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A protein ‘passport’ that helps nanoparticles get past immune system

A protein ‘passport’ that helps nanoparticles get past immune system | Amazing Science | Scoop.it

Macrophages — literally, "big eaters" — are a main part of the body's innate immune system . These cells find and engulf invaders, like bacteria, viruses, splinters and dirt. Unfortunately, macrophages also eat helpful foreigners, including nanoparticles that deliver drugs or help image tumors.


Along with members of his lab, Dennis Discher, professor of chemical and biomolecular engineering in the School of Engineering and Applied Science, has developed a "passport" that could be attached to therapeutic particles and devices, tricking macrophages into leaving them alone. 

Taking a cue from a membrane protein that the body's own cells use to tell macrophages not to eat them, the researchers engineered a the simplest functional version of that protein and attached it to plastic nanoparticles. These passport-carrying nanoparticles remained in circulation significantly longer than ones without the peptide, when tested in a mouse model.


In 2008, Discher’s group showed that the human protein CD47, found on almost all mammalian cell membranes, binds to a macrophage receptor known as SIRPa in humans. Like a patrolling border guard inspecting a passport, if a macrophage’s SIRPa binds to a cell’s CD47, it tells the macrophage that the cell isn’t an invader and should be allowed to proceed on.

 

“There may be other molecules that help quell the macrophage response,” Discher said. “But human CD47 is clearly one that says, ‘Don’t eat me’.” Since the publication of that study, other researchers determined the combined structure of CD47 and SIRPa together. Using this information, Discher’s group was able to computationally design the smallest sequence of amino acids that would act like CD47. This “minimal peptide” would have to fold and fit well enough into the receptor of SIRPa to serve as a valid passport. After chemically synthesizing this minimal peptide, Discher’s team attached it to conventional nanoparticles that could be used in a variety of experiments. “Now, anyone can make the peptide and put it on whatever they want,” Rodriguez said.

 

The research team’s experiments used a mouse model to demonstrate better imaging of tumors and as well as improved efficacy of an anti-cancer drug-delivery particle.

 

As this minimal peptide might one day be attached to a wide range of drug-delivery vehicles, the researchers also attached antibodies of the type that could be used in targeting cancer cells or other kinds of diseased tissue. Beyond a proof of concept for therapeutics, these antibodies also served to attract the macrophages’ attention and ensure the minimal peptide’s passport was being checked and approved.


Video is here: http://tinyurl.com/b6dthgb

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MIT: Carbon Nanotube Transistors Orders of Magnitude Better at Spotting Prostate Cancer Than PSA Tests

MIT: Carbon Nanotube Transistors Orders of Magnitude Better at Spotting Prostate Cancer Than PSA Tests | Amazing Science | Scoop.it
Arrays of carbon-nanotube transistors can detect prostate cancer with a much higher sensitivity than conventional techniques.

 

The early detection of many diseases dramatically improves prognoses. Prostate cancer is a case in point, with a 60 to 90 percent long-term survival rate in patients who are diagnosed at an early stage. The problem, of course, is making such a diagnosis quickly and accurately. The standard test is for prostate-specific antigen, which is produced by a cancerous prostate in relatively high quantities. However, the trouble with PSA tests is they produce a significant number of false positives and false negatives. So some healthy men end up undergoing invasive tests while others with the disease go undetected.

 

There is another biomarker of the disease known as osteopontin, or OPN. The state-of-the art technique for spotting this is known as ELISA. In this test, OPN from a sample is attached to a surface. The surface is washed with OPN-binding antibodies, which are themselves attached to colour-changing enzymes. If these antibodies bond with the OPN, the colour change can be easily detected. But while this technique is sensitive, it is relatively time-consuming and difficult to use to quantify the amount of OPN.

 

So more sensitive and accurate techniques are highly sought after. Today, Mitchell Lerner at the University of Pennsylvania and a few buddies reveal just such a technique that uses an array of carbon nanotube transistors on a silicon chip to detect antigens such as OPN.

 

The trick they’ve perfected is a way of attaching an OPN-binding antibody to the carbon nanotube in each transistor. The electronic characteristics of the antibody-nanotube transistor can then be easily measured by the on-chip electronics. When the chip is immersed in a sample, the OPN binds to the antibodies connected to the nanotubes, and this changes the electronic characteristics of the transistor. So measuring the current and voltage through each transistor is an accurate way of measuring how much OPN there is in the sample.

 

Lerner and co say their device can detect OPN at concentrations of 1 picogram per millilitre. That’s a concentration three orders of magnitude weaker than ELISA can manage. And by replacing the OPN-binding antibody with molecules sensitive to other antigens, the carbon nanotube transistors can be made sensitive to other diseases. Lerner and co say they have successfully used the technique to detect Lyme disease and salmonella. 

 

That’s impressive work that has the potential to improve the diagnosis and detection of many diseases and pathogens. Of course, more work is needed to characterise the behaviour of these chips and in particular the circumstances in which they might give false positives or negatives. But in the meantime, expect to hear more about them.

