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  • richardmitnick 12:26 pm on September 14, 2014 Permalink | Reply
    Tags: , Chemistry, ,   

    From Rutgers: “Rutgers Physics Professors Find New Order in Quantum Electronic Material” 

    Rutgers University
    Rutgers University

    January 30, 2013
    Media Contact: Carl Blesch
    732-932-7084 x616
    E-mail: cblesch@ur.rutgers.edu

    May open door to new kinds of materials, magnets and superconductors

    Two Rutgers physics professors have proposed an explanation for a new type of order, or symmetry, in an exotic material made with uranium – a theory that may one day lead to enhanced computer displays and data storage systems and more powerful superconducting magnets for medical imaging and levitating high-speed trains.

    pc
    Piers Coleman

    Their discovery, published in this week’s issue of the journal Nature, has piqued the interest of scientists worldwide. It is one of the rare theory-only papers that this selective publication accepts. Typically the journal’s papers describe results of laboratory experimentation.

    Collaborating with the Rutgers professors was a postdoctoral researcher at Massachusetts Institute of Technology (MIT) who earned her doctorate at Rutgers.

    “Scientists have seen this behavior for 25 years, but it has eluded explanation.” said Piers Coleman, professor in the Department of Physics and Astronomy in the School of Arts and Sciences. When cooled to 17.5 degrees above absolute zero or lower (a bone-chilling minus 428 degrees Fahrenheit), the flow of electricity through this material changes subtly.

    The material essentially acts like an electronic version of polarized sunglasses, he explains. Electrons behave like tiny magnets, and normally these magnets can point in any direction. But when they flow through this cooled material, they come out with their magnetic fields aligned with the material’s main crystal axis.

    This effect, claims Coleman, comes from a new type of hidden order, or symmetry, in this material’s magnetic and electronic properties. Changes in order are what make liquid crystals, magnetic materials and superconductors work and perform useful functions.

    “Our quest to understand new types of order is a vital part of understanding how materials can be developed to benefit the world around us,” he said.

    Similar discoveries have led to technologies such as liquid crystal displays, which are now ubiquitous in flat-screen TVs, computers and smart phones, although the scientists are quick to acknowledge that their theoretical discovery won’t transform high-tech products overnight.

    pc
    Premala Chandra
    Nick Romanenko

    Coleman, along with Rutgers colleague Premala Chandra and MIT collaborator Rebecca Flint, describe what they call a “hidden order” in this compound of uranium, ruthenium and silicon. Uranium is commonly known for being nuclear reactor fuel or weapons material, but in this case physicists value it as a heavy metal with electrons that behave differently than those in common metals.

    Recent experiments on the material at the National High Magnetic Field Laboratory at Los Alamos National Laboratory in New Mexico provided the three physicists with data to refine their discovery.

    “We’ve dubbed our fundamental new order ‘hastatic’ order, named after the Greek word for spear,” said Chandra, also a professor in the Department of Physics and Astronomy. The name reflects the highly ordered properties of the material and its effect on aligning electrons that flow through it.

    “This new category of order may open the world to new kinds of materials, magnets, superconductors and states of matter with properties yet unknown,” she said. The scientists have predicted other instances where hastatic order may show up, and physicists are beginning to test for it.

    The scientists’ work was funded by the National Science Foundation and the Simons Foundation. Flint is a Simons Postdoctoral Fellow in physics at MIT.

    See the full article here.

    Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

    Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

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  • richardmitnick 1:49 pm on September 3, 2014 Permalink | Reply
    Tags: , , Chemistry, , , Peptoids   

    From LBL: “Peptoid Nanosheets at the Oil/Water Interface” 

    Berkeley Logo

    Berkeley Lab

    September 3, 2014
    Lynn Yarris (510) 486-5375

    From the people who brought us peptoid nanosheets that form at the interface between air and water, now come peptoid nanosheets that form at the interface between oil and water. Scientists at the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have developed peptoid nanosheets – two-dimensional biomimetic materials with customizable properties – that self-assemble at an oil-water interface. This new development opens the door to designing peptoid nanosheets of increasing structural complexity and chemical functionality for a broad range of applications, including improved chemical sensors and separators, and safer, more effective drug delivery vehicles.

    Supramolecular assembly at an oil-water interface is an effective way to produce 2D nanomaterials from peptoids because that interface helps pre-organize the peptoid chains to facilitate their self-interaction,” says Ron Zuckermann, a senior scientist at the Molecular Foundry, a DOE nanoscience center hosted at Berkeley Lab. “This increased understanding of the peptoid assembly mechanism should enable us to scale-up to produce large quantities, or scale- down to screen many different nanosheets for novel functions.”

    nano
    Peptoid nanosheets are among the largest and thinnest free-floating organic crystals ever made, with an area-to-thickness equivalent of a plastic sheet covering a football field. Peptoid nanosheets can be engineered to carry out a wide variety of functions.
    two
    Ron Zuckerman and Geraldine Richmond led the development of peptoid nanosheets that form at the interface between oil and water, opening the door to increased structural complexity and chemical functionality for a broad range of applications.

    Zuckermann, who directs the Molecular Foundry’s Biological Nanostructures Facility, and Geraldine Richmond of the University of Oregon are the corresponding authors of a paper reporting these results in the Proceedings of the National Academy of Sciences (PNAS). The paper is titled Assembly and molecular order of two-dimensional peptoid nanosheets at the oil-water interface. Co-authors are Ellen Robertson, Gloria Olivier, Menglu Qian and Caroline Proulx.

