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First step towards self-assembled solid-state biomedical, electro-optical nanodevices

First step towards self-assembled solid-state biomedical, electro-optical nanodevices | Amazing Science | Scoop.it

Engineers at the University of Washington have created genetically engineered peptides that self-assemble into arrays of nanowires on two-dimensional nanosheets (single-layer graphene and molybdenum disulfide) to relay information across a bio-nano interface — a first step towards fully self-assembled future biomedical and electro-optical bionanoelectronic devices.

 

Arrays of peptides could provide organized scaffolds for functional biomolecules, enabling nanoscale bioelectronics interfaces. And designed peptides could be incorporated with metal ions or nanoparticles with specific physical characteristics, thus fine-tuning 2D device performance for chemical and biological sensors.

 

“Bridging this divide would be the key to building the genetically engineered biomolecular solid-state devices of the future,” said UW professor Mehmet Sarikaya in the Departments of Materials Science & Engineering, senior author ofan open-access paper published Sept. 22 in Scientific Reports.

 

The UW team is also planning to develop genetically engineered peptides with specific chemical and structural properties. Their ideal peptide would change the physical properties of synthetic materials and respond to that change.

 

That way, it would transmit “information” from the synthetic material to other biomolecules — bridging the chemical divide between biology and technology.

The peptides function through molecular recognition — the same principles that underlie biochemical interactions such as an antibody binding to its specific antigen or protein binding to DNA.

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Researchers generate proton beams using a combination of nanoparticles and laser light

Researchers generate proton beams using a combination of nanoparticles and laser light | Amazing Science | Scoop.it

Light, when strongly concentrated, is enormously powerful. Now, a team of physicists led by Professor Jörg Schreiber from the Institute of Experimental Physics – Medical Physics, which is part of the Munich-Centre for Advanced Photonics (MAP), a Cluster of Excellence at LMU Munich, has used this energy source with explosive effect. The researchers focus high-power laser light onto beads of plastic just a few micrometers in size. The concentrated energy blows the nanoparticles apart, releasing radiation made up of positively charged atoms (protons). Such proton beams could be used in future for treating tumors, and in advanced imaging techniques. Their findings appear in the journal Physical Review E.

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Graphene made superconductive by doping with lithium atoms

Graphene made superconductive by doping with lithium atoms | Amazing Science | Scoop.it

A team of researchers from Germany and Canada has found a way to make graphene superconductive—by doping it with lithium atoms.

 

By now, most everyone in the science community is aware of graphene, the single carbon atom layer of material that is being studied to figure out how it can be mass produced and connected to other devices to take advantage of its superior electrical properties. Some have also been looking into whether the material could be made into a superconductor—prior research a decade ago showed that graphite could be made superconductive by coating it with other materials. Since that time, the search has been on to find just the right coating for graphene. Three years ago, a group in Italy created a model that suggested lithium might be the right choice, now, based on the work done by this latest team, it appears that they might have been right.

 

In this effort, the researches first grew samples of graphene on a silicon-carbide substrate—those samples were then placed in a vacuum and cooled to 8K and were then "decorated" very precisely with a layer of lithium atoms. To convince themselves that the result was superconductive, the team tested the material with angle-resolved photoemission spectroscopy—doing so revealed that electrons sent through the material slowed down, which they suggest was the result of electron-phonon coupling (the creation of Cooper pairs)—one of the hallmarks of a superconductor. The team also identified an energy gap between those electrons that were conducting and those that were not, energy that would be needed to brake electron-phonon coupling.

 

Further tests will have to be done to discover if it is possible to demonstrate a complete loss of electrical resistance and the expulsion of an external magnetic field, tests that can prove the material to be a true superconductor.

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Plasmon-enhanced thermophoresis for the reversible assembly of plasmonic nanoparticles

Plasmon-enhanced thermophoresis for the reversible assembly of plasmonic nanoparticles | Amazing Science | Scoop.it

The optical manipulation of plasmonic nanoparticles – metal nanoparticles that are highly efficient at absorbing and scattering light – has advantages for applications such as nanofabrication, drug delivery and biosensing. To that end, researchers have been developing techniques for the reversible assembly of plasmonic nanoparticles that can be used to modulate their structural, electrical and optical properties.The latest such technique is a low-power assembly that is enabled by thermophoretic migration of nanoparticles due to the plasmon-enhanced photothermal effect and the associated enhanced local electric field over a plasmonic substrate.

 

An international research team, led by Yuebing Zheng, Assistant Professor of Mechanical Engineering and Materials Science & Engineering at the University of Texas at Austin, has developed a new optical assembly technique known as plasmon-enhanced thermophoresis to assemble plasmonic nanoparticles reversibly by optically controlling a temperature field.This plasmon-enhanced thermophoresis can be exploited to confine plasmonic nanoparticles in a higher-temperature regime under a thermoelectric field.The researchers reported their findings in the September 17, 2016 online edition of ACS Nano ("Light-Directed Reversible Assembly of Plasmonic Nanoparticles Using Plasmon-Enhanced Thermophoresis").

