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Modulators can be designed to stabilize the inactive and active states of ion channels, but whether intermediate (IM) states of channel gating are druggable remains underexplored. In this study, using molecular dynamics simulations of the TWIK-related potassium channel 1 (TREK-1) channel, a two-pore domain potassium channel, we captured an IM state during the transition from the down (inactive) state to the up (active-like) state. The IM state contained a druggable allosteric pocket that was not present in the down or up state. Drug design targeting the pocket led to the identification of the TKIM compound as an inhibitor of TREK-1. Using integrated methods, we verified that TKIM binds to the pocket of the IM state of TREK-1, which differs from the binding of common inhibitors, which bind to channels in the inactive state. Overall, this study identified an allosteric ligand-binding site and a new mechanistic inhibitor for TREK-1, suggesting that IM states of ion channels may be promising druggable targets for use in discovering allosteric modulators.

Three-dimensional carbon fiber (3D-CF) reinforced resin matrix composites are successfully prepared by vacuum impregnation and hot pressing process. The microstructure analysis shows that the resin...

Carbon fiber reinforced shape memory polymer composite (SMPC) is a kind of smart material with shape memory characteristics, which is widely used in aerospace, biomedicine, robotics and other field...

Metal ions sensing play critical roles in environmental monitoring and in biology. In this assay, we report the development of a facile fluorometric method for the sensing of Ag+ ions via the in situ formation of metal coordination polymer, based on the selective interactions of GSH with Ag+. The formation of coordination polymer with net multiple negative charges in an aqueous buffer solution (Tris-HAc, pH 9.0) resulted in aggregation and fluorescence quenching of a cationic perylene probe. The difference in emission intensity spurred us to develop a new strategy for sensing Ag+ ions. The proposed Ag+ detection method is simple, convenient, selective and sensitive, and can be used for Ag+ detection in lake water samples.

To overcome the adverse effects of salt on the mechanical properties of hydrogels, a facile double cross-linking method has been proposed to synthesize salt-enhanced tough hydrogels. Herein, a poly(hexafluorobutyl methacrylate-acrylamide) hydrogel [P(AAm-co-HFBMA) hydrogel] is prepared by the copolymerization of acrylamide (AAm) and hexafluorobutyl methacrylate (HFBMA) with N,N'-methylene bisacrylamide (NMBA) as a cross-linking agent in a dimethylformamide (DMF)/aqueous solution; DMF is then replaced by water. The results indicate that the tensile fracture stress of the P(AAm-co-HFBMA) hydrogel (20 mol% HFBMA) is as high as 0.43 MPa, which is far better than that of the PAAm hydrogel (ca. 30 kPa). Additionally, with a further increase in the hydrophobic structural units (25 mol% HFBMA), the tensile fracture stress of the P(AAm-co-HFBMA) hydrogel can be increased up to 2.34 MPa. The mechanical strength of the P(AAm-co-HFBMA) hydrogel is significantly enhanced to 3.50 MPa (2 M) from 2.34 MPa (0 M) after it is soaked in aqueous NaCl solutions with various salt concentrations. The mechanical properties and the results of the DSC analysis indicate that the main reason for its mechanical strength to exhibit a unique salt-enhancement trend can be explained as follows. After the P(AAm-co-HFBMA) hydrogel is soaked in the salt solution, the network gradually collapses with the penetration of the small molecules of salt. Thus, the hydrophobic C-F units easily form dynamic cross-linking junctions due to the switchable hydrophobic interaction between C-F groups, which can endow the P(AAm-co-HFBMA) hydrogel with a more effective dynamic energy dissipation mechanism in salt solution.