 

Refs: 

• arxiv.org/abs/1302.2961: Detecting Lyme Disease Using Antibody-Functionalized SingleWalled Carbon Nanotube Transistors

• arxiv.org/abs/1302.2959: A Carbon Nanotube Immunosensor for Salmonella

• arxiv.org/abs/1302.2958: Hybrids of a Genetically Engineered Antibody and a Carbon Nanotube Transistor for Detection of Prostate Cancer

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NIH: Taking the sting out of vaccination - polymer multilayer tattooing for DNA vaccines

NIH: Taking the sting out of vaccination - polymer multilayer tattooing for DNA vaccines | Amazing Science | Scoop.it

This might be a new way to get a shot. Funded in part by the NIH, this vaccine patch [1] is coated in a thin film that literally melts into the skin when the patch is applied. The film contains DNA, rather than protein, which is absorbed by the skin cells and triggers an immune reaction. It seems to be effective in animal models. DNA vaccines are attractive because they may not require refrigeration like typical protein vaccines and can be stably stored for weeks. And, though this patch looks spiky, the length of the needles can be adjusted so that they don’t reach the skin layers that contain nerves. Thus: no pain at all.

 

[1] Polymer multilayer tattooing for enhanced DNA vaccination. Demuth PC, Min Y, Huang B, Kramer JA, Miller AD, Barouch DH, Hammond PT, Irvine DJ. Nat Mater. 2013 Jan 27.

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First test of a seismic invisibility cloak using a metamaterial that strongly reflects seismic waves

First test of a seismic invisibility cloak using a metamaterial that strongly reflects seismic waves | Amazing Science | Scoop.it

The secret of invisibility cloaks lies in engineering a material on a scale smaller than the wavelength of the waves it needs to manipulate.  The appropriate sub-wavelength structures can then be arranged in a way that steers waves.

 

A group from the Institut Fresnel in Marseille and the ground improvement specialist company, Menard, both in France, recently reported that they have built and tested a seismic invisibility cloak in an alluvial basin in southern France. That’s the first time such a device has been constructed. The French team created its so-called metamaterial by drilling three lines of  empty boreholes 5 metres deep in a basin of silted clay up to 200 metres deep. They then monitored the area with acoustic sensors.

 

The experiment consisted of creating waves with a frequency of 50 Hertz and a horizontal displacement of 14 mm from a source on one side of the array. They then measured the way the waves propagated across it.


The French team say its metamaterial strongly reflected the seismic waves, which barely penetrated beyond the second line of boreholes.


The metamaterial is designed to work at the specific wavelength used in the test andseismic waves cannot be guaranteed to have this same wavelength. But by matching the array to the resonant frequency of a building, the thinking is that it could still provide some protection.


There are important caveats, however. One problem with this kind of array is that the reflected waves could end up doing more damage to buildings nearby. That’s why some groups are looking at metamaterials that absorb energy rather than steer or reflect it. 


Nevertheless, there are bound to be installations that could benefit from this kind of protection. And since creating these arrays looks relatively simple, it looks to be only a matter of time before we will see them in action for real. 


More info: arxiv.org/abs/1301.7642: Seismic Metamaterial: How to Shake Friends and Influence Waves?

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Listening to cells: Scientists probe human cells with ultrasound pulses

Listening to cells: Scientists probe human cells with ultrasound pulses | Amazing Science | Scoop.it

Researchers from the University of Bordeaux in Franceused high-frequency sound waves to test the stiffness and viscosity of the nuclei of individual human cells to help answer questions such as how cells adhere to medical implants and why healthy cells turn cancerous.

 

“We have developed a new non-contact, non-invasive tool to measure the mechanical properties of cells at the sub-cell scale,” says Bertrand Audoin, a professor in the mechanics laboratory at the University of Bordeaux. “This can be useful to follow cell activity or identify cell disease.”

 

The technique, called picosecond ultrasonics, was initially developed to measure the thickness of semiconductor chip layers.

 

The researchers grew cells on a metal plate and then flashed the cell-metal interface with an ultra-short laser pulse to generate high-frequency sound waves. Another laser measured how the sound pulse propagated through the cells, giving the scientists clues about the mechanical properties of the individual cell components.

 

“The higher the frequency of sound you create, the smaller the wavelength, which means the smaller the objects you can probe” says Audoin. “We use gigahertz waves, so we can probe objects on the order of a hundred nanometers.” For comparison, a cell’s nucleus is about 10,000 nanometers wide.

 

In the coming years, the team envisions studying cancer cells with sound. “A cancerous tissue is stiffer than a healthy tissue,” notes Audoin. “If you can measure the rigidity of the cells while you provide different drugs, you can test if you are able to stop the cancer at the cell scale.”

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Katie Johnson's curator insight, April 30, 2013 11:23 AM

This article shows the different kinds of work ultra sounds can be used for, not just in pregnancy and other normal cases. It shows the variety of things I could be doing while on the job.

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Tiny 3-D printed spaceship constructed: Only 125 µm long - and it took only 50 sec to produce

Tiny 3-D printed spaceship constructed: Only 125 µm long - and it took only 50 sec to produce | Amazing Science | Scoop.it

The tiny spaceship in the video above was built using a microscale 3-D printer. At 125 micrometers long, the craft is about the length of a dust mite, and it took less than 50 seconds to produce. The super-fast, high-resolution printer that made the spaceship was introduced this week at the Photonics West fair by Nanoscribe GmbH, a company based in Germany that specializes in nanophotonics and 3-D laser lithography.

