Latest ArticlesPhomaketals A (1) and B (2), two tropolonic meroterpenoids with the unprecedented pentacyclic skeletons, were isolated from the solid-substrate fermentation cultures of a eupC overexpressed mutant strain of the fungus Phoma sp., together with a biogenetically related secondary metabolite pughiinin B (3), and the known one noreupenifeldin B (4). The structures of 1–3 were elucidated primarily by nuclear magnetic resonance (NMR) experiments. The absolute configurations of 1 and 2 were assigned by electronic circular dichroism calculations and the calculated NMR with DP4+ analysis, while that of 3 was established by single-crystal X-ray diffraction analysis using Cu Kα radiation. Biogenetically, phomaketals A (1) and B (2) could be derived from the hypothetical tropolonic sesquiterpene intermediates neosetophomone B (6) and 9-R-neosetophomone B (6′), respectively, via different reactions cascades. Compound 1 showed antiproliferative effect only against the SUPB15 cells, with an 50% inhibitory concentration (IC50) value of 4.85 µmol/L, while the co-isolated known meroterpenoid 4 displayed potent effects against three tumor cell lines, SUPB15, EL4, and H9, showing IC50 values of 0.36–27.08 µmol/L.
Lithium-sulfur (Li-S) batteries with high theoretical capacity and energy density need to solve problems such as the high decomposition energy barrier of Li2S and large volume change of sulfur in the charging process caused by the shuttle effect before practical application. Herein, a green synthesis method is used to prepare polyacrylic acid (PAA) superabsorbent material, and then the pyrolyzed PAA (P/PAA) material is obtained as the positive electrode of Li-S battery. Density functional calculation reveals that the oxygen self-doping pyrolyzed polyacrylic acid (P/PAA) delivered stronger binding energy toward Li2S species in carbonyl C=O than that of graphite powder (GP) which are −1.58 eV and −1.02 eV, respectively. Coupled with the distribution of relaxation time analysis and the in-situ electrochemical impedance approach, it is further demonstrated that the designed P/PAA as sulfur host plays a physical/chemical adsorption dual function in maintaining the stability and rate performance of batteries. With an initial discharge capacity of 1258 mAh/g at 0.1 C and a minimal capacity decline of 0.05% per cycle even after 800 cycles at 0.5 C, the produced cathode demonstrated outstanding electrochemical performance. The average Coulombic efficiency is nearly 100%. The P/PAA electrodes may typically retain 96% of their capacity while declining on average only 0.033% per cycle after 130 cycles at 3 C. This effort provides a new method for the future development of heteroatomic self-doping superabsorbent with promising adsorption properties for polysulfides as cathode materials of Li-S batteries.
Diatomic-site catalysts (DASCs) have emerged as a kind of promising heterogeneous candidate catalysts for electrochemical CO2 reduction (ECR), which is considered to retain the advantage of single-atom catalysts (SACs) but also introduce opportunities to exceed the limit of single-atom catalysts. In the past few years, tremendous progress has been achieved in this field. Herein, the recent progress in ECR on DASCs has been summarized. It will start with the classification of DASCs. Then the challenges in the precise fabrication and characterization of DASCs have been emphasized. By introducing the advanced ECR performance on DASCs, superior to that on SACs, the synergistic effects of the dual metal atoms are highlighted, as this origin of the advanced ECR performance on DASCs is comprehensively summarized. Finally, the major challenges and perspectives of DASCs have been proposed to shed light on the development of DASCs for ECR application.
Fungal alkylresorcinols are a class of polyketides, which are commonly synthesized by the hybridization of highly reducing polyketide synthase (hrPKS) with non-reducing polyketide synthase (nrPKS). In this study, we identified and demonstrated a new assembly model for synthesizing alkylresorcinol (scirpilin A, 1), which was accomplished by collaboration of a hrPKS (FscA) and a type Ⅲ PKS (FscB). Furthermore, three post-tailoring enzymes (FscC, FscD, and FscE) act iteratively on 1 skeleton, including successive 14e− oxidation of inert carbons, di-halogenation, and di-methylation, to form highly oxidized and multi-substituted alkylresorcinols. Our work presents an unusual synthesis manner of alkylresorcinols, sheds light on the collaborative mechanism between hrPKS and type Ⅲ PKS and provides three valuable enzymatic catalysts for the tailoring of alkylresorcinol family natural products in future.
Two-dimensional (2D) mesoporous pseudocapacitive polymer/graphene heterostructures combine the advanced merits of 2D materials and mesoporous materials, possessing unique nanosheet structure, large specific surface area (SSA), abundant oxygen/nitrogen-containing groups, desirable electrical conductivity and admirable electrochemical redox activity, and hold great potential for constructing high-performance planar micro-supercapacitors (MSCs). Herein, we demonstrate the interfacial assembly of 2D mesoporous polydopamine/graphene (mPDG) heterostructures with well-defined mesopore structure (12 nm) and adjustable thickness (7.5–14.1 nm) for planar high-energy pseudocapacitive MSCs. Attributed to medium thickness, exposed mesopore of 12 nm and large SSA of 108 m2/g, the mPDG with 10.8 nm thickness reveals prominent mass capacitance of 419 F/g and impressive cycling stability with ~96% capacitance retention after 5000 cycles. Furthermore, the symmetric mPDG-based MSCs with "water-in-salt" gel electrolyte present wide voltage window of 1.6 V, superior volumetric energy density of 11.5 mWh/cm3, outstanding flexibility and self-integration ability. Therefore, this work offers a new platform of controllably synthesizing 2D mesoporous heterostructures for high-performance MSCs.
