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

Researchers at the U.S. Department of Energy's Oak Ridge National Laboratory have transformed a common household plastic into a reusable adhesive with a rare combination of strength and ductility, making it one of the toughest materials ever reported. The researchers aimed at upcycling a rubbery polymer material that is easy to process but not engineered for tough adhesion. They modified its chemical structure with dynamic crosslinking to make it more robust. Boronic esters were used to couple the polymer material with silica nanoparticles, a filler material used to strengthen polymers, yielding a novel crosslinked boronic ester-silica nanoparticle composite material.

Researchers from Texas Tech University have investigated how novel hydrophilic nanoparticles, known as nanoantibiotics, can kill pathogens that lead to human infection without affecting healthy cells. Nanoantibiotics look like tiny hairy spheres, each composed of many hydrophilic polymer brushes grafted onto silica nanoparticles. The researchers discovered that the degree of antibiotic activity is affected by the size of the hairy spheres. Those measuring 50 nanometers and below appear to be much more active than those whose size exceeds 50 nanometers.

Two brothers working in a Rice University laboratory have described the real-time analysis of laser-induced graphene production through sound. Laser-induced graphene is prepared by direct laser writing with a laser on carbon materials in ambient conditions. Audio analysis allows for quality control capabilities that, the scientists say, are orders of magnitude faster than characterization of laser-induced graphene by microscopy techniques. 

Researchers at Cornell University have developed new nanophotonic tweezers that can fit on a chip less than one square inch, making it easier and more efficient to manipulate single molecules using light to investigate biological systems. The nanoscale device can apply enough force to perform a range of standard single-molecule experiments, including stretching and unzipping DNA molecules and disrupting and mapping protein-DNA interactions. This advance is the first demonstration of a nanophotonic platform – rather than a bulky tabletop setup – for high-force single-molecule manipulation.

Researchers at the University of Michigan have shown that when nanoparticles form a crystal structure (when they are crowded together), they are held together by a type of interaction, called entropic bonding, that is analogous to the chemical bonds formed by atoms. But unlike atoms, there aren't electron interactions holding these nanoparticles together. 

Over the past few decades, #transplanting groups of #pancreatic cells that secrete #insulin has emerged as a potential cure for type 1 #diabetes. But transplantation efforts have faced setbacks as the #immune system eventually rejects the transplanted cells, and #immunosuppressive drugs offer inadequate protection for transplanted cells and are plagued by undesirable side effects. Now, a team of researchers at Northwestern University has discovered a technique to help make #immunomodulation more effective. The method uses nanoparticles to re-engineer the commonly used #immunosuppressant #rapamycin. Using these rapamycin-loaded nanoparticles, the researchers generated a new form of immunosuppression capable of targeting specific cells related to the #transplant without suppressing wider immune responses.

Researchers at Cornell University have shown that a single material system can toggle between two of the wildest states in condensed matter physics: the quantum anomalous Hall insulator and the two-dimensional topological insulator. The researchers stacked an ultrathin monolayer of molybdenum ditelluride on top of an ultrathin monolayer of tungsten diselenide, twisting them at a 180-degree angle. After applying a voltage, they observed the quantum anomalous Hall effect. The researchers also found that by simply tweaking the voltage, they could turn their semiconductor stack into a two-dimensional topological insulator.

Researchers from Northwestern University and the University of Michigan have shown, for the first time, how low-symmetry colloidal crystals can be made – including one phase for which there is no known natural equivalent. In this research, metal nanoparticles whose surfaces were coated with designer DNA were used to create the crystals. The DNA acted as an encodable bonding material, transforming them into what are called programmable atom equivalents.

Scientists at the University of Oregon have made nanocrystals that are the smallest and most stable kind of metal-organic framework (MOF). Such nanocrystals could have a wide range of potential applications, from surface coatings that can store electric charge to filters that can remove contaminants from air or water. MOFs form via a series of chemical reactions that join metal ions with linker molecules. The scientists added a third ingredient: molecules that mimic the linkers but can only bind to something on one end. Like edge pieces on a jigsaw puzzle, they act like dead-ends for the growing MOF, ensuring it stays small.

Researchers at the University of Michigan and the University of Bath in the United Kingdom have shown that twisted nanoscale semiconductors can manipulate light in a new way. The photonic effect could help enable rapid development and screening of new antibiotics and other drugs through automation. It offers a new analysis tool for high-throughput screening, a method to analyze vast libraries of chemical compounds.