 

The printer crafted the spaceship using two-photon polymerization, in which ultra-short laser pulses activate photosensitive building materials. Afterward, the ship — based on a Hellcat fighter from the Wing Commander Saga — was inspected using an electron microscope. While the spacecraft can’t fly, thereby limiting its usefulness for space exploration (unlike, say, 3-D printed astrofood), the technology’s other tiny productsinclude biological scaffolds, ultralight metamaterials, and channels that have found homes in biological research, photonics, and microfluidics.

 

Next step? We’d love to watch this thing launch into space, piloted by an army of microbes.

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Tiny nanoscale capsule effectively kills cancer cells without harming normal cells

Tiny nanoscale capsule effectively kills cancer cells without harming normal cells | Amazing Science | Scoop.it

The development of stimuli-responsive, nano-scale therapeutics that selectively target and attack tumors is a major research focus in cancer nanotechnology. A potent therapeutic option is to directly arming the cancer cells with apoptotic-inducing proteins that are not affected by tumoral anti-apoptotic maneuvers. The avian virus-derived apoptin forms a high-molecular weight protein complex that selectively accumulates in the nucleus of cancer cell to induce apoptotic cell death. To achieve the efficient intracellular delivery of this tumor-selective protein in functional form, we synthesized degradable, sub-100 nm, core–shell protein nanocapsules containing the 2.4 MDa apoptin complexes. Recombinant apoptin is reversibly encapsulated in a positively charged, water soluble polymer shell and is released in native form in response to reducing conditions such as the cytoplasm. As characterized by confocal microscopy, the nanocapsules are efficiently internalized by mammalian cells lines, with accumulation of rhodamine-labeled apoptin in the nuclei of cancer cells only. Intracellularly released apoptin induced tumor-specific apoptosis in several cancer cell lines and inhibited tumor growth in vivo, demonstrating the potential of this polymer–protein combination as an anticancer therapeutic.

 

The process does not present the risk of genetic mutation posed by gene therapies for cancer, or the risk to healthy cells caused by chemotherapy, which does not effectively discriminate between healthy and cancerous cells, Tang said.


"This approach is potentially a new way to treat cancer," said Tang. "It is a difficult problem to deliver the protein if we don't use this vehicle. This is a unique way to treat cancer cells and leave healthy cells untouched."


The cell-destroying material, apoptin, is a protein complex derived from an anemia virus in birds. This protein cargo accumulates in the nucleus of cancer cells and signals to the cell to undergo programmed self-destruction.


The polymer shells are developed under mild physiological conditions so as not to alter the chemical structure of the proteins or cause them to clump, preserving their effectiveness on the cancer cells.


Tests done on human breast cancer cell lines in laboratory mice showed significant reduction in tumor growth.


"Delivering a large protein complex such as apoptin to the innermost compartment of tumor cells was a challenge, but the reversible polymer encapsulation strategy was very effective in protecting and escorting the cargo in its functional form," said Muxun Zhao, lead author of the research and a graduate student in chemical and biomolecular engineering at UCLA.

 

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Scientists use Amazon Cloud to view molecular machinery in remarkable detail

Scientists use Amazon Cloud to view molecular machinery in remarkable detail | Amazing Science | Scoop.it

Salk researchers share a how-to secret for biologists: code for Amazon Cloud that significantly reduces the time necessary to process data-intensive microscopic images

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The method promises to speed research into the underlying causes of disease by making single-molecule microscopy of practical use for more laboratories.

 

"This is an extremely cost-effective way for labs to process super-resolution images," says Hu Cang, Salk assistant professor in the Waitt Advanced Biophotonics Center and coauthor of the paper. "Depending on the size of the data set, it can save over a week's worth of time."

 

The latest frontier in basic biomedical research is to better understand the "molecular machines" called proteins and enzymes. Determining how they interact is key to discovering cures for diseases. Simply put, finding new therapies is akin to troubleshooting a broken mechanical assembly line-if you know all the steps in the manufacturing process, it's much easier to identify the step where something went wrong. In the case of human cells, some of the parts of the assembly line can be as small as single molecules.

 

According to the Abbe limit, it is impossible to see the difference between any two objects if they are smaller than half the wavelength of the imaging light. Since the shortest wavelength we can see is around 400 nanometers (nm), that means anything 200 nm or below appears as a blurry spot. The challenge for biologists is that the molecules they want to see are often only a few tens of nanometers in size.

 

"You have no idea how many single molecules are distributed within that blurry spot, so essential features and ideas remain obscure to you," says Jennifer Lippincott-Schwartz, a Salk non-resident fellow and coauthor on the paper.

 

In the early 2000s, several techniques were developed to break through the Abbe Limit, launching the new field of super-resolution microscopy. Among them was a method developed by Lippincott-Schwartz and her colleagues called Photoactivated Localization Microscopy, or PALM.

 

PALM, and its sister techniques, work because mathematics can see what the eye cannot: within the blurry spot, there are concentrations of photons that form bright peaks, which represent single molecules. The downside to these approaches is that it can take several hours to several days to crunch all the numbers required just to produce one usable image.

