Latest ArticlesMnS as anode material for sodium-ion batteries (SIBs) has recently attracted great attention because of the high theoretical capacity, great natural abundance, and low cost. However, it suffers from inferior electrical conductivity and large volume expansion during the charge/discharge process, leading to tremendous damage of electrodes and subsequently fast capacity fading. To mitigate these issues, herein, a three-dimensional (3D) interlaced carbon nanotubes (CNTs) threaded into or between MnS hollow microspheres (hollow MnS/CNTs composite) has been designed and synthesized as an enhanced anode material. It can effectively improve the electrical conductivity, buffer the volume change, and maintain the integrity of the electrode during the charging and discharging process based on the synergistic interaction and the integrative structure. Therefore, when evaluated as anode for SIBs, the hollow MnS/CNTs electrode displays enhanced reversible capacity (275 mAh/g at 100 mA/g after 100 cycles), which is much better than that of pure MnS electrode (25 mAh/g at 100 mA/g after 100 cycles) prepared without the addition of CNTs. Even increasing the current density to 500 mA/g, the hollow MnS/CNTs electrode still delivers a five times higher reversible capacity than that of the pure MnS electrode. The rate performance of the hollow MnS/CNTs electrode is also superior to that of pure MnS electrode at various current densities from 50 mA/g to 1000 mA/g.
The exploitation of multifunctional nanocomposites is highly desired in environmental monitoring, biosensors, and medical diagnosis. In this paper, a simple approach has been proposed to fabricate MoS2 decorated N-doped carbon nanotubes (NCNTs@MoS2) hybrid composites as efficient peroxidase-like mimics. The combination of the MoS2 and N-doped carbon nanotubes (NCNTs) brings about an enhanced synergistic effect, leading to remarkably decent intrinsic peroxidase-mimic activities than that of the single components. Due to the high catalytic efficiency of the resultant NCNTs@MoS2 hybrid nanotubes as peroxidase-like mimics, a convenient colorimetric approach for the sensitive determination of H2O2 and ascorbic acid have been developed with a detection limit of about 0.14 μmol/L and 0.12 μmol/L, respectively. The work offers a new strategy for the fabrication of peroxidase-like nanomaterials with excellent catalytic activity, which indicates great promising applications in sensitive detections in real samples.
Infectious diseases have always been a major cause of mobility and mortality, early and accurate diagnosis is important for their management. However, current clinical diagnosis for bacterial infection still remains troublesome. Recently, many attempts on molecular imaging have been made for prompt bacteria detection, especially for early and precise disease diagnosis. Among them, maltohexaose-based probes serve as a superb candidate due to the bacteria-specific maltodextrin transport pathway. These probes can visualize bacterial foci with unparalleled sensitivity and specificity. Such metabolism-based targeting strategy offers a powerful delivery platform for imaging and theranostic agents, providing good translational potential for developing antibacterial agents.
Here, we use two important biomaterials, protein and DNA, to construct self-assembled linear nanostructures through Watson-Crick base-paring of DNAs. We apply a simple magnetic separation method to purify traptavidin-DNA conjugates, and demonstrate synthesis of linear arrays of traptavidinDNA conjugates via the step-growth polymerization approach with pre-determined DNA sequences. Using the traptavidin-DNA array as a template, we assemble gold nanoparticles to form linear plasmonic nanostructures in a programmable manner. The traptavidin-DNA conjugates thus provide a convenient platform for one-dimensional assembly of biotinylated nanomaterials for many biomedical applications from drug delivery to bio-sensing.
Stimuli-responsive polypeptides have been intensively investigated for controlled drug release, owing to their favorable biocompatibility and biodegradability. In this work, we designed and synthesized a new kind of polypeptide bearing 1, 4-dithiane pendants for reactive oxygen species (ROS)-responsive drug release. The polypeptide-based block copolymer was facilely synthesized by ring-opening polymerization (ROP) of 1, 4-dithian-substituted L-glutamate N-carboxyanhydride (DTG-NCA) monomer using an amino-terminated poly(ethylene glycol) methyl ether (mPEG-NH2) as the macromolecular initiator. The resultant block copolymer, mPEG-b-PDTG, could self-assemble into uniform micelles in aqueous medium owing to its amphiphilic structure. Then, the H2O2-triggered oxidation behaviors of the mPEG-b-PDTG micelles were studied by dynamic light scattering (DLS), FT-IR and turbidimetric assay. It was revealed that the oxidation of thioether into sulfoxide in the side chains would result in disassembly of the micelles. Furthermore, the ROS-responsive drug release behavior of the mPEG-b-PDTG micelles was verified by using Nile Red as a model drug. MTT assay also proved that mPEG-b-PDTG was non-toxic in B16F10 and L929 cells. Therefore, such a new class of oxidation-responsive polypeptide might provide a promising platform for ROS-responsive drug delivery.
