ACS Publications最新文献

A series of tetracene (Tc)-alkanethiol-functionalized gold nanoclusters (Au_m: m = 25, 38) dyads with varying alkyl chain lengths (n = 5, 11) (denoted as Tc-C_n-Au_m) were synthesized to investigate the excited-state dynamics through the triplet excited state of these gold nanoclusters. Transient absorption measurements revealed bidirectional intramolecular energy transfer processes, including the initial singlet–singlet energy transfer (S-SEnT) from Tc to Au₂₅, followed by the subsequent triplet–triplet energy transfer (T-TEnT) from Au₂₅ to Tc in Tc-C_n-Au₂₅ (n = 5, 11), with nearly similar rate constants regardless of the alkyl chain length (n). In the case of Tc-C₅-Au₃₈, intramolecular S-SEnT from Tc to Au₃₈ was similarly observed; however, T-TEnT from Au₃₈ to Tc was not detected. The differences in excited-state dynamics between Tc-C₅-Au₂₅ and Tc-C₅-Au₃₈ can be attributed to variations in the triplet energies of Au_m. These results clearly demonstrate the triplet character of Au₂₅ and Au₃₈.

Fragment-based drug discovery has emerged as a powerful approach for developing therapeutics against challenging targets, including the GTPase KRAS. Here, we report an NMR-based screening campaign employing state-of-the-art techniques to evaluate a library of 890 fragments against the oncogenic KRAS G12V mutant bound to GMP-PNP. Further HSQC titration experiments identified hits with low millimolar affinities binding within the SI/SII switch region, which forms the binding interface for the effector proteins. To elucidate the binding modes, we applied NMR molecular replacement (NMR²) structure calculations, bypassing the need for a conventional protein resonance assignment. Traditionally, NMR² relies on isotope-filtered nuclear Overhauser effect spectroscopy experiments requiring double-labeled [¹³C,¹⁵N]-protein. We introduce a cost-efficient alternative using a relaxation-based filter that eliminates isotope labeling while preserving structural accuracy. Validation against standard isotopically labeled workflows confirmed the equivalence of the derived protein–ligand structures. This approach enabled the determination of 12 NMR² KRAS–fragment complex structures, providing critical insights into structure–activity relationships to guide ligand optimization. These results demonstrate the streamlined integration of NMR² into a fragment-based drug discovery pipeline composed of screening, binding characterization, and rapid structural elucidation with or without isotopic labeling.

Skeletal manipulation of aromatic compounds has emerged as a potent tool in synthetic chemistry, but simultaneous multiring manipulation remains largely unexplored due to the inherent complexities of ring and site selectivity. Herein, we report an unprecedented multiring skeletal manipulation that fuses four 5-membered aromatic rings, comprising two organic and two metal-containing aromatic systems, into a novel metal-bridged 6/6/6/6-membered ring scaffold. The sequential ring fusion is accomplished through an atom-mutual-embedding strategy; this strategy entails the stepwise insertion of two nitrogen atoms into separate metal–carbon bonds and simultaneously integrates a metal atom as a bridge across two isoxazole moieties. The presence of a central metal atom is crucial for ensuring precise substrate alignment and enhancing both the ring and site specificity. The resulting tetrahexacyclic products exhibit remarkable stability and superior near-infrared (NIR) functional properties, surpassing those of the precursor compounds. This work not only establishes a conceptual foundation for designing versatile substrate molecules amenable to intricate editing but also contributes to the rational and performance-targeted manipulation of molecular architectures.

Barnase, derived from Bacillus amyloliquefaciens, is a key enzyme in biocatalysis with widespread applications in pharmaceutical synthesis. However, its stability under extreme conditions, such as high temperatures and extreme pH, limits its industrial applications. Therefore, enhancing both its catalytic efficiency and stability through genetic engineering has become a critical focus of research. In this study, AlphaFold was employed to predict the structure of Barnase, followed by molecular docking and molecular dynamics simulations using GROMACS to design and construct 24 mutants. The results demonstrated that the enzymatic activity of the S28H and D101 K mutants increased by 75.28% and 71.86%, respectively, while the stability of D101 K declined under high temperatures. To address this, D101 K was immobilized onto a ZIF-8 carrier. Under optimized immobilization conditions (1.5 M 2-methylimidazole, 1.5 mL enzyme solution, 20 °C), ZIF-8@D101 K exhibited significantly enhanced thermal stability and pH adaptability. Recycling experiments showed that 96.21% of its activity was retained after three cycles, and 72.47% after eight cycles, demonstrating superior reusability and stability, making it more suitable for industrial applications.

