Latest ArticlesAqueous rechargeable Zn//MnO2 batteries have been considered as the promising candidate for future energy storage system due to their economic and environmental merits. However, the high-performance Zn//MnO2 batteries are plagued by poor sluggish reaction kinetics and capacity degradation due to the strong electrostatic interactions and complicated reaction process. Herein, the synergistic effect of atom defects engineering and phase transformation mechanism is confirmed as the effective strategy to enhance ion/charge transfer kinetics and structural stability. Defects gradient controlling and electrochemically induced phase transformation from spinel to layered structure render the aqueous Zn//λ-MnO2 system delivers a high discharge capacity of 285 mAh/g and capacity retention of 81% after 500 cycles.
The most practical high-temperature proton exchange membranes (PEMs) are phosphoric acid (PA)-doped polymer electrolytes. However, due to the plasticizing effect of PA, it is a challenge to address the trade-off between the proton conductivity and the mechanical performance of these materials. Here, we report an effective strategy to fabricate robust high-temperature PEMs based on the in situ electrostatic crosslinking of polyoxometalates and polymers. A comb copolymer poly(ether-ether-ketone)-grafted-poly(2-ethyl-2-oxazoline) (PGE) with transformable side chains was synthesized and complexed with H3PW12O40 (PW) by electrostatic self-assembly, forming PGE/PW nanocomposite membranes with bicontinuous nanostructures. After a subsequent PA-treatment of these membranes, high-temperature PEMs of PGE/PW/PA ternary nanocomposites were obtained, in which the in situ electrostatic crosslinking effect between PW and PGE side chains was generated in the hydrophilic domains of the bicontinuous structures. The microphase separation structure and the electrostatic crosslinking feature endow the PGE/PW/PA membranes with excellent anhydrous proton conductive ability while retaining high mechanical performance. The membranes show a high proton conductivity of 42.5 mS/cm at 150 ℃ and a high tensile strength of 13 MPa. Our strategy can pave a new route based on electrostatic control to design nanostructured polymer electrolytes.
Isostructural multicomponent crystals provide a promising way for fine-tuning physicochemical properties, whereas their design remains quite challenging. The purpose of this work was to provide a new strategy for obtaining isostructural multicomponent crystals by introducing coformers with functional group positional isomerism. Five isostructural salts of an antitumor drug dimethylaminomicheliolide (DMAMCL) were reported and designed with a series of dihydroxybenzoic acid regioisomers for the first time, which were identified by power and single-crystal X-ray diffractions. Similar lattice parameters suggested these obtained salts may have the same crystal packing mode. The quantitative similarity parameters via XPac, CrystalCMP and Mercury program further proved these crystal structures are 3D isostructural. Hirshfeld surface maps and 2D fingerprint plots show that the isostructural salts have similar intermolecular interactions. Compared with DMAMCL, obvious improvement was observed in the thermal stability, hygroscopicity, and solubility of these isostructural salts. Meanwhile, isostructural crystals may have different physicochemical properties, even though the shape and molecular size are similar and the packing of crystal structures is equally matched.
Acetaminophen (APAP), a classic nonsteroidal anti-inflammatory drug (NSAID), has attracted much attention due to the overdose-induced hepatotoxicity in the past several decades. N-Acetyl-p-benzoquinone imine (NAPQI), the P450-dependent metabolism of APAP, leads to GSH depletion, protein binding, mitochondrial oxidative stress, and eventually the liver injury. Herein, we develop a Fe-based metal-organic framework (MOF) to deliver and transform acetaminophen into toxic "chemo" drug through the cascade reaction for enhanced cancer therapy. In the acidic tumor microenvironment, the Fe-based MOF collapses and releases abundant Fe ions to generate hydroxyl radicals (•OH) via Fenton reaction, subsequently catalyzing nontoxic APAP into toxic NAPQI. Meanwhile, NAPQI depletes intracellular glutathione (GSH) rapidly, leading to alleviating the antioxidant ability of cancer cells and amplifying Fenton activity. The intracellular oxidative stress and the toxic metabolite of APAP can provide a synergistic effect on antitumor activity.
Exosome, which is a kind of extracellular vesicles with size around 40-160 nm, plays an important role in cell-to-cell communication in multiple diseases. Especially in tumor microenvironment, exosomes are the important pathway to transit proteins, nucleic acids and small molecules between different kinds of cells. Based on these characteristics, exosomes are served as both therapeutic agents and drug delivery systems in cancer therapy. In this review, the applications of exosomes as drug delivery systems in cancer therapy were summarized and classified according to the cell source of the exosomes, including normal cells, immune cells and tumor cells. Different modifications of exosomes and drug loading methods were presented. Finally, some challenges that hindered the clinical translation of exosomes were also discussed.