    Peptoids are synthetic versions of proteins. Like their natural counterparts, peptoids fold and twist into distinct conformations that enable them to carry out a wide variety of specific functions. In 2010, Zuckermann and his group at the Molecular Foundry discovered a technique to synthesize peptoids into sheets that were just a few nanometers thick but up to 100 micrometers in length. These were among the largest and thinnest free-floating organic crystals ever made, with an area-to-thickness equivalent of a plastic sheet covering a football field. Just as the properties of peptoids can be chemically customized through robotic synthesis, the properties of peptoid nanosheets can also be engineered for specific functions.

    “Peptoid nanosheet properties can be tailored with great precision,” Zuckermann says, “and since peptoids are less vulnerable to chemical or metabolic breakdown than proteins, they are a highly promising platform for self-assembling bio-inspired nanomaterials.”

    In this latest effort, Zuckermann, Richmond and their co-authors used vibrational sum frequency spectroscopy to probe the molecular interactions between the peptoids as they assembled at the oil-water interface. These measurements revealed that peptoid polymers adsorbed to the interface are highly ordered, and that this order is greatly influenced by interactions between neighboring molecules.

    “We can literally see the polymer chains become more organized the closer they get to one another,” Zuckermann says.

    ft
    Peptoid polymers adsorbed to the oil-water interface are highly ordered thanks to interactions between neighboring molecules.

    The substitution of oil in place of air creates a raft of new opportunities for the engineering and production of peptoid nanosheets. For example, the oil phase could contain chemical reagents, serve to minimize evaporation of the aqueous phase, or enable microfluidic production.

    “The production of peptoid nanosheets in microfluidic devices means that we should soon be able to make combinatorial libraries of different functionalized nanosheets and screen them on a very small scale,” Zuckermann says. “This would be advantageous in the search for peptoid nanosheets with the molecular recognition and catalytic functions of proteins.”

    Zuckermann and his group at the Molecular Foundry are now investigating the addition of chemical reagents or cargo to the oil phase, and exploring their interactions with the peptoid monolayers that form during the nanosheet assembly process.

    “In the future we may be able to produce nanosheets with drugs, dyes, nanoparticles or other solutes trapped in the interior,” he says. “These new nanosheets could have a host of interesting biomedical, mechanical and optical properties.”

    This work was primarily funded by the DOE Office of Science and the Defense Threat Reduction Agency. Part of the research was performed at the Molecular Foundry and the Advanced Light Source, which are DOE Office of Science User Facilities.

    See the full article here.

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  • richardmitnick 1:41 pm on August 29, 2014 Permalink | Reply
    Tags: , , , , Chemistry,   

    From LBL: “Going to Extremes for Enzymes” 

    Berkeley Logo

    Berkeley Lab

    August 29, 2014
    Lynn Yarris (510) 486-5375

    In the age-old nature versus nurture debate, Douglas Clark, a faculty scientist with Berkeley Lab and the University of California (UC) Berkeley, is not taking sides. In the search for enzymes that can break lignocellulose down into biofuel sugars under the extreme conditions of a refinery, he has prospected for extremophilic microbes and engineered his own cellulases.

    ext
    Extremophiles thriving in thermal springs where the water temperature can be close to boiling can be a rich source of enzymes for the deconstruction of lignocellulose.

    Speaking at the national meeting of the American Chemical Society (ACS) in San Francisco, Clark discussed research for the Energy Biosciences Institute (EBI) in which he and his collaborators are investigating ways to release plant sugars from lignin for the production of liquid transportation fuels. Sugars can be fermented into fuels once the woody matter comprised of cellulose, hemicellulose, and lignin is broken down, but lignocellulose is naturally recalcitrant.

    “Lignocellulose is designed by nature to stand tall and resist being broken down, and lignin in particular acts like a molecular glue to help hold it together” said Clark, who holds appointments with Berkeley Lab’s Physical Biosciences Division and UC Berkeley’s Chemical and Biomolecular Engineering Department where he currently serves as dean of the College of Chemistry. “Consequently, lignocellulosic biomass must undergo either chemical or enzymatic deconstruction to release the sugars that can be fermented to biofuels.”

    dc
    Douglas Clark holds joint appointments with Berkeley Lab and UC Berkeley and is a principal investigator with the Energy Biosciences Institute. (Photo by Roy Kaltschmidt)

    For various chemical reasons, all of which add up to cost-competitiveness, biorefineries could benefit if the production of biofuels from lignocellulosic biomass is carried out at temperatures between 65 and 70 degrees Celsius. The search by Clark and his EBI colleagues for cellulases that can tolerate these and even harsher conditions led them to thermal springs near Gerlach, Nevada, where the water temperature can be close to boiling. There they discovered a consortium of three hyperthermophilic Archaea that could grow on crystalline cellulose at 90 degrees Celsius.

    “This consortium represents the first instance of Archaea able to deconstruct lignocellulose optimally above 90°C,” Clark said.

    Following metagenomic studies on the consortium, the most active high-temperature cellulase was identified and named EBI-244.

    “The EBI-244 cellulase is active at temperatures as high as 108 degrees Celsius, the most extremely heat-tolerant enzyme ever found in any cellulose-digesting microbe,” Clark said.

    The most recent expedition of Clark and his colleagues was to thermal hot springs in Lassen Volcanic National Park, where they found an enzyme active on cellulose up to 100°C under highly acidic conditions – pH approximately 2.2.