In this study, we report the synthesis of Ce-doped UiO-67 nanocrystals via one-step hydrothermal method and their potential use for waste water treatment to remove organic dyes. The as-prepared samples were characterized by using SEM, TEM, FT-IR, XRD, XPS and TG techniques and the results demonstrate the formation of the framework structure of the Ce-doped UiO-67. The adsorption study of the material shows that the Ce-doped UiO-67 nanoparticles preferentially adsorb the cationic dyes such as rhodamine B and malachite green rather than the anionic dyes such as methyl orange. Adsorption capacities are 754.4, 589.2 and 191.6 mg g−1 for rhodamine B, malachite green and methyl orange respectively. Based on its zeta potential and adsorption isotherm, it is understood that Ce doping increases its electrostatic interactions, and as a consequence, improves the adsorption capacity for cationic dyes. In addition, it is found that a pseudo-second-order kinetics and the Langmuir isothermal model were suitable for describing the adsorption behavior of cationic dyes onto the Ce-doped UiO-67.

Cyclic methylsiloxanes (CMS) were listed as candidates of substances of very high concerns in 2018 by the REACH. These compounds can enter environmental waters, and potentially cause harmful effects to aquatic organisms and human beings. Until now, reaction mechanisms of these pollutants with hydroxyl radicals (HO ) in aqueous phase were unknown. In this study, reaction mechanisms of three typical CMS (D4 ∼ D6) with HO in aqueous phase were investigated by employing both UV/H2O2 experiments and density functional theoretical calculations. Bimolecular reaction rate constants (kHO·) of D4 ∼ D6 with HO were determined as kHO·(D4) = 8kHO·(D5) = 12kHO·(D6) = 6.6 × 108 L mol−1 s−1. Half-lives of HO oxiding D4 ∼ D6 ranged from 12 to 140 days at [HO ] = 10−15 mol L−1 in sunlit surface water, and were comparable to (D4, D5) or much shorter (D6) than hydrolytic half-lives. The reactivity to HO decreased with the increasing size of siloxane ring in aqueous phase, in an order totally opposite to that in gaseous phase. Calculation results indicated that HO oxidation of the three CMS proceeded spontaneously through an exothermic H-abstraction process at the first step. Water molecules participated into H-abstraction of CMS and caused energy barrier of D5 higher than that of D4. Thus, H-bonds formed by water molecules were responsible for the reverse reactivity of CMS in aqueous phase. This work provided basic evidences suggesting environmental persistence of CMS in aqueous phase completely different from that in gaseous phase.

On the basis of the reaction of 5,5-dimethylhydantoin potassium salt with dibrominated alkane, a series of hydantoin derivatives in which two hydantoin rings are bridged by an alkyl chain with different length (C2, C6, C8, and C12) were synthesized. Upon chlorination, these compounds were transformed into hydantoin-based N-halamines. The structures of these samples were fully characterized with 1H NMR, FT-IR, UV/vis, thermal analyses, and iodometric titration. The antibacterial activity of these N-halamines was assessed with 4 × 109 CFU/mL of Gram-negative Escherichia coli under different chlorine concentrations and over different periods of contact time. It was found that the antibacterial properties and the releasing characteristics of the active chlorine of the hydantoin-based N-halamines changed obviously with increased alkyl chain length, and the factors influencing the antibacterial efficacy were discussed in terms of water solubility, steric effect, electron-donating effect, and action mechanism.

Developing supercapacitors with high energy density, fast charging rates, and superior cycle life is crucial to the ever-increasing electric energy storage. However, how to construct a new type of supercapacitors involving pseudocapacitive performance and electric double-layer capacitive performance and exhibiting enhanced electronic conductivity is still challenging. Here, hierarchical Ni x Co 2x (OH) y @Ni@ZnO/ITO architecture is successfully fabricated by growing Ni x Co 2x (OH) y nanosheets on surface of well-aligned Ni@ZnO nanorod using co-electrodeposition method. Ni x Co 2x (OH) y with layered structure is wrapped like rippled silk and increases the specific surface area, which is crucial and benefit for fast ion adsorption/de-adsorption and fast surface redox reactions. Importantly, interlayer Ni serves as a nanostructured current collector and electronic conductor, playing an important role in rate capability. By virtue of structure features, the self-support Ni x Co 2x (OH) y @Ni@ZnO/ITO as binder-free electrode for supercapacitors manifests higher specific capacitance (124 mF cm −2 at 0.1 mA cm −2 , the mass of active material per square centimeter is typically in 100s micrograms). Furthermore, the Ni x Co 2x (OH) y @Ni@ZnO/ITO exhibits remarkable cycling stability with about 95% specific capacitance retention after 5000 cycles. The results show that Ni-Co nanostructure constructed on surface of embedded conductive “core” materials is promising for high-energy supercapacitors.

