Latest ArticlesAs an emerging star in the family of two-dimensional (2D) materials, 2D transition metal carbides, carbonitrides and nitrides, collectively referred to as MXenes, have large specific surface area, rich active sites, metallic conductivity and adjustable surface chemical properties. These features make MXenes promising candidates for gas-sensing materials. For the past few years, MXene-based sensors have drawn increasing attention due to their enhanced sensor performance. Based on this, this review systematically represents the structure, synthesis methods and properties of MXenes, and summarizes their applications in gas sensors. Firstly, the types, structure, main synthesis methods and properties of MXenes are introduced in a comprehensive way. Next, the corresponding design principle and working mechanism of MXene-based gas sensor are clarified. Subsequently, the sensing performances of pristine MXenes and the MXene-based nanocomposite are discussed. Finally, some future opportunities and challenges of MXene-based sensors are pointed out.
Aqueous rechargeable ammonium-ion batteries (AIBs) have drew considerable attention because of their capacity for high rates, low cost, and high safety. However, developing desired electrodes requiring stable structure in the aqueous fast ammoniation/de-ammoniation becomes urgent. Herein, an ammonium ion full battery using Cu3[Fe(CN)6]2 (CuHCF) acting to be a cathode and barium vanadate (BVO) acting to be an anode is described. Its excellent electrochemical behavior of Prussian blue analogs and the perfectly matched lattice structure of NH4+ is expected. And the open structure of vanadium compounds satisfies the fast ammoniation/de-ammoniation of NH4+ is also achieved. As a result of these synergistic effects, the BVO//CuHCF full cell retains 80.5 percent of its capacity following 1000 cycling. These achievements provide new ideas for developing low-cost and long-life AIBs.
Polycyclic aromatic hydrocarbons (PAHs) play an important role in the industry, and the development of new materials for the selective separation of PAHs is of great significance. In this work, we report a hexahedral metal-organic cage with low symmetry by subcomponent self-assembly. In this cage, the eight ZnⅡ centers adopt an interesting ΛΛ/ΔΔΔΔΔΔ or ΛΛΛΛΛΛ/ΔΔ configuration. This cage with a cavity volume of 520 Å3 can bind anthracene, phenanthrene, and pyrene to form 1:1 host-guest complexes, while the bigger triphenylene, chrysene, perylene, and coronene cannot be encapsulated. The binding constant Ka of pyrene is about 1.110 × 103 (mol/L)−1, which is more than an order of magnitude larger than that of anthracene and phenanthrene (111 (mol/L)−1, 277 (mol/L)−1, respectively). X-ray structure studies reveal that the pyrene is located in the cavity and stabilized by multiple CH⋅⋅⋅π interactions. After separation from a mixture of PAHs, pyrene with > 96.1% purity can be obtained. This work provides a useful method for the first time for the selective separation of pyrene from PAHs mixture by utilizing a metal-organic cage as the material, making it a useful tool for purifying and separating specific compounds from complex mixtures.
Inflammatory bowel disease (IBD) is a refractory chronic intestinal inflammatory disease caused by a malfunction of immune system. As the key immune cells in the intestine, macrophages play an important role in maintaining intestinal homeostasis and tissue repair of the IBD. Pharmacological modulation of macrophage function exhibits the promising therapeutic effect for IBD. In this study, mannose-modified liposomes (MAN-LPs) are prepared for macrophage targeting to improve therapeutic efficiency. Rosiglitazone (ROSI) as an agonist of peroxisome proliferators-activated receptor γ (PPAR-γ) is used as the model drug to fabricate different sized liposomes. The impacts of mannose modification and particle size for macrophage targeting are investigated in cells, zebrafish, and mouse models and the therapeutic effects of the MAN-LPs are evaluated on dextran sulfate sodium (DSS)-induced IBD mouse. Compared to unmodified liposome, MAN-LPs display higher uptake by RAW 264.7 cells and better co-localization with macrophage in zebrafish model. Furthermore, MAN-LPs could effectively accumulate in the inflammatory intestinal sites in IBD mouse model. Most importantly, the targeting ability of MAN-LPs is obviously enhanced with the increasing of particle size, whereas the largest MAN-LPs particles achieve the best anti-inflammatory effect in cells, and a higher therapeutic efficiency in IBD mouse model. Therefore, mannose-modified liposome is a promising strategy for macrophage-targeting in IBD treatment. Particle size of MAN-LPs will affect macrophage targeting ability, as well as the therapeutic effect in-vivo.
Viruses are ubiquitous in human life. Some viruses can be used as vectors of genetic engineering and specific pesticides. Other viruses trigger a variety of diseases in humans, animals and plants, resulting in high infection rates and mortality. Therefore, convenient, accurate and rapid detection of viruses is of great significance for the diagnosis and treatment of subsequent diseases. In contrast to traditional methods of detection, which rely on time-consuming and complex techniques such as polymerase chain reaction (PCR), fluorescent probes and imaging methods generate real-time results, with high specificity, and have been widely used in viral detection. In this review, the application of viral fluorescent probes in analyzing the molecular structure, detection and biological imaging is discussed. In particular, we categorized the probes based on their specificity for human and plant viruses, reviewing the latest findings and analyzing their limitations. The potential of fluorescent molecular probes in the treatment of viral disease and environmental analysis, and their possible combinations with protein and immune technology are discussed.
