Category Archives: Nanoscale science and technology

“Squeezed light” used to monitor molecules inside living cells

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MIT Technology Review: A lot of internal cellular activity occurs at subnanometer scales. Such activity is hard to view with conventional imaging techniques because of diffraction, or the way that light shone on an object is deflected as it strikes tiny particles in the object. The amount of diffraction depends on a phenomenon called quantum noise—uncertainties concerning the light photons’ positions. A new technique developed by Michael Taylor of the University of Queensland, Australia, and his colleagues uses “squeezed light”—carefully manipulated photons that reduce the amount of quantum noise. The researchers were able to attain a resolution of 10 nm, a 14% improvement over conventional imaging. The technique has allowed them to monitor the motions and interactions of nanoparticles inside a living cell. By monitoring multiple areas throughout the cell, they were able to create a map of nanoparticle diffusion patterns. And because of the lower diffraction rate, they were also able to image the cell to the same resolution as conventional techniques but at much lower light intensity, and therefore less risk of damage to the cell.

Smartphone screen protector enables 3D viewing

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MIT Technology Review: A Singapore company called Nanoveu is marketing a plastic screen protector for smartphones and tablets that allows users to view three-dimensional content. The EyeFly3D, based on lenticular lens technology, comprises half a million tiny lenses, each sitting above a single pixel image on the LCD display. The lenses send separate images to the left and right eyes to create the illusion of depth. Through the use of nanoimprint lithography, Nanoveu has been able to mass produce the screen protectors at relatively low cost. Selling for just $35, the EyeFly3D promises both high-quality 3D viewing and distortion-free 2D viewing, writes Mike Orcutt for MIT Technology Review.

Giving artificial skin the same sensitivity as a human finger

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BBC: Piezoelectric materials generate electricity when subjected to physical stresses. When the material is also a nanoscale semiconducting wire, the material can act as a transistor. Zhong Lin Wang of Georgia Tech and his colleagues used zinc oxide nanowires to create an array of about 8000 such transistors. When the array is pressed against an object, each of the wires individually produces an electrical signal. The combination of the size of the array and the density of the wires produces a sensitivity comparable to that of a human fingertip. The arrays could be incorporated into artificial skin materials to produce signals that are transmitted to nerve cells. They could also be used to create better tactile sensitivity in robotics.

Biomimetic nanoparticles used to treat bacterial infections

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MIT Technology Review: Many infectious bacteria produce toxins that attack and kill red blood cells. Current treatments have to be targeted to a specific toxin. Now, Liangfang Zhang of the University of California, San Diego, and his colleagues have created a nanoparticle “sponge” whose coating of red blood cell membrane traps all such toxins. Because 3000 nanosponges can be created from a single red blood cell, the decoys greatly outnumber the real red blood cells in the circulatory system. When toxins attack the sponges, they get stuck. Eventually they reach the liver, which disposes of both the sponges and the toxins. In animal testing, biopsies showed no significant accumulation of toxins in the liver nor any signs of sickness. If the nanoparticles receive regulatory approval, they will be especially useful in treating antibiotic-resistant bacterial strains.

Rust on nanoparticle catalyst reversed by high-intensity light

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Discovery: Propylene oxide, a chemical precursor to making plastics, is difficult to manufacture. Researchers are therefore looking for catalysts that will simplify and speed up the process. Marimuthu Andiappan of the University of Michigan and his colleagues were experimenting on the effects of metallic copper in the reaction. Although the copper did provide some improved reactions, much of the copper itself reacted with the oxygen, forming copper oxide rust. In an attempt to reduce the oxidation of the catalyst, they formed the copper into nanoparticles and coated them with silica. As a result, 20% of the propylene and oxygen reactants were converted into propylene oxide before the catalyst rusted. When they exposed the reaction to high-intensity light, 50% of the reactants were converted, meaning that the oxygen that had been trapped in the copper oxide had been released to react with the propylene. The successful catalyzation of the reaction is the more useful of the results, but the reversal of the rusting is the first known example of light changing the oxidization state of a metal.

