Radioresistance resulted from the intrinsic features of tumors often gives rise to unsatisfied therapeutic outcome. In particular, the tumor microenvironment (TME) with abundant antioxidants, ...elevated hydrogen peroxide (H2O2) and hypoxia has been believed as a tremendous obstacle for radiotherapy. Therefore, developing an effective radiosensitizer in response to both X-ray and the TME is highly imperative but remains a challenge so far. Here, we for the first time explore bismuth heteropolytungstate (BiP5W30) nanoclusters as radiosensitizers for the TME-manipulated enhancement of radiotherapy. On the one hand, BiP5W30 nanoclusters can increase radiation dose deposition within tumors by high-Z elements like Bi and W. On the other hand, in virtue of the unique electron structure and multi-electron property, they have the capability of depleting glutathione (GSH) via redox reaction and catalyzing the decomposition of H2O2 to HO to enhance ROS generation upon X-ray radiation. Moreover, reduced graphene oxide (rGO) coupled with BiP5W30 can further improve radiocatalytic activity through promoting electron-hole separation. Simultaneously, due to the considerable near-infrared absorption of rGO, photothermal therapy can overcome the tumor hypoxia microenvironment and thus synergize with radiotherapy. In addition to providing a promising radiosensitizer, this finding is expected to extend the application of polyoxometalates used in the biomedical field.
The tumor microenvironment-manipulated bismuth heteropolytungstate nanoclusters could serve as a simple yet powerful radiocatalytic sensitizer for achieving tumor-specific radiotherapy by simultaneously increasing X-ray dose deposition and reversing the radio-resistance through the improvement of hypoxia environment, depletion of glutathione, and radiocatalytic conversion of overproduced hydrogen peroxide into highly toxic hydroxyl radical. Display omitted
Graphene‐based ternary composite photocatalysts with genuine heterostructure constituents have attracted extensive attention in photocatalytic hydrogen evolution. Here we report a new graphene‐based ...ternary composite consisting of CdS nanorods grown on hierarchical layered WS2/graphene hybrid (WG) as a high‐performance photocatalyst for hydrogen evolution under visible light irradiation. The optimal content of layered WG as a co‐catalyst in the ternary CdS/WS2/graphene composites was found to be 4.2 wt %, giving a visible light photocatalytic H2‐production rate of 1842 μmol h−1 g−1 with an apparent quantum efficiency of 21.2 % at 420 nm. This high photocatalytic H2‐production activity is due to the deposition of CdS nanorods on layered WS2/graphene sheets, which can efficiently suppress charge recombination, improve interfacial charge transfer, and provide reduction active sites. The proposed mechanism for the enhanced photocatalytic activity of CdS nanorods modified with hierarchical layered WG was further confirmed by transient photocurrent response. This work shows that a noble‐metal‐free hierarchical layered WS2/graphene nanosheets hybrid can be used as an effective co‐catalyst for photocatalytic water splitting.
Effective co‐operation: Ternary CdS/WS2/graphene composite photocatalyst exhibits high visible‐light H2‐production activity and 21.2 % quantum efficiency without the use of a noble metal co‐ catalyst. This high photocatalytic activity arises from the positive synergetic effects between the layered WS2 and graphene sheets as the components of co‐catalyst, which can efficiently suppress charge recombination, improve interfacial charge transfer, and provide reduction active sites.
Peptide assembly has reached exquisite levels of efficiency in the creation of bioactive materials. However, we have not yet been able to take what we have learned from peptide assembly to develop a ...general strategy for the fabrication of biomimetic underwater adhesives, which retain significant advantages as medical glue for clinical treatment. Herein we report a simple approach to prepare peptide-based adhesives through the supramolecular polymerization of cationic peptides drove by polyoxometalates (PMs). Mass spectra, Fourier-transform infrared spectra and 183W NMR spectra confirmed the structural integrity of peptides and PMs during the coassembly process. Scanning electron microscopy demonstrated that the multivalent interactions between peptides and polyoxometaltes led to the formation of robust 3D network structures. The rheological study revealed that the peptide/PM assemblies exhibited mechanically rigid gel-like behavior and self-healing property. Interestingly, the assemblies showed the capacity to adhere various wet solid materials under waterline. The shear strength of the peptide-based adhesives are stronger than that of the commercially available fibrin glue. This finding is exciting and serves to expand our capability of the fabrication of peptide-based materials.
