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Category: nanotechnology – Page 2

Catching light in air: Programmable Mie voids boost light matter interaction

Atomically thin semiconductors such as tungsten disulfide (WS2) are promising materials for future photonic technologies. Despite being only a single layer of atoms thick, they host tightly bound excitons—pairs of electrons and holes that interact strongly with light—and can efficiently generate new colors of light through nonlinear optical processes such as second-harmonic generation.

These properties make them attractive for quantum optics, sensing, and on-chip light sources. At the same time, their extreme thinness imposes a basic limitation: There is very little material for light to interact with. As a result, emission and frequency conversion are often weak unless the surrounding photonic environment is carefully engineered.

A study published in Advanced Photonics introduces a new way to address this challenge by reshaping not the two-dimensional material itself, but the space beneath it. The researchers demonstrate a hybrid platform in which a monolayer of WS2 is placed on top of nanoscale air cavities, known as Mie voids, carved into a high-index crystal of bismuth telluride (Bi2Te3). The work shows that these voids can strongly enhance light emission and nonlinear optical signals, while also allowing direct visualization of localized optical modes.

Structures of hantavirus glycoprotein tetramers

This surface protein complex for the Andes virus is a mushroom-shaped structure called a Gn-Gc tetramer. To map the 3D structures, the team first produced virus-like particles that mimic a real virus, but without the genome that makes a virus infectious. They then used a cryo-electron microscope—which shines an electron beam through a frozen sample and detects the shadows created by molecules—to reconstruct the three-dimensional structures of the Gn-Gc tetramers on the surface of the virus-like particles.

But there was a twist: To obtain extremely high-resolution structures, the researchers painstakingly identified and isolated shadows from only the tetramers that were pointing sidewise relative to the electron beam and ignored those pointing in other directions. This allowed them to borrow a reconstruction method typically used on individual proteins.

The resulting structures have an extremely high resolution of 2.3 angstroms, meaning details the size of just a couple of atoms were effectively captured. That’s enough to represent a transformational improvement over another team’s model of the tetramer from a few years ago, at a resolution of 12 angstroms, still tiny but large enough to produce some key inaccuracies – ones effectively corrected with the newer method and resulting structure.

These latest structures show the Gn-Gc tetramer in a particular state before it has infected a cell. For vaccines or antibody therapies to be most effective against a hantavirus, mimicking surface proteins at this pre-infection stage is essential. ScienceMission sciencenewshighlights.

Hantaviruses, transmitted from rodents to people, have a death rate approaching 40%. They’re found around the world, and because there are no approved vaccines or treatments, they’re among the pathogens of highest concern for future pandemics. They made news in the United States last year when Betsy Arakawa, the wife of actor Gene Hackman, died from a hantavirus infection in New Mexico in March.

New findings published in the journal Cell about the Andes virus, a hantavirus endemic to the southwestern U.S. and other parts of North and South America, represent a crucial first step towards much-needed vaccines and antibody therapies for this and other hantaviruses.

Continue reading “Structures of hantavirus glycoprotein tetramers” | >

Attenuating age-related decline in dendritic cell migration improves vaccine efficacy via gut-immune crosstalk

Dai and colleagues implicate defective dendritic cell migration in impaired vaccine responses in aged mice. Oral delivery of yeast-derived nanoparticles promotes migration of dendritic cells from the gut to lymph nodes and restores vaccine efficacy in aged mice.

Size-shifting nanoparticles successfully deliver mRNA medicine to the pancreas

In recent years, mRNA in lipid nanoparticles (mRNA–LNPs) has emerged as a promising strategy for treating numerous conditions, including COVID-19, various cancers and chronic genetic disorders. To date, this technology has not been successfully used for pancreatic diseases, but that could be about to change. In a paper published in Nature, scientists from China report the development of a new lipid nanoparticle drug-delivery system specifically designed for the pancreas.

Lipid nanoparticles are a special class of fat-based carriers that encapsulate and deliver nucleic acids such as messenger RNA into cells. Among the reasons they have not worked for the pancreas until now is that most LNPs naturally accumulate in the liver and spleen. That means the therapeutic molecules they carry can’t accumulate to high enough levels to be beneficial.

However, the research team realized that while the liver and spleen are wrapped in a dense, protective outer layer called a capsule, the pancreas is only covered by a thin layer of connective tissue. They wondered if these organ capsules act as a biological filter. If so, they could perhaps design nanoparticles large enough to be physically blocked by the walls of the spleen and liver, leaving the pancreas as the only place to go. They named this discovery the capsule-filter-mediated pancreatic-targeted (CAMP) mechanism.