    “The Lassen enzyme is the most acidothermophilic cellulase yet discovered,” Clark said. “The final products that it forms are similar to those produced by EBI244.”

    three
    A consortium of three hyperthermophilic Archaea that could grow on crystalline cellulose at 90 degrees Celsius yielded EBI-244, the most active high-temperature cellulase ever identified.

    In addition to bioprospecting for heat tolerant enzymes, Clark and his colleagues have developed a simple and effective mutagenesis method to enhance the properties of natural enzymes. Most recently they used this technique to increase the optimal temperature and enhance the thermostability of Ce17A, a fungal cellulase that is present in high concentrations in commercial cellulase cocktails. They engineered yeast to produce this enzyme with encouraging results.

    “The yeast Saccharomyces cerevisiae has often been used both in the engineering and basic study of Cel7A; however, Cel7A enzymes recombinantly expressed in yeast are often less active and less stable than their native counterparts,” Clark said. “We discovered that an important post-translational modification that was sometimes absent in the yeast-expressed enzyme was the underlying cause of this disparity and successfully carried out the post-translational modification in vitro. After this treatment, the properties of Cel7A recombinantly expressed in yeast were improved to match those of the native enzyme.”

    Collaborators in this research include Harvey Blanch, who also holds joint appointments with Berkeley Lab and UC Berkeley, and Frank Robb from the University of Maryland.

    EBI, which provided the funding for this research, is a collaborative partnership between BP, the funding agency, UC Berkeley, Berkeley Lab and the University of Illinois at Urbana-Champaign.

    See the full article here.

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  • richardmitnick 4:29 pm on August 28, 2014 Permalink | Reply
    Tags: , Chemistry,   

    From PNNL Lab: “Playing Twenty Questions with Molecules at Plasmonic Junctions” 


    PNNL Lab

    August 2014
    Toward engineering ultrasensitive probes of nanoscale physical and chemical processes

    Results: Sometimes, it seems as if molecules struggle to communicate with scientists. When it comes to junction plasmons, essentially light waves trapped at tiny gaps between noble metals, what the molecules have to say could radically change the design of detectors used for science and security. Single molecule detection sensitivity is feasible through Raman scattering from molecules coaxed into plasmonic junctions. Scientists at Pacific Northwest National Laboratory (PNNL) found that sequences of Raman spectra recorded at a plasmonic junction, formed by a gold tip and a silver surface, exhibit dramatic intensity fluctuations, accompanied by switching from familiar vibrational line spectra of a molecule to broad band spectra of the same origin. The fluctuations confirm the team’s earlier model that assigns enhanced band spectra in Raman scattering from plasmonic nanojunctions to shorting of the junction plasmon through intervening molecular bridges.

    “It’s all about asking it the right questions and listening to what it has to say,” said Dr. Patrick El-Khoury, who has been working on this project for 2 years.

    charts
    “This is a paradigm shift in molecular spectroscopy, as we are no longer after molecular properties. Rather, we use those properties — in this study the symmetry of the observable vibrational modes — to tell us about the rich environments in which molecules reside,” said Dr. Patrick El-Khoury. (A) Time evolution of contact mode spectra of DMS on a 15 nm silver film. (B) Cross-correlation map of the individually normalized spectra shown in the image on the top. Copyright 2014: American Chemical Society

    Why It Matters: A host of emerging state-of-the-art devices and instruments rely on molecule-plasmon interactions. Recent works demonstrated yoctomolar detection sensitivity in Raman scattering from plasmonic nanojunctions, or the ability to detect 1 molecule in 602,214,000,000,000,000,000,000. Plasmonic sensors operating at this detection limit are able to determine the chemical identity of minute quantities of radioactive and environmental hazards. The development of single molecule chemical nanoscopes could answer fundamental questions about physical and chemical processes taking place over nanometer length scales. The fundamentals gained from this study could impact the design of ultrasensitive plasmonic sensors and chemical nanoscopes used to understand the fundamental chemistry behind energy storage and production, as well as the blueprints of extremely tiny electronic devices.

    “Before you can engineer the devices you need, you need to know how molecules behave over length scales comparable to their characteristic dimensions. Our research is fundamental, providing novel insights into how molecules interact with junction plasmons,” said Dr. Wayne Hess, a chemical physicist at PNNL

    See the full article here.

    Pacific Northwest National Laboratory (PNNL) is one of the United States Department of Energy National Laboratories, managed by the Department of Energy’s Office of Science. The main campus of the laboratory is in Richland, Washington.

    PNNL scientists conduct basic and applied research and development to strengthen U.S. scientific foundations for fundamental research and innovation; prevent and counter acts of terrorism through applied research in information analysis, cyber security, and the nonproliferation of weapons of mass destruction; increase the U.S. energy capacity and reduce dependence on imported oil; and reduce the effects of human activity on the environment. PNNL has been operated by Battelle Memorial Institute since 1965.

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  • richardmitnick 2:39 pm on August 19, 2014 Permalink | Reply
    Tags: , Chemistry, , Nuclear magnetic resonance,   

    From Berkeley Lab: “News Center NMR Using Earth’s Magnetic Field” 

    Berkeley Logo

    Berkeley Lab

    August 19, 2014
    Rachel Berkowitz

    Earth’s magnetic field, a familiar directional indicator over long distances, is routinely probed in applications ranging from geology to archaeology. Now it has provided the basis for a technique which might, one day, be used to characterize the chemical composition of fluid mixtures in their native environments.

    Researchers from the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) conducted a proof-of-concept NMR experiment in which a mixture of hydrocarbons and water was analyzed using a high-sensitivity magnetometer and a magnetic field comparable to that of the Earth.