Extensive structure-activity relationships (SARs) study of JND3229 was conducted to yield a series of new reversible 2-oxo-3, 4-dihydropyrimido[4, 5-d]pyrimidine privileged scaffold as EGFRC797S inhibitors. One of the most potent compound 6i potently suppressed EGFRL858R/T790M/C797S kinase with an IC50 value of 3.1 nmol/L, and inhibited the proliferation of BaF3 cells harboring EGFRL858R/T790M/C797S and EGFR19D/T790M/C797S mutants with IC50 values of 290 nmol/L and 316 nmol/L, respectively. Further, 6i dose-dependently induced suppression of the phosphorylation of EGFRL858R/T790M/C797S and EGFR19D/T790M/C797S in BaF3 cells. Compound 6i may serve as a promising lead compound for further drug discovery overcoming the acquired resistance of non-small cell lung cancer (NSCLC) patients.
Herein, a WO3-CuWO4 nanostructured heterojunction was prepared by a facile two-step hydrothermal method. It is composed of a WO3 square microplate and CuWO4 nanoparticles. Then, the gas sensing properties were investigated under optimal operating temperature (120 ℃). The WO3-CuWO4 heterostructure shows good sensing performance towards n-butanol, with a response value up to 9.4 to towards 30 ppm n-butanol, and the response value is about 3 times higher than that of pristine WO3. Its detection limit for n-butanol is 0.1 ppm, which indicates a potential application in lower concentration detection. Moreover, the response time of WO3-CuWO4 nanostructured heterojunction and the pristine WO3 are 21 s and 240 s respectively, revealing that there is a faster gas sensing process in the heterostructure. A possible sensing mechanism was then proposed on the basis of experimental data and band structure analysis. The significant enhancement of WO3-CuWO4 heterostructure could be attributed to the formation of heterojunction, which brings electronic sensitization and electron transport pathway modulation. The work offered a kind of novel and cost-effective sensing materials, and inspired more novel devices based on nanostructured heterojunction mechanism.
The widely accepted theory concerning the electrochemical energy storage mechanism of copper hexacyanoferrate (CuHCF) for supercapacitors is that CuHCF stores charge by the reversible redox processes of Fe3+/Fe2+ couple and Cu cations are electrochemically inactive. In this work, CuHCF nanocubes (CuHCF-NC) were synthesized in the presence of potassium citrate and its electrochemical properties were tentatively studied in 1 mol/L Na2SO4 aqueous electrolyte. Good supercapacitive performance was exhibited. The combined analyses of cyclic voltammogram (CV) and X-ray photoelectron spectroscopy (XPS) disclosed that the CuHCF nanocubes underwent the redox reactions of Fe3+/Fe2+ and Cu2+/Cu+ couples to store charges. The Cu2+/Cu+ redox couple was activated due to the strong coordination interaction between the carboxylate groups of citrate ions and surface Cu cations.
Au or other metal nanostructures have the ability to strongly quench the fluorescence of fluorophores. This feature has made AuNP-conjugates attractive for the construction of platforms for various bioanalytes to overcome the limitations of small molecule fluorophores (poor solubility, long reaction time). In this paper, an ultrafast "Turn-On" fluorescent sensor for biothiols was constructed. The sensor is based on the fluorescent resonance energy transfer (FRET) effect between the fluorophore (PN) and AuNPs, which effectively quenches the fluorescence of the fluorophore. In the presence of thiols, PN is displaced and released from AuNP surfaces, and thus, the fluorescence is rapidly restored. The sensor features appreciable water solubility and ultrafast response time (a few seconds for Cys). In addition, it exhibits high selectivity and a detection limit as low as 12 nmol/L for Hcy. Moreover, the sensor presents good biocompatibility and has been successfully applied for imaging biothiols in living cells.
A series of novel 1, 2, 4-oxadiazole-containing N-pyridylpyrazole derivatives 12a-h were efficiently synthesized with pivaldehyde, pyridylpyrazole carboxylic acid and arylamine as raw materials via 1, 3-dipolar cycloaddition. Their structures were identified by melting points, 1H NMR, 13C NMR and elemental analysis or HRMS. The exploration on the single-crystal structures of 12c and 12g revealed the stereochemical and substituent oriental characteristics, and the relevance of the structure and the reaction activity of this type of compounds. The preliminary bioassays indicated that several compounds had good insecticidal activities, among which 12c showed a lethality rate of 80% towards Mythimna separata Walker at 200 μg/mL; some of the compounds exhibited favorable fungicidal activities at 50 μg/mL against Physalospora piricola, Rhizoctonia cereal, Sclerotinia sclerotiorum, etc. Among which, 12a, 12b, 12c and 12h could be considered as new fungicidal leading compounds for further structural optimization. These discoveries along with the structure-activity relationship analysis in this paper will provide useful guidance for the innovative studies on new pyridylpyrazole derivatives and their applications in agrochemical area.
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