Latest ArticlesPeroxymonosulfate (PMS) activation and photocatalysis are effective technologies to remove organic pollutants, but the adsorption effect of the catalyst is usually unheeded in degradation process. Herein, a bifunctional catalyst of amorphous MoSx (a-MoSx) with 3D layer-by-layer superstructure was synthesized by assembling basic active units [Mo3S13]2- of MoS2. The large interlayer spacing and high exposure of active sites render a-MoSx to have excellent synergy of adsorption and photo-assisted PMS activation for tetracycline (TC) degradation. Experiments and DFT calculation show that TC can be efficiently enriched on a-MoSx by pore filling, π-π interaction, hydrogen bonding and high adsorption energy. Subsequently, PMS can be quickly activated through electron transfer with a-MoSx, resulting in high TC degradation efficiency of 96.6% within 20 min. In addition, the synergistic mechanism of adsorption and photo-assisted PMS activation was explored, and the degradation pathway of TC was expounded. This work is inspirational for constructing bifunctional catalysts with superior synergistic adsorption and catalytic capabilities to remove refractory organic pollutants in water.
The microphases and miscibility in binary curcumin (Cur) solid dispersions (SDs) with amorphous polyvinylpyrrolidone K30 (PVP K30) and semi-crystalline poloxamer (P407) and poly(ethylene glycol) 6000 (PEG6000) as carriers were investigated by fluorescence contrasting utilizing confocal laser scanning microscopy. A super sensitive fluorophore P4 with typical aggregation-caused quenching properties was employed to stain the continuous polymer phases and contrasted with the autofluorescence of the model drug Cur. In addition, differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) were utilized to assist in explanation of the fluorescence results. In all three SD systems, there is always a homogenous polymer phase stained by P4 and it is difficult to adulterate Cur crystals by P4. Cur-enriched rather than polymer-enriched domains could be detected. In the Cur-PVP K30 system, Cur exists in an amorphous form at a Cur loading level of 50% and below, while Cur crystallines phase out and continuously grow with the increase of Cur loading from 60% to 90%. The phase behaviors in the Cur-P407 and Cur-PEG 6000 systems are similar but with minor differences. In both systems, Cur phases out as clusters of drug-enriched domains at a loading level of 20% and below, which however cannot be correlated with crystallization, as evidenced by both DSC and PXRD. There is a transition from an amorphous to a crystalline state from 20% to 30% Cur loading, above which Cur crystallines can be detected. It is interesting that a co-mix phase of both Cur- and PEG 6000-enriched domains can be identified at Cur loading levels of 10% and less. Taking together, it is concluded that contrasting Cur autofluorescence with the signals of P4 proves to be a functional strategy to reveal multiple phases in the binary SD systems investigated.
Microbial contamination in water has emerged as a critical concern and thus developing biocide materials for controlling microbial contamination is crucial. Removing all pathogenic bacteria in water is difficult when using traditional water treatment technologies. Moreover, these bacteria can easily reproduce during pipeline distribution. In this work, a facile and effective chitosan derivative biocide denoted as PCC was developed by grafting with quaternary phosphonium salt (QPS). PCC became positively charged with a wide range of pH and demonstrated antibacterial activity up to 95% and 100% against Escherichia coli and Staphylococcus aureus as model pathogens, respectively. The grafting of QPS may disrupt the cell membrane and lead to bacterial inactivation, as demonstrated by the scanning electron microscopy image and the concentration of intracellular substance leakage. MTT assay results indicate that PCC achieved good biocompatibility with negligible in vitro cytotoxicity. These findings introduce a promising approach for bacterial decontamination due to its low cytotoxicity and high biocidal activity.
To solve the volume expansion and poor electrical conductivity of germanium-based anode materials, Ge/rGO/CNTs nanocomposites with three-dimensional network structure are fabricated through the dispersion of polyethylene-polypropylene glycol (F127) and reduction of hydrogen. An interesting phenomenon is discovered that F127 can break GeO2 polycrystalline microparticles into 100 nm nanoparticles by only physical interaction, which promotes the uniform dispersion of GeO2 in a carbon network structure composed of graphene (rGO) and carbon nanotubes (CNTs). As evaluated as anode material of Lithium-ion batteries, Ge/rGO/CNTs nanocomposites exhibit excellent lithium storage performance. The initial specific capacity is high to 1549.7 mAh/g at 0.2 A/g, and the reversible capacity still retains 972.4 mAh/g after 100 cycles. The improved lithium storage performance is attributed to that Ge nanoparticles can effectively slow down the volume expansion during charge and discharge processes, and three-dimensional carbon networks can improve electrical conductivity and accelerate lithium-ion transfer of anode materials.
High-efficiency hydrogen production through photoelectrochemical (PEC) water splitting has emerged as a promising solution to address current global energy challenges. Ⅲ-nitride semiconductor photoelectrodes with nanostructures have demonstrated great potential in the near future due to their high light absorption, tunable direct band gap, and strong physicochemical stability. However, several issues, including surface trapping centers, surface Fermi level pinning, and surface band bending, need to be addressed. In this work, enhanced photovoltaic properties have been achieved using gallium nitride (GaN) nanowires (NWs) photoelectrodes by adopting an alkaline solution surface treatment method to reduce the surface states. It was found that surface oxides on NWs can be removed by an alkaline solution treatment without changing the surface morphology through X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and other characterization methods. These findings provide new insights to the development of high-efficiency photoelectrodes for new energy source applications.