The scope of stereochemistry recognition usually occurs near the chiral scaffold of a ligand or catalyst. Remote stereocontrol, which can surpass the limits of stereorecognition of remote prochiral centers, has long been a challenging object of great interest in asymmetric catalysis. The current work realized the remote stereocontrol of 1,7-zwitterion intermediates formed from Huang's o-amino aryl MBH carbonates. With simple and easily accessible β-ICD as the bifunctional catalyst, multifunctionalized tetrahydroquinoline derivatives could be synthesized via (4 + 2) cycloadditions with excellent enantioselectivity and diastereoselectivity under mild conditions. The strategy possesses broad substrate scope, and three types of electron-deficient enones are successfully applied. Mechanistic studies disclosed the Lewis base-catalyzed reaction pathway, and H-bonding between the catalyst and enones is crucial for long-range stereocontrol. Scale-up reaction and transformations of the tetrahydroquinoline products demonstrated the potential of this strategy.
While nickel(Ⅱ) complexes have been widely used as catalysts for carbon-carbon coupling reactions, the exploration of their photophysical and photochemical properties is still in the infancy. Here, a series of square-planar Ni(Ⅱ) complexes [(diNHC)NiX2] bearing chelating benzimidazole-based bis(N-heterocyclic carbene) ligands and varying anionic coligands (1, X = Cl; 2, X = Br; 3, X = I) are synthesized and structurally characterized. In solid state, both 1 and 2 exhibit orange-red photoluminescence under ambient conditions. The photophysical and electrochemical measurements along with density functional theory (DFT) calculations reveal that the low-energy emissions can be attributed to singlet excited states with ligand-to-ligand charge-transfer (LLCT) character. This work suggests that strong-field N-heterocyclic carbene ligands play a crucial role to achieve the luminescence of Ni(Ⅱ) complexes.
Methane chemistry is one of the "Holy Grails of catalysis". It is highly desirable but challenge to transform methane into value-added chemicals, because of its high C-H bonding energy (435 kJ/mol), lack of π bonding or unpaired electrons. Currently, commercial methane conversion is usually carried out in harsh conditions with enormous energy input. Photocatalytic partial oxidation of methane to liquid oxygenates (PPOMO) is a future-oriented technology towards realizing high efficiency and high selectivity under mild conditions. The selection of oxidant is crucial to the PPOMO performance. Hence, attentions are paid to the research progress of PPOMO with various oxidants (O2, H2O, H2O2 and other oxidants). Moreover, the activation of the selected oxidants is also highly emphasized. Meanwhile, we summarized the methane activation mechanisms focusing on the C-H bond that was broken mainly by •OH radical, O− specie or photogenerated hole (h+). Finally, the challenges and prospects in this subject are briefly discussed.
Due to the limitations of conventional chemotherapy including side effects, poor prognosis, and drug resistance, there is an urgent need for the development of a novel multi-functional combined therapy strategy. Dopamine-modified oxaliplatin prodrug (OXA-DA) was successfully synthesized in this study to ameliorate the organ distribution of oxaliplatin for improving the drug efficacy and reducing toxic side effects, and OXA-DA was applied to develop a porous oxaliplatin cross-linked polydopamine nanoparticle for loading siPD-L1 to construct multifunctional nanoplatform. The multifunctional nanoplatform was modified with poly(2-ethyl-2-oxazoline) (PEOz), which occurred charge reversal in the tumor microenvironment, and exerted the lysosomal escape effect in tumor cells to improve the bioavailability of small interfering RNA targeting programmed cell death-ligand 1 (siPD-L1). The pH-responsive charge reversal, photothermal, biodegradation, lysosomal escape ability, PD-L1 protein degradation, toxicity properties and multiple antitumor effects were comprehensively evaluated in vitro and in vivo experiments. The findings indicated that OXA-DA-siPD-L1@PDA-PEOz excellently induced tumor cell necrosis and apoptosis as a result of the synergistic effect of chemo-photothermal therapy, and upregulated CD8+ T cells produced interferon-γ (IFN-γ) to further attack the tumor cells. In conclusion, the novel nanoplatform-mediated chemo/photothermal/immunotherapy has promising clinical applications in the treatment of malignant tumors.
Graphite tailings produced by natural graphite is usually regarded as garbage to be buried underground, which would result in a certain waste of resources. Here, in order to explore the utilization of natural graphite tailings (NGT), a liquid-polyacrylonitrile (LPAN) is used to modify the NGT fragments and aggregate them together to form secondary graphite particles with low surface area and high tap density. Moreover, the modified NGT show much better electrochemical performances than those of original one. When tested in full cells coupled with NMC532 cathode, the material achieves a high rate capability and cycle stability at the cutoff voltage of 4.25 V as well as 4.45 V, which maintains 84.32% capacity retention after 500 cycles at 1 C rate (4.25 V), higher than that of the pristine one (73.65%). The enhanced performances can be attributed to the use of LPAN to create a unique carbon layer upon graphite tailings to reconstruct surface and repair defects, and also to granulate an isotropic structure of secondary graphite particles, which can help to weaken the anisotropy of Li+ diffusion pathway and form a uniform, complete and stable solid-electrolyte-interface (SEI) on the surface of primary NGT fragments to promote a fast Li+ diffusion and suppress lithium metal dendrites upon charge and discharge.
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