A "turn on" time-resolved fluorometric aptasensor is described for the simultaneous detection of zearalenone (ZEN), trichothecenes A (T-2), and aflatoxin B.sub.1 (AFB.sub.1). Multicolor-emissive ...nanoparticles doped with lanthanide ions (Dy.sup.3+, Tb.sup.3+, Eu.sup.3+) were functionalized with respective aptamers and applied as a bioprobe, and tungsten disulfide (WS.sub.2) nanosheets are used as a quencher of time-resolved fluorescence. The assay exploits the quenching efficiency of WS.sub.2 and the interactions between WS.sub.2 and the respective DNA aptamers. The simultaneous recognition of the three mycotoxins can be performed in a single solution. In the absence of targets, WS.sub.2 is easily adsorbed by the mixed bioprobes via van der Waals forces between nucleobases and the WS.sub.2 basal plane. This brings the bioprobe and WS.sub.2 into close proximity and results in quenched fluorescence. In the presence of targets, the fluorescence of the bioprobes is restored because the analytes react with DNA probe and modify their molecular conformation to weaken the interaction between the DNAs and WS.sub.2. Under the optimum conditions and at an excitation wavelength of 273 nm, the time-resolved fluorescence intensities (peaking at 488, 544 and 618 nm and corresponding to emissions of Dy.sup.3+, Tb.sup.3+ and Eu.sup.3+) were used to quantify ZEN, T-2 and AFB.sub.1, respectively, with detection limits of 0.51, 0.33 and 0.40 pg mL.sup.-1 and a linear range from 0.001 to 100 ng mL.sup.-1. The three mycotoxins can be detected simultaneously without mutual interference. The assay was applied to the quantification of ZEN, T-2 and AFB.sub.1 in (spiked) maize samples. This homogeneous aptamer based assay can be performed within 1 h. Conceivably, it can become an alternative to other heterogeneous methods such as the respective enzyme-linked immunosorbent assays.
This study reports a simple synthesis of amorphous nickel tungstate (NiWO4) nanostructure and its application as a novel cathode material for supercapacitors. The effect of reaction temperature on ...the electrochemical properties of the NiWO4 electrode was studied, and results demonstrate that the material synthesized at 70 °C (NiW-70) has shown the highest specific capacitance of 586.2 F g–1 at 0.5 A g–1 in a three-electrode system. To achieve a high energy density, a NiW-70//activated carbon asymmetric supercapacitor is successfully assembled by use of NiW-70 and activated carbon as the cathode and anode, respectively, and then, its electrochemical performance is characterized by cyclic voltammetry and galvanostatic charge–discharge measurements. The results show that the assembled asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a high specific capacitance of 71.1 F g–1 at 0.25 A g–1, which can deliver a maximum energy density of 25.3 Wh kg–1 at a power density of 200 W kg–1. Furthermore, this asymmetric supercapacitor also presented an excellent, long cycle life along with 91.4% specific capacitance being retained after 5000 consecutive times of cycling.
In this work, an underwater impulse discharge initiated in polyaniline (PANI) aqueous dispersion between tungsten rods is applied to produce metal oxide nanoparticles and create polymer ...nanocomposites. The prepared materials were analyzed by X-ray diffraction (XRD), ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). XRD, FTIR, and TEM confirmed the presence of tungsten oxide particles in the final composite, while spectroscopic characterization revealed the interaction between the metal oxide and PANI. The results showed that the incorporation of WOsub.3 into the PANI matrix could improve the optical bandgap of the nanocomposites. In addition, the electrochemical performance of the hybrid nanocomposites was tested by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The results obtained indicated that the PANI + WOsub.3 nanocomposite could be a promising candidate as an electrode material for high-power supercapacitor applications.
WO.sub.3/SiO.sub.2 catalysts were synthesized by ultrasonic-impregnation method. The physical and chemical characteristics of these catalysts and their performance for dimethyl sulfide (DMS) ...thiolation to methanethiol were investigated. Tungsten oxide enhanced the acidity of the catalyst, and the tungsten oxide loading determined the quantity of surface acidic sites. DMS conversion was significantly enhanced with increasing WO.sub.3 content. The purpose of SiO.sub.2 was to provide mechanical strength to enhance the durability of the catalysts for long-term exposure to industrial high-pressure and sour conditions. The ultrasonic treatment had a positive effect on the structure of the catalysts and their performance. A comprehensive analysis of the conversion, selectivity, and industrial application of these catalysts showed that the 6%WO.sub.3/SiO.sub.2(100 W-1 h) catalyst, which was ultrasonicated at 100 W for 1 h, was the optimal catalyst.
