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  • richardmitnick 12:33 pm on February 1, 2021 Permalink | Reply
    Tags: "Unlocking the power of a molecule’s spin", , , New research provides a theoretical framework that could help experimentalists better control chemical reactions with possible implications for recycling rare earth metals., One of the properties of a metal is that it has certain spin properties., , Photochemistry, Rare earth metals- a group of 17 elements that because they aren’t found in concentrated deposits require energy-intensive and toxic methods to extract., , Theoretical chemistry   

    From Penn Today: “Unlocking the power of a molecule’s spin” 


    From Penn Today

    January 29, 2021
    Erica K. Brockmeier

    New research provides a theoretical framework that could help experimentalists better control chemical reactions, with possible implications for recycling rare earth metals.

    1
    A new study led by Joseph Subotnik (right) describes a theoretical framework that could allow experimentalists to have better control over chemical reactions by using a molecule’s spin. Using this framework, future experiments conducted through the Center for Sustainable Separations of Metals (CSSM) with Eric Schelter (far left) and Jessica Anna could help researchers develop more energy-efficient ways to purify and recycle scarce materials such as rare earth metals. (Pre-pandemic image). Credit: Eric Sucar.

    3
    Toward Control of Spin States for Molecular Electronics. Credit: ALS LBNL.

    Behind the devices that shape modern life is an array of natural and human-made materials. One such component of smartphones and computers are rare earth metals, a group of 17 elements that, because they aren’t found in concentrated deposits, require energy-intensive and toxic methods to extract. While recycling rare earth metals from used devices is one way to relieve strained supply chains and reduce environmental damage, the fundamental chemistry required for efficiently separating and reusing these metals remains a challenge.

    Now, new research provides a theoretical framework that could change the paradigm for how chemicals are separated. Graduate student Yanze Wu and professor Joseph Subotnik describe in Nature Communications how a molecule’s spin can be used to control a chemical reaction. Based on this concept, future experiments conducted through the Center for Sustainable Separations of Metals (CSSM) could help researchers develop more energy-efficient ways to purify and recycle scarce materials such as rare earth metals.

    The goal of the CSSM, established in 2019 and led by a team of Penn chemists, is to develop chemical separation methods that make the process of recycling metals from consumer products more cost-effective. CSSM brings together theoretical and experimental chemistry groups, with the goal of conducting fundamental research that provides creative, scientifically-driven solutions to the rare earth metal supply chain crisis.

    Subotnik, a theoretical chemist, had previously been working on questions related to photochemistry and was interested in understanding how light impacts molecules. In the process of trying to better understand the dynamics of photochemical reactions, he and Wu began to postulate the role of spin during light-induced changes to a molecule’s energy state. After spending a year delving deeply into this area of study, Subotnik realized through conversations with CSSM Director Eric Schelter that this theoretical work could also have implications for metal separation.

    “One of the reasons rare earth metal separation is hard is because a lot of metals are very similar to each other. But one of the properties of a metal is that it has certain spin properties,” Subotnik says. “One idea is that if you want to separate metals, you might be able to use spin properties, which can be very different.”

    2
    To help validate their findings, Subotnik will be working with Schelter and Anna to conduct follow-up experiments and combine those data with new theoretical models. (Pre-pandemic image). Credit: Eric Sucar.

    In this new theoretical framework, the researchers show that spin helps molecules as they pass through unstable geometries during a chemical reaction. Subotnik uses the analogy of finding a secret mountain pass and how controlling spin could enable someone to travel to a specific place, in this case a particular product of a chemical reaction, on the other side. “We show that a little bit of spin can force you to take one pass versus the other with a huge fidelity, and just a little bit of spin can guide which product you’re going to make,” he says.

    What’s significant about this idea is that a molecule’s spin can be changed using a very small amounts of energy, and this small change in spin also has enormous effects on how a chemical reaction proceeds. While using spin to power devices has been the ambition of fields like spintronics, its implications in fundamental chemistry have not been widely explored. “The question is, Can you use these really small energies to make nonintuitive chemistry happen,” says Subotnik. “If I understand spin and can manipulate it, could I promote one reaction or the other, to get one metal to separate rather than another?”

    But what makes this discovery exciting also makes the next steps challenging: “It’s powerful, but it’s hard to diagnose,” Subotnik says. Because a molecule’s spin rotates with the molecule itself and averages out during experiments, it’s difficult to isolate spin’s impacts in lab measurements. To help validate their findings, Subotnik will be working with Schelter and Jessica Anna to conduct follow-up experiments and combine those data with new theoretical models.