FMS-like tyrosine kinase 3 (FLT3) is a viable and important therapeutic target for acute myeloid leukemia (AML). FLT3 internal tandem duplication (FLT3-ITD) mutations have been identified in approximately 30% of AML patients, and are associated with unfavorable prognosis, higher risk of relapse, drug resistance, and poor clinical outcome. Even FLT3 inhibitors have demonstrated promising efficacy, they cannot cure AML or even significantly extend the lives of patients with FLT3-ITD mutations. This is partly because of poor water solubility, insufficient membrane penetration and short half-life of small molecule inhibitors. Besides, the presence of enzymes like CYP3A4 in bone marrow accelerate the elimination and metabolism of FLT3 inhibitors, resulting in low plasma concentrations and side effects. Here we report the erythrocyte membrane-camouflaged FLT3 inhibitor nanoparticles to enhance FLT3-ITD AML treatment. Briefly, we physically coextruded red blood cell (RBC) membrane vesicles with nanoparticles derived from FLT3 inhibitor F30 to obtain F30@RBC-M, which exhibited comparable potent FLT3-ITD inhibitory effects compared to free F30 in vitro, while displaying a higher potent antitumor efficacy in xenograft models due to the prolonged circulation properties. Furthermore, administration of F30@RBC-M significantly extended the survival of mice in a transplanted mouse model than F30 free drug. These findings suggest that RBC membrane-coated nanoparticles derived from FLT3 inhibitors hold promise as a tool to enhance the therapeutic efficacy to treat FLT3-ITD AML.
Single-atom catalysts were widely used to treat atmospheric pollution and alleviate energy crises through photocatalysis. However, how to prevent the aggregation of single atoms during the preparation and catalytic processes remained a great challenge. Herein, a novel ultrathin two-dimensional porphyrin-based single-atom photocatalyst Ti-MOF (abbreviated as TMPd) obtained through a simple hydrothermal synthesis strategy was used for photocatalytic hydrogen evolution and NO removal, in which the single-atom Pd tightly anchored in the center of porphyrin to ensure single-atom Pd stable existence. Compared with most reported MOFs-based photocatalysts, the TMPd showed an excellent hydrogen evolution rate (1.32 mmol g−1 h−1) and the NO removal efficiency (62%) under visible light irradiation. Aberration-corrected high-angle annular dark-field scanning transmission electron microscope (HAADF-STEM) and synchrotron-radiation-based X-ray absorption fine-structure spectroscopy (XAFS) proved that pd in TMPd existed in an isolated state, and the atomic force microscope (AFM) proved the ultrathin morphology of TMPd. DFT calculations had demonstrated that single-atom Pd could serve as the active center and more effectively achieve electron transfer, indicating that single-atom Pd played a vital role in photocatalytic hydrogen evolution. In addition, a possible photocatalytic pathway of NO removal was proposed based on ESR and in-situ infrared spectra, in which the catalysts anchored with single-atom Pd could produce more active substances and more effectively oxidize NO to NO2− or NO3−. The results suggested that coordinating single-atom metal species as the active site in the center of porphyrin could be a feasible strategy to obtain various ultrathin porphyrin-based single-atom photocatalysts to acquire excellent photocatalytic performance further.
Organic electrode materials (OEMs) have attracted substantial attention for aqueous zinc-ion batteries (AZIBs) due to their advantages in relieving resource and environmental anxiety. However, the potential of OEMs is plagued by their low achievable capacity and high solubility. Here, we have proposed a new concept of "co-coordination force" and designed a rigid-flexible coupling crystalline polymer that can overcome the abovementioned limitations. The obtained crystalline polymer (BQSPNs) with multiredox centres makes the BQSPNs exist intermolecular hydrogen bonds (HB) among -C=O, -C=N, and -NH and consequently exhibits transverse two-dimensional arrays and longitudinal π-π stacking structure. Additionally, in-situ FTIR, Raman, variable temperature FTIR spectra, and 2D nuclear overhauser effect spectroscopy (NOESY) well capture the existence and evolution process of HB during the electrochemistry reaction process of BQSPNs, uncovering the effect of HB in stabilizing the structure and promoting the reaction kinetics. As a result, the BQSPNs with rationally designed "co-coordination force" deliver a high capacity of 459.6 mAh/g and a stable cycling lifetime for more than 100,000 cycles at 10 A/g in AZIBs. Our results disclose the HB effect and provide a brand-new strategy for high-performance OEMs design.
Catalytic C-H activation-initiated annulation reactions have emerged as a versatile strategy for the efficient construction of diverse ring structural units and complex cyclic molecules in synthetic chemistry. Herein, we describe a new Rh(Ⅲ)-catalyzed C-H activation-initiated transdiannulation reaction of N, N-dimethyl enaminones with gem-difluorocyclopropenes in the presence of H2O, enabling a facile and oxygen transfer access to ring-fluorinated tricyclic γ-lactones with a 6-5 ring-junction tetrasubstituted stereocenter. This approach features bond-forming/annulation efficiency, good functional group tolerance and complete regioselectivity, which may include a complex process consisting of Rh(Ⅲ)-catalyzed C(sp2)H activation, cyclic alkene insertion, defluorinated ring-opening of gem-difluorocyclopropane, intramolecular oxygen transfer, intramolecular cyclization and oxidative hydration.
An efficient and scalable electrochemical asymmetric protocol with metal-free catalysts and even without additional oxidants for the cross-dehydrogenative coupling reaction (CDC) of two C(sp3)-H bonds is reported. A series of aldehydes including natural products and various substrates containing C(sp3)-H bonds including xanthenes, acridines, cycloheptatrienes and even diarylmethane have been shown to undergo asymmetric CDC to afford a series of carbon-carbon bond coupling products with up to 94% yield and 98% ee. Mechanistic studies such as radical clock experiment suggest that the reaction proceeds via nucleophilic attack by enamine under electrochemical conditions.
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