One of the most attractive areas in inorganic chemistry is the synthesis of polyoxometalates (POMs) exhibiting new properties and applications. Since the impact of POMs in biochemistry and related ...fields of research has increased in the last few years, there has been a special interest in this topic. Significant progress in biological applications has been made where the interaction of POMs with amino acids, peptides and proteins is relevant. Versatile POMs play a series of different roles in the interaction with these biomolecules as described in this review. Various types of interactions are established, depending on the POM shape and charge, the amino acid side chain, peptide sequence or protein structure. Experimental conditions such as temperature, acidity, solvent,
etc
. are also important factors that influence the binding/reactivity of POM with biomolecules, as described herein. This understanding allows the adequate design of the POM-biomolecule couple for tailoring and controlling mechanisms of action such as catalysis, inhibition, and aggregation, or the crystallising agent.
This perspective provides a comprehensive description of the different roles of POMs in their interaction with relevant biological molecules.
12-Tungstophosphoric acid supported on nanosilica (TPA/SiOsub.2) was employed as a catalyst for the tertiary butylation of p-cresol using tertiary butanol as an alkylating agent. The TPA/SiOsub.2 ...catalyst was synthesized using the wet impregnation method followed by steaming at 150 °C for 6 h. The catalysts were characterized by means of X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM) analysis. The surface acidity of the untreated and steamed catalysts was characterized via FTIR and DSC thermal analysis using pyridine as a probe molecule. The fresh and spent catalysts were characterized via TGA analysis. The catalytic activity studies showed that the steamed catalyst displayed higher activity, with a higher desired yield of 2-tert-butyl cresol (2-TBC) compared to the untreated catalyst, and that this activity was related to the presence of stronger Brønsted acid sites in the steamed catalyst. A detailed analysis of the TPA/SiOsub.2 steamed catalyst was performed to study the effects of reactant time-on-stream, reactant feed rate, reaction temperature, and the molar ratio of tert-butanol to p-cresol. The optimum reaction temperature, tert-butanol/p-cresol molar ratio, feed rate, and time-on-stream were 413 K, a molar ratio of 2:1, 6 mL/min, and 2 h, respectively. The present study demonstrates that the TPA/SiOsub.2 catalyst exhibits high activity in terms of % conversion and high % selectivity of 2-TBC under the optimized conditions. The characterization of fresh and spent catalysts confirmed the occurrence of coke deposition after the catalytic reaction. The catalyst was regenerated via heat treatment at 400 °C for 5 h. The regenerated catalyst was reused for subsequent runs for three cycles without showing a loss in its activity.
•TX100 strongly enhanced the adsorption and photodegradation of NOF in Bi2WO6 dispersions under visible light irradiation (400–750nm).•Cu2+ (10mM) significantly suppressed the photocatalytic ...degradation of NOF.•FT-IR demonstrated that the NOF adsorbed on Bi2WO6 was completely degraded.•Three possible photocatalytic degradation pathways of NOF were proposed, according to the HPLC/MS/MS analysis.
Photocatalytic degradation is an alternative method to remove pharmaceutical compounds in water, however it is hard to achieve efficient rate because of the poor solubility of pharmaceutical compounds in water. This study investigated the photodegradation of norfloxacin in a nonionic surfactant Triton-X100 (TX100)/Bi2WO6 dispersion under visible light irradiation (400–750nm). It was found that the degradation of poorly soluble NOF can be strongly enhanced with the addition of TX100. TX100 was adsorbed strongly on Bi2WO6 surface and accelerated NOF photodegradation at the critical micelle concentration (CMC=0.25mM). Higher TX100 concentration (>0.25mM) lowered the degradation rate. In the presence of TX100, the degradation rate reached the maximum value when the pH value was 8.06. FTIR analyses demonstrated that the adsorbed NOF on the catalyst was completely degraded after 2h irradiation. According to the intermediates identified by HPLC/MS/MS, three possible degradation pathways were proposed to include addition of hydroxyl radical to quinolone ring, elimination of piperazynilic ring in fluoroquinolone molecules, and replacement of F atoms on the aromatic ring by hydroxyl radicals.