Fenton catalytic oxidation is an efficient and green method to remove pollutants, and the preparation of Fenton catalyst by MOF is a significant task. In this work, Ce-doped UiO-67−400 was successfully synthesized by introducing cerium into zirconium based UiO-67 skeleton by one-step hydrothermal synthesis approach followed by calcination at high temperature. The as-prepared samples were characterized by using the SEM, TEM, XRD, FT-IR, XPS and N2 adsorption-desorption techniques. The synthesized materials were used as catalyst in the Fenton-like oxidation of methylene blue model reaction with H2O2 as an oxidant. The experimental results of the catalyst showed that the Ce-doped UiO-67-400 catalyst calcined at 400 °C has a larger pore size, which is conducive to H2O2 decomposition and ·OH catalysis of methylene blue as compared to non-doped one. Under the optimal conditions, methylene blue removal rate reached 94.1 % within 30 min. We hope that the results of the present work could play a significant role in the waste water treatment research avenue.

A post-synthetic approach using nitrogen-containing substances modify UiO-67 was proposed to enhance its adsorption for Congo red (CR). The newly synthesized materials were thoroughly analyzed by SEM, TEM, EDX, XPS, XRD, FT-IR, TGA and BET techniques. Results showed that N was successfully incorporated into UiO-67 frameworks to prepare of NX-UiO-67, through coordination interaction with Zr-O clusters. Compared to parent UiO-67, the obtained NX-UiO-67 exhibited a significant increase in adsorption of CR, and the adsorption capacities for CR were in the following order: NU-UiO-67 (2360 mg g−1) > NT-UiO-67 (1986.3 mg g−1) > NA-UiO-67 (1493 mg g−1). Moreover, the pseudo-second-order kinetics and the Langmuir isothermal model exhibited a better fit to describe the adsorption behavior of CR onto the NX-UiO-67.

A ratiometric fluorescence assay for acetylcholinesterase activity is established, which is based on controlled perylene probe assembly and monomer–excimer transition. In a buffer solution, a perylene probe with two negatively charged groups (PDI-DHA) mainly exists in monomeric form. In the presence of cationic lauroylcholine and lauric acid, PDI-DHA can form supramolecular assemblies and the perylene excimer emission can be observed. AChE can catalyze the hydrolysis of lauroylcholine to anionic lauric acid and choline. The hydrolysis process can trigger the breakdown of the supramolecular assemblies. The perylene excimer recovers to the monomeric form because of the de-aggregation of the probe. The excimer–monomer transition can be detected, and a ratiometric fluorescence assay for AChE activity and inhibitor screening is therefore established.

A solid-phase extraction (SPE) method based on conductive polypyrrole (PPy) nanofibers which were fabricated by electrospinning and in situ polymerization was developed. PPy nanofibers-mediated SPE followed by high performance liquid chromatography (HPLC) was used for the determination of three synthetic estrogens, namely diethylstilbestrol (DES), dienestrol (DIS), or hexestrol (HS) in milk sample. Extraction conditions including extraction nanofibers, donor solution pH and salt concentration were optimized. The target compounds were extracted from a 0.5 mL aqueous sample at pH 5.0 through PPy fibers, and then were eluted with 0.1 mL methanol. After extraction, the eluant was directly injected into an HPLC system for detection. Under the optimized extraction conditions, a large enrichment factor was achieved for three estrogens. The limit of detection (LOD) at a signal to noise ratio (S/N) of 3 ranged from 0.02 to 0.05 µg mL-1 for the estrogens in milk sample.