(Funded by the National Institutes of Health)
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).

(Funded by the U.S. Department of Energy)
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.

(Funded by the National Science Foundation and the U.S. Department of Energy)
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.

(Funded by the U.S. Department of Energy)
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.

(Funded by the National Science Foundation)
Cornell University researchers have made headway into understanding how twisted bilayer graphene becomes a superconductor. In 2023, the scientists developed a theoretical formalism to compute the highest possible superconducting transition temperature in any material obtained by stacking and twisting two-dimensional materials. For the current work, the scientists applied this theoretical formalism to twisted bilayer graphene. “One of the remarkable properties of twisted bilayer graphene is the associated tunability,” said Debanjan Chowdhury, one of the scientists involved in this study. “You have unprecedented control over temperature and the twist angle – the tiny electric fields that are applied to switch the material from being an insulator versus a superconductor – making it very easy to explore all sorts of exciting regimes in this material.”