    The work was conducted in the NMR laboratory of Alexander Pines, one of the world’s foremost NMR authorities, as part of a long-standing collaboration with physicist Dmitry Budker at the University of California, Berkeley, along with colleagues at the National Institute of Standards and Technology (NIST). The work will be featured on the cover of Angewandte Chemie and is published in a paper titled Ultra-Low-Field NMR Relaxation and Diffusion Measurements Using an Optical Magnetometer. The corresponding author is Paul Ganssle, who was a PhD student in Pines’ lab at the time of the work.

    “This fundamental research program seeks to answer a broad question: how can we sense the interior chemical and physical attributes of an object at a distance, without sampling it or encapsulating it?” says Vikram Bajaj, a principal investigator in Pines’ group. “A particularly beautiful aspect of magnetic resonance is its ability to gently peer within intact objects, but it’s tough to do that from far away.”

    High-field and low-field NMR

    The exquisite sensitivity of NMR for detecting chemical composition, and the spatial resolution which it can provide in medical applications, requires large and precise superconducting magnets. These magnets are expensive and immobile. Further, the sample of interest must be placed inside the magnet, such that the entire sample is exposed to a homogeneous magnetic field. This well-developed method is called high-field NMR. The sensitivity of high-field NMR is proportional to magnetic field strength.

    three
    (From left) Alex Pines, Dimitry Budker and Scott Seltzer led a proof-of-concept NMR experiment using a high-sensitivity magnetometer and a magnetic field comparable to that of the Earth. (Photo by Roy Kaltschmidt)

    But chemical characterization of objects that cannot be placed inside a magnet requires a different approach. In ex situ NMR measurements, the geometry of a typical high-field experiment is reversed such that the detector probes the sample surface, and the magnetic field is projected into the object. A main challenge with this situation is generating a homogeneous magnetic field over a sufficiently large sample area: it is not feasible to generate field strengths necessary to make conventional high-resolution NMR measurements.

    Instead of a superconducting magnet, low-field NMR measurements may rely on Earth’s magnetic field, given a sufficiently sensitive magnetometer.

    “One nice thing about Earth’s magnetic field is that it’s very homogeneous,” explains Ganssle. “The problem with its use in inductively-detected MRI [MRI – magnetic resonance imaging – is NMR’s technological sibling] is that you need a magnetic field that’s both strong and homogeneous, so you need to surround the whole subject with superconducting coils, which is not something that’s possible in an application like oil-well logging.”

    “Sensitivity of magnetic resonance depends profoundly on the magnetic field, because the field causes the detected spins to align slightly,” adds Bajaj. “The stronger the applied field, the stronger the signal, and the higher its frequency, which also contributes to the detection sensitivity.”

    pg
    Paul Ganssle is the corresponding author of a paper in Angewandte Chemie describing the ultra-low-field NMR using an optical magnetometer. (Photo by Roy Kaltschmidt)

    Earth’s magnetic field is indeed very weak, but optical magnetometers can serve as detectors for ultra-low-field NMR measurements in the ambient field alone without any permanent magnets. This means that ex-situ measurements lose chemical sensitivity due to field strength alone. But this method offers other advantages.

    Relaxation and diffusion

    In high-field NMR, the chemical properties of a sample are determined from their resonance spectrum, but this is not possible without either extremely high fields or extremely long-lived coherent signals (neither of which are possible with permanent magnets). In contrast, relaxation and diffusion measurements in low-field NMR are more than sufficient to determine bulk materials properties.

    “The approach at low-field, which you can achieve using permanent magnets or Earth’s magnetic field, is to measure spin relaxation,” explains Ganssle. Relaxation refers to the rate at which polarized spin returns to equilibrium, based on chemical and physical characteristics of the system. Additionally, NMR experiments resolve chemical compounds based on their different diffusion coefficients, which depend on the size and shape of the molecule.

    A key difference between this and conventional experiments is that the relaxation and diffusion properties are resolved through optically-detected NMR, which operates sensitively even in low magnetic fields.

    “A previous achievement of our collaboration has been the development of magnetometers for the detection of NMR,” says Bajaj. “This experiment represents the first time magnetometers have been used to make combined relaxation and diffusion measurements of multicomponent mixtures.”

    Relaxation and/or diffusion measurements are already commonly used in the oil industry for underground NMR measurements, though conventional probes use a permanent magnet to increase the local magnetic field. There were attempts to perform oil well logging starting in the 1950s using the Earth’s ambient field, but insufficient detection sensitivity led to the introduction of magnets, which are now ubiquitous in logging tools.

    “What’s novel here is that using magnetometers, we finally have technology that might be sensitive enough for efficient detection in the Earth’s field, perhaps ultimately enabling detection at longer distances,” explains Scott Seltzer, a co-author on the study.

    The design was tested in the lab by measuring relaxation coefficients first for various hydrocarbons and water by themselves, then for a heterogeneous mixture, as well as in two-dimensional correlation experiments, using a magnetometer and an applied magnetic field representative of Earth’s.

    “This proof of concept might be productively applied in the oil industry,” says Ganssle. “We mixed hydrocarbons and water, pre-polarized them with a magnet, and applied a magnetic field the same as the Earth’s. Then we made measurements with our magnetometer and determined that we had easily enough sensitivity to separate components of oil and water based on their relaxation spectra.”

    This technology could help the oil industry to characterize fluids in rocks, because water relaxes at a different rate from oil. Other applications include measuring the content of water and oil flowing in a pipeline by measuring chemical composition with time, and inspecting the quality of foods and any kind of polymer curing process such as cement curing and drying.