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New nanocrystalline alloy with high-temperature creep resistance

New nanocrystalline alloy with high-temperature creep resistance | Amazing Science | Scoop.it

A combined team of researchers affiliated with the Army Research Laboratory at Aberdeen Proving Ground, Arizona State University and the University of North Texas has developed a nanocrystalline alloy that combines high mechanical strength with high-temperature creep resistance. In their paper published in the journal Nature, the team describes how they created the material and its properties.

 

Jonathan Cormier with Institut Pprime, UPR CNRS offers a News & Views piece on the work done by the team in the same journal issue and outlines some of the hurdles that stand in the way of the alloy being used in industrial applications.

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Killing superbugs with star-shaped polymers, not antibiotics

Killing superbugs with star-shaped polymers, not antibiotics | Amazing Science | Scoop.it
Tiny, star-shaped molecules are effective at killing bacteria that can no longer be killed by current antibiotics, new research shows.

 

The study, published Nature Microbiology, holds promise for a new treatment method against antibiotic-resistant bacteria (commonly known as superbugs). The star-shaped structures, are short chains of proteins called 'peptide polymers', and were created by a team from the Melbourne School of Engineering. The team included Professor Greg Qiao and PhD candidate Shu Lam, from the Department of Chemical and Biomolecular Engineering, as well as Associate Professor Neil O'Brien-Simpson and Professor Eric Reynolds from the Faculty of Medicine, Dentistry and Health Sciences and Bio21 Institute.

 

Professor Qiao said that currently the only treatment for infections caused by bacteria is antibiotics. However, over time bacteria mutate to protect themselves against antibiotics, making treatment no longer effective. These mutated bacteria are known as 'superbugs'. "It is estimated that the rise of superbugs will cause up to ten million deaths a year by 2050. In addition, there have only been one or two new antibiotics developed in the last 30 years," he said.

 

Professor Qiao and his team have been working with peptide polymers in the past few years. Recently, the team created a star-shaped peptide polymer that was extremely effective at killing Gram-negative bacteria – a major class of bacteria known to be highly prone to antibiotic resistance – while being non-toxic to the body.

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New nanomaterial combines attributes of both batteries and supercapacitors

New nanomaterial combines attributes of both batteries and supercapacitors | Amazing Science | Scoop.it

 

A powerful new material developed by Northwestern University chemist William Dichtel and his research team could one day speed up the charging process of electric cars and help increase their driving range.

 

An electric car currently relies on a complex interplay of both batteries and supercapacitors to provide the energy it needs to go places, but that could change. “Our material combines the best of both worlds -- the ability to store large amounts of electrical energy or charge, like a battery, and the ability to charge and discharge rapidly, like a supercapacitor,” said Dichtel, a pioneer in the young research field of covalent organic frameworks (COFs).

 

Dichtel and his research team have combined a COF -- a strong, stiff polymer with an abundance of tiny pores suitable for storing energy -- with a very conductive material to create the first modified redox-active COF that closes the gap with other older porous carbon-based electrodes.

 

“COFs are beautiful structures with a lot of promise, but their conductivity is limited,” Dichtel said. “That’s the problem we are addressing here. By modifying them -- by adding the attribute they lack -- we can start to use COFs in a practical way.”

 

And modified COFs are commercially attractive: COFs are made of inexpensive, readily available materials, while carbon-based materials are expensive to process and mass-produce.

 

Dichtel, the Robert L. Letsinger Professor of Chemistry at the Weinberg College of Arts and Sciences, is presenting his team’s findings in a paper published by the journal ACS Central Science.

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Gold and Lasers Produce Plasmonic Nanobubbles to Kill Residual Cancer Cells

Gold and Lasers Produce Plasmonic Nanobubbles to Kill Residual Cancer Cells | Amazing Science | Scoop.it

A team of scientists headed by folks at Rice University have developed a way of killing off neoplastic cells that often remain after surgical procedures and supportive therapies.

 

Failure of cancer surgery to intraoperatively detect and eliminate microscopic residual disease (MRD) causes lethal recurrence and metastases, and the removal of important normal tissues causes excessive morbidity. Here, scientists now show that a plasmonic nanobubble (PNB), a non-stationary laser pulse-activated nanoevent, intraoperatively detects and eliminates MRD in the surgical bed. PNBs were generated in vivo in head and neck cancer cells by systemically targeting tumors with gold colloids and locally applying near-infrared, low-energy short laser pulses, and were simultaneously detected with an acoustic probe.

