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Category: chemistry – Page 4

Archimedean screw inspires new way to encode chirality into magnetic materials

In physics and materials science, the term “spin chirality” refers to an asymmetry in the arrangement of spins (i.e., the intrinsic angular momentum of particles) in magnetic materials. This asymmetry can give rise to unique electronic and magnetic behaviors that are desirable for the development of spintronics, devices that leverage the spin of electrons and electric charge to process or store information.

The creation of materials that exhibit desired spin chirality and associated physical effects on a large scale has so far proved challenging. In a recent paper published in Nature Nanotechnology, researchers at École Polytechnique Fédérale de Lausanne (EPFL), the Max Planck Institute for Chemical Physics of Solids and other institutes introduced a new approach to encode chirality directly into materials by engineering their geometry at a nanoscale.

“Dirk and myself were initially inspired by the elegance of the Archimedean screw and began wondering whether we could build a magnonic analog, something that could ‘pump’ magnons (i.e., collective electron spin excitations) in a similarly directional way,” Dr. Mingran Xu, first author of the paper, told Tech Xplore.

Physicists bring unruly molecules to the quantum party

Scientists have made leaps and bounds in bending atoms to their will, making them into everything from ultraprecise clocks to bits of quantum data. Translating these quantum technologies from obedient atoms to unruly molecules could offer greater possibilities. Molecules can rotate and vibrate. That makes molecules more sensitive to certain changes in the environment, like temperature.

“If you’re sensitive to something, it can be a curse, because you would like to not be sensitive, or it can be a blessing,” said NIST physicist Dietrich Leibfried. “You can use that sensitivity to your advantage.”

But that same sensitivity has made molecules difficult to control. Recently, physicists at the National Institute of Standards and Technology (NIST) achieved new levels of control over molecules. In a study published in Physical Review Letters, they were able to manipulate a calcium hydride molecular ion—made up of one atom of hydrogen and one atom of calcium, with one electron removed to make it a charged molecule—with almost perfect success. And this control opens possibilities for quantum technology, chemical research and exploring new physics.

Silicon atom processor links 11 qubits with more than 99% fidelity

In order to scale quantum computers, more qubits must be added and interconnected. However, prior attempts to do this have resulted in a loss of connection quality, or fidelity. But, a new study published in Nature details the design of a new kind of processor that overcomes this problem. The processor, developed by the company Silicon Quantum Computing, uses silicon—the main material used in classical computers—along with phosphorus atoms to link 11 qubits.

The new design uses precision-placed phosphorus atoms in isotopically purified silicon-28, which are arranged into two multi-nuclear spin registers. One register contains four phosphorus atoms, while the other contains five, and each register shares an electron spin. The two registers are linked by electron exchange interaction, allowing for non-local connectivity across the registers and 11 linked qubits.

Because of the placement of silicon and phosphorus in the periodic table, the design is referred to as the “14|15 platform.” This 11-qubit atom processor in silicon is the largest of its kind to date, marking a major accomplishment for quantum computing.

Light-printed electrodes turn skin and clothing into sensors

Researchers in Sweden have unveiled a way to create high-performance electronic electrodes using nothing more than visible light and specially designed water-soluble monomers. This gentle, chemical-free approach lets conductive plastics form directly on surfaces ranging from glass to textiles to living skin, enabling surprisingly versatile electronic and medical applications.

A vision of chromosome organization

The DNA of eukaryotic organisms is packaged by histone proteins into chromatin. The structural organization of chromatin is tied to its function. Loosely packed, more transcriptionally active regions of chromatin are known as euchromatin, whereas highly condensed, less transcriptionally active regions are known as heterochromatin.

Despite advances in the study of chromatin structure over the past 100 years, a biochemical understanding of how basic structural motifs beget higher-order chromatin organization remains lacking.

In a new Science study, researchers present an approach that enables imaging and analysis of the structure of chromatin condensates in situ, which moves the field much closer toward defining the structural chromatin motifs that underpin its nuclear functions.

Learn more in a new Science Perspective.

Cryogenic electron tomography of condensed chromatin enables multiscale analysis of its structure.

Kaite Zhang and Vijay Ramani Authors Info & Affiliations

Continue reading “A vision of chromosome organization” | >

Non-opioid analgesic binding sites on glycine transporter 2

Glycine is a major inhibitory neurotransmitter that reduces nerve activity, helping to regulate pain signals, motor control and sensory processing. Glycine transporter 2 (GlyT2) is a key regulator of glycinergic neurotransmission because it removes glycine from the synaptic clefts. When GlyT2 is inhibited, glycine reuptake is reduced, allowing synaptic glycine levels to rise and enhance inhibitory signaling. Because of its ability to modulate glycinergic transmission, GlyT2 is an attractive therapeutic target for neuropathic pain. It is particularly attractive because it suggests new means of non-opioid pain management.