With the increasing emergence of bacterial infections, especially multidrug-resistant (MDR) bacteria, poses an urgent threat. This study demonstrated a novel multifunctional nanotheranostics platform developed by the strategic integration of both in-situ bio-assembly imaging and target bacteria inactivation. Through the introduction of copper ions into bacteria, the Cu2+ could spontaneously bio-self-assembled into a multifunctional copper nanoclusters (NCs) which efficiently enhanced epigallocatechin gallate (EGCG) uptake into bacteria. While visualizing the bacteria, the developed theranostic nanoplatform exhibited highly efficient disinfection activities with negligible side effects as reflected by higher cell viability and insignificant hemolytic effects. Furthermore, the exosomal formulation of EGCG integrated with Cu2+ showed an increased intracellular antibacterial activity, which could eliminate most of the methicillin-resistant Staphylococcus aureus (MRSA) phagocytosed by macrophages, guide macrophages toward M2-like phenotype polarization and alleviate inflammation, without exhibiting obvious cytotoxicity on host RAW264.7. The regimen could be viewed as an effective strategy for the sterilization of intractable bacterial infections.
Biomacromolecules are attractive in biomedical applications as therapeutic agents and potential drug carriers due to their natural active components, good biocompatibility, and high targeting. However, their large relative molecular weight, complex structure, susceptibility to degradation, and poor stability limit their usefulness. Nanotechnology can address these issues by improving the therapeutic value, bioavailability, permeability, and absorption of biomacromolecules while regulating their retention time in the body. Especially, compelling evidence has been reported that supercritical fluid (SCF) technology has emerged as an alternative that maintains the integrity of biomacromolecules and reduces environmental contamination. In this review, we highlight a set of unique nanosizing strategies based on SCF technology for biomacromolecular nanomedicine, and extensively discuss their characteristics and mechanisms. In particular, the protein-based, nucleic acid-based, and polysaccharide-based nanomedicine preparations via SCF technology and their biomedical applications are summarized, and the potential for industrial production of biomacromolecular drugs is also considered. We further provide perspectives on the opportunities and challenges in this excellent field of biomacromolecular drugs nanotechnology.
The steep reduction in costs and systematic optimization of renewable electricity has ignited an intensifying interest in harnessing electroreduction of carbon dioxide (CO2RR) for the generation of chemicals and fuels. The focus of research over the past few decades has been on the optimization of the electrode and the electrolyte environment. Notably, cation species in the latter have recently been found to dramatically alter the selectivity of CO2RR and even their catalytic activity by multiple orders of magnitude. As a result, the selection of cations is a critical factor in designing catalytic interfaces with high selectivity and efficiency for targeted products. Informed decision-making regarding cation selection relies on a comprehensive understanding of prevailing electrolyte effect models that have been used to elucidate observed experimental trends. In this perspective, we review the hypotheses that explain how electrolyte cations influence CO2RR by mechanisms such as through tuning of the interfacial electric field, buffering of the local pH, stabilization of the key intermediates and regulation of the interfacial water. Our endeavor is to elucidate the molecular mechanisms underpinning cation effects, thus fostering the evolution of more holistic and universally applicable predictive models. In this regard, we highlight the current challenges in this area of research, while also identifying potential avenues for future investigations.
The preparation of hydrogel adsorbents with admirable performance for efficient selective remove Pb(Ⅱ) in complex wastewater still remains a great challenge. Herein, a novel bifunctional modified polymer hydrogel PAM-PAMPS was prepared by crosslinking acrylamide (AM) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS). Compared with PEG, PAA and PAMPS, PAM-PAMPS exhibited both the maximum adsorption capacity of Pb(Ⅱ) (541.90 mg/g) and satisfactory selectivity for Pb(Ⅱ) in multiple heavy metal ions coexistence solutions. Various characterizations indicated that SO3H and NH2 as active sites on PAM-PAMPS occur the synergistic effects of ion-exchange and coordination with Pb(Ⅱ) during the adsorption process, respectively. The adsorption energy Ead(PAM-PAMPS) obtained from density functional theory (DFT) calculations was lower than the other three hydrogels, manifesting that PAM-PAMPS formed the most stable complex with Pb(Ⅱ), which further demonstrated that Pb(Ⅱ) preferred to combine with PAM-PAMPS to selective capture of Pb(Ⅱ). The practice utilization of PAM-PAMPS was assessed by wastewater of electroplate containing Pb(Ⅱ). Meanwhile, the removal ratio of PAM-PAMPS was maintained at about 89% after 4 adsorption-desorption cycles. This study establishes a new and effective idea for the design and fabrication of bifunctionalized modified polymer hydrogels.
Constructing composited electrode material is considered to be an efficient strategy to improve their electrochemical performance. It can accelerate the charge transfer speed of ions and enhance the conductivity of electrode. Meanwhile, the formation of the hybrid structure can largely avoid the aggregation of two dimensional materials and increase the electrochemical active area of the electrode. In this work, we synthesize NiMoSSe electrode materials on nickel foam by a facile hydrothermal avenue. The prepared composite shows a specific capacitance of 1035 C/g at 1 A/g due to the synergistic effect between MoS2 and MoSe2 phases. In addition, the devices are assembled with NiMoSSe samples, which offers an energy density of 82.71 Wh/kg at a power density of 2700 W/kg.
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