Communications Chemistry最新文献

RegIIIα is an antibacterial protein primarily operating in the digestive tract to defend against bacterial infection through direct bactericidal activity. A previous study proposed that RegIIIα forms hexameric pores on the membrane of Gram-positive bacteria, leading to cell lysis. These RegIIIα hexamers can further assemble into filaments, diminishing RegIIIα activity. However, the high-resolution structure of RegIIIα assembly remains elusive, impeding the comprehension of the molecular mechanisms underlying RegIIIα function. In this study, we determined the cryo-electron microscopy (cryo-EM) structure of RegIIIα filaments formed in vitro at a resolution of 2.2 Å. Our structure reveals a similar subunit arrangement but a distinct subunit orientation compared to the previously reported low-resolution model of RegIIIα filaments. Through structural analysis and biochemical assays, we identified two essential interfaces for RegIIIα assembly, offered a potential explanation for the necessity of lipids in RegIIIα assembly, and elucidated the inhibitory mechanism of the pro-segment of RegIIIα. Collectively, our study presents the first near-atomic structure of filaments formed by C-tyle lectin containing proteins, providing structural insights into RegIIIα assembly that are closely related to its physiological functions and regulations.

Understanding how electrolyte-catalyst interactions govern reaction kinetics is crucial for advancing electrocatalytic hydrogen production. Here, we elucidate the atomic-scale synergy between alkali cations and platinum surface structure in accelerating the alkaline hydrogen evolution reaction (HER) through combined constant-potential density functional theory and ab initio molecular dynamics simulations. Our simulations demonstrate that stepped Pt(311) surfaces uniquely stabilize Na⁺ cations through formation of a Pt-H₂O-Na⁺(H₂O)ₓ adduct at step edges, positioning cations 2.3 Å closer to the surface than on Pt(111) terraces. This proximity creates a stronger interfacial electric field that polarizes adjacent water molecules, inducing partial O-H bond dissociation and lowering the Volmer step activation energy by 0.14 eV - threefold greater than the reduction observed on Pt(111). The stark facet dependence arises from fundamental differences in ion-surface coordination, with Pt(111) maintaining distant cation solvation that minimally perturbs HER kinetics. These findings establish cation-facet cooperativity as a key design principle, showing how atomic-scale control of both surface geometry and the electrochemical double layer can overcome intrinsic kinetic limitations of alkaline HER catalysis.

Ultrafast photoinduced excited-state proton transfer (ESPT) plays a crucial role in protecting biomolecules and functional materials from photodamage. However, the influence of solute-solvent interactions on ESPT dynamics remains under active investigation. Here, we present an ultrafast spectroscopic study of ESPT in the photobase 2-(2´-pyridyl)benzimidazole (PBI) in methanol. Ultrafast absorption spectroscopy, supported by quantum chemical calculations, reveals three distinct kinetic steps: (1) a 2.2 ps solvent-to-solute proton transfer, (2) subsequent nonradiative relaxation to the ground state within 31 ps, producing a vibrationally hot ensemble with substantial excess kinetic energy, and (3) equilibration as this energy dissipates into the surrounding solvent bath over 186 ps. Femtosecond-resolved dynamics exhibit oscillatory signals indicative of coherent wavepacket motion on the S₁ potential energy surface. A phase flip in the excited-state absorption maximum confirms this assignment. Fourier analysis resolves two dominant periods (∼117 fs and ∼340 fs), corresponding to in-plane and out-of-plane vibrational modes coupled between PBI and the hydrogen-bonded methanol molecule. The rapid dephasing ( < 300 fs) suggests that the nuclear wavefunction evolves on an anharmonic potential energy surface while traversing the ESPT reaction coordinate.

Isocyanic acid (HNCO) is a toxic atmospheric constituent emitted by biomass burning and catalytic converters in car engines. The major sinks for HNCO were thought to be heterogeneous loss processes and dry deposition in the free troposphere. Based on the rigorous electronic structure calculations and kinetic simulations, here we show that HNCO is highly reactive to the stabilized Criegee intermediates (sCIs, e.g., CH₂OO and syn-CH₃CHOO) in the atmosphere. The energetically most preferable reaction route refers to a concerted mechanism by which the H atom is transferred from N of HNCO to the terminal O site of sCIs with simultaneous addition of N or O in HNCO to the other CH₂ (resp. CHCH₃) end, leading to the highly exothermic HOOCH₂NCO and HOOCH₂OCN (resp. HOOCH(CH₃)NCO and HOOCH(CH₃)OCN). The precursor complexes are stabilized via H-bond/p-π interactions and the barriers are submerged below reactants. The reaction of HNCO with CH₂OO occurs with an average rate coefficient of 8×10^-13 cm³molecule^-1s^-1 at 275 K and 760 Torr, which is a factor of 10³ faster than the HNCO + OH reaction. The total rate coefficients exhibit negative temperature dependence under the tropospheric conditions. sCIs might be one of the potential sinks for the budget of HNCO in the atmosphere.

