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

Researchers from the California NanoSystems Institute at the University of California, Los Angeles, have developed a sensor technology based on natural biochemical processes that can continuously and reliably measure multiple metabolites at once. The sensors are built onto electrodes made of tiny cylinders called single-wall carbon nanotubes. These electrodes use enzymes and other molecules to perform reactions that mirror the body’s metabolic processes. Depending on the target metabolite, the sensors either detect it directly or first convert it into a detectable form through a chain of intermediary enzymatic reactions. The team measured metabolites in sweat and saliva samples from patients receiving treatment for epilepsy and detected a gut bacteria-derived metabolite in the brain that could cause neurological disorders if it accumulates.

Researchers at the University of Pennsylvania have developed a new process that transports DNA into cells using lipid nanoparticles. Unlike messenger RNA (mRNA), DNA remains active in cells for months, or even years, and can be programmed to work only in targeted cells. But past attempts to use lipid nanoparticles to deliver DNA failed, because DNA can trigger severe immune reactions. The researchers discovered that by adding a natural anti-inflammatory molecule, called nitro-oleic acid, to the lipid nanoparticles, these immune reactions could be eliminated. With this advancement, treated cells produced intended therapeutic proteins for about six months from a single dose – much longer than the few hours seen with mRNA therapies.  

Researchers at The Ohio State University have developed a new material that, by harnessing the power of sunlight, can clear water of dangerous pollutants. Solar fuel systems that use titanium dioxide nanoparticles can cause significant challenges to implementation, including low efficiency and the need for complex filtration systems. So, the researchers added copper to the nanoparticles, and the new structures, called nanomats, can now absorb enough light energy to break down harmful pollutants in air and water. These lightweight, easy-to-remove fiber mats can float and operate atop any body of water and are even reusable through multiple cleaning cycles. Because the nanomats are so effective, the researchers envision that they could be used to rid water of industrial pollutants in developing countries, turning otherwise contaminated rivers and lakes into sources of clean drinking water. 

Scientists from the U.S. Department of Energy’s (DOE) Argonne National Laboratory (ANL) and SLAC National Accelerator Laboratory; the University of Chicago; the University of Vermont; Middlebury College; Brown University; Stanford University; and Northwestern University have observed that when semiconductor nanocrystals called quantum dots were exposed to short bursts of light, the symmetry of the crystal structure changed from a disordered state to a more organized one. The return of symmetry directly affected the electronic properties of the quantum dots by causing a decrease in the bandgap energy, which is the difference in energy that electrons need to jump from one state to another within a semiconductor material. This change can influence how well quantum dots conduct electricity and respond to electric fields. Part of this work was conducted at the Center for Nanoscale Materials, a DOE Office of Science user facility at ANL.

Stacking single layers of sub-nanometer-thick semiconductor materials, known as transition metal dichalcogenides, can generate a moiré potential – a “seascape” of potential energy with regularly repeating peaks and valleys. These peaks and valleys were previously thought to be stationary, but now, researchers from the Molecular Foundry, a user facility at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, and the University of California, Berkeley, along with international collaborators, have shown that the moiré potentials that emerge when transition metal dichalcogenides are stacked are constantly moving, even at low temperatures. Their discovery contributes to foundational knowledge in materials science and holds promise for advancing the stability of quantum technologies, because controlling moiré potentials could help mitigate decoherence in qubits and sensors. (Decoherence occurs when interference causes the quantum state and its information to be lost.)

Researchers from the City University of New York, Yale University, Caltech, Kansas State University, and international collaborators have discovered a new way of generating phonon-polaritons, a unique type of electromagnetic wave that occurs when light interacts with vibrations in a material’s crystal lattice structure. This advance could pave the way for cheaper, smaller long-wave infrared light sources and more efficient device cooling. The researchers made that discovery by using a thin layer of graphene sandwiched between two hexagonal boron nitride slabs. Until now, exciting and detecting phonon-polariton waves has been expensive – typically involving costly mid-infrared or terahertz lasers and near-field scanning probes – but in this study, the researchers used a cheaper alternative: an electrical current generated by applying an electric field to the graphene.  

Researchers from Oregon State University, Oregon Health & Science University, and international collaborators have developed magnetic nanoparticles in the shape of a cube sandwiched between two pyramids for the treatment of ovarian cancer. Made of iron oxide and doped with cobalt, the nanoparticles show exceptional heating efficiency when exposed to an alternating magnetic field. When the particles accumulate in cancerous tissue after intravenous injection, they are able to quickly rise to temperatures that weaken or destroy cancer cells. A cancer-targeting peptide helps the nanoparticles accumulate in the tumor, and because the nanoparticles’ heating efficiency is strong, the necessary concentration of nanoparticles can be achieved without a high dosage, limiting toxicity and side effects.

Researchers at Caltech have developed an on-chip transducer that converts microwave photons to optical photons. The device involves a tiny silicon beam that vibrates at 5 gigahertz and couples to a microwave resonator – essentially a nanoscale box in which photons bounce around, also at 5 GHz. Using a technique called electrostatic actuation, a microwave photon is converted within that box to a mechanical vibration of the beam, and that mechanical oscillation, with the help of laser light, gets converted by the resonator into an optical photon. Such a conversion could enable the construction of large-scale distributed superconducting quantum computers.

Researchers at Cornell University have, for the first time, identified what happens when bacteria receive electrons from quantum dots. Using fluorescence lifetime imaging microscopy with two-photon excitation on a quantum dot and bacteria, the researchers identified a distinct halo surrounding the bacteria, which suggested the charge transfer was receiving some peripheral assistance. It turned out that an electron could either move directly from the quantum dot to the bacterium or be transferred from the bacterium via shuttle molecules. Photosynthetic biohybrids of this sort could potentially convert carbon dioxide into value-added chemical products, such as bioplastics and biofuels, and control other microbial processes. 

By taking two flakes of special materials that are just one atom thick and twisting them at high angles, researchers at the University of Rochester have unlocked unique optical properties that could be used in quantum computers and other quantum technologies. Until now, scientists have explored the optical and electrical properties of 2D materials when layered on top of one another and twisted at very small angles (typically 1.1 degree). In this study, the researchers twisted layers of a 2D material, called molybdenum diselenide, at up to 40 degrees, and found that the resulting structure produced excitons – essentially, artificial atoms – that can act as quantum information bits, or qubits, and can retain information when activated by light. The research was conducted at the University of Rochester’s Integrated Nanosystems Center.