ACS Publications最新文献

Highly π-conjugated self-assembly of organic semiconductors near gate dielectrics is important for achieving high performance in organic thin film transistors (OTFTs). This paper reports that a preexisting N,N-ditridecyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C₁₃) monolayer (ML) on a polymer-passivated silicon oxide dielectric stimulates the 2D crystal growth of the same ad-molecules during subsequent film deposition, resulting in a dramatic enhancement of the π-conjugated structure with suppressed grain boundaries. The crystal template-mediated PTCDI-C₁₃ films could develop layered crystallites with highly intermolecular ordering of edge-on semiconductor molecules perpendicular to the substrate. The crystal reorganization of PTCDI-C₁₃ deposited on the ML-thick crystal template drove the 2D crystal growth of a semiconductor on a heterointerface instead of 3D crystal growth. The charge carrier mobility along the template-mediated crystal grains within a 40 nm-thick film was up to 2.70 cm² V^–1 s^–1, 4 times higher than the 0.68 cm² V^–1 s^–1 in the ordinary polycrystalline domains developed directly at a heterointerface. Thus, using the predeposited crystal templates may be a good strategy to control the crystal structure and obtain high-quality organic thin films by vacuum deposition or orthogonal solvent film procedures.

In immunotherapy for malignant tumors, the dysregulation of the balance between effector T cells and regulatory T cells (Tregs) and the uncertain efficacy due to individual differences have been considered as two critical challenges. In this study, we engineered an injectable nanocomposite hydrogel system (SNAs@M-Gel) capable of suppressing Treg proliferation and blocking PD-1/PD-L1-mediated immune evasion effectively, achieved through the stimulus-responsive modulation of multiple tumor-associated microRNAs. Simultaneously, this system enables microRNA-dependent photothermal immunotherapy, facilitating a highly efficient and personalized approach to tumor treatment. Specifically, oxidized sodium alginate (OSA) and cancer cell membrane (CCM)-encapsulated spherical nucleic acid nanoparticles (SNAs@M) were used to construct the SNAs@M-Gel hydrogel in situ at the tumor site through the formation of pH-sensitive Schiff base bonding and cross-linking using endogenous calcium ions (Ca²⁺). During treatment, SNAs@M-Gel was retained locally for up to 10 days, and SNAs@M nanoparticles were continuously released into the tumor microenvironment. Through the targeting ability of CCM, SNAs@M precisely entered tumor cells and specifically hybridized with the overexpressed miR-214 and miR-130a, leading to a significant downregulation of PD-L1 expression on tumor cells and the restoration of cytotoxic T lymphocyte (CTL) function suppressed by Tregs, thereby remodeling the immune microenvironment. In addition, miRNAs functioned as cross-linking agents, facilitating the aggregation of SNAs and allowing the localized production of photothermal agents directly inside tumor cells, which, under near-infrared (NIR) irradiation, promoted highly selective photothermal therapy. This cascade of events not only led to the destruction of the primary tumor but also resulted in the release of a substantial number of tumor-related antigens, which triggered the maturation of adjacent dendritic cells (DCs) and subsequent priming of tumor-specific CTLs, while simultaneously depleting Tregs, thereby reversing the tumor-promoting immune microenvironment and enhancing the overall therapeutic efficacy of photothermal immunotherapy.

Natural polyphenols can be oxidized into reactive quinones, which might play a key role in the removal of specific contaminants in natural polyphenol-related advanced oxidation processes (AOPs). In this study, peracetic acid (PAA) was employed in combination with natural protocatechuic acid (PCA) to remove sulfonamide antibiotics (SAs) from water. More than 95% removal of sulfamethoxazole (SMX) and other SAs was observed in the PCA/PAA system, and neutral pH conditions (5.0–8.0) were more conducive to the removal of SMX. The PCA/PAA system exhibited a great anti-interference ability against complex water matrices. ortho-Quinone, generated from the oxidation of PCA by PAA, played a dominant role in the SMX removal. Electrons tended to transfer from SMX to the generated ortho-quinones and form covalent bonds, resulting in the production of less toxic oligomers via the overlooked polymerization pathway. A reduction in the toxicity of the SMX solution was found following treatment with the PCA/PAA system. More interestingly, several polyphenols structurally related to PCA could also facilitate SMX removal using PAA as the oxidant. Overall, this study proposes a novel strategy for developing reactive quinones dominated AOPs with robust anti-interference performance, as well as enhances the understanding of contaminant removal via an overlooked polymerization pathway in natural polyphenol-related AOPs.

