and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory have discovered a way to make ions move more than ten times faster in mixed organic ion-electronic conductors. These conductors combine the advantages of the ion signaling used by many biological systems with the electron signaling used by computers. The new development speeds up ion movement in these conductors by using molecules that attract and concentrate ions into a separate nanochannel creating a type of tiny “ion superhighway.” These types of conductors hold a lot of potential because they allow movement of both ions and electrons at once, which is critical for battery charging and energy storage. 

Physicists at the Massachusetts Institute of Technology (MIT) have taken a key step toward solving the puzzle of what leads electrons to split into fractions of themselves. The new work is an effort to make sense of a discovery that was reported earlier this year by other physicists at MIT, who found that electrons appear to exhibit "fractional charge" in pentalayer graphene – a configuration of five graphene layers that are stacked atop a similarly structured sheet of boron nitride. Through calculations of quantum mechanical interactions, the scientists showed that the electrons form a sort of crystal structure, the properties of which are ideal for fractions of electrons to emerge. “This crystal has a whole set of unusual properties that are different from ordinary crystals, and leads to many fascinating questions for future research,” said Senthil Todadri, the scientist who led the new study.

Many messenger RNA (mRNA) medicines contain tiny fatty spheres, known as lipid nanoparticles, that encode proteins used by the body to treat or prevent a variety of illnesses. But most versions of lipid nanoparticles for the delivery of mRNA don't work for inhalable medications, because the nanoparticles clump together or increase in size when sprayed into the air. Now, researchers at the Massachusetts Institute of Technology have shown that a polymer with repeating units of positively and negatively charged components – called a zwitterionic polymer – can enable mRNA-containing lipid nanoparticles to withstand nebulization (turning a liquid into a mist).

Researchers from Case Western Reserve University, the University of Virginia, Cleveland Clinic, the University of Maryland School of Medicine, University Hospitals Cleveland Medical Center, the Louis Stokes Veterans Affairs Medical Center (Cleveland, OH), and CVPath Institute, Inc. (Gaithersburg, MD) have identified a new target to treat atherosclerosis, a condition where plaque clogs arteries and causes major cardiac issues, including stroke and heart attack. The researchers identified an inflammation-reducing molecule, called itaconate, and developed a new lipid nanoparticle-based treatment that allows itaconate to accumulate in plaque and bone marrow, where it reduces inflammation. "We've found that itaconate is crucial to the diet's ability to stabilize plaques and reduce inflammation, which has been a mystery until now," said Andrei Maiseyeu, one of the scientists involved in this study. "This discovery marks a major leap forward in the understanding of how diet-induced plaque resolution occurs at a molecular level." 

Researchers at the University of Massachusetts Amherst and the University of Massachusetts-Chan Medical School in Springfield, MA, have invented a new, sprayable delivery system for psoriasis medication that can be applied easily and locally to psoriasis lesions. The delivery system makes use of nanoparticles that contain psoriasis drugs, and these nanoparticles act like a trojan horse – the immune cells do not recognize the nanoparticles as a threat, but the medication they carry disrupts the overactive immune response. The researchers designed and tested nanoparticles in different shapes: rods, ellipses and spheres and discovered that nanorods inhibited 3.8 times more inflammation due to psoriasis than nanoellipses and 4.5 times more than nanospheres. 

Researchers from Florida State University, the Shanghai Institute of Microsystem and Information Technology, and Wuhan University have revealed how various physical manipulations of graphene, such as layering and twisting, impact its optical properties and conductivity. The researchers found that the optical conductivity of twisted bilayer graphene is not heavily impacted by such manipulations and instead depends more on how the material's geometry structure changes by interlayer twisting. To conduct the study, the team captured images of plasmons – tiny waves of energy that happen when electrons in a material move together – that appeared in various regions of the twisted bilayer graphene.

Researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, the University of California at Berkeley, the Massachusetts Institute of Technology, Arizona State University, and the National Institute for Materials Science in Tsukuba, Japan, have captured direct images of a new quantum phase of an electron solid – the Wigner molecular crystal. Whereas Wigner crystals are characterized by a honeycomb arrangement of electrons, Wigner molecular crystals have a highly ordered pattern of artificial “molecules” made of two or more electrons. The scientists formed a nanomaterial, called a “twisted tungsten disulfide moiré superlattice,” and doped it with electrons, which filled each 10-nanometer-wide unit cell of the material with just two or three electrons. In a surprising result, these filled unit cells formed an array of moiré electron molecules throughout the superlattice – resulting in a Wigner molecular crystal.  

Researchers from New York University; the Center for Functional Nanomaterials (CFN), a U.S. Department of Energy Office of Science user facility at Brookhaven National Laboratory; and the National Institute for Materials Science in Tsukuba, Japan, have used a special robotic system to assemble very large pieces of atomically clean two-dimensional materials into stacks. These materials, called graphene heterostructures, consist of sheets just a few atoms thick, have record-setting dimensions – as large as 7.5 square millimeters, which is very large in the world of microelectronics. The robotic assembly tool helped the scientists discover a new interface cleaning mechanism that combines mechanical and thermal forces. Overall, this study opens a new opportunity to develop a more effective process to make large and clean layered heterostructure devices.

Researchers from the Massachusetts Institute of Technology and the University of Udine in Italy have created a new type of three-dimensional transistor using a unique set of ultrathin semiconductor materials. It features vertical nanowires only a few nanometers wide, which can deliver performance comparable to state-of-the-art silicon transistors while operating efficiently at much lower voltages than conventional devices. The transistor’s extremely small size would enable more of these 3D transistors to be packed onto a computer chip, resulting in fast, powerful electronics that are also more energy-efficient. “This is a technology with the potential to replace silicon, so you could use it with all the functions that silicon currently has, but with much better energy efficiency,” says Yanjie Shao, the scientist who led this study.