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

Researchers at Penn State have combined laser writing and responsive sensor technologies to fabricate the first highly customizable microscale gas sensing devices. The researchers developed a process that enables the simultaneous creation and integration of metal oxides directly into sensor platforms. Metal oxides react to various compounds, triggering the sensing mechanism. With laser writing, the researchers dissolve metal salts in water, then focus the laser into the solution. The high temperature decomposes the solution, leaving behind metal oxide nanoparticles that can be sintered onto the sensor platform.

Researchers at the National Institute of Standards and Technology have discovered an unexpected property in a material called "SeedGel": Its temperature determines which color of light can pass through it.  In other words, shine white light at the gel, and depending on the gel's temperature, only a specific wavelength, or color, will pass through it. The material begins as a transparent fluid made of water and liquid solvents, with silica nanoparticles added. If this mix is heated to a certain temperature, the liquids and nanoparticles form a physical gel, which initially remains transparent but then its internal structure changes: the liquids form interlocking microscopic channels, with the nanoparticles confined within these channels. 

Researchers at Arizona State University and the Institute of Biophysics of the Czech Academy of Sciences have used crystallography techniques to describe the characteristics of 36 basic variants of the Holliday junction, which forms when two segments of double stranded DNA cross each other. The researchers showed that the effectiveness of a given Holliday junction for the construction of crystalline nanoarchitectures depends not only on the arrangement of the four nucleotide pairs forming the junction but also on sequences forming the junction's four protruding arms. In the case of the 36 variants of the Holliday junction, some DNA sequences acted to enhance the crystallization process of these forms, while six of the 36 Holliday junction variants failed to form crystals. 

Researchers from Rice University, Technion-Israel Institute of Technology, NASA Langley Research Center, the National Institute of Aerospace, and BNNT Materials, LLC, have reported that boron nitride nanotubes can assemble themselves into liquid crystals under the right conditions. These liquid crystals are easier to process than the tangled nanotubes that usually form in solution. Boron nitride nanotubes are like carbon nanotubes, but with alternating boron and nitrogen atoms, instead of carbon in their hexagonal lattices. 

As they grow, solid tumors surround themselves with a thick, hard-to-penetrate wall of molecular defenses. Getting drugs past that barricade is notoriously difficult. Now, scientists from the University of Texas Southwestern Medical Center and the University of Texas at Arlington have developed nanoparticles that can break down the physical barriers around tumors to reach cancer cells. Once inside, the nanoparticles released their payload: a gene editing system that alters DNA inside the tumor, blocking its growth, and activating the immune system.

Researchers from the University of Pittsburgh and Princeton University have unexpectedly discovered that two-dimensional polymer sheets can rise and rotate in spiral helices without the application of external power. Through computational modeling, the researchers placed passive, uncoated polymer sheets around a circular, catalytic patch within a fluid-filled chamber and then added hydrogen peroxide to initiate a catalytic reaction. They noticed that the polymer sheets autonomously self-assembled into a tower-like structure.

Researchers from the University of Pittsburgh, Georgia Tech, and Allegheny Health Network have created patient-specific 3D-printed smart metamaterial implants that double as sensors to monitor spinal column healing. The power, generated using a built-in triboelectric nanogenerator mechanism, eliminates the need for a separate power source. Also, a tiny chip records data, which can be read noninvasively using a portable ultrasound scanner.

Researchers from North Carolina State University, the University of North Carolina at Chapel Hill, and the Institute for Physical Chemistry and Polymer Physics in Dresden, Germany, have demonstrated a technique that allows them to align gold nanorods using magnetic fields, while preserving the underlying optical properties of the gold nanorods. The researchers made separate solutions of gold nanorods and iron oxide nanoparticles and then mixed the solutions, causing the iron oxide nanoparticles to assemble onto the surface of the gold nanorods. The resulting "coated" nanorods could then be controlled using a low-strength magnetic field.

According to a team of scientists from the National Institute of Standards and Technology, Purdue University, Duke University, and North Carolina State University, 2D materials and their interfaces – which researchers intend to be flat when stacked on top of each other – may not, in fact, be flat. Potential benefits from this study include giving the scientific community more control over the fabrication of transistor devices that incorporate 2D materials.

The silicon-based computer chips that power our modern devices require vast amounts of energy to operate, so researchers in the electronics and materials sciences communities are seeking ways to sustainably manage the global need for computing power. Now, a team of researchers at the U.S. Department of Energy’s Lawrence Berkeley National Laboratory and the University of California, Berkeley, have identified an energy-efficient route by creating films of barium titanate just 25 nanometers thin, whose orientation of charged atoms, or polarization, switches as quickly and efficiently as in the bulk version of a computer chip.