    The next step involves understanding the depth in a geological formation that could be imaged with this technology.

    “Our next study will be tailored to that question,” says Bajaj. “We hope that this technology will eventually peer a meter or more into the formation and elucidate the chemistry within.”

    Eventually, probes could be used to characterize entire borehole environments in this way, while current devices can only image inches deep. The combination of terrestrial magnetism and versatile sensing technology again offers an elegant solution.

    Other authors on the Angewandte Chemie paper include Hyun Doug Shin, Micah Ledbetter, Dmitry Budker, Svenja Knappe, John Kitching, and Alexander Pines. The current publication presents some of the work for which Berkeley Lab won an R&D 100 award earlierthis year on optically-detected oil well logging by MRI.

    This research was supported by the U.S. Department of Energy’s Office of Science.

    See the full article here.

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  • richardmitnick 2:31 pm on August 15, 2014 Permalink | Reply
    Tags: , , Chemistry,   

    From Berkeley Lab: “Of Metal Heads and Imaging” 

    Berkeley Logo

    Berkeley Lab

    August 15, 2014
    Lynn Yarris (510) 486-5375

    You don’t have to listen to heavy-metal music to be a metal head. The human brain harbors far more copper, iron and zinc than anywhere else in the body. Abnormally high levels of these metals can lead to disorders such as Alzheimer’s and Parkinson’s diseases. Chris Chang, a faculty chemist with Berkeley Lab’s Chemical Sciences Division, has spent the past several years developing new probes and techniques for imaging the molecular activity of these metals in the brain. Speaking at the national meeting of the American Chemical Society (ACS) in San Francisco, he discussed challenges and recent achievements in this area of research.

    “Brain physiology relies on unique inorganic chemistry not found elsewhere in the body,” Chang said. “Although it accounts for only two-percent of total body mass, it is the body’s most oxidatively active organ, consuming more than 20 percent of the oxygen we breathe. This high oxygen intake combined with the brain’s high content of copper and iron can lead to oxidative damage and subsequent neuronal death when levels of these redox-active metals rise and become misregulated.”

    cc
    Chris Chang is a faculty chemist with Berkeley Lab and UC Berkeley, and an HHMI investigator. (Photo by Roy Kaltschmidt)

    Chang, who also holds faculty appointments with the University of California (UC) Berkeley’s Chemistry Department and is an investigator with the Howard Hughes Medical Institute (HHMI), described a series of small-molecule fluorescent probes he and his group developed to safely image copper levels in living cells. Their first success was Coppersensor-3 (CS3), a probe that can be used to image labile copper pools in living cells at endogenous basal levels.

    “We used CS3 in conjunction with synchrotron-based X-ray fluorescence microscopy (XRFM) to establish the first link between mobile copper and major cell signaling pathways,” Chang said. “Neuronal cells move significant pools of copper upon activation and these copper movements are dependent on calcium signaling.”

    The most recent copper probe from Chang’s group is Coppersensor 790 (CS790), a fluorescent sensor that features near-infrared excitation and emission capabilities, ideal for penetrating thicker biological specimens.

    “CS790 can be used to monitor fluctuations in exchangeable copper stores under basal conditions, as well as under copper overload or deficiency conditions,” he said.

    For monitoring iron in the brain, Chang and his group have developed Iron Probe 1 (IP1), which enables researchers to monitor changes in natural cellular iron stores.

    “IP1 is a new type of reaction-based turn-on fluorescent probe for monitoring exchangeable iron ion pools in aqueous solution and living cells,” he said. “It is sensitive enough to detect endogenous, basal labile iron pools and can identify and visualize expansions in these iron pools upon stimulation with either the hormone hepcidin or vitamin C.”

    These and other probes being developed by Chang and his group will help provide a better understanding of the contributions by metals such as copper and iron to the functioning of the brain in various stages of health and disease.

    “The brain offers a grand challenge for a molecular understanding of memory and senses such as sight, smell, and taste, as well as for developing new therapeutics for stroke, aging and neurodegenerative diseases such as Alzheimer’s and Parkinson’s,” Chang said.

    See the full article here.

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  • richardmitnick 5:08 pm on August 12, 2014 Permalink | Reply
    Tags: , Chemistry, , Michigan State University,   

    From Symmetry: “Rare isotopes facility underway at Michigan State” 

    Symmetry

    August 12, 2014
    Jessica Orwig

    In July 140 truckloads of concrete arrived at Michigan State University to begin construction of the Facility for Rare Isotope Beams.

    null

    Michigan State University’s campus will soon feature a powerful [particle] accelerator capable of producing particles rarely observed in nature.

    The under-construction Facility for Rare Isotope Beams at MSU will eventually generate atomic nuclei to be used in nuclear, biomedical, material and soil sciences, among other fields of research. FRIB (pronounced ef-rib) could even help scientists investigate a mystery of particle physics.

    FRIB will produce beams of rare isotopes, highly unstable atomic nuclei that decay within fractions of a second after forming.

    Nature produces bounteous amounts of rare isotopes in supernovae through a series of nuclear processes that physicists have yet to fully understand. But supernovae explode many light years away. Therefore to study rare isotopes, scientists must produce them in the laboratory.

    On July 23, construction trucks poured enough concrete to fill four Olympic-sized swimming pools into a massive rectangular hole in the ground at MSU. It was the first of four installments for the floor of the 1500-by-70-foot tunnel that will house FRIB’s linear accelerator.

    cement
    Photo by Derrick L. Turner, Michigan State University

    FRIB, which is funded by the Department of Energy’s Office of Science, Michigan State University and the State of Michigan, will support the mission of DOE’s Office of Nuclear Physics and will be available for use by researchers from around the world. It is scheduled for completion in 2022.