 

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Flexible, high-strength polymer aerogels deliver "super-insulation" properties

Flexible, high-strength polymer aerogels deliver "super-insulation" properties | Amazing Science | Scoop.it
New polymer aerogels from NASA Glenn Research Center are flexible and 500 times stronger than traditional aerogels.

 

The new class of polymer aerogels also have superior mechanical properties. For example silica aerogels of a similar density have a resistance to comperession and tensile limit more than 100 times smaller than the new polymer aerogels.

 

The image above shows a Smart car parked on top of a thick piece of NASA's new polymer aerogel.

 

Silica aerogels would crush to powder if placed under a car tire. As seen above, the same is not true of the new polymer aerogels, even if the car is only a Smart car. Overall, the mechanical properties are rather like those of a synthetic rubber, save that the aerogel has the same properties (and far smaller thermal conductivity) with only about 10 percent of the weight.

Applications in clothing as well as insulation of pipes, buildings, water heaters, and the like are enabled by these materials. Tents and sleeping bags can also benefit from the combination of light weight and thermal insulation. NASA is even considering the new polymer aerogels for use asinflatable heat shields. The practicality of many such applications will depend on the cost of polymer aerogel in commercial quantities. In any case, these types of products now have another dimension of design flexibility.

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Nanoparticles that look and act like cells hide even from the immune system

Nanoparticles that look and act like cells hide even from the immune system | Amazing Science | Scoop.it

By cloaking nanoparticles in the membranes of white blood cells, scientists at The Methodist Hospital Research Institute may have found a way to prevent the body from recognizing and destroying them before they deliver their drug payloads.

 

"Our goal was to make a particle that is camouflaged within our bodies and escapes the surveillance of the immune system to reach its target undiscovered," said Department of Medicine Co-Chair Ennio Tasciotti, Ph.D., the study's principal investigator. "We accomplished this with the lipids and proteins present on the membrane of the very same cells of the immune system. We transferred the cell membranes to the surfaces of the particles and the result is that the body now recognizes these particles as its own and does not readily remove them."

 

Nanoparticles can deliver different types of drugs to specific cell types, for example, chemotherapy to cancer cells. But for all the benefits they offer and to get to where they need to go and deliver the needed drug, nanoparticles must somehow evade the body's immune system that recognizes them as intruders. The ability of the body's defenses to destroy nanoparticles is a major barrier to the use of nanotechnology in medicine. Systemically administered nanoparticles are captured and removed from the body within few minutes. With the membrane coating, they can survive for hours unharmed.

 

"Our cloaking strategy prevents the binding of opsonins—signaling proteins that activate the immune system," Tasciotti said. "We compared the absorption of proteins onto the surface of uncoated and coated particles to see how the particles might evade the immune system response."

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Discovery Opens Door for Quantum Dots in Photodetectors, Sensors and Lasers

Discovery Opens Door for Quantum Dots in Photodetectors, Sensors and Lasers | Amazing Science | Scoop.it

Researchers at the National Institute of Standards and Technology (NIST) have shown that by bringing gold nanoparticles close to the dots and using a DNA template to control the distances, the intensity of a quantum dot's fluorescence can be predictably increased or decreased. Their research was published in Angewandte Chemie. This breakthrough opens a potential path to using quantum dots as a component in better photodetectors, chemical sensors and nanoscale lasers.

 

Anyone who has tried to tune a radio knows that moving their hands toward or away from the antenna can improve or ruin the reception. Although the reasons are well understood, controlling this strange effect is difficult, even with hundred-year-old radio technology. Similarly, nanotechnology researchers have been frustrated trying to control the light emitted from quantum dots, which brighten or dim with the proximity of other particles.

 

The NIST team developed ways to accurately and precisely place different kinds of nanoparticles near each other and to measure the behavior of the resulting nanoscale constructs. Because nanoparticle-based inventions may require multiple types of particles to work together, it is crucial to have reliable methods to assemble them and to understand how they interact.

 

The researchers looked at two types of nanoparticles, quantum dots, which glow with fluorescent light when illuminated, and gold nanoparticles, which have long been known to enhance the intensity of light around them. The two could work together to make nanoscale sensors built using rectangles of woven DNA strands, formed using a technique called "DNA origami."

 

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Novel Nanosized Magnets for Controlled and Targeted Release of Drugs

Novel Nanosized Magnets for Controlled and Targeted Release of Drugs | Amazing Science | Scoop.it

Certain drugs are toxic by nature. For example, anti-cancer drugs developed to kill diseased cells also harm healthy ones. To limit the side effects of chemotherapy, it would be a great step forward if it were possible to release a drug only in the affected area of the body. In the context of the National Research Programme "Smart Materials" (NRP 62) - a cooperation between the SNSF and the Commission for Technology and Innovation (CTI) - researchers of ETH Lausanne, the Adolphe Merkle Institute and the University Hospital of Geneva have discovered a method that might represent an important step towards the development of an intelligent drug of this kind. By combining their expert knowledge in the areas of material sciences, biological nanomaterials and medicine, they were able to prove the feasibility of using a nanovehicle to transport drugs and release them in a controlled manner.

