(Press-News.org) Images
Micron-sized "bow ties," self-assembled from nanoparticles, form a variety of different curling shapes that can be precisely controlled, a research team led by the University of Michigan has shown.
The development opens the way for easily producing materials that interact with twisted light, providing new tools for machine vision and producing medicines.
While biology is full of twisted structures like DNA, known as chiral structures, the degree of twist is locked in—trying to change it breaks the structure. Now, researchers can engineer the degree of twist.
Such materials could enable robots to accurately navigate complex human environments. Twisted structures would encode information in the shapes of the light waves that reflect from the surface, rather than in the 2D arrangement of symbols that comprises most human-read signs. This would take advantage of an aspect of light that humans can barely sense, known as polarization. The twisted nanostructures preferentially reflect certain kinds of circularly polarized light, a shape that twists as it moves through space.
"It is basically like polarization vision in crustaceans," said Nicholas Kotov, the Irving Langmuir Distinguished University Professor of Chemical Sciences and Engineering, who led the study. "They pick up a lot of information in spite of murky environments."
Robots could read signs that look like white dots to human eyes; the information would be encoded in the combination of frequencies reflected, the tightness of the twist and whether the twist was left- or right-handed.
By avoiding the use of natural and ambient light, relying instead on circularly polarized light generated by the robot, robots are less likely to miss or misinterpret a cue, whether in bright or dark environments. Materials that can selectively reflect twisted light, known as chiral metamaterials, are usually hard to make—but the bow ties aren't.
"Previously, chiral metasurfaces have been made with great difficulty using multimillion dollar equipment. Now, these complex surfaces with multiple attractive uses can be printed like a photograph," Kotov said.
Twisted nanostructures may also help create the right conditions to produce chiral medicines, which are challenging to manufacture with the correct molecular twist.
"What hasn't been seen in any chiral systems before is that we can control the twist from a fully twisted left-handed structure to a flat pancake to a fully twisted right-handed structure. We call this a chirality continuum," said Prashant Kumar, a U-M postdoctoral research fellow in chemical engineering and first author of the study in Nature.
Kumar tested the bow ties as a sort of paint, mixing them with polyacrylic acid and dabbing them onto glass, fabric, plastic and other materials. Experiments with lasers showed that this paint reflected twisted light only when the twist in the light matched the twist in the bow tie shape.
The bow ties are made by mixing cadmium metal and cystine, a protein fragment that comes in left- and right-handed versions, in water spiked with lye. If the cystine was all left-handed, left-handed bow ties formed, and right-handed cystine yielded right-handed bow ties—each with a candy-wrapper twist.
But with different ratios of left-and right-handed cystine, the team made intermediate twists, including the flat pancake at a 50-50 ratio. The pitch of the tightest bow ties, basically the length of a 360-degree turn, is about 4 microns long—within infrared light's range of wavelengths.
"Not only do we know the progression from the atomic scale all the way up to the micron-scale of the bow ties, we also have theory and experiments that show us the guiding forces. With that fundamental understanding, you can design a bunch of other particles," said Thi Vo, a former U-M postdoctoral researcher in chemical engineering.
He worked with Sharon Glotzer, co-corresponding author of the study and the Anthony C. Lembke Department Chair of Chemical Engineering at U-M.
In contrast with other chiral nanostructures, which can take days to self-assemble, the bow ties formed in just 90 seconds. The team produced 5,000 different shapes within the bow tie spectrum. They studied the shapes in atomic detail using X-rays at Argonne National Laboratory ahead of the simulation analysis.
Additional material analysis and contributions to theory were provided by collaborators at U-M, the University of Pennsylvania, the University of Palermo in Italy and Pro Vitam Ltd, Romania. The study was supported by the Office of Naval Research, National Science Foundation and Army Research Office.
Kotov is also the Joseph B. and Florence V. Cejka Professor of Engineering and a professor of chemical engineering and macromolecular science and engineering. Vo is now a professor of chemical and biomolecular engineering at Johns Hopkins University. Glotzer is also the John Werner Cahn Distinguished University Professor of Engineering, the Stuart W. Churchill Collegiate Professor of Chemical Engineering, and a professor of materials science and engineering, macromolecular science and engineering, and physics.