 

In mouse models, between 3 and 30 residual cancer cells and MRD (undetectable with current methods) were non-invasively detected up to 4 mm deep in the surgical bed within 1 ms. In resectable MRD, PNB-guided surgery prevented local recurrence and delivered 100% tumor-free survival. In unresectable MRD, PNB nanosurgery improved survival twofold compared with standard surgery.

 

These results show that PNB-guided surgery and nanosurgery can rapidly and precisely detect and remove MRD in simple intraoperative procedures.

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Nanoribbons in solutions mimic nature

Nanoribbons in solutions mimic nature | Amazing Science | Scoop.it
Graphene nanoribbons (GNRs) bend and twist easily in solution, making them adaptable for biological uses like DNA analysis, drug delivery and biomimetic applications, according to scientists at Rice University.

 

Knowing the details of how GNRs behave in a solution will help make them suitable for wide use in biomimetics, according to Rice physicist Ching-Hwa Kiang, whose lab employed its unique capabilities to probe nanoscale materialslike cells and proteins in wet environments. Biomimetic materials are those that imitate the forms and properties of natural materials. The research led by recent Rice graduate Sithara Wijeratne, now a postdoctoral researcher at Harvard University, appears in the Nature journal Scientific Reports.

 

Graphene nanoribbons can be thousands of times longer than they are wide. They can be produced in bulk by chemically "unzipping" carbon nanotubes, a process invented by Rice chemist and co-author James Tour and his lab.

 

Their size means they can operate on the scale of biological components like proteins and DNA, Kiang said. "We study the mechanical properties of all different kinds of materials, from proteins to cells, but a little different from the way other people do," she said. "We like to see how materials behave in solution, because that's where biological things are." Kiang is a pioneer in developing methods to probe the energy states of proteins as they fold and unfold.

 

She said Tour suggested her lab have a look at the mechanical properties of GNRs. "It's a little extra work to study these things in solution rather than dry, but that's our specialty," she said.

 

Nanoribbons are known for adding strength but not weight to solid-state composites, like bicycle frames and tennis rackets, and forming an electrically active matrix. A recent Rice project infused them into an efficient de-icer coating for aircraft.

But in a squishier environment, their ability to conform to surfaces, carry current and strengthen composites could also be valuable.

 

"It turns out that graphene behaves reasonably well, somewhat similar to other biological materials. But the interesting part is that it behaves differently in a solution than it does in air," she said. The researchers found that like DNA and proteins, nanoribbons in solution naturally form folds and loops, but can also form helicoids, wrinkles and spirals.

 

Kiang, Wijeratne and Jingqiang Li, a co-author and student in the Kiang lab, used atomic force microscopy to test their properties. Atomic force microscopy can not only gather high-resolution images but also take sensitive force measurements of nanomaterials by pulling on them. The researchers probed GNRs and their precursors, graphene oxide nanoribbons.

 

The researchers discovered that all nanoribbons become rigid under stress, but their rigidity increases as oxide molecules are removed to turn graphene oxide nanoribbons into GNRs. They suggested this ability to tune their rigidity should help with the design and fabrication of GNR-biomimetic interfaces.

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Scientists count microscopic particles without microscope

Scientists count microscopic particles without microscope | Amazing Science | Scoop.it

Scientists from Russia and Australia have put forward a simple new way of counting microscopic particles in optical materials by means of a laser. A light beam passing through such a material splits and forms a characteristic pattern consisting of numerous bright spots on a projection screen. The researchers found that the number of these spots corresponds exactly to the number of scattering microscopic particles in the optical material. Therefore, the structure and shape of any optical material can be determined without resorting to the use of expensive electron or atomic-force microscopy. According to the researchers, the new method will help design optical devices much faster. The work was published in Scientific Reports.

 

The production of optical circuits requires devices that can amplify optical signals, bring them into focus, rotate and change their type of motion. Ordinary lenses cannot cope with these tasks at nanoscale, so scientists are working with artificial optical materials - photonic crystals and metamaterials, which can control the propagation of light in most extraordinary ways. However, fabricating optical materials with desired properties is a laborious process that needs constant improvement.

 

The scientists from ITMO University, Ioffe Institute, and Australian National University for the first time suggested analyzing the structure of photonic crystals using optical diffraction method, that is, by looking at the light pattern generated while the sample is exposed to a laser beam. The study has shown that the number of these spots is equal to the number of scattering microscopic particles in the sample structure. Previously, such small particles could only be seen and counted with powerful and expensive electron or atomic-force microscopes.

 

"The light senses heterogeneity," says Mikhail Rybin, first author of the paper, senior researcher at the Department of Nanophotonics and Metamaterials at ITMO University.