    FRIB will produce the highest-intensity beam of uranium ions of any rare isotope facility in the world. When scientists accelerate uranium ions to about half the speed of light and then smash them into a target such as a disc of graphite, they create a slew of particles—including some rare isotopes.

    The more intense the beam, the heavier and larger variety of rare isotopes that scientists can produce, says FRIB Project Manager Thomas Glasmacher: “The more incoming beam of particles you have, the better.”

    FRIB should be able to produce a variety of different rare isotopes, says Walter Henning, former director for the GSI Laboratory in Germany that performs similar research.

    “With FRIB, and other major facilities, one hopes to get further out on the periodic table and be more complete,” he says.

    Nearly two dozen facilities across the globe produce rare isotopes. Facilities such as the ATLAS accelerator facility at Argonne National Laboratory and the Radioactive Ion Beam Factory at the RIKEN Institute in Japan focus their efforts on creating rare isotopes for scientists to study the nuclear properties and behavior. Other facilities, such as the Heavy Ion Research Facility in Lanzhou, China, and TRIUMF Laboratory in Canada, offer research in additional applications such as cancer treatment. FRIB will offer researchers the chance to do a little bit of both and more.

    “There are four pillars of the FRIB science program,” says MSU professor Bradley Sherrill, chief scientist of FRIB: Understanding the stability of atomic nuclei; discovering their origin and history in the universe; testing the fundamental laws of symmetries of nature; and identifying industrial applications of rare isotopes.

    The properties and behaviors of rare isotopes and how they decay could hold clues to why matter is far more abundant than antimatter in the universe—a mystery that concerns particle physicists.

    The big bang should have created equal amounts of matter and antimatter particles. If particles and antiparticles behave differently, that could be the cause of the imbalance that allows us to exist. The decay behavior of rare isotopes could divulge never-before-seen particles or interactions that would offer further insight to this mystery.

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 4:24 pm on August 1, 2014 Permalink | Reply
    Tags: , , Chemistry,   

    From Carnegie Mellon: “Carnegie Mellon Chemists Create Nanofibers Using Unprecedented New Method” 

    Carnegie Mellon University logo
    Carnegie Mellon university

    Thursday, July 31, 2014

    Jocelyn Duffy, jhduffy@andrew.cmu.edu, 412-268-9982

    Researchers from Carnegie Mellon University have developed a novel method for creating self-assembled protein/polymer nanostructures that are reminiscent of fibers found in living cells. The work offers a promising new way to fabricate materials for drug delivery and tissue engineering applications. The findings were published in the July 28 issue of Angewandte Chemie International Edition.

    ribbin
    No legend, no image credit.

    “We have demonstrated that, by adding flexible linkers to protein molecules, we can form completely new types of aggregates. These aggregates can act as a structural material to which you can attach different payloads, such as drugs. In nature, this protein isn’t close to being a structural material,” said Tomasz Kowalewski, professor of chemistry in Carnegie Mellon’s Mellon College of Science.

    The building blocks of the fibers are a few modified green fluorescent protein (GFP) molecules linked together using a process called click chemistry. An ordinary GFP molecule does not normally bind with other GFP molecules to form fibers. But when Carnegie Mellon graduate student Saadyah Averick, working under the guidance of Krzysztof Matyjaszewski, the J.C. Warner Professor of Natural Sciences and University Professor of Chemistry in CMU’s Mellon College of Science, modified the GFP molecules and attached PEO-dialkyne linkers to them, they noticed something strange — the GFP molecules appeared to self-assemble into long fibers. Importantly, the fibers disassembled after being exposed to sound waves, and then reassembled within a few days. Systems that exhibit this type of reversible fibrous self-assembly have been long sought by scientists for use in applications such as tissue engineering, drug delivery, nanoreactors and imaging.

    “This was purely curiosity-driven and serendipity-driven work,” Kowalewski said. “But where controlled polymerization and organic chemistry meet biology, interesting things can happen.”

    The research team observed the fibers using confocal light microscopy, confirmed their assembly using dynamic light scattering and studied their morphology using atomic force microscopy (AFM). They also observed that the fibers were fluorescent, indicating that the GFP molecules retained their 3-D structure while linked together.

    To determine what processes were driving the self-assembly, Matyjaszewski and Kowalewski turned to Anna Balazs, Distinguished Professor of Chemical Engineering and the Robert v. d. Luft Professor at the University of Pittsburgh. A leading expert in modeling the dynamics and mechanical properties of mesoscale systems, Balazs ran a computer simulation of the GFP molecules’ self-assembly process using a technique called dissipative particle dynamics, a type of coarse-grained molecular dynamics method. The simulation confirmed the modified GFP’s tendency to form fibers and revealed that the self-assembly process was driven by the interaction of hydrophobic patches on the surfaces of individual GFP molecules. In addition, Balazs’s simulated fibers closely corresponded with what Kowalewski observed using AFM imaging.

    “Our protein-polymer system gives us an atomically precise, very well-defined nanoscale building object onto which we can attach different handles in very precisely defined positions. It can be used in a way that wasn’t ever intended by biology,” Kowalewski said.