Study: Photonically active bow tie nanoassemblies with chirality continuum (DOI: 10.1038/s41586-023-05733-1) (available when embargo lifts)
END
For the first time, controlling the degree of twist in nanostructured particles
Being able to decide not only whether a micron-scale particle twists but also how much could open new avenues for machine vision and more
2023-03-15
ELSE PRESS RELEASES FROM THIS DATE:
Study unravels a cause of resistance to novel drug in patients with acute leukemia
2023-03-15
BOSTON – A new targeted drug has not only sparked remissions in patients with a common form of leukemia but also induced the cancer cells to reveal one of their schemes for resisting the drug, investigators at Dana-Farber Cancer Institute and other research centers report in a new pair of studies in the journal Nature.
One of the papers presents results of a clinical trial in which approximately 40% of patients with acute leukemia subtypes had a complete response – a disappearance of all signs of cancer – to treatment with the drug revumenib. The other paper uncovers a molecular countermove by which leukemia cells come to sidestep the drug and reassert their growth.
The ...
Making sense of scents: Deciphering our sense of smell
2023-03-15
Breaking a longstanding impasse in our understanding of olfaction, scientists at UC San Francisco (UCSF) have created the first molecular-level, 3D picture of how an odor molecule activates a human odorant receptor, a crucial step in deciphering the sense of smell.
The findings, appearing online March 15, 2023, in Nature, are poised to reignite interest in the science of smell with implications for fragrances, food science, and beyond. Odorant receptors - proteins that bind odor molecules on the surface of olfactory cells - make up half of the largest, most diverse family of receptors in our bodies; A deeper understanding of them paves the way for ...
Scientists discover key information about the function of mitochondria in cancer cells
2023-03-15
Scientists have long known that mitochondria, the "powerhouses" of cells, play a crucial role in the metabolism and energy production of cancer cells. However, until now, little was known about the relationship between the structural organization of mitochondrial networks and their functional bioenergetic activity at the level of whole tumors.
In a new study, published in Nature, researchers from the UCLA Jonsson Comprehensive Cancer Center used positron emission tomography (PET) in combination ...
Artificial Sweetener could dampen immune response to disease in mice
2023-03-15
Francis Crick Institute press release
Under strict embargo: 16:00hrs GMT Wednesday, March 15, 2023
Peer reviewed
Experimental study
Animals / Cells
Artificial Sweetener could dampen immune response to disease in mice
Scientists at the Francis Crick Institute have found that high consumption of a common artificial sweetener, sucralose, lowers activation of T-cells, an important component of the immune system, in mice.
If found to have similar effects in humans, one day it could be used therapeutically to help dampen T-cell responses. For example, in patients with autoimmune diseases who ...
New research shows recovering tropical forests offset just one quarter of carbon emissions from new tropical deforestation and forest degradation
2023-03-15
A pioneering global study has found deforestation and forests lost or damaged due to human and environmental change, such as fire and logging, are fast outstripping current rates of forest regrowth.
Tropical forests are vital ecosystems in the fight against both climate and ecological emergencies. The research, published today in Nature and led by the University of Bristol, highlights the carbon storage potential and the current limits of forest regrowth to addressing such crises.
The findings showed degraded forests recovering from human disturbances, and secondary forests regrowing ...
Targeting menin induces responses in acute leukemias with KMT2A rearrangements or NPM1 mutations
2023-03-15
Researchers from The University of Texas MD Anderson Cancer Center showed that inhibiting menin with revumenib, previously known as SNDX-5613, yielded encouraging responses for advanced acute leukemias with KMT2A rearrangements or mutant NPM1. Findings from the Phase I AUGMENT-101 trial were published today in Nature.
The overall response rate among 60 patients was 53%, and the rate of complete remission or complete remission with partial hematologic recovery was 30%, with 78% of patients achieving clearance of measurable residual disease. Responses were seen across multiple dose ...
