Latest ArticlesThree imidazole-modified Ag-polyoxovanadates frameworks (APFs) with a controllable molar ratio of Ag+ to polyoxovanadates (POVs) [Ag(IM)2]2V4O12·2Ag(IM)2 (APF-1), [Ag2(1-eIM)4]2[Ag(1-eIM)2]3·2Ag(1-eIM)2·3(1-HeIM)[V10O28]2 (APF-2) and [Ag(1-pIM)2]3[HV10O28]·2Ag(1-pIM)2·2H2O (APF-3) (IM = imidazole; 1-eIM = 1-ethylimidazole and 1-pIM = 1-propylimidazole) have been successfully achieved by self-assembly of POVs, Ag+ cations, and three different imidazole derivatives. Interestingly, the molar ratios of Ag+ to POVs vary from 4:1, 4.5:1 to 5:1 by changing the vanadium resources and imidazole derivatives. Notably, the coordination environment of Ag+ cations and the structure of POVs in the APFs are also different. Specifically, for APF-1, the four Ag atoms adopt three-coordinated and four-coordinated geometries, respectively, and Ag-imidazole complexes and [V4O12]4− cluster form the one-dimensional polymeric chains. While Ag atoms in APF-2 and APF-3 exhibit two-, four- and five-coordinated geometries for APF-2, four-, five- and six-coordinated geometries for APF-3, respectively. These Ag+ cations and decavanadate clusters are assembled into the 2D supramolecular structure through the Ag-O bonds and Ag…Ag argentophilic interaction. Remarkably, thus-obtained APF-2 can serve as powerful efficient heterogeneous catalyst for construction of CN bond and detoxification of simulant sulfur mustard (yields up to 99%), which enable successful recycling for three cycles with remained catalytic activities and structure stability.
Two-dimensional (2D) layered materials provide a promising alternative solution for overcoming the scaling limits in conventional Si-based devices. However, practical applications of 2D materials are facing crucial bottlenecks, particularly that arising from the instability under ambient condition. The studies of degradation mechanisms and protecting strategies for overcoming the ambient instability of 2D materials have attracted extensive research attentions, both experimentally and theoretically. This review attempts to provide an overview on the recent progress of the encapsulation strategies for 2D materials. The encapsulation strategies of mechanical transfer, polymer capping, atomic layer deposition, in-situ oxidation, and surface functionalization are systematically discussed for improving the ambient stability of 2D materials. In addition, the current advances in air-stable and high-performance 2D materials-based field effect transistors (FETs) and photodetectors assisted by the encapsulation strategies are outlined. Furthermore, the future directions of encapsulation techniques of 2D materials for FETs and photodetectors applications are suggested.
Injectable filling material is a simple and efficient method for soft tissues reconstruction and is extremely popular in not only plastic surgery but also cosmetic industry. However, there is a lack of soft tissue fillers with perfect performance on the market currently. Here, we constructed a new microsphere/hydrogel composite and evaluated its potential as a candidate for soft tissue augmentation. mPEG-PDLLA microspheres were prepared by utilizing a SPG membrane emulsifier which endowed microspheres with good sphericity and particle size uniformity. PDLLA-PEG-PDLLA hydrogel which shared the same component with the mPEG-PDLLA copolymer acted as a carrier and fixed the microspheres at the injected sites. The mPEG-PDLLA microsphere/PDLLA-PEG-PDLLA hydrogel composite was flowable in room temperature and transformed into gel after being heated to body temperature. This feature is convenient for subcutaneous filling. In vivo assessment on mice showed good safety profile of the composite. Moreover, the density of collagen fibers increased over 13 weeks. Overall, this biocompatible microsphere/hydrogel composite involves simple component and no extra crosslinking agents, and has the ability to stimulate collagen production, thus, may be a candidate for soft tissue augmentation.
Tumor heterogeneity plays a critical role in the determination of appropriate anticancer therapy. As circulating tumor cells (CTCs) contain all tumor-related information, the genetic changes on CTCs could help us choose the appropriate treatments for different patients. Single-base mutations are very common in tumor genetic changes which may result in drug resistance. Here, we introduce a single-cell mutation detection platform based on droplet microfluidics. This platform integrates cell capsulation, cell lysis, polymerase chain reaction (PCR) and the observation process. The droplets' generation speed is over 6000 per minute and more than 600 cells could be encapsulated in one second. To verify the performance of our platform in practical use, we performed the mutation analysis of 4 kinds of cells with our platform and noted that the genetic status of each single cell was clearly discriminated. Moreover, these results agreed with those from direct sequencing. Compared with other forms of single-cell mutation detection techniques, our platform has high throughput, short experimental time and less experimental operations.
The tandem reaction of photoinduced double hydrogen-atom transfer and deoxygenative transborylation for chemo- and site-selective reduction of nitroarenes into aryl amines under catalyst-free, room temperature conditions was disclosed in excellent yields. In this reaction, isopropanol (iPrOH) was used as hydrogen donor and tetrahydroxydiboron [B2(OH)4] as deoxygenative reagent with green, cheap, and commercially available credentials. In particular, a wide range of reducible functional groups such as halogen (-Cl, -Br and even -I), alkenyl, alkynyl, aldehyde, ketone, carboxyl, and cyano are all tolerated. Moreover, the reaction preferentially reduces the nitro group at the electron-deficient site over another nitro group in the same molecule. A detailed mechanistic investigation in combination of experiments and theoretical calculations gave a reasonable explanation for the reaction pathway.