 

This nanocontainer is a liposome, which takes the shape of a vesicle. It has a diameter of 100 to 200 nanometers and is 100 times smaller than a human cell. The membrane of the vesicle is composed of phospholipids and the inside of the vesicle offers room for the drug. On the surface of the liposome, specific molecules help to target malignant cells and to hide the nanocontainer from the immune system, which might otherwise consider it a foreign entity and seek to destroy it. Now the researchers only needed to discover a mechanism to open up the membrane at will.

 

This is exactly what the researchers succeeded in doing. How they did it? By integrating into the liposome membrane superparamagnetic iron oxide nanoparticles (SPION), which only become magnetic in the presence of an external magnetic field. Once they are in the field, the SPION heat up. The heat makes the membrane permeable and the drug is released.

 

Researchers proved the feasibility of such a nanovehicle by releasing in a controlled manner a coloured substance contained in the liposomes. "We can really talk of nanomedicine in this context because, by exploiting superparamagnetism, we are exploiting a quantum effect which only exists at the level of nanoparticles," explains Heinrich Hofmann of the Powder Technology Laboratory of EPFL. SPION are also an excellent contrast agent in magnetic resonance imaging (MRI). A simple MRI shows the location of the SPION and allows for the release of the drug once it has reached the targeted spot.

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Bioinspired fibers change color when stretched

Bioinspired fibers change color when stretched | Amazing Science | Scoop.it

Color-tunable photonic fibers mimic the fruit of the “bastard hogberry” plant.

 

Since the evolution of the first eye on Earth more than 500 million years ago, the success of many organisms has relied upon the way they interact with light and color, making them useful models for the creation of new materials. For seeds and fruit in particular, bright color is thought to have evolved to attract the agents of seed dispersal, especially birds.

 

The fruit of the South American tropical plant, Margaritaria nobilis, commonly called “bastard hogberry,” is an intriguing example of this adaptation. The ultra-bright blue fruit, which is low in nutritious content, mimics a more fleshy and nutritious competitor. Deceived birds eat the fruit and ultimately release its seeds over a wide geographic area.

 

A team of materials scientists at Harvard University and the University of Exeter, UK, have invented a new fiber that changes color when stretched. Inspired by nature, the researchers identified and replicated the unique structural elements that create the bright iridescent blue color of a tropical plant’s fruit.

 

The multilayered fiber, described today in the journal Advanced Materials, could lend itself to the creation of smart fabrics that visibly react to heat or pressure.

 

“Our new fiber is based on a structure we found in nature, and through clever engineering we’ve taken its capabilities a step further,” says lead author Mathias Kolle, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS). “The plant, of course, cannot change color. By combining its structure with an elastic material, however, we’ve created an artificial version that passes through a full rainbow of colors as it’s stretched.”

 

The photonic fibers are made by wrapping multiple layers of polymer around a glass core, which is later etched away. The thickness of the layers determines the apparent color of the fiber, which can range across the entire visible spectrum of light (see image).

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Alcohol Intoxicated Mice Sober Up Fast After Nanoparticle Injection

Alcohol Intoxicated Mice Sober Up Fast After Nanoparticle Injection | Amazing Science | Scoop.it

Researchers in California packed up complementary enzymes in a nano-capsule, producing what basically amounts to a tiny enzyme pill. The capsule coating, made of a superthin polymer, keeps the enzymes together and protects them from breaking down in the body.

 

Led by Yunfeng Lu, a chemical and biomolecular engineering professor at UCLA, researchers injected mice with three enzymes related to the breakdown of sugars, and after this worked, they tried it with two enzymes related to the breakdown of alcohol, alcohol oxidase (AOx) and catalase. They wanted to test the enzymes as both an intoxication preventive and a treatment.

 

When mice were fed a diet of alcohol and the nano-capsule at the same time, their blood alcohol concentrations were greatly reduced within 30-minute increments, compared to mice that were fed just alcohol or alcohol plus one of the enzymes. The team also tested it on drunk mice, and found the treatment greatly lowered yet another enzyme, alanine transaminase, which is a biomarker for liver damage.

 

“Nanocomplexes containing alcohol oxidase and catalase could reduce blood alcohol levels in intoxicated mice, offering an alternative antidote and [preventive treatment] for alcohol intoxication. Three enzymes are combined with a DNA scaffold along with their enzymatic inhibitors, leading to a triple-compound architecture. A thin polymer is grown around the enzymes, encapsulating them in a sort of nano-pill. Enzymes working in close proximity ensures they can clean up after each other's toxic byproducts.

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A molecular imprint nanosensor for ultrasensitive detection of proteins

A molecular imprint nanosensor for ultrasensitive detection of proteins | Amazing Science | Scoop.it

Molecular imprinting (MI) is a technique for preparing polymer scaffolds that function as synthetic receptors, and imprinted polymers that can selectively recognize organic compounds have been proven useful for sensor development. Although creating synthetic MI polymers (MIPs) that recognize proteins remains challenging, nanodevices and nanomaterials show promise for protein recognition into sensor architectures. Arrays of carbon nanotube (nanotube) tips imprinted with a non-conducting polymer coating can be used to recognize proteins with subpicogram per liter sensitivity using electrochemical impedance spectroscopy. Specific MI sensors for human ferritin and human papillomavirus derived E7 protein were developed by one research group. The MI-based nanosensor can also discriminate between Ca2+-induced conformational changes in calmodulin. This ultrasensitive, label-free electrochemical detection of proteins offers an alternative to biosensors based on biomolecule recognition.