Artificial antibodies made from nanoparticles

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Ars Technica: The human body produces antibodies in response to viral infections, but it often cannot create them fast enough the first time it is infected. To stimulate the body’s immune system, researchers developed vaccines, which are often weakened forms of the virus. Now, Patrick Shahgaldian of the University of Applied Sciences and Arts Northwestern Switzerland and his colleagues have decided to bypass that intermediate step and just create the antibodies themselves. First, they made imprints of viruses on the surface of silica nanoparticles by attaching the viruses with a binding agent and then coating them with a layer of polymer. After using ultrasound to dislodge the viruses, Shahgaldian’s team introduced the “virus imprinted particles” (VIPs) into solutions of infected human blood serum. They found that, within 30 minutes of exposure, the VIPs could trap up to 88% of the viruses, even at concentrations as low as 65 picomolars. Once clinical testing has been completed, the VIPs will likely be first used as a diagnostic tool to determine if a patient is infected, said Shahgaldian. Before VIPs can be used for therapy, they will need to be produced quickly and in large quantities.

Nanoparticles increase the effectiveness of stem cell therapy

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Ars Technica: Cardiac stem cell therapy is a treatment for heart-related diseases—the leading cause of death in the industrialized world. Implantation of the stem cells is currently a process of trial and error involving inserting them via a catheter into the heart’s coronary artery then using expensive and slow magnetic resonance imaging (MRI) scans to determine if the cells have reached the damaged tissues. Jesse Jokerst of Stanford University and his colleagues have developed a silica nanoparticle that they embed in the stem cells prior to their implantation. The nanoparticles are easily detected by ultrasound, which allows for real-time tracking of the stem cells. Coupling the use of ultrasound detection with targeted injections makes the stem cell therapy process much simpler and faster than the current technique. Jokerst’s team also added fluorescent dye and small amounts of gadolinium to the nanoparticles, which allowed them to track the location and effectiveness of the stem cells for up to two weeks via MRI.

Mechanical computing gets second birth…on the nanoscale

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The Telegraph: Charles Babbage was a British inventor who designed steam-powered, mechanical computers, 100 years before electronic computers were invented. However, his creations never caught on, and are now quite limited in comparison to their electric brethren. Now, nanotechnology is giving the idea of mechanical computers a second life. David Leigh of Manchester University has described how moving molecular pieces could serve as switches, levers, gears, and other mechanical components of systems that behave like Babbage’s Analytical Engine. One international team has already created nanoscale gears and motors and hopes to move on to more complicated constructions. However, the macroscopic machines can’t just be scaled down to nanoscopic levels because quantum mechanical effects influence how the molecules interact. The researchers do have real-world guides for their work, though. Naturally occurring molecules such as proteins behave and interact mechanically with each other in processes that could influence nanomechanical design.

Manipulating cells to study internal specialization

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Ars Technica: Most cells are able to form specialized and localized internal structures in response to signals from their environment. Current methods for altering the behavior of a cell affect the whole cell, however, and thus make them ineffective in studying the processes behind the local specialization. Now, an international team of researchers has developed a technique that uses magnetic nanoparticles to deliver proteins to specific locations within a cell. By linking the nanoparticles to fluorescent molecules, the researchers could use a magnetic tip to move the nanoparticles and the attached proteins around the cell. They tested the technique, which they call “magnetogenetics,” by coating the nanoparticles with activated proteins associated with cell movement. When they moved the nanoparticles near the cell wall, the proteins caused a protrusion of actin fibers in that location—much like what happens when the cell is about to move in that direction. If the technique can be applied to other proteins, it could provide a new and effective way to study cells’ internal processes.

Cicada wings tear apart bacteria using nanoscale spikes

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Nature: The veined wings of clanger cicadas are able to kill bacteria using nothing more than the wing’s physical structure. Elena Ivanova of the Swinburne University of Technology in Hawthorne, Australia, and her colleagues studied the structure to determine how that was possible. They discovered that the wings are covered with an array of hexagonal nanoscopic pillars—blunt spikes similar in size to bacteria. When a bacterium hits the wing’s surface, the cell membrane sticks to the pillars while the rest of the cell is stretched down into the crevices. Ivanova’s team found that if the cell membrane is soft enough, the bacterium will rupture. Further study may allow the principles behind the structures to be applied in manmade materials for use on public surfaces, such as handrails, to kill infectious bacteria.