Electrocatalytically reducing NO₃^– to N₂ is of great significance for environmental remediation and global nitrogen cycling. However, it is currently hindered by low N₂ selectivity since adsorbate N-intermediates are hard to migrate and couple each other during the N–N coupling step. Herein, an in situ assembly strategy was taken to attach Pd@Cu₂O nanoparticles with CuO nanowire arrays to form an equipotential cathode CuO-Pd@Cu₂O, which optimized N₂ selectivity to 91%, much higher than that of directly loaded Pd–Cu cathode (55%). Theoretical calculations combined with in situ spectroscopies demonstrated that the equipotential cathode can shield the electric field and enrich NO₂^– intermediate inside. Meanwhile, a unique reaction pathway was revealed that the enriched NO₂^– can directly couple with *N and also tune the Pd d-band center, avoiding the hurdles in N–N coupling. The approach here provides a new perspective in cathode design and a mechanistic understanding for the N–N coupling reaction.

Device-associated infections are a major challenge for healthcare and cause patient morbidity and mortality as well as pose a significant economic burden. Infection-causing bacteria and fungi are equally notorious and responsible for biofilm formation and the development of antibiotic and antifungal-resistant strains. Biomaterials resisting bacterial and fungal adhesion can address device-associated infections more safely and efficiently than conventional systemic antibiotic therapies. Herein, we present a combination of potent antibacterial nitric oxide (NO) with antifungal fluconazole codelivery system from a polymeric matrix to combat bacterial and fungal infections simultaneously. The NO donor S-nitroso-N-acetyl-penicillamine (SNAP)-blended low-water-uptake polycarbonate urethane (TSPCU) was dip-coated with high-water-uptake polyether urethane (TPU) containing fluconazole to have an antibacterial and antifungal surface. The composites were characterized for surface wettability and coating stability using water contact angle (WCA) analysis. The real-time NO release (72 h) was evaluated using a chemiluminescence-based nitric oxide analyzer which showed physiologically relevant levels of NO released. The composites released fluconazole for 72 h under physiological conditions. Antibacterial analysis demonstrated a > 3-log reduction of viable Staphylococcus aureus and >2-log reduction of viable Escherichia coli compared to controls. The antifungal evaluation resulted in ∼98% reduction in adhered and ∼92% reduction in planktonic Candida albicans. The SNAP-fluconazole composites also showed biocompatibility against mouse fibroblast cells. This novel preventative strategy to combat bacterial and fungal infections may offer a promising tool for further translational research.

The development of high-mobility metal oxide semiconductor (MOS) thin-film transistors (TFTs) is of increasing interest. It is well-known that increasing the indium (In) concentration in MOS enhances the crystal volume fraction and mobility. However, the high carrier concentration resulting from a high In content induces TFT depletion mode and degrades device stability. Here, we introduce the incorporation of lanthanum (La) cation into the high-In-containing indium–gallium oxide (InGaO) films grown by spray pyrolysis at a substrate temperature of 375 °C. As the La ratio increases from 3 to 20%, La-incorporated InGaO (LaInGaO) experiences an elevation in both mass density and optical bandgap, but its crystallinity degrades. The coplanar LaInGaO TFTs, optimized with a La ratio of 7%, exhibit an average threshold voltage (V_TH) of 0.01 V, field-effect mobility of 30.63 cm² V^–1 s^–1, and a subthreshold swing of 0.23 V dec^–1. Moreover, compared to pristine InGaO TFTs, the bias temperature and photostability of 7% LaInGaO TFTs have been enhanced, resulting in shifts of V_TH under positive and negative bias temperature stresses, as well as negative illumination bias stress conditions by 0.2, 0.1, and −1.6 V, respectively. Additionally, the gate driver circuit employing 7% LaInGaO TFTs demonstrates fast rising and falling times of 437.3 and 557.9 ns, respectively. Therefore, the highly reliable 7% LaInGaO TFTs grown by spray pyrolysis can be utilized for large-area, cost-effective TFT electronics.