High-grade gliomas are devastating cancers with dismal prognosis, largely because current chemotherapeutics fail to cross the blood-brain barrier and lack tumor-cell specificity. Nanotechnology aims to overcome these limitations through targeted drug delivery. Here, a quadruple-conjugated nanomodel was synthesized using carbon dots (C-dots) as biocompatible nanocarriers via a one-pot reaction that covalently links two targeting peptides and two anticancer agents. The short peptide (shPep-1) targets the tumor-restricted receptor IL13Rα2, whereas the long peptide (lnPep-1) contains a nuclear localization signal for enhanced intracellular trafficking. Therapeutic cargo consists of epirubicin and the temozolomide metabolite 5-aminoimidazole-4-carboxamide. This nanomodel displays potent cytotoxicity in multiple high-grade glioma cell lines at 50 nM while remaining relatively non-toxic to normal cells (IC₅₀ > 2 µM). Despite a lower drug-loading capacity than single-peptide formulations, it induced greater glioma cell death, underscoring the enhanced therapeutic synergy of its dual-peptide, dual-drug design. Fluorescence studies confirm superior uptake and nuclear delivery, establishing C-dots as a stable, cost-effective, modular platform for next-generation personalized cancer nanotherapies.

Two carbazole-based donor-acceptor dyes, CBZ-Gly and CBZ-EG, featuring glycerol- and ethylene glycol-like side chains, were designed and synthesized to achieve synergistic compatibility with DES-based electrolytes, and systematically investigate their impact on DSSCs performance. These dyes were tested in DSSCs employing two neat deep eutectic solvent (DES) electrolytes (choline chloride/ethylene glycol and choline chloride/glycerol) under both simulated sunlight (AM 1.5G) and indoor lighting (1000 lux). By combining molecular-level dye design with a tailored DES-based electrolyte, we achieved an improvement in long-term device stability over several months and demonstrated a record indoor power conversion efficiency of 9.4%, thereby establishing a new benchmark for fully sustainable, DES-based DSSCs under low-light conditions.

It is well established that a significant amount of heat produced in the Earth's mantle is due to the decay of uranium. However, uranium cannot be incorporated in large amounts into the most common mantle minerals. Here, we suggest that carbonates could be host phases for uranium in carbon-rich mantle lithologies. Two anhydrous uranium carbonates, U₂[CO₃]₃ and U[CO₃]₂, were simultaneously synthesized by a reaction of UO₂ with CO₂ in a laser-heated diamond anvil cell at 20(1) GPa and 1800(200) K. Their crystal structures were obtained from synchrotron-based single crystal diffraction data and reproduced by density functional theory-based calculations. In U₂[CO₃]₃ trivalent uranium cations are present, while uranium is four-valent in U[CO₃]₂. The synthesis of U₂[CO₃]₃ and U[CO₃]₂ is a significant extension of the chemistry of uranium compounds and we provide a straightforward synthesis route for a U^III-containing compound.

Polydiacetylene (PDA)-based colorimetric sensors offer a promising platform for rapid and visual detection, through a chromatic transition from blue to red. However, their broader applications are hindered by challenges in sensitivity, selectivity, and stability. This review comprehensively overviews functionalization strategies to overcome existing limitations, including chemical modification with reactive groups, conjugation with specific ligands or receptors, and integration with nanomaterials. Alternative approaches are also discussed. The interplay between base materials, deposition methods, and functionalization efficiencies is emphasized. Furthermore, this review addresses remaining challenges, proposes feasible solutions, and offers insights into future strategic directions for creating more advanced PDA-based colorimetric sensors.

Sample consumption for serial femtosecond crystallography with X-ray free electron lasers remains a major limitation preventing broader use in macromolecular crystallography. This drawback is exacerbated in time-resolved (TR) experiments, where the amount of sample required per reaction time point is multiplied by the number of time points investigated. To reduce this limitation, we demonstrate a segmented droplet generation strategy coupled to a mix-and-inject approach for TR studies at the European XFEL. The injector produces synchronized droplet trains that enable stable and reproducible injection of protein crystal slurries at significantly reduced flow rates. Using the human flavoenzyme NAD(P)H:quinone oxidoreductase 1 (NQO1) as a test system, we collected diffraction data after mixing with NADH at 0.3 s and 1.2 s delays. The segmented injection approach achieved up to 97% reduction in sample consumption compared with continuous-flow injection while maintaining data quality suitable for TR crystallography. Reproducible electron density features consistent with low-occupancy NADH binding illustrate both the feasibility and the current limits of studying dynamic redox enzymes using this approach. This work establishes segmented droplet generation as a sample-efficient and XFEL-compatible method for future time-resolved serial crystallography experiments.