 

MI technology offers considerable potential as a cost-effective alternative to the use of biomolecule-based recognition in a variety of sensor applications. MIPs afford the creation of specific recognition sites in synthetic polymers by a process that involves co-polymerization of functional monomers and cross-linkers around template molecules. The molecules are removed from the polymer, rendering complementary binding sites capable of subsequent template molecule recognition. Although deposition of MIPs onto the surface of nanostructures may improve sensitivity for recognition of a range of organic compounds, electronic nanosensors capable of recognizing proteins continue to be a challenge to implement, in part, because: 1) the MIP film may attenuate signals generated in response to template binding (due to the large thickness); 2) the detection mechanisms do not readily allow for effective signal conversion of template molecule binding; and 3) the sensor platforms do not support highly sensitive detection.

 

In conclusion, these types of nanosensors should prove highly useful in diagnosis of human disease, such as detection of cancer biomarkers, and in a host of proteomic applications.

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Synthetic oscillating gel acts alive and rebuilds itself through chemical communication, similar to bacteria

Synthetic oscillating gel acts alive and rebuilds itself through chemical communication, similar to bacteria | Amazing Science | Scoop.it

Synthetic self-moving gels can “act alive” and mimic primitive biological communication, University of Pittsburghresearchers have found. The synthetic system can reconfigure itself through a combination of chemical communication and interaction with light.

 

“This is the closest system to the ultimate self- recombining material, which can be divided into separated parts and the parts move autonomously to assemble into a structure resembling the original, uncut sample,” the researchers say.

 

“We also show that the gels’ coordinated motion can be controlled by light, allowing us to achieve selective self-aggregation and control over the shape of the gel aggregates.”

 

Anna Balazs, principal investigator of the study and Distinguished Professor of Chemical and Petroleum Engineering in Pitt’s Swanson School of Engineering, has long studied the properties of the Belousov-Zhabotinsky (BZ) gel, a material first fabricated in the late 1990s and shown to pulsate in the absence of any external stimuli.

 

In a previous study, the Pitt team noticed that long pieces of gel attached to a surface by one end “bent” toward one another, almost as if they were trying to communicate by sending signals. This hint that “chatter” might be taking place led the team to detach the fixed ends of the gels and allow them to move freely.

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Nanomanipulation of individual atoms: 3D optical manipulation of a single electron spin in solution

Nanomanipulation of individual atoms: 3D optical manipulation of a single electron spin in solution | Amazing Science | Scoop.it

Researchers in the group led by ICFO Prof. Romain Quidant, in collaboration with Prof. Frank Koppens at ICFO, CSIC and Macquarie University in Australia, have developed a new technique, similar to the MRI but with a much higher resolution and sensitivity, which has the ability to scan individual cells. The paper published in Nature Nanotech, and highlighted by Nature, explains how this was accomplished using artificial atoms, diamond nanoparticles doped with nitrogen impurity, to probe very weak magnetic fields such as those generated in some biological molecules.

Individual atoms are structures that are highly sensitive to their environment, with a great ability to detect nearby electromagnetic fields. The challenge these atoms present is that they are so small and volatile that in order to be manipulated, they must be cooled to temperatures near the absolute zero. This complex process requires an environment that is so restrictive that it makes individual atoms unviable for potential medical applications. Artificial atoms used by Quidant and his team are formed by a nitrogen impurity captured within a small diamond crystal. "This impurity has the same sensitivity as an individual atom but is very stable at room temperature due to its encapsulation. This diamond shell allows us to both move and rotate the nitrogen impurity. In addition, because such control is achieved in solution, our technique is compatible with measurements on a living cell" argues Dr. Quidant.

To trap and manipulate these artificial atoms, researchers use laser light. The laser works like tweezers, leading the atoms above the surface of the object to study and extract information from its tiny magnetic fields.

The emergence of this new technique could strongly benefit the field of medical imaging, providing a new class of information that could contribute to early detection of diseases, and thus a higher probability for successful treatment. 

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Magnetoelectrics could advance computer memory, ending reliance on 1s and 0s

Magnetoelectrics could advance computer memory, ending reliance on 1s and 0s | Amazing Science | Scoop.it

Generally, hardware upgrades incrementally — processors slowly gain more cores, graphics cards slowly become more powerful, and storage devices slowly gain more capacity. Hardware rarely upgrades with a significant leap, jumping from one form to another that is so significantly upgraded that it barely resembles what came before it. These leaps do happen though — in just a matter of a few years dumbphones evolved into smartphones and a great deal of laptops become super slim tablets. Now, utilizing a new type of magnetoelectric material, computer memory may take that significant leap.