Designing a high-efficiency catalyst for the cathode oxygen reduction reaction (ORR) in fuel cells still faces enormous challenges due to the stringent requirements for high power density and long-term durability. Palladium (Pd) metallene, on account of its unique properties and high Pd utilization efficiency, is recognized as a prospective candidate for enhancing the ORR catalytic performance. Herein, we present atomic cobalt (Co)-doped Pd metallene (Co-Pdene), featuring an ultrathin and highly curved morphology, developed via a straightforward wet-chemical approach for efficient ORR electrocatalysis in alkaline media. Resulting from the metallene structure and transition metal Co doping, the Co-Pdene catalyst demonstrates exceptional electrocatalytic performance, achieving an electrochemical mass activity (MA) of 3.14 A per milligram palladium at 0.85 V while maintaining structural integrity over 30000 potential cycles. Theory simulations (DFT) manifest that the single-atom Co sites optimize the electronic structure of palladium in the Co-Pdene, thereby lowering the theoretical overpotential to 0.29 V. This work proposes an innovative design strategy of single-atom transition metal-doped Pd metallene as a highly efficient ORR electrocatalyst.

In this study, we investigated the effect(s) of side-chain length distribution on the transient elongational hardening behavior of polymer melts. For either entangled or unentangled systems, we successfully prepared a series of samples, poly(butyl methacrylate), poly(methyl methacrylate-co-hexyl methacrylate), and poly(methyl methacrylate-co-lauryl methacrylate), abbreviated as PBMA, P(MMA-co-HMA), and P(MMA-co-LMA), respectively, that have the same average length of side chains and similar weight-average molecular weight. These samples exhibited quite different nonlinear elongational behavior despite a similarity of their linear viscoelastic behavior. The transient strain hardening is enhanced on an increase of the side-chain length distribution, namely, in the order of PBMA < P(MMA-co-HMA) < P(MMA-co-LMA), consistently for either the unentangled or entangled series. Given this consistency, the detailed hardening behavior is different, where the unentangled samples exhibit thickening at the Rouse Weissenberg number Wi_R > 0.1 and thinning at the higher Wi_R > 1, which can be explained by a combination of the finite extensional nonlinear elasticity and the frictional reduction when chains are highly stretched and coaligned. The degree of friction reduction relies on the length distribution according to the interpenetration of side chains. In comparison, the entangled samples exhibit consistent thinning even when Wi_R is lower than one, which is attributable to the concurrence of the flow-induced disentanglement.

Heavy metal pollutants, such as Cu²⁺, pose significant environmental and health risks due to their toxicity and persistence in water systems. Simultaneously, the increasing accumulation of waste poly(ethylene terephthalate) (PET) bottles represents a growing environmental challenge, contributing to plastic pollution. This study addresses both issues by converting waste PET bottles into porous activated carbon (APC) via pyrolysis, creating an efficient and sustainable adsorbent for Cu²⁺ removal from aqueous solutions. The APC materials were thoroughly characterized by SEM, BET, and XPS analyses, revealing a highly porous structure and abundant oxygen-containing functional groups, which enhance Cu²⁺ adsorption. The adsorption process was determined to be spontaneous, with a low activation energy of 7.47 kJ/mol, indicating a favorable and energy-efficient adsorption mechanism. Among the APC samples, APC-800 exhibited the best performance, achieving a Cu²⁺ removal efficiency of 99.30% and a maximum adsorption capacity of 5.85 mg/g. Recyclability tests confirmed the material’s durability, maintaining over 96% efficiency during the first three cycles, with a slight decline in later cycles. This study demonstrates a dual environmental benefit: mitigating plastic waste by repurposing PET bottles and providing an effective solution for heavy metal pollution, aligning with circular economy principles, and promoting sustainability in environmental management.