    In addition to Averick, Balazs, Kowalewski and Matyjaszewski, co-authors of the study include Carnegie Mellon’s Orsolya Karacsony and Jacob Mohin, University of Pittsburgh’s Xin Yong and Nicholas M. Moellers, Oregon State University’s Bradley F. Woodman and Ryan A. Mehl, and Zhejiang University’s Weipu Zhu. The research was supported by the U.S. Department of Energy, National Science Foundation, Carnegie Mellon’s CRP Consortium and Oregon State University.

    See the full article here.

    Carnegie Mellon University (CMU) is a global research university with more than 12,000 students, 95,000 alumni, and 5,000 faculty and staff.
    CMU has been a birthplace of innovation since its founding in 1900.
    Today, we are a global leader bringing groundbreaking ideas to market and creating successful startup businesses.
    Our award-winning faculty members are renowned for working closely with students to solve major scientific, technological and societal challenges. We put a strong emphasis on creating things—from art to robots. Our students are recruited by some of the world’s most innovative companies.
    We have campuses in Pittsburgh, Qatar and Silicon Valley, and degree-granting programs around the world, including Africa, Asia, Australia, Europe and Latin America.


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  • richardmitnick 9:13 am on August 1, 2014 Permalink | Reply
    Tags: , , , Chemistry   

    From Brookhaven Lab: “Nanostructured Metal-Oxide Catalyst Efficiently Converts CO2 to Methanol” 

    Brookhaven Lab

    July 31, 2014
    Karen McNulty Walsh, (631) 344-8350 or Peter Genzer, (631) 344-3174printer iconPrint

    Highly reactive sites at interface of two nanoscale components could help overcome hurdle of using CO2 as a starting point in producing useful products

    people
    Dario Stacchiola and Kumudu Mudiyanselage make notes in the data log while Fang Xu (seated) and Jose Rodriguez view microscopic images of the catalyst and Ping Liu and Sanjaya Senanayake adjust the ambient-pressure scanning tunneling microscope. No image credit

    Scientists at the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory have discovered a new catalytic system for converting carbon dioxide (CO2) to methanol—a key commodity used to create a wide range of industrial chemicals and fuels. With significantly higher activity than other catalysts now in use, the new system could make it easier to get normally unreactive CO2 to participate in these reactions.

    “Developing an effective catalyst for synthesizing methanol from CO2 could greatly expand the use of this abundant gas as an economical feedstock,” said Brookhaven chemist Jose Rodriguez, who led the research. It’s even possible to imagine a future in which such catalysts help mitigate the accumulation of this greenhouse gas, by capturing CO2 emitted from methanol-powered combustion engines and fuel cells, and recycling it to synthesize new fuel.

    That future, of course, will be determined by a variety of factors, including economics. “Our basic research studies are focused on the science—the discovery of how such catalysts work, and the use of this knowledge to improve their activity and selectivity,” Rodriguez emphasized.

    The research team, which included scientists from Brookhaven, the University of Seville in Spain, and Central University of Venezuela, describes their results in the August 1, 2014, issue of the journal Science.

    New tools for discovery

    fu
    Fang Xu, a Stony Brook University PhD student working with the Brookhaven Lab team on studies to identify more effective catalysts for industrial processes, peers into the ambient-pressure scanning tunneling microscope used in these experiments.

    Because CO2 is normally such a reluctant participant in chemical reactions, interacting weakly with most catalysts, it’s also rather difficult to study. These studies required the use of newly developed in-situ (or on-site, meaning under reaction conditions) imaging and chemical “fingerprinting” techniques. These techniques allowed the scientists to peer into the dynamic evolution of a variety of catalysts as they operated in real time. The scientists also used computational modeling at the University of Seville and the Barcelona Supercomputing Center to provide a molecular description of the methanol synthesis mechanism.

    The team was particularly interested in exploring a catalyst composed of copper and ceria (cerium-oxide) nanoparticles, sometimes also mixed with titania. The scientists’ previous studies with such metal-oxide nanoparticle catalysts have demonstrated their exceptional reactivity in a variety of reactions. In those studies, the interfaces of the two types of nanoparticles turned out to be critical to the reactivity of the catalysts, with highly reactive sites forming at regions where the two phases meet.

    To explore the reactivity of such dual particle catalytic systems in converting CO2 to methanol, the scientists used spectroscopic techniques to investigate the interaction of CO2 with plain copper, plain cerium-oxide, and cerium-oxide/copper surfaces at a range of reaction temperatures and pressures. Chemical fingerprinting was combined with computational modeling to reveal the most probable progression of intermediates as the reaction from CO2 to methanol proceeded.

    These studies revealed that the metal component of the catalysts alone could not carry out all the chemical steps necessary for the production of methanol. The most effective binding and activation of CO2 occurred at the interfaces between metal and oxide nanoparticles in the cerium-oxide/copper catalytic system.

    “The key active sites for the chemical transformations involved atoms from the metal [copper] and oxide [ceria or ceria/titania] phases,” said Jesus Graciani, a chemist from the University of Seville and first author on the paper. The resulting catalyst converts CO2 to methanol more than a thousand times faster than plain copper particles, and almost 90 times faster than a common copper/zinc-oxide catalyst currently in industrial use.

    two
    Scanning tunneling microscope image of a cerium-oxide and copper catalyst (CeOx-Cu) used in the transformation of carbon dioxide (CO2) and hydrogen (H2) gases to methanol (CH3OH) and water (H2O). In the presence of hydrogen, the Ce4+ and Cu+1 are reduced to Ce3+ and Cu0 with a change in the structure of the catalyst surface.

    This study illustrates the substantial benefits that can be obtained by properly tuning the properties of a metal-oxide interface in catalysts for methanol synthesis.