Via Szabolcs Kósa
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Nganguem Victor's comment, February 11, 2013 1:22 AM
j'aime ça
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Electricity Gives Soap Bubbles Super Strength

Electricity Gives Soap Bubbles Super Strength | Amazing Science | Scoop.it

Any kid can blow a soap bubble, but only a physicist would think to electrify one. Left to its own devices, a bubble will weaken and pop as the fluid sandwiched between two thin layers of soap succumbs to gravity and drains toward the floor. But when researchers trapped a bubble between two platinum electrodes (pictured) and cranked up the voltage, the fluid reversed direction and actually flowed up, against the force of gravity. The newly strong and stable bubbles could live for hours, and even visibly change colors as their walls grew fatter, the team reports in the current issue of Physical Review Letters. Because soap film is naturally only nanometers thick, this whimsical experiment could help scientists create more efficient labs-on-chips, the mazes of nanotunnels that can diagnose disease based on the movements of a miniscule drop of blood.

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Killing silicon: Inside IBM’s carbon nanotube computer chip lab

Killing silicon: Inside IBM’s carbon nanotube computer chip lab | Amazing Science | Scoop.it

At IBM’s Watson Research Center in upstate New York, some of the world’s best physicists, chemists, and nanoengineers are trying to create the first high-density, self-assembling carbon nanotube computer chip process. In much the same way that Jack Kilby at Texas Instruments discovered the monolithic VLSI process for making silicon chips in 1958, IBM desperately wants to find the process that enables the creation of carbon nanotube chips. In the next decade — or thereabouts; the goalposts keep shifting — silicon is expected to reach a miniaturization roadblock.

 

At some point, we simply won’t be able to make silicon transistors any smaller. When this happens, there will be a few materials jostling to fill the void, most notably silicon-germanium, galium arsenide, and various forms of carbon (nanotubes, nanowires, graphene). In theory, computer chips made from carbon nanotubes are massively desirable — they would be many times faster than silicon, use less power, and can scale down to just a couple of nanometers. In practice, working with carbon nanotubes — just like graphene — is proving to be rather difficult. It’s sometimes easy to forget that we have decades of experience and billions of R&D dollars plowed into silicon; expertise with new materials won’t come easy.

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Researchers report first transparent paper-based transistors, which could lead to green electronics

Researchers report first transparent paper-based transistors, which could lead to green electronics | Amazing Science | Scoop.it

But to make paper-based circuits that can perform calculations or control displays, researchers need to find a way to print transistors. Unfortunately, previous paper transistors perform poorly because the surface of regular paper is bumpy and uneven. For a transistor to perform optimally, electrons have to move easily through super thin layers of conducting and semiconducting materials. These layers are only a couple hundred nanometers thick, while the bumps on the surface of regular paper are tens of micrometers tall. The paper bumps disrupt the flat layers of electronic materials and interrupt the device’s electron flow.

 

In addition to its rough surface, regular paper’s other limitation is its opaqueness. To produce electronics for transparent displays, researchers need a transparent material, like plastic or glass.

 

So for printed transistors, Liangbing Hu, a materials scientist at the University of Maryland, College Park, turned to a smooth and transparent kind of paper called nanopaper. Instead of the micrometer-sized cellulose fibers found in regular paper, sheets of this material contain nanoscale fibers that produce an even surface and allow light to pass through.

 

Hu’s group made their own nanopaper using previously reported methods, which involve treating paper pulp with oxidizing chemicals. The nanopaper has cellulose fibers with an average diameter of 10 nm. “It’s as flat as plastic,” Hu says.

 

The Maryland researchers then built transistors on the paper by depositing a layer each of three materials: first carbon nanotubes, next an insulating organic molecule, and then a semiconducting organic molecule. To complete the device, the team topped it with electrodes, also made by laying down carbon nanotubes. Besides serving as electrodes for the transistors, the nanotubes provided a structural backbone, preventing excessive wrinkling in the paper after the solvents used in the fabrication process evaporated.

The resulting transistors are about 84% transparent, and their performance decreases only slightly when bent. Still, Hu says the performance of these first transistors is not optimal. He thinks decreasing wrinkling in the nanopaper will improve the devices.

 

Jeffrey Youngblood, a materials engineer at Purdue University, calls these nanopaper-based transistors “another step down the road to renewable printed electronics.” For such devices to be practical, he says, the researchers will have to find a way to produce the transistors via a scalable process, such as roll-to-roll printing, instead of the tedious layer-by-layer process

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Self-organizing crystals could be a step toward creating self-repairing smartphones

Self-organizing crystals could be a step toward creating self-repairing smartphones | Amazing Science | Scoop.it

A study in which chemical compounds are prompted to self-form into crystals could be a step toward creating self-repairing smartphone screens, experts say, or even body armor.

 

Showing that microscopic particles can be made to come together or break apart on their own "opens a new area for design and production of novel and moving structures," wrote the study authors, a team of physicists and chemists from New York University and Brandeis University in Waltham, Mass.

 

The researchers said they were inspired by the way flocks of birds and schools of fish are able to move as if they are a single living organism. The team wanted to see if they could duplicate — and control — that collective motion using non-living objects.

 

The objects they used were made of simple chemicals including sodium, iron, chloride, oxygen and hydrogen. Roughly the size of a single bacterium, they included a piece of the mineral hematite that jutted out, like the front of a car.

 

The researchers placed hundreds of these particles into a drop of a liquid solution on a glass slide. One of the ingredients in the solution was hydrogen peroxide, which is like fuel to a piece of hematite when it's exposed to blue-violet light.

 

Without the specialized light, the particles pretty much vibrated in place like so many tiny idling engines. When the scientists turned on the light, the hydrogen peroxide and hematite began a chemical reaction that propelled the particles forward.

