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

Scientists from the U.S. Food and Drug Administration, Northwestern University, and the Illinois Institute of Technology have found evidence that silver nanoparticles embedded in packaging used as an antimicrobial agent were able to seep into the dry food the packaging is meant to protect. The scientists created samples of silver nanoparticles and embedded them in polyethylene film wraps, which could hold various types of food items. They tested wheat flour, slices of cheese, ground rice, and spinach leaves. They found that the nanoparticles had made their way to all the foods, though to varying degrees. They found, for example, that there was far more contamination of the cheese than there was of the spinach leaves.

University of Missouri scientists are unlocking the secrets of halide perovskites – a material that might bring us closer to energy-efficient optoelectronics. The scientists are studying the material at the nanoscale. At this level, the material is astonishingly efficient at converting sunlight into energy. To optimize the material for electronic applications, the scientists used a method called ice lithography, known for its ability to fabricate materials at the nanometer scale. This ultra-cool method allowed the team to create distinct properties for the material using an electron beam. 

Measuring temperature and humidity in a variety of crop-growing circumstances has prompted the development of numerous sensors, but ensuring these devices are effective while remaining environmentally friendly and cost-effective is a challenge. Now, researchers at Auburn University in Alabama have developed paper-based temperature and humidity sensors that are accurate and reliable, as well as eco-friendly. The researchers created the sensors by printing silver lines on four types of commercially available paper through a process called dry additive nanomanufacturing. The sensors successfully detected changes in relative humidity levels from 20% to 90% and temperature variations from 25°C to 50°C. 

Researchers from Case Western Reserve University, the University of Illinois Urbana-Champaign, Adamas Nanotechnologies (Raleigh, NC), the University of Luxembourg in Luxemburg, Umeå University in Sweden, and Aix Marseille University in France have found that boron-doped diamonds exhibit plasmons – waves of electrons that move when light hits them – allowing electric fields to be controlled and enhanced on a nanometer scale. Previously, boron-doped diamonds were known to conduct electricity and become superconductors, but not to have plasmonic properties. Plasmonic materials, which affect light at the nanoscale, have captivated humans for centuries. For example, the vibrant colors in medieval stained-glass windows result from metal nanoparticles embedded in the glass, and when light passes through, these nanoparticles generate plasmons that produce specific colors.

Researchers from Northwestern University, Duke University, and Cornell University have developed the first two-dimensional mechanically interlocked material. Looking like the interlocking links in chainmail, the nanoscale material exhibits exceptional flexibility and strength. With further work, this material holds promise for use in high-performance, light-weight body armor and other uses that demand lightweight, flexible, and tough materials. "We made a completely new polymer structure," said William Dichtel, the study's corresponding author. "It's similar to chainmail in that it cannot easily rip because each of the mechanical bonds has a bit of freedom to slide around. If you pull it, it can dissipate the applied force in multiple directions. And if you want to rip it apart, you would have to break it in many, many different places.”

Researchers from the University of Pennsylvania; the Wistar Institute in Philadelphia, PA; Central South University in Changsha, China, have engineered small nano-sized capsules called extracellular vesicles from human cells to target a cell-surface receptor called DR5 (death receptor 5) that many tumor cells have. When activated, DR5 can trigger the death of these tumor cells by a self-destruct process called apoptosis. Researchers have been trying for more than 20 years to develop successful DR5-targeting cancer treatments. The new approach outperformed DR5-targeting antibodies, which have been considered a leading DR5-targeting strategy. The small extracellular vesicles efficiently killed multiple cancer cell types in lab-dish tests and blocked tumor growth in mouse models, enabling longer survival than DR5-targeting antibodies.

Researchers from The Johns Hopkins University School of Medicine, the Van Andel Institute in Grand Rapids, MI, and the Chinese Academy of Sciences have discovered that a mouse protein, called STELLA, disrupts cancer-causing chemical changes to genes associated with human colorectal cancer cells. First, the researchers found the part of the protein, or peptide, that was required to activate tumor suppressor genes in human colorectal cancer cells. Then, they designed a lipid nanoparticle – an ultratiny drug delivery vehicle made of fatty molecules – to deliver the messenger RNA (mRNA) that codes for this peptide to cells. The therapy performed well in mice, activating tumor suppressor genes and impairing tumor growth. Next, the researchers plan to test this therapy on human patients through clinical trials.

Researchers from the Massachusetts Institute of Technology, Purdue University, Stanford University, Rice University, and the U.S. Department of Energy’s Lawrence Berkeley National Laboratory, Argonne National Laboratory, and Oak Ridge National Laboratory have described how a type of quasiparticle, called a polaron, behaves in tellurene, a nanomaterial made up of tiny chains of tellurium atoms. A polaron forms when charge-carrying particles such as electrons interact with vibrations in the atomic or molecular lattice of a material. The researchers had hypothesized that as tellurene transitions from bulk to nanometer thickness, polarons change from large, spread-out electron-vibration interactions to smaller, localized interactions. Computations and experimental measurements backed up this scenario.

Researchers from Columbia University, the University of Chicago, the University of Vienna in Austria, Politecnico di Milano in Italy, and Universita Degli Studi Dell’ Aquila in Italy have created a device that can generate photon pairs more efficiently than previous methods while being less prone to error. To create the device, the researchers used thin crystals of a van der Waals semiconducting transition metal called molybdenum disulfide. Then, they layered six of these crystal pieces into a stack, with each piece rotated 180 degrees relative to the crystal slabs above and below. As light travels through this stack, a phenomenon called quasi-phase-matching manipulates properties of the light, enabling the creation of paired photons. "We believe this breakthrough will establish van der Waals materials as the core of next-generation nonlinear and quantum photonic architectures,” said James Schuck, one of the scientists involved in this study.

Researchers from Georgia Tech and the University of California Riverside have developed biosensors made of iron oxide nanoparticles and special molecules called cyclic peptides that recognize tumor cells better than current biosensors. The cyclic peptides respond only when they encounter two specific types of enzymes – one secreted by the immune system, the other by cancer cells. In animal studies, the biosensors distinguished between tumors that responded to a common cancer treatment that enhances the immune system from tumors that resisted treatment.