Bird flu associated with hundreds of seal deaths in New England in 2022, Tufts researchers find
2023-03-15
Researchers at Cummings School of Veterinary Medicine at Tufts University found that an outbreak of highly pathogenic avian influenza (HPAI) was associated with the deaths of more than 330 New England harbor and gray seals along the North Atlantic coast in June and July 2022, and the outbreak was connected to a wave of avian influenza in birds in the region.
The study was published on March 15 in the journal Emerging Infectious Disease.
HPAI is more commonly known as bird flu, and the H5N1 strain has been responsible for about 60 million poultry ...
Designing more useful bacteria
2023-03-15
In a step forward for genetic engineering and synthetic biology, researchers have modified a strain of Escherichia coli bacteria to be immune to natural viral infections while also minimizing the potential for the bacteria or their modified genes to escape into the wild.
The work promises to reduce the threats of viral contamination when harnessing bacteria to produce medicines such as insulin as well as other useful substances, such as biofuels. Currently, viruses that infect vats of bacteria can halt production, compromise ...
New laser technology developed by EPFL and IBM
2023-03-15
Scientists at EPFL and IBM have developed a new type of laser that could have a significant impact on optical ranging technology. The laser is based on a material called lithium niobate, often used in the field of optical modulators, which controls the frequency or intensity of light that is transmitted through a device.
Lithium niobate is particularly useful because it can handle a lot of optical power and has a high “Pockels coefficient”, which means that it can change its optical properties when an electric field is applied to it.
The researchers achieved their breakthrough by combining ...
How genome doubling helps cancer develop
2023-03-15
A single cell contains 2-3 meters of DNA, meaning that the only way to store it is to package it into tight coils. The solution is chromatin: a complex of DNA wrapped around proteins called histones. In the 3D space, this complex is progressively folded into a multi-layered organization composed of loops, domains, and compartments, which makes up what we know as chromosomes. The organization of chromatin is closely linked to gene expression and the cell’s proper function, so any problems in chromatin structure can have detrimental effects, including the development of cancer.
A common event in around 30% of all human cancers is “whole genome doubling” ...
LAST 30 PRESS RELEASES:
DGIST restores the performance of quantum dot solar cells as if “flattening crumpled paper!”
Hoarding disorder: ‘sensory CBT’ treatment strategy shows promise
Water fluoridation less effective now than in past
Toddlers get nearly half their calories from ultra-processed foods
Detroit researchers to examine links between bacterial infections, environmental pollution and preterm birth
In lab tests, dietary zinc inhibits AMR gene transmission
Two UMD Astronomy space probes advance to next round of $1 billion NASA mission selection
New MSU research sheds light on impact and bias of voter purging in Michigan
Funding to create world's first ovarian cancer prevention vaccine
Scientists develop novel method for strengthening PVC products
Houston Methodist part of national consortium to develop vaccine against herpesviruses
UT Health San Antonio School of Dentistry earns first NIH grant under new center for pain therapeutics and addiction research
Do MPH programs prepare graduates for employment in today's market? Mostly yes, but who is hiring may be surprising
New article provides orientation to using implementation science in policing
Three beer-related discoveries to celebrate Oktoberfest
AAAS launches user research project to inform the new AAAS.org
In odd galaxy, NASA's Webb finds potential missing link to first stars
Adding beans and pulses can lead to improved shortfall nutrient intakes and a higher diet quality in American adults
What happens in the brain when a person with schizophrenia “hears voices”?
Ant agriculture began 66 million years ago in the aftermath of the asteroid that doomed the dinosaurs
A new era of solar observation
The true global impact of species-loss caused by humans is far greater than expected – new study reveals
Smartphone-assisted “scavenger hunt” identifies people at risk for dementia
Green subsidies may have hidden costs, experts warn
Small brains can accomplish big things, according to new theoretical research
UTA professor honored for science education leadership
Decline of mpox antibody responses after modified vaccinia Ankara–Bavarian Nordic vaccination
Wider use of convalescent plasma might have saved thousands more lives during pandemic
Strong coupling between Andreev qubits mediated by a microwave resonator
UNF biological sciences professor receives NIH grant to study muscle atrophy
[Press-News.org] For the first time, controlling the degree of twist in nanostructured particlesBeing able to decide not only whether a micron-scale particle twists but also how much could open new avenues for machine vision and more