 

The scientists watched under a microscope as, at first, the particles moved about at random. Then, about 25 seconds into the chaos, the limited space and directionless driving produced a traffic jam of particles, said study leader Jeremie Palacci, a postdoctoral fellow at NYU.

 

The jammed particles forced themselves against each other in the pattern of a crystal, each dot surrounded by six others in a hexagonal shape. When they reached a certain size, some of the particles on the edge broke off and grew into other crystals, which slowly moved about. When the blue-violet light was switched off, it took about 10 seconds for the crystals to dissolve.

 

In additional tests, the researchers induced a magnetic field in the liquid to see if they could steer the crystals in a particular way. They found that the iron in the particles was drawn toward the magnetic field, making it possible to control the crystals' movement.

 

Since the crystals are able to sense changes in their environment and move accordingly, they are alive in a fundamental way, the researchers said.

"They're flocking," just like birds, said Paul Chaikin, a coauthor of the study and an NYU physicist.

 

Creating materials that can respond to conditions around them is a long-held goal of scientists and engineers working in the field of active materials, said Aparna Baskaran, a physicist at Brandeis who wasn't involved in the study.

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Nanomaterials Key to Developing Stronger Artificial Hearts

Nanomaterials Key to Developing Stronger Artificial Hearts | Amazing Science | Scoop.it

Creation of these ultra-thin cardiac patches put medicine a step closer to durable, high-functioning artificial tissues that could be used to repair damaged hearts and other organs.


The cardiac tissue patches utilize a hydrogel scaffolding reinforced by nanomaterials called carbon nanotubes. To create the patches, the researchers seeded neonatal rat heart muscle tissue onto carbon nanotube-infused hydrogels. These novel patches showed excellent mechanical integrity and advanced electrophysiological functions. Moreover, they demonstrated a protective effect against chemicals toxic to heart tissue.

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Controlling Particles for Directed Self-Assembly of Colloidal Crystals

Controlling Particles for Directed Self-Assembly of Colloidal Crystals | Amazing Science | Scoop.it

Researchers from the NIST Center for Nanoscale Science and Technology and the Johns Hopkins University have developed a technique to reliably manipulate hundreds of individual micrometer-sized colloid particles to create crystals with controlled dimensions.*  The accomplishment is an important milestone for understanding how to direct and control the assembly of microscale and nanoscale objects for nanomanufacturing applications.

 

The experiment uses four electrodes patterned on a microscope coverslip to move the micrometer-sized particles suspended in liquid by applying a combination of AC and DC electric fields.  Using a nonuniform, high-frequency AC field, the dielectrophoretic forces exerted on the dielectric particles are tuned to adjust the strength of their attraction to a collection area in the center of the electrodes.  When these forces are low enough, electrophoretic-electroosmotic flows induced by applying a DC field allow the researchers to selectively remove particles from the area and trim the particle assemblies to a chosen size and shape.

 

By independently varying the AC and DC electrode potentials, the researchers can direct the self-assembly of two-dimensional (2D) rafts made of precise numbers of particles; i.e., 2D colloidal crystals.  Once the desired crystal size is reached, the attractive forces holding the particles in the collection area are increased to stabilize the structure.  An important component of this work is the application of a computer vision-based, real-time feedback system that dynamically adjusts the AC and DC fields to automate the directed assembly process.

 

This work shows how the combination of multiple actuators offers extra degrees of freedom that can be used to manipulate ensembles of colloidal components to create desired sizes and shapes.  The researchers are now developing measurement methods sensitive enough to track nanometer-scale structures that will allow these methods to be extended to control the assembly of nanoscale materials.

 

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Norwegians trap sunlight with microbeads, produce solar cells that are 20 times thinner, cheaper

Norwegians trap sunlight with microbeads, produce solar cells that are 20 times thinner, cheaper | Amazing Science | Scoop.it

Researchers from the University of Oslo have used a bunch of “wonderful tricks” to produce silicon solar cells that are twenty times thinner than commercial solar cells. This breakthrough means that solar cells can be produced using 95% less silicon, reducing production costs considerably — both increasing profits (which are almost nonexistent at the moment), and reducing the cost of solar power installations.

 

Standard, commercial photovoltaic solar cells are fashioned out of 200-micrometer-thick (0.2mm) wafers of silicon, which are sliced from a large block of silicon. This equates to around five grams of silicon per watt of solar power, and also a lot of wastage — roughly half of the silicon block is turned into sawdust by the slicing process. With solar cells approaching 50 cents per watt (down from a few dollars per watt a few years ago), something needs to change.

 

Reducing the thickness of solar cells obviously makes a lot of sense from a commercial point of view, but it introduces another issue: As the wafer gets thinner, more light passes straight through the silicon, dramatically reducing the amount of electricity produced by the photovoltaic effect. This is due to wavelengths: Blue light, which has a short wavelength (450nm), can be captured by a very thin wafer of silicon — but red light, with a longer wavelength (750nm), can only be captured by thicker slabs of silicon. This is part of the reason that current solar cells use silicon wafers that are around 200 micrometers — and also why they’re mirrored, which doubles the effective thickness, allowing them to capture more of the visible spectrum.

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