This study explores the endo-levanase from Bacillus licheniformis (LevB1), providing new insights into how this enzyme selectively hydrolyzes levan chains. By analyzing the first resolved crystal structure of LevB1, conducting detailed simulations, and comparing it to other endo- and exo-fructanases, we identified key factors underlying its specificity. Experiments designed to explore this specificity revealed the critical role of three minus and three plus subsites in determining the enzyme’s endo-specificity. We identified six specific subsites essential for the enzyme’s ability to cleave levan chains at random internal linkages (endo-specificity) rather than at defined fructosyl nonreducing ends (exo-specificity). This research underscores the importance of enzyme–fructan interaction stability during the catalytic reaction in this process, highlighting the need for dynamic modeling to fully capture enzyme specificity, as conventional docking alone cannot fully explain the stability and motion of carbohydrate chains in the catalytic site. These findings contribute to a deeper understanding of the factors that influence endo- and exo-cleavage specificity in levan and inulin polymers, with broader implications for fructan metabolism and, eventually, the industrial production of fructose and/or fructo-oligosaccharides.

The role of endophytic bacterial communities in aiding the degradation of organic pollutants like phthalates (PAEs) in soil and in planta, as well as their effects on pollutant accumulation in plants, remains unclear. Herein, microcosm experiments were conducted with rice cultivated in agricultural soil polluted with di(2-ethylhexyl) phthalate (DEHP) and further verified with PAE-degrading endophytic consortia. Soil indigenous microbes, especially PAE-degrading bacteria, significantly contributed to DEHP dissipation in soil and diminished DEHP accumulation in rice. Endophytic bacterial communities participated in DEHP degradation in planta, as validated by efficient DEHP degradation by in vitro culturable endophytic consortia and abundant PAE-degrading genes. The inoculation of PAE-degrading endophytic consortia demonstrated their immigration between soil and roots (especially in low-PAE-accumulating cultivar), which enhanced DEHP degradation in soil and in planta and subsequently reduced rice PAE accumulation. This study underscores the facilitative role of endophytic bacterial communities in PAE degradation and in lowering PAE accumulation in crops.

The shift toward a circular economy has increased efforts to derive valuable chemicals from renewable resources, including chitin-rich waste. Mushroom cultivation generates significant waste, particularly the stalks left behind on breeding beds, which contain a substantial amount of chitin with untapped potential. This research establishes a proof of concept for valorizing this waste stream by converting it into valuable chitin oligosaccharides, which have applications across food, feed, agriculture, and pharmaceuticals. Using a combined approach of enzymatic saccharification with five chitinolytic enzymes, followed by precision fermentation of the resulting N-acetyl-d-glucosamine (GlcNAc), we successfully produced defined chitinpentaose. Chitin extracted from Agaricus bisporus brown demonstrated the highest saccharification efficiency, achieving a GlcNAc conversion of 31 ± 1% (w/w). Our findings highlight the necessity of purifying the saccharification product to ensure product specificity during fermentation, although the production strain’s growth remained suboptimal compared to commercially available GlcNAc. Using an engineered E. coli strain, we achieved pure chitinpentaose, with a yield of 0.0327 g/L at a 10 mL scale and production levels (g/OD₆₀₀) comparable to those obtained with HPLC-grade commercial GlcNAc. This study provides a foundation for further research aimed at improving biocatalyst recycling and optimizing the growth phase, thereby enhancing the cost-efficiency and scalability of this sustainable bioconversion process.

Medical catheters require lubrication and antimicrobial properties to reduce complications, such as tissue trauma and bacterial infections. Coating hydrogel on the catheter surface is a promising strategy; however, it usually faces the challenge of weak interfacial adhesion, thus leading to coating delamination or fracture and failure. Here, a waterborne polyurethane (WPU)-triggered surface bonding strategy was presented to construct hydrogel coatings, which involved two key steps: (i) coating a sticky WPU layer on the catheter surface and (ii) dip-coating the WPU-coated catheter with a monomer solution consisting of quaternary ammonium chitosan (QCS), sulfobetaine methacrylate (SBMA), N-vinylpyrrolidone (NVP), and zinc sulfate heptahydrate (ZnSO₄·7H₂O) for growing the hydrogel layer by ultraviolet initiation. The hydrogel coating demonstrated tough adhesion performance to the catheter, and the interfacial bonding strength achieved 536 N/m. Meanwhile, the hydrogel coating had a variable thickness adjusted by QCS and possessed excellent hydrophilicity (WCA = 24.6°) and low surface friction properties (COF = 0.0357) based on the formation of the hydration layer. Furthermore, the introduction of ZnSO₄·7H₂O endowed the hydrogel coating with prominent antimicrobial properties against Escherichia coli (Gram-negative bacteria) and Bacillus subtilis (Gram-positive bacteria). This approach paves an avenue for fabricating hydrogel coatings with strong interface stability, controllable thickness, lubrication, and antibacterial properties.