Reconfigurable single-walled carbon nanotube ferroelectric field-effect transistors

Rhee et al. report scalable reconfigurable carbon nanotube transistors with a ferroelectric aluminum scandium nitride gate dielectric. They show balanced ambipolar currents, strong memory retention, and enable ternary content-addressable memory with fewer devices than traditional silicon circuits.

Metasurface-based SLM could enhance AR, VR and LiDAR performance

Many cutting-edge technologies, ranging from augmented reality (AR) and virtual reality (VR) to LiDAR (light detection and ranging) systems, rely on components that enable the precise control of light. These components include so-called spatial light modulators (SLMs), systems that dynamically adjust the position of a light wave within its cycle (i.e., phase), as well as its amplitude or direction across several pixels.

Conventional SLMs rely on liquid crystals, materials in a state of matter at the intersection between solid and liquid. While these components are widely used, they typically struggle to reach the speed and pixel density required to create high-quality three-dimensional (3D) images known as holographs.

Researchers at Huazhong University of Science and Technology and other institutes recently developed a new metasurface, an ultrathin and nano-engineered surface, that could be used to produce dynamic and high-quality holographic images in real time, with a remarkable definition. The new metasurface, introduced in a paper published in Nature Nanotechnology, was used to create a SLM that could be used to enhance the performance of AR, VR, and LiDAR technology.

Nano-cage removes up to 98% of PFAS in tap water tests

Contamination of ground, surface and drinking water by perfluoroalkyl and polyfluoroalkyl substances (PFAS) affects millions of people worldwide. A promising new method developed by Flinders University scientists paves the way to help remove the most difficult-to-capture variants of these persistent pollutants from water.

The research team, led by Flinders ARC Research Fellow Dr. Witold Bloch, has discovered adsorbents that effectively capture PFAS, including short-chain forms that are especially difficult to remove using existing technologies.

The study, published in the Angewandte Chemie International Edition, showcases the use of a nano-sized molecular cage that acts as a highly selective “PFAS trap.”

Nanoparticles for Targeted Drug Delivery to Cancer Stem Cells: A Review of Recent Advances

Cancer stem cells (CSCs) are a subpopulation of cells that can initiate, self-renew, and sustain tumor growth. CSCs are responsible for tumor metastasis, recurrence, and drug resistance in cancer therapy. CSCs reside within a niche maintained by multiple unique factors in the microenvironment. These factors include hypoxia, excessive levels of angiogenesis, a change of mitochondrial activity from aerobic aspiration to aerobic glycolysis, an upregulated expression of CSC biomarkers and stem cell signaling, and an elevated synthesis of the cytochromes P450 family of enzymes responsible for drug clearance. Antibodies and ligands targeting the unique factors that maintain the niche are utilized for the delivery of anticancer therapeutics to CSCs. In this regard, nanomaterials, specifically nanoparticles (NPs), are extremely useful as carriers for the delivery of anticancer agents to CSCs.

Lipid nanoparticle GM-CSF replacement for autoimmune pulmonary alveolar proteinosis

One of the most-viewed PNAS articles in the last week is “Lipid nanoparticle GM-CSF replacement for autoimmune pulmonary alveolar proteinosis.” Explore the article here: https://ow.ly/QMWH50Yl87H

For more trending articles, visit https://ow.ly/pmKX50Yl87I.

Granulocyte–macrophage colony-stimulating factor (GM-CSF) deficiency drives autoimmune pulmonary alveolar proteinosis (aPAP), a disease characterized by impaired macrophage-mediated clearance of pulmonary surfactants. Clinical data suggest that inhaled recombinant GM-CSF reduces symptoms in aPAP patients, providing a rationale for mRNA-based GM-CSF replacement therapies. However, these require effective mRNA delivery after nebulization. Here, we report the iterative in vivo design of a lipid nanoparticle, named nebulized lung delivery 2 (NLD2), that efficiently delivers mRNA after nebulization. NLD2 carrying GM-CSF mRNA transfected alveolar macrophages in vivo, leading to interleukin-10 pathway activation and subsequent surfactant lipoprotein clearance. In a preclinical disease model of aPAP, GM-CSF mRNA delivery reduced surfactant protein thickness more than recombinant GM-CSF. These data support continued exploration of nebulized lipid nanoparticle therapies for aPAP.

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