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Ultrasonic wireless ‘neural dust’ sensors monitor nerves and muscles in real time

Ultrasonic wireless ‘neural dust’ sensors monitor nerves and muscles in real time | Amazing Science | Scoop.it

Prototype wireless battery-less neural dust mote (3 x 1 x 1 millimeters) with electrodes attached to a nerve fiber in a rat.

 

University of California, Berkeley engineers have designed and built millimeter-scale device wireless, battery-less “neural dust” sensors and implanted them in muscles and peripheral nerves of rats to make in vivo electrophysiological recordings.

The new technology opens the door to “electroceuticals” — bioelectronic methods to monitor and record wireless electromyogram (EMG) signals from muscle membranes and electroneurogram (ENG) signals from local neuron electrical activity, and to stimulate the immune system, reduce inflammation, and treat disorders such as epilepsy.

 

The technology could also improve neural control of prosthetics (allowing a paraplegic to control a computer or a robotic arm, for example) by stimulating nerves and muscles directly, instead of requiring implanted wires.

 

The neural-dust sensors use ultrasound technology to both power the sensors and read out measurements. Ultrasound is already well-developed for hospital use and can penetrate nearly anywhere in the body, unlike radio waves.

 

The researchers reported their findings August 3 in an open-access paper in the journal Neuron.

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Scientists detect thermal boundary that hinders ultracold experiments

Scientists detect thermal boundary that hinders ultracold experiments | Amazing Science | Scoop.it
Rice University scientists who analyze the properties of materials as small as a single molecule have encountered a challenge that appears at very low temperatures.

 

In trying to measure the plasmonic properties of gold nanowires, the Rice lab of condensed matter physicist Douglas Natelson determined that at room temperature, the wire heated up a bit when illuminated by a laser; but confoundingly, at ultracold temperatures and under the same light, its temperature rose by far more.

 

This is an issue for scientists like Natelson whose experiments require ultracold materials to stay that way. Laser heating, while it may seem minimal, presents a thermal barrier to simultaneous inelastic electron tunneling spectroscopy and surface-enhanced optical spectroscopy, which measure a material's electrical and optical properties. Their report on the phenomenon appears in the American Chemical Society journal ACS Nano.

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Researchers generate 3D images using just one photon per pixel

Researchers generate 3D images using just one photon per pixel | Amazing Science | Scoop.it

Every time you take a photograph, your camera detects more than a billion photons. For a basic one-megapixel camera, that's more than 1,000 photons per pixel. Now in a new study, researchers have developed an algorithm that is so efficient that it can generate high-quality 3D images using a single-photon camera that detects just one signal photon per pixel.

 

The researchers, led by Jeffrey Shapiro, a professor of electrical engineering and computer science at the Massachusetts Institute of Technology (MIT), along with coauthors at MIT, Politecnico di Milano, and Boston University, have published a paper on the new photon-efficient approach to imaging with a single-photon camera in a recent issue of Nature Communications.

 

"Our work shows that we can use these new photon-counting cameras at much lower fluxes and much higher efficiencies than previously thought," Shapiro explains. Compared to other camera-based 3D imaging techniques that have recently been developed, the new framework has the highest photon efficiency to date, resulting in a visibly better reconstruction accuracy and an order of magnitude better depth resolution.

 

To demonstrate how the new single-photon imaging algorithm works in low-light environments, the researchers illuminated a scene of interest (such as a mannequin and sunflower) with a pulsed laser that emits low-light pulses every 50 nanoseconds. A light diffuser spatially spreads out the pulses so that they flood the entire scene.

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Nanosensors could help determine tumors' ability to remodel tissue

Nanosensors could help determine tumors' ability to remodel tissue | Amazing Science | Scoop.it

MIT researchers have designed nanosensors that can profile tumors and may yield insight into how they will respond to certain therapies.

 

Once adapted for humans, this type of sensor could be used to determine how aggressive a tumor is and help doctors choose the best treatment, says Sangeeta Bhatia, the John and Dorothy Wilson Professor of Health Sciences and Technology and Electrical Engineering and Computer Science and a member of MIT's Koch Institute for Integrative Cancer Research.

 

"This approach is exciting because people are developing therapies that are protease-activated," Bhatia says. "Ideally you'd like to be able to stratify patients based on their protease activity and identify which ones would be good candidates for these therapies."

 

Once injected into the tumor site, the nanosensors are activated by a magnetic field that is harmless to healthy tissue. After interacting with and being modified by the target tumor proteins, the sensors are secreted in the urine, where they can be easily detected in less than an hour.

 

Bhatia and Polina Anikeeva, the Class of 1942 Associate Professor of Materials Science and Engineering, are the senior authors of the paper, which appears in the journal Nano Letters. The paper's lead authors are Koch Institute postdoc Simone Schurle and graduate student Jaideep Dudani.