Three kinds of carbonized polymer dots (CPDs) synthesized via a one-pot process from o-phenylenediamine (OPD), m-phenylenediamine (MPD) and p-phenylenediamine (PPD) exhibit excitation-wavelength independent yellow, green and red emissions, respectively. In sharp contrast, two kinds of CPDs prepared via a hydrothermal process from citric acid (CA) and diethylenetriamine (DETA) exhibit obvious excitation-wavelength dependent emissions. Through the characterization and comparison of the two types of CPDs, it is concretely revealed that the polymer structure types during the formation of CPDs can effectively control the fluorescence excitation-wavelength independence/dependence. The homogeneous polymer structures contained in CPDs contribute to excitation-wavelength independence, whereas random copolymer structures contribute to excitation-wavelength dependence. These studies are of great significance for further understanding the polymer structures and designing unique optical properties of CPDs.
The serum cholesterol level is an important indicator of healthy and there is a great necessity for frequent cholesterol monitoring to some cardiovascular-related diseases, which puts forward higher requirements for point-of-care testing (POCT) of cholesterol. In this work, a cascade catalytic system of cholesterol is developed by encapsulation of cholesterol oxidase (ChOx) and PdCuAu nanoparticles into zeolitic imidazolate framework-L (ChOx/PCA@ZIF-L). Results indicate that ZIF-L carrier can significantly increase the catalytic activity of single or multiple enzymes, due to its high loading capacity and efficient molecular transport. Under the optimal conditions, the absorbance of reaction system performs linear relationships with the concentration of cholesterol in two intervals from 0.0005 mmol/L to 1.0000 mmol/L, with a limit of detection of 0.2176 µmol/L. The proposed colorimetric strategy based on ChOx/PCA@ZIF-L performs a good agreement with the results provided by chemiluminescence method for the serum cholesterol detection. Interestingly, a simple paper-based sensing system is constructed through a pre-reaction-transfer operation, which gets rid of the complex pre-processing requirements of traditional operations on filter paper. The presented strategy allows for the sensitive, convenient, costless assay of serum cholesterol, and paves a new way to design the POCT device for daily monitoring of healthy.
Eight polycyclic furanobutenolide-containing norcembrane diterpenoids featuring C19 frameworks (1–8) were rapidly recognized and isolated from the Hainan soft coral Sinularia sp. by the HSQC-based small molecule accurate recognition technology. Yonarolide A (1a), featuring an unprecedented 5/6/4/4/7 pentacyclic ring skeleton, was surprisingly obtained as a transformed product by leaving compound 1 under indoor natural light, and was further proved to be a [2 + 2] cycloaddition product of 1 by photochemical reaction. The absolute stereochemistry of 1a and the three known norcembrane diterpenoids 1, 4, and 7 were determined by using X-ray diffraction (XRD) analyses. Further, with the aid of XRD analysis, the structure of scabrolide B (2), which was previously reported of possessing 5/6/7 tricyclic skeleton, was firmly revised as 2a with the rare inelegane skeleton featured by the highly oxygenated 5/7/6 tricyclic carbocycle.
Hawanoids A‒E (1‒5), five highly cyclized diterpenoids were isolated from the deep-sea-derived fungus Paraconiothyrium hawaiiense FS482. Compounds 1 and 2 possessed an unprecedented tetracyclo[6.6.2.02,7.011,15]cetane carbon skeleton while 3 and 4 possessed an unusual 11, 14-macrocyclic ether moiety in phomactin family. Their structures including the stereo-chemistry were determined through spectroscopic analysis, X-ray diffractions and computational calculations. The plausible biosynthetic pathway was proposed based on the predicted biosynthetic gene cluster. All of the isolated compounds exhibited inhibitory activities against PAF-induced platelet aggregation. The molecular docking study was carried out understand the interaction between the PAF receptor and hawanoids with different skeletons.
From ZINC database with a total of 1.8 million small molecules, four compounds are identified as prolyl hydroxylase 2 inhibitors through a virtual screening workflow that sequentially incorporates machine learning, molecular docking, and molecular dynamics. Among them, compound 103, (E)-5-(5-((2-(1H-tetrazol-5-yl)hydrazineylidene)methyl)furan-2-yl)isoindoline-1,3-dione, promotes the migration and capillary tube formation capacity of human umbilical vein endothelial cells through enhancing the stability of hypoxia inducible factor-1α and increasing the level of vascular endothelial growth factor.
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