    “The recent announcements by the Biden administration and General Motors for a wholesale shift to electric vehicles will create huge demands for mining lithium, cobalt, rare earths, and other critical metals,” says Schelter, “Joe and Yanze’s work has important implications for fundamentally new and selective separations of critical metals that could reduce energy consumption, waste, and greenhouse gas production associated with mining, or enable critical metals recycling.”

    Beyond its implications for metal separation, this framework also paves the way for a new paradigm on how electrical, spin, and other chemical properties could be combined in ways that have not been explored before. “Nobody’s really combined these aspects of spin and chemistry before, so I do’’t know what’s going to happen,” Subotnik says. “The dream would be that you make some process way more efficient. That’s fundamental science at its best.”

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U Penn campus

    Academic life at Penn is unparalleled, with 100 countries and every U.S. state represented in one of the Ivy League’s most diverse student bodies. Consistently ranked among the top 10 universities in the country, Penn enrolls 10,000 undergraduate students and welcomes an additional 10,000 students to our world-renowned graduate and professional schools.

    Penn’s award-winning educators and scholars encourage students to pursue inquiry and discovery, follow their passions, and address the world’s most challenging problems through an interdisciplinary approach.

     
  • richardmitnick 9:33 am on January 25, 2021 Permalink | Reply
    Tags: "Researchers use lasers and molecular tethers to create perfectly patterned platforms for tissue engineering", A biologically compatible 3D scaffold in which cells can grow, , , Biomaterials, , Decorate the biologically compatible 3D scaffold with biochemical messages in the correct configuration to trigger the formation of the desired organ or tissue., , Laboratory-grown organs and tissues, , Light-based methods to modify synthetic scaffolds with protein signals, mCherry proteins, , Photochemistry, Protein-based biochemical messages that affect cell behavior, The signals that the team added to the hydrogels are proteins., The tethered proteins were fully functional delivering desired signals to cells., Two types of biological polymers: collagen and fibrin,   

    From University of Washington: “Researchers use lasers and molecular tethers to create perfectly patterned platforms for tissue engineering” 

    From University of Washington

    January 18, 2021
    James Urton

    1
    Top view of a collagen hydrogel that researchers decorated with immobilized mCherry proteins, which glow red under fluorescent light. The team shined UV light on the hydrogel through a mask cut out in the shape of a former University of Washington logo. Black regions were masked from the light, and so the mCherry protein did not adhere to those portions of the hydrogel. Scale bar is 50 micrometers.Batalov et al., PNAS, 2021.

    2
    Top view of two collagen hydrogels that researchers decorated with immobilized mCherry proteins, which glow red under fluorescent light. The team scanned near-infrared lasers in the shapes of a monster (left) and the Space Needle (right) to create these patterns. Black regions were not scanned with the laser, and so the mCherry protein did not adhere to those portions of the hydrogel. Scale bar is 50 micrometers.Batalov et al., PNAS, 2021.

    3
    The team used near-infrared lasers to create this intricate pattern in the shape of a human heart of immobilized mCherry proteins, which glow red under fluorescent light, within a collagen hydrogel. On the left is a composite image of 3D slices from the gel. On the right are cross-sectional views of the mCherry patterns. Scale bar is 50 micrometers.Batalov et al., PNAS, 2021.

    4
    This is a top view of a cylindrical fibrin hydrogel. By design, the right side of the hydrogel contains immobilized Delta-1 proteins, which activate Notch signaling pathways within cells. The left side does not contain immobilized Delta-1 (see insert). The team introduced human bone cancer cells, which were engineered to glow when their Notch signaling pathways are activated, into the hydrogel. The right side of the hydrogel glows brightly, indicating that cells in that region have activated their Notch signaling pathways. Cells on the left side of the hydrogel have not. Scale bar is 1 millimeter.Batalov et al., PNAS, 2021.

    Imagine going to a surgeon to have a diseased or injured organ switched out for a fully functional, laboratory-grown replacement. This remains science fiction and not reality because researchers today struggle to organize cells into the complex 3D arrangements that our bodies can master on their own.

    There are two major hurdles to overcome on the road to laboratory-grown organs and tissues. The first is to use a biologically compatible 3D scaffold in which cells can grow. The second is to decorate that scaffold with biochemical messages in the correct configuration to trigger the formation of the desired organ or tissue.