 

Tumors, especially aggressive ones, often have elevated protease levels. These enzymes help tumors spread by cleaving proteins that compose the extracellular matrix, which normally surrounds cells and holds them in place.

 

In 2014, Bhatia and colleagues reported using nanoparticles that interact with a type of protease known as matrix metalloproteinases (MMPs) to diagnose cancer. In that study, the researchers delivered nanoparticles carrying peptides, or short protein fragments, designed to be cleaved by the MMPs. If MMPs were present, hundreds of cleaved peptides would be excreted in the urine, where they could be detected with a simple paper test similar to a pregnancy test.

 

In the new study, the researchers wanted to adapt the sensors so that they could report on the traits of tumors in a known location. To do that, they needed to ensure that the sensors were only producing a signal from the target organ, unaffected by background signals that might be produced in the bloodstream. They first designed sensors that could be activated with light once they reached their target. That required the use of ultraviolet light, however, which doesn't penetrate very far into tissue.

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NIST suggests nanoscale electronic motion sensor as DNA sequencer

NIST suggests nanoscale electronic motion sensor as DNA sequencer | Amazing Science | Scoop.it

Researchers from the National Institute of Standards and Technology (NIST) and collaborators have proposed a design for the first DNA sequencer based on an electronic nanosensor that can detect tiny motions as small as a single atom.

 

The proposed device—a type of capacitor, which stores electric charge—is a tiny ribbon of molybdenum disulfide suspended over a metal electrode and immersed in water. The ribbon is 15.5 nm long and 4.5 nm wide. Single-stranded DNA, containing a chain of bases (bits of genetic code), is threaded through a hole 2.5 nm wide in the thin ribbon. The ribbon flexes only when a DNA base pairs up with and then separates from a complementary base affixed to the hole. The membrane motion is detected as an electrical signal.

 

As described in a new paper, the NIST team made numerical simulations and theoretical estimates to show the membrane would be 79 to 86 percent accurate in identifying DNA bases in a single measurement at speeds up to about 70 million bases per second. Integrated circuits would detect and measure electrical signals and identify bases. The results suggest such a device could be a fast, accurate and cost-effective DNA sequencer, according to the paper.

 

Conventional sequencing, developed in the 1970s, involves separating, copying, labeling and reassembling pieces of DNA to read the genetic information. Newer methods include automated sequencing of many DNA fragments at once—still costly—and novel "nanopore sequencing" concepts. For example, the same NIST group recently demonstrated the idea of sequencing DNA by passing it through a graphene nanopore, and measuring how graphene's electronic properties respond to strain.

 

The latest NIST proposal relies on a thin film of molybdenum disulfide—a stable, layered material that conducts electricity and is often used as a lubricant. Among other advantages, this material does not stick to DNA, which can be a problem with graphene. The NIST team suggests the method might even work without a nanopore—a simpler design—by passing DNA across the edge of the membrane.

 

"This approach potentially solves the issue with DNA sticking to graphene if inserted improperly, because this approach does not use graphene, period," NIST theorist and lead author Alex Smolyanitsky said. "Another major difference is that instead of relying on the properties of graphene or any particular material used, we read motions electrically in an easier way by forming a capacitor. This makes any electrically conductive membrane suitable for the application."

 

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Researchers Create Microscopic Pacman Scenario

A novel project has emerged from the research environment at the Department of Micro- and Nanosystem Technology (IMST): The legendary labyrinth from the 80s computer game Pac-Man has been recreated in microscale, with a diameter of under a millimeter, and filled with microscopic prey and predators swimming around in a nutrient rich fluid.

 

The single celled organisms Euglena and Ciliates can be viewed as «Pac-Men», being hunted by "Ghosts" in the form of the multicellular microscopic animals called Rotifers. Using micro scenography the films creator, Adam Bartley, used neon lighting to recreate the staging familiar from Pac-Man and capture it on film.

 

Although the simplest lifeforms appear to move around randomly, researchers discovered an eye-catching behavior in the multicellular rotifers: "When the rotifers were first introduced into the labyrinth, they were very cautious and proceeded slowly. However, after a lag of about a day, this changed and they dashed forward in a more focused way." Johannessen suggests that this may be due to chemical traces they leave behind, making it easier for them to find their way forward.

 

Digital tracing of paths taken by the different species, in order to elucidate if there is logic in the way that they maneuver, will be one focus in a continuation of the project.  "By creating a more complex habitat, in the form of a labyrinth, it makes it possible to establish zones that may be favorable for the organisms one is studying. Johannessen comments that behavioral changes on repeated exposure to the same environmental conditions could be revealed using digital tracing."

 

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Multifunctional Hybrid Rust-Au Nanoparticles for Efficient Plasmonic Heating

Multifunctional Hybrid Rust-Au Nanoparticles for Efficient Plasmonic Heating | Amazing Science | Scoop.it

Researchers from the University of Georgia are giving new meaning to the phrase "turning rust into gold"—and making the use of gold in research settings and industrial applications far more affordable.