A novel fluorescent sensor was prepared from sulfonated calix[4]arene (SC4A) by the host-guest complexation method using the fluorescent dye rhodamine B (RB) as a structure-directing agent. The crystal structure of the host-guest complex (RB@(SC4A)3) was confirmed by X-ray diffraction studies while its performance and sensing mechanism for metal ion pollutants were characterized using fluorescence and nuclear magnetic resonance spectroscopies. The results showed that RB@(SC4A)3 had a triangular branch structure resulting from host-guest mediation of the interactions between the three SC4A host molecules and the three terminal groups of the guest molecule RB. The host-guest complex exhibited sensitive and selective sensing towards Fe3+ ions via a fluorescence quenching mechanism. The results indicated that RB@(SC4A)3 could be a promising sensitive and selective fluorescent sensor for metal ion pollutants monitoring. It also provided new insights into the synthesis of calixarene-based host-guest complex.
Adjusting the electronic structure of graphitic carbon nitride (g-C3N4) photocatalyst through π-π conjugation is an effective method to achieve efficient photogenerated carrier separation. One key challenge of π-π conjugation control is to tune the degree of such conjugation without destroying the g-C3N4 structure. Herein we report a conceptual design that achieves a coplanar heterojunction by enhancing the π-π conjugation via the doping of crystalline g-C3N4 using a conjugated double bond ring molecule, 1,3,5-benzenetriol, during calcination process. The selection of the dopant enables the facile creation of a unique coplanar heterojunction which not only retains the pristine network structure of g-C3N4, but remarkably promotes separation and transfer of photogenerated carriers through the enhanced π-conjugated endogenous electric field. As a result, the new g-C3N4 photocatalyst efficiently photocatalytically produces hydrogen from water under visible light irradiation with a high H2 production rate up to 94.94 μmol/h, and a notable external quantum efficiency of 16.4% at 420 nm.
By combining 5, 10, 15, 20-tetra(4-chlorine)phenylporphyrin (TClPP) and α-Keggin polyoxometalate H5PV2Mo10O40 (H5PVMo) via a simple ion-exchange method, an organic-inorganic hybrid material [C44H28N4Cl4]1.5[H2PMo10V2O40]·2C2H6O (H2TClPP-H2PVMo) was prepared and thoroughly characterized by a variety of techniques. The homogeneous photocatalytic degradation of 2-chloroethyl ethyl sulfide (CEES) (5 µL) by H2TClPP-H2PVMo (1 × 10−6 mol/L) was studied in methanol and methanol-water mixed solvent (v/v = 1:1), in which the degradation rate of CEES reached 99.52% and 99.14%, respectively. The reaction followed first-order reaction kinetics, and the half-life and kinetic constant in methanol and the mixed solvent were respectively 33.0 min, −0.021 min−1 and 15.7 min, −0.043 min−1. Mechanism analysis indicated that under visible light irradiation in the air, CEES was degraded via oxidation and alcoholysis/hydrolysis in methanol and the mixed solvent. O2·− and 1O2 generated by H2TClPP-H2PVMo selectively oxidized CEES into a nontoxic sulfoxide. Singlet oxygen capture experiments showed that H2TClPP-H2PVMo (ϕ = 0.73) had a higher quantum yield of singlet oxygen than TClPP (ϕ = 0.35) under an air atmosphere and visible light irradiation.
An efficient chlorination reaction of in situ generated (β-diazo-α, α-difluoroethyl)phosphonates has been achieved with hydrochloric acid as a chlorine source under mild and operationally convenient conditions. The reaction does not need any catalyst and tolerates a wide scope of substrates, which affords the (β-chlorodifluoroethyl)phosphonate products in good to excellent yields. This reaction represents the first example of the halogenation of difluoroalkyl diazo compounds, and also provides an easy way for the synthesis of difluoromethylenephosphonate-containing compounds.
Cell migration proceeds in 3D matrices in vivo, which can naturally switch to distinct phenotypes for better invasion in confined microenvironments. The studies of important metabolites under confinement are extremely meaningful for comprehensive insights into cancer metastasis. The integration of cell confinement device and analytical techniques is a key point for in-situ analysis of significant metabolites in vitro. Herein, an electrochemiluminescence (ECL) sensing platform was designed for in-situ monitoring of cell-secreted lactate in highly confined microenvironments. The 3-µm confiner was exactly fabricated via microfabrication and microfluidics technique, and cells in high confinement and low adhesion tended to be round with contractile blebs on cell margins. Significantly, in-situ monitoring of lactate was successfully achieved on the ECL platform with the catalysis of lactate oxidase, in which the levels in different time intervals were acquired in the luminol-hydrogen peroxide system. Furthermore, the results were verified by the liquid chromatography-tandem mass spectrometry (LC-MS/MS) technology, which showed similar fluctuations with the ECL platform. This system offered an available avenue for metabolites analysis in highly confined microenvironments, which may advance deeper insights into metabolic mechanisms of cancer metastasis
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