    “It is a very interesting step, and appears to create a new strategy for the design of highly active catalysts for the synthesis of alcohols and related molecules,” said Brookhaven Lab Chemistry Department Chair Alex Harris.

    The work at Brookhaven Lab was supported by the DOE Office of Science. The studies performed at the University of Seville were funded by the Ministerio de Economía y Competitividad of Spain and the European Regional Development Fund. The Instituto de Tecnologia Venezolana para el Petroleo supported part of the work carried out at the Central University of Venezuela.

    Brookhaven National Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

    See the full article, with video, here.

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.
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  • richardmitnick 9:08 am on July 21, 2014 Permalink | Reply
    Tags: , , Chemistry, , ,   

    From M.I.T.: “More than glitter” 


    M.I.T.

    July 21, 2014
    Anne Trafton | MIT News Office

    Scientists explain how gold nanoparticles easily penetrate cells, making them useful for delivering drugs.

    A special class of tiny gold particles can easily slip through cell membranes, making them good candidates to deliver drugs directly to target cells.

    A new study from MIT materials scientists reveals that these nanoparticles enter cells by taking advantage of a route normally used in vesicle-vesicle fusion, a crucial process that allows signal transmission between neurons. In the July 21 issue of Nature Communications, the researchers describe in detail the mechanism by which these nanoparticles are able to fuse with a membrane.

    cell
    MIT engineers created simulations of how a gold nanoparticle coated with special molecules can penetrate a membrane. At left, the particle (top) makes contact with the membrane. At right, it has fused to the membrane. Image: Reid Van Lehn

    The findings suggest possible strategies for designing nanoparticles — made from gold or other materials — that could get into cells even more easily.

    “We’ve identified a type of mechanism that might be more prevalent than is currently known,” says Reid Van Lehn, an MIT graduate student in materials science and engineering and one of the paper’s lead authors. “By identifying this pathway for the first time it also suggests not only how to engineer this particular class of nanoparticles, but that this pathway might be active in other systems as well.”

    The paper’s other lead author is Maria Ricci of École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. The research team, led by Alfredo Alexander-Katz, an associate professor of materials science and engineering, and Francesco Stellacci from EPFL, also included scientists from the Carlos Besta Institute of Neurology in Italy and Durham University in the United Kingdom.

    Most nanoparticles enter cells through endocytosis, a process that traps the particles in intracellular compartments, which can damage the cell membrane and cause cell contents to leak out. However, in 2008, Stellacci, who was then at MIT, and Darrell Irvine, a professor of materials science and engineering and of biological engineering, found that a special class of gold nanoparticles coated with a mix of molecules could enter cells without any disruption.

    “Why this was happening, or how this was happening, was a complete mystery,” Van Lehn says.

    Last year, Alexander-Katz, Van Lehn, Stellacci, and others discovered that the particles were somehow fusing with cell membranes and being absorbed into the cells. In their new study, they created detailed atomistic simulations to model how this happens, and performed experiments that confirmed the model’s predictions.

    Stealth entry

    Gold nanoparticles used for drug delivery are usually coated with a thin layer of molecules that help tune their chemical properties. Some of these molecules, or ligands, are negatively charged and hydrophilic, while the rest are hydrophobic. The researchers found that the particles’ ability to enter cells depends on interactions between hydrophobic ligands and lipids found in the cell membrane.

    Cell membranes consist of a double layer of phospholipid molecules, which have hydrophobic lipid tails and hydrophilic heads. The lipid tails face in toward each other, while the hydrophilic heads face out.

    In their computer simulations, the researchers first created what they call a “perfect bilayer,” in which all of the lipid tails stay in place within the membrane. Under these conditions, the researchers found that the gold nanoparticles could not fuse with the cell membrane.

    However, if the model membrane includes a “defect” — an opening through which lipid tails can slip out — nanoparticles begin to enter the membrane. When these lipid protrusions occur, the lipids and particles cling to each other because they are both hydrophobic, and the particles are engulfed by the membrane without damaging it.

    In real cell membranes, these protrusions occur randomly, especially near sites where proteins are embedded in the membrane. They also occur more often in curved sections of membrane, because it’s harder for the hydrophilic heads to fully cover a curved area than a flat one, leaving gaps for the lipid tails to protrude.

    “It’s a packing problem,” Alexander-Katz says. “There’s open space where tails can come out, and there will be water contact. It just makes it 100 times more probable to have one of these protrusions come out in highly curved regions of the membrane.”

    Mimicking nature

    This phenomenon appears to mimic a process that occurs naturally in cells — the fusion of vesicles with the cell membrane. Vesicles are small spheres of membrane-like material that carry cargo such as neurotransmitters or hormones.

    The similarity between absorption of vesicles and nanoparticle entry suggests that cells where a lot of vesicle fusion naturally occurs could be good targets for drug delivery by gold nanoparticles. The researchers plan to further analyze how the composition of the membranes and the proteins embedded in them influence the absorption process in different cell types. “We want to really understand all the constraints and determine how we can best design nanoparticles to target particular cell types, or regions of a cell,” Van Lehn says.

    “One could use the results from this paper to think about how to leverage these findings into improved nanoparticle delivery vehicles — for instance, perhaps new surface ligands for nanoparticles could be engineered to have improved affinity for both surface groups and lipid tails,” says Catherine Murphy, a professor of chemistry at the University of Illinois at Urbana-Champaign who was not involved in the study.

    The research was funded by the National Science Foundation and the Swiss National Foundation.

    See the full article, with video, here.


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