 

The research is akin to a type of modern-day alchemy, said Simona Hunyadi Murph, adjunct professor in the UGA Franklin College of Arts and Sciences department of physics and astronomy. Researchers combine small amounts of gold nanoparticles with magnetic rust nanoparticles to create a hybrid nanostructure that retains both the properties of gold and rust.

 

"Medieval alchemists tried to create gold from other metals," she said. "That's kind of what we did with our research. It's not real alchemy, in the medieval sense, but it is a sort of 21st century version."

 

Gold has long been a valuable resource for industry, medicine, dentistry, computers, electronics and aerospace, among others, due to unique physical and chemical properties that make it inert and resistant to oxidation. But because of its high cost and limited supply, large scale projects using gold can be prohibitive.

 

At the nanoscale, however, using a very small amount of gold is far more affordable.

In the new study published this summer in the Journal of Physical Chemistry C, the researchers used solution chemistry to reduce gold ions into a metallic gold structure using sodium citrate. In this process, if other ingredients-rust in this case-are present in the reaction pot during the transformation process, the metallic gold structures nucleate and grow on these "ingredients," otherwise known as supports.

"We are really excited to share our new discoveries.

 

When researchers are looking at gold as a potential material for research, we talk about how expensive gold is. For the first time ever, we've been able to create a new class of cheaper, highly efficient, nontoxic, magnetically reusable hybrid nanomaterials that contain a far more abundant material-rust-than the typical noble metal gold," said Murph, who is also a principal scientist in the National Security Directorate at the Savannah River National Laboratory in Aiken, South Carolina.

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Nanoparticles that carry three or more drugs hold potential for targeted cancer therapy

Nanoparticles that carry three or more drugs hold potential for targeted cancer therapy | Amazing Science | Scoop.it

Nanoparticles offer a promising way to deliver cancer drugs in a targeted fashion, helping to kill tumors while sparing healthy tissue.

 

MIT chemists have now shown that they can package three or more drugs into a novel type of nanoparticle, allowing them to design custom combination therapies for cancer. In tests in mice, the researchers showed that the particles could successfully deliver three chemotherapy drugs and shrink tumors.

 

In the same study, which appears in the Sept. 14 issue of the Journal of the American Chemical Society, the researchers also showed that when drugs are delivered by nanoparticles, they don't necessarily work by the same DNA-damaging mechanism as when delivered in their traditional form.

 

That is significant because most scientists usually assume that nanoparticle drugs are working the same way as the original drugs, says Jeremiah Johnson, the Firmenich Career Development Associate Professor of Chemistry and the senior author of the paper. Even if the nanoparticle version of the drug still kills cancer cells, it's important to know the underlying mechanism of action when choosing combination therapies and seeking regulatory approval of new drugs, he says.

 

"People tend to take it as a given that when you put a drug into a nanoparticle it's the same drug, just in a nanoparticle," Johnson says. "Here, in collaboration with Mike Hemann, we conducted detailed characterization using an RNA interference assay that Mike developed to make sure the drug is still hitting the same target in the cell and doing everything that it would if it weren't in a nanoparticle."

 

The paper's lead authors are Jonathan Barnes, a former MIT postdoc; and Peter Bruno, a postdoc at MIT's Koch Institute for Integrative Cancer Research. Other authors are grad students Hung Nguyen and Jenny Liu, former postdoc Longyan Liao, and Michael Hemann, an associate professor of biology and member of the Koch Institute.

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Tiny nano-structures give a peacock spider its radiant rump

Tiny nano-structures give a peacock spider its radiant rump | Amazing Science | Scoop.it

Male peacock spiders know how to work their angles and find their light. The arachnids, native to Australia, raise their derriere — or, more accurately, a flap on their hind end — skyward andshake it to attract females. Hairlike scales cover their bodies and produce the vibrant colorations that make peacock spiders so striking.

 

Doekele Stavenga of the University of Groningen in the Netherlands and his colleagues collected Maratus splendens peacock spiders from a park outside Sydney and zoomed in on those scales. Using microscopy, spectrometry and other techniques, the team found that the spiders’ red, yellow and cream scales rely on two pigments, 3-OH-kynurenine and xanthommatin, to reflect their colors. Even white scales contain low levels of pigment. Spines lining these scales  scatter light randomly, giving them slightly different hues from different angles.

 

Blue scales are an entirely different story. They’re transparent and pigment-free. Instead, the scales’ architecture reflects iridescent blue and purple hues. Each peapodlike scale is lined with tiny ridges on the outside and a layer of threadlike fibers on the inside. Fiber spacing may determine whether scales appear more blue or more purple.