    In a major step toward transforming this hope into reality, researchers at the University of Washington have developed a technique to modify naturally occurring biological polymers with protein-based biochemical messages that affect cell behavior. Their approach, published the week of Jan. 18 in the PNAS, uses a near-infrared laser to trigger chemical adhesion of protein messages to a scaffold made from biological polymers such as collagen, a connective tissue found throughout our bodies.

    Mammalian cells responded as expected to the adhered protein signals within the 3D scaffold, according to senior author Cole DeForest, a UW associate professor of chemical engineering and of bioengineering. The proteins on these biological scaffolds triggered changes to messaging pathways within the cells that affect cell growth, signaling and other behaviors.

    These methods could form the basis of biologically based scaffolds that might one day make functional laboratory-grown tissues a reality, said DeForest, who is also a faculty member with the UW Molecular Engineering and Sciences Institute and the UW Institute for Stem Cell and Regenerative Medicine.

    “This approach provides us with the opportunities we’ve been waiting for to exert greater control over cell function and fate in naturally derived biomaterials — not just in three-dimensional space but also over time,” said DeForest. “Moreover, it makes use of exceptionally precise photochemistries that can be controlled in 4D while uniquely preserving protein function and bioactivity.”

    DeForest’s colleagues on this project are lead author Ivan Batalov, a former UW postdoctoral researcher in chemical engineering and bioengineering, and co-author Kelly Stevens, a UW assistant professor of bioengineering and of laboratory medicine and pathology.

    Their method is a first for the field, spatially controlling cell function inside naturally occurring biological materials as opposed to those that are synthetically derived. Several research groups, including DeForest’s, have developed light-based methods to modify synthetic scaffolds with protein signals. But natural biological polymers can be a more attractive scaffold for tissue engineering because they innately possess biochemical characteristics that cells rely on for structure, communication and other purposes.

    “A natural biomaterial like collagen inherently includes many of the same signaling cues as those found in native tissue,” said DeForest. “In many cases, these types of materials keep cells ‘happier’ by providing them with similar signals to those they would encounter in the body.”

    They worked with two types of biological polymers: collagen and fibrin, a protein involved in blood clotting. They assembled each into fluid-filled scaffolds known as hydrogels.

    The signals that the team added to the hydrogels are proteins, one of the main messengers for cells. Proteins come in many forms, all with their own unique chemical properties. As a result, the researchers designed their system to employ a universal mechanism to attach proteins to a hydrogel — the binding between two chemical groups, an alkoxyamine and an aldehyde. Prior to hydrogel assembly, they decorated the collagen or fibrin precursors with alkoxyamine groups, all physically blocked with a “cage” to prevent the alkoxyamines from reacting prematurely. The cage can be removed with ultraviolet light or a near-infrared laser.

    Using methods previously developed in DeForest’s laboratory, the researchers also installed aldehyde groups to one end of the proteins they wanted to attach to the hydrogels. They then combined the aldehyde-bearing proteins with the alkoxyamine-coated hydrogels, and used a brief pulse of light to remove the cage covering the alkoxyamine. The exposed alkoxyamine readily reacted with the aldehyde group on the proteins, tethering them within the hydrogel. The team used masks with patterns cut into them, as well as changes to the laser scan geometries, to create intricate patterns of protein arrangements in the hydrogel — including an old UW logo, Seattle’s Space Needle, a monster and the 3D layout of the human heart.

    The tethered proteins were fully functional, delivering desired signals to cells. Rat liver cells — when loaded onto collagen hydrogels bearing a protein called EGF, which promotes cell growth — showed signs of DNA replication and cell division. In a separate experiment, the researchers decorated a fibrin hydrogel with patterns of a protein called Delta-1, which activates a specific pathway in cells called Notch signaling. When they introduced human bone cancer cells into the hydrogel, cells in the Delta-1-patterned regions activated Notch signaling, while cells in areas without Delta-1 did not.

    These experiments with multiple biological scaffolds and protein signals indicate that their approach could work for almost any type of protein signal and biomaterial system, DeForest said.

    “Now we can start to create hydrogel scaffolds with many different signals, utilizing our understanding of cell signaling in response to specific protein combinations to modulate critical biological function in time and space,” he added.

    With more-complex signals loaded on to hydrogels, scientists could then try to control stem cell differentiation, a key step in turning science fiction into science fact.

    The research was funded by the National Science Foundation, the National Institutes of Health and Gree Real Estate.

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    u-washington-campus
    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.
    So what defines us —the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
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