In a new study published in PNAS, researchers reported high-resolution cryo-EM structures of GlyT2 in three major conformational states. These structures illuminate the transporter’s molecular mechanisms and provide critical insights into how analgesic compounds are recognized.

The researchers identified a previously unknown third sodium-binding site (Na3) on GlyT2. Whereas other neurotransmitter transporters use two Na ⁺ ions and one Cl ⁻ ion, the additional binding site demonstrates that GlyT2 uses three Na ⁺ ions and one Cl ⁻ ion to transport glycine per cycle. This additional sodium ion supplies the extra energetic drive required for glycine transport and offers new understanding of Na ⁺ /Cl ⁻-coupled substrate binding and conformational changes, supporting GlyT2’s specialized physiological function.

The researchers also uncovered a distinctive allosteric binding pocket that accommodates lipid-based inhibitors such as oleoyl-D-lysine, a derivative of the endogenous lipid N-arachidonyl glycine. Structural and biochemical analyzes revealed features that determine the inhibitory potency of this class of lipid molecules, providing a foundation for rational design of improved lipid-based GlyT2 analgesics.

Additionally, the researchers resolved structures of GlyT2 bound to several small-molecule inhibitors, including ALX1393, opiranserin, and ORG25543. These structures reveal distinct competitive and allosteric inhibition mechanisms and identify key residues responsible for selectivity between GlyT1 and GlyT2.

Shortest light pulse ever created captures ultrafast electron dynamics

Electrons determine everything: how chemical reactions unfold, how materials conduct electricity, how biological molecules transfer energy, and how quantum technologies operate. But electron dynamics happens on attosecond timescales—far too fast for conventional measurement tools.

Researchers have now generated a 19.2-attosecond soft X-ray pulse, which effectively creates a camera capable of capturing these elusive dynamics in real time with unprecedented detail, enabling the observation of processes never observed before. Dr. Fernando Ardana-Lamas, Dr. Seth L. Cousin, Juliette Lignieres, and ICREA Prof. Jens Biegert, at ICFO, has published this new record in Ultrafast Science. At just 19.2 attoseconds long, it is the shortest and brightest soft X-ray pulse ever produced, giving rise to the fastest “camera” in existence.

Flashes of light in the soft X-ray spectral range provide fingerprinting identification, allowing scientists to track how electrons reorganize around specific atoms during reactions or phase transitions. Generating an isolated pulse this short, required innovations in high-harmonic generation, advanced laser engineering, and attosecond metrology. Together, these developments allow researchers to observe electron dynamics, which define material properties, at their natural timescales.

Molecular basis of DNA cross-linking by bacteria

The relevance of the gut microbiome, the community of microorganisms living in the digestive tract, to human health is a topic of intense interest. However, among the numerous benevolent bacteria living in the gut, there are some species that are harmful to humans.

For example, certain strains of Escherichia coli produce the genotoxin colibactin, which causes DNA damage and is linked with colon cancer. However, the colibactin molecule is complex and unstable, which has made it challenging to elucidate its chemical structure and the mechanism by which it damages DNA. In the culmination of years of research from multiple laboratories, researchers in a new Science study reveal the structure of the active form of colibactin bound to DNA.

The findings go a long way toward explaining the mutation signatures associated with colibactin exposure and provide substantial insight into how colibactin contributes to colorectal carcinogenesis.

Learn more in a new Science Perspective.

The structure of the bacterial genotoxin colibactin bound to DNA shows how it might contribute to cancer risk.

Orlando D. Schärer Authors Info & Affiliations

Continue reading “Molecular basis of DNA cross-linking by bacteria” | >

Microgel-based antioxidant system advances biohybrid brain research

Researchers have unveiled a breakthrough technology that could transform the way scientists build and study lab-grown brain tissue models. The innovation, called Cellular RedOx Spreading Shield (CROSS), delivers long-lasting antioxidant protection to stem cells, enabling the reliable production of high-quality extracellular vesicles (EVs) that strengthen neuron-glia networks.

The study, published in the journal Advanced Functional Materials, was led by University of Illinois Urbana-Champaign chemical and biomolecular engineering professor Hyunjoon Kong and chemistry professor Hee Sun Han, and performed by Ryan Miller, currently a post-doctoral fellow at Georgia Tech.

Jonghwi Lee, in the chemical engineering department at Chung-Ang University in South Korea, and Young Jun Kim at the Korean Institute of Science and Technology–Europe, collaborated on the project.

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