 

Whether peacock spiders’ eyes can actually see these posterior patterns is an open question, Stavenga and his colleagues write in the August Journal of the Royal Society Interface. Given that other jumping spiders see at least three color ranges, it seems unlikely that such vivid come-hither choreography plays out in black and white.

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Seeing the invisible: Visible light superlens made from nanobeads

Seeing the invisible: Visible light superlens made from nanobeads | Amazing Science | Scoop.it
Nanobeads are all around us- and are, some might argue, used too frequently in everything from sun-screen to white paint, but a new ground-breaking application is revealing hidden worlds.

 

A paper in Science Advances (12 August) provides proof of a new concept, using new solid 3D superlenses to break through the scale of things previously visible through a microscope.

Illustrating the strength of the new superlens, the scientists describe seeing for the first time, the actual information on the surface of a Blue Ray DVD. That shiny surface is not as smooth as we think. Current microscopes cannot see the grooves containing the data- but now even the data itself is revealed.

 

Led by Dr Zengbo Wang at Bangor University, UK and Prof Limin Wu at Fudan University, China, the team created minute droplet-like lens structures on the surface to be examined. These act as an additional lens to magnify the surface features previously invisible to a normal lens.

 

Made of millions of nanobeads, the spheres break up the light beam. Each bead refracts the light, acting as individual torch-like minute beam. It is the very small size of each beam of light which illuminate the surface, extending the resolving ability of the microscope to record-breaking levels. The new superlens adds 5x magnification on top of existing microscopes.

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Swarms of Microscale 'Transformer' Robots Can Break Through Blocked Arteries

Swarms of Microscale 'Transformer' Robots Can Break Through Blocked Arteries | Amazing Science | Scoop.it

Swarms of microscopic, magnetic, robotic beads could be scrubbing in next to the world’s top vascular surgeons—all taking aim at blocked arteries. These microrobots, which look and move like corkscrew-shaped bacteria, are being developed by mechanical engineers at Drexel University as a part of a surgical toolkit being assembled by the Daegu Gyeongbuk Institute of Science and Technology (DGIST) in South Korea.

 

MinJun Kim, PhD, a professor in the College of Engineering and director of the Biological Actuation, Sensing & Transport Laboratory (BASTLab) at Drexel, is adding his team’s extensive work in bio-inspired microrobotics to an $18-million international research initiative from the Korea Evaluation Institute of Industrial Technologies (KEIT) set on creating a minimally invasive, microrobot-assisted procedure for dealing with blocked arteries within five years.

 

DGIST, a government-funded research entity in Daegu, South Korea, is the leader of the 11-institution partnership, which includes some of the top engineers and roboticists in the world. Drexel’s team, the lone representatives from the United States, is already well on its way to tailoring robotic “microswimmer” technology for clearing arteries.

 

“Microrobotics is still a rather nascent field of study, and very much in its infancy when it comes to medical applications,” Kim said. “A project like this, because it is supported by leading institutions and has such a challenging goal, is an opportunity to push both medicine and microrobotics into a new and exciting place.”

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How mechanical force triggers blood clotting at the molecular scale

How mechanical force triggers blood clotting at the molecular scale | Amazing Science | Scoop.it
Using a unique single-molecule force measurement tool, a research team has developed a clearer understanding of how platelets sense the mechanical forces they encounter during bleeding to initiate the cascading process that leads to blood clotting.

 

Beyond providing a better understanding of this vital bodily process, research into a mechanoreceptor molecule that triggers clotting could provide a potential new target for therapeutic intervention. Excessive clotting can lead to heart attack and stroke - major killers worldwide - while insufficient clotting allows life-threatening bleeding.

 

"We have opened a new door to study how mechanical force triggers biochemical signals inside living cells," said Lining (Arnold) Ju, who was part of the team conducting the research as a Ph.D. student in the Wallace H. Coulter Department of Biomedical Engineering at Georgia Tech and Emory University.

 

The research, supported by the National Institutes of Health and the National Science Foundation, was reported July 19 in the journal eLife. It is believed to be the first detailed mechanobiology study on how mechanical forces acting on a single molecule on a platelet are sensed and transduced into biochemical signals. Beyond blood clotting, the work could have implications for other cellular systems that respond to mechanical force.

 

In the beginning of the clotting process, human platelets use a highly specialized molecule known as glycoprotein Ibα (GPIbα) to receive mechanical signals. In a process known as mechanosensing, the mechanical information is converted into chemical signals - the release of different types of calcium ions - that alter adhesion between platelets and other components of the clotting process. Using their unique experimental equipment, the research team correlated various forces applied to the GPIbα molecule with different chemical signals, working to understand the operation of this natural transducer built into human platelets.