Chiral spirocyclic oxetanes [2-oxo-spiro(3H-indole-3,2′-oxetanes)] were subjected to irradiation in the presence of a chiral thioxanthone catalyst (5 mol %) at λ = 398 nm. An efficient kinetic resolution was observed, which led to an enrichment of one oxetane enantiomer as the major enantiomer (15 examples, 37−50% yield, 93−99% ee). The minor enantiomer underwent decomposition, and the decomposition products were carefully analyzed. They arise from a photocycloreversion (retro-Paternò–Büchi reaction) into a carbonyl component and an olefin. The cycloreversion offers two cleavage pathways depending on whether a C−O bond scission or a C−C bond scission occurs at the spirocyclic carbon atom. The course of this reaction was elucidated by a suite of mechanistic, spectroscopic, and quantum chemical methods. In the absence of a catalyst, cleavage occurs exclusively by initial C−O bond scission, leading to formaldehyde and a tetrasubstituted olefin as cleavage products. Time-resolved spectroscopy on the femtosecond/picosecond time scale, synthetic experiments, and calculations suggest the reaction to occur from the first excited singlet state (S₁). In the presence of a sensitizer, triplet states are populated, and the first excited triplet state (T₁) is responsible for cleavage into an isatin and a 1,1-diarylethene by an initial C−C bond scission. The kinetic resolution is explained by the chiral catalyst recruiting predominantly one enantiomer of the spirocyclic oxindole. A two-point hydrogen-bonding interaction is responsible for the recognition of this enantiomer, as corroborated by NMR titration studies and quantum chemical calculations. Transient absorption studies on the nanosecond/microsecond time scale allowed for observing the quenching of the catalyst triplet by either one of the two oxetane enantiomers with a slight preference for the minor enantiomer. In a competing situation with both enantiomers present, energy transfer to the major enantiomer is suppressed initially by the better-binding minor enantiomer and─as the reaction progresses─by oxindole fragmentation products blocking the binding site of the catalyst.

Dynamic organic phosphorescent materials present great potential for practical applications. But the temperature-sensitive nature of organic phosphors makes the development of high-temperature dynamic organic phosphorescence (HTDOP) a significant challenge. Herein, we report a HTDOP system assembled from β-cyclodextrins (β-CDs) and 4-diphenylamino-benzoic acid (TPAC). The TPAC@β-CDs complex system exhibits only short-lived fluorescence at room temperature but transitions to phosphorescence emission with an ultralong emission lifetime of up to 567 ± 13 ms upon heating. A mechanistic study combining spectroscopic analysis, ¹H NMR, and Fourier Transform Infrared Spectroscopy revealed that the intermolecular hydrogen bonding interactions effectively suppressed nonradiative relaxation of triplets even at temperature as high as 140 °C. Meanwhile, elevated temperatures also drive oxygen out of the system, significantly reducing quenching processes and ensuring the robust survival of HTDOP. Additionally, the introduction of fluorescent dyes permits color regulation of the afterglow from green to red through Förster resonance energy transfer from the triplet to the singlet state. Moreover, this system’s fast and reliable response upon high temperature makes it an excellent candidate for overtemperature trace detection in electronic components and circuit diagnostics. This work discloses an effective strategy for constructing HTDOP systems that can be fully exploited in a range of fields.

In this work, we present two alternative computational strategies to determine the populations of nonbonded aggregates. One approach extracts these populations from molecular dynamics (MD) simulations, while the other employs quantum mechanical partition functions for the most relevant minima of the multimolecular potential energy surfaces (PESs), identified by automated conformational sampling. In both cases, we adopt a common graph-theory-based framework, introduced in this work, for identifying aggregate conformations, which enables a consistent comparative assessment of both methodologies and provides insight into the underlying approximations. We apply both strategies to investigate phenol aggregates, up to the tetramer, at different concentrations in phenol/carbon tetrachloride mixtures. Subsequently, we simulate the concentration-dependent OH stretching IR region by averaging the harmonic Infrared (IR) spectra of aggregates using the populations predicted by each strategy. Our results indicate that the populations extracted from MD trajectories yield OH stretching signals that closely follow the experimental trends, outperforming the spectra from populations obtained by systematic conformational searches. Such a better performance of MD is attributed to a better description of the entropic contributions. Moreover, the proposed protocol not only successfully addresses a very challenging problem but also offers a benchmark to assess the accuracy of the intermolecular force fields.