 

How cells sense their mechanical environment and transduce forces into biochemical signals is a crucial, yet unresolved question in mechanobiology, the researchers noted in their paper. The researchers studied how mechanical forces outside the platelets trigger the release of calcium ions inside the cells. They applied force on the GPIbα molecule via the binding of von Willebrand factor and a mutant form of this plasma protein that causes von Willibrand Disease, a bleeding disorder.

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Condensed DNA dominos packed onto a chip

Condensed DNA dominos packed onto a chip | Amazing Science | Scoop.it

Normally, individual molecules of genetic material repel each other. However, when space is limited DNA molecules must be packed together more tightly. This case arises in sperm, cell nuclei and the protein shells of viruses. An international team of physicists has now succeeded in artificially recreating this so-called DNA condensation on a biochip.

 

Recreating important biological processes in cells to better understand them currently is a major topic of research. Now, physicists at TU Munich and the Weizmann Institute in Rehovot have for the first time managed to carry out controlled, so-called DNA condensation on a biochip. This process comes into play whenever DNA molecules are closely packed into tight spaces, for example in circumstances that limit the available volume.

 

This situation arises in cell nuclei and in the protein shells of viruses, as well as in the heads of sperm cells. The phenomenon is also interesting from a physical perspective because it represents a phase transition, of sorts. DNA double helices, which normally repel each other because of their negative charges, are then packed together tightly. "In this condensed state they take on a nearly crystalline structure," says co-author and TU professor Friedrich Simmel.

 


Via Integrated DNA Technologies
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Optical spring detects single molecules

Optical spring detects single molecules | Amazing Science | Scoop.it

A team of engineering researchers from the University of Victoria (UVic) and the University of Rochester (UR) has developed a way to detect single molecules using a light-based technology inspired by the "whispering gallery" of St. Paul's Cathedral in London

 

The new technology, described in a study published today in the peer-reviewed journal, Nature Communications, has many potential applications, including medical diagnostics, drug development, security screening and environmental science.

 

"The ability to detect a single molecule or nanoparticle is essential for many applications," says Wenyan Yu, a PhD student and one of the paper's authors along with photonic engineer Tao Lu of UVic, and optical engineers Wei Jiang and Qiang Lin of UR. "To date, many approaches have been used to observe single particles. Our discovery may allow scientists the ability to detect particles as miniscule as a single atom, or a single base pair of DNA."

 

The whispering gallery of St. Paul's Cathedral in London is an acoustic marvel. When a person whispers against one wall, the voice travels around the chamber's circular rim and is clearly audible over 34 metres away on the other side. A "whispering gallery microcavity" is a kind of gallery-in-miniature, typically 100 microns in diameter—about the width of a human hair—in which waves of light, rather than sound, can be confined in a microstructure.

 

Light circulating inside the cavity produces a force that makes the cavity vibrate, or quiver, creating the so-called optical spring effect. The research team discovered that when an individual particle or biomolecule lands on the surface of quivering microcavity, the optical spring force changes the vibration in a particular and measurable way.

 

"Although the optical spring effect has been known for more than a decade," says Wei Jiang, "this discovery significantly enhances the sensitivity of the device."

 

Lu and the team are now refining the detection sensitivity and says eventually it could be used to detect specific protein molecules to diagnose cancer at an early stage, or to find out whether a drug interacts with single biomolecules.

 

The UVic team fabricated the devices, prepared the samples, conceived, designed and performed the experiments, and processed the data. The UR team discovered the sensing principle and mechanism, developed the theory, and conducted the numerical simulation. The teams worked together on the analysis and interpretation.

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Molecular flip in crystals driven by light creates microrobotic propulsion

Molecular flip in crystals driven by light creates microrobotic propulsion | Amazing Science | Scoop.it

Hokkaido University researchers have designed a crystal material that continually flips between two positions like a paddle, propelling an attached structure, when stimulated by blue light. It could lead to bio-inspired microrobots that deliver drugs to target tissues, for example.

 

The team made azobenzene-oleic acid crystals, composed of an organic compound called azobenzene, commonly used in dye manufacturing, and oleic acid, commonly found in cooking oil. Azobenzene molecules take two structurally different forms: cis and trans, and they were found to switch back and forth when stimulated by the light.

 

The frequency of the motion also increased with increased light intensity. Some crystal complexes they created even exhibited swimming-like motions in the water, the researchers report. Previously reported light-responsive materials have been limited in their ability to deform, the researchers noted.

 

“The importance of this study lies in the realization of macroscopic self-oscillation by the repeated reversible reaction of a molecular machine with the cooperative transformation of a molecular assembly,” the researchers note in a paper published in the journal Angewandte Chemie.

 

“These results provide a fundamental strategy for constructing dynamic self-organizations in supramolecular systems to achieve bioinspired molecular systems.”

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