Latest ArticlesHigh-performance carbon dots (CDs) allowing the application in high-end display devices are highly desirable and usually limited by the absence of simple and easy synthesis methods. In this work, we exploited an easy-to-implement strategy for the one-step synthesis of green-emitting CDs (G-CDs) with superb optical properties. The G-CDs were synthesized using m-phenylenediamine (m-PD) as a single precursor, and the reaction reacted at 180 ℃ for 12 h The resultant G-CDs exhibit high-purity and excitation-independent green fluorescence with the photoluminescence (PL) peak located at 516 nm, full width at half maximum (FWHM) of 46 nm, and PL quantum yield (QY) of ~80% under the 470 nm excitation light. The G-CDs and corresponding composite film prepared with polyvinyl butyral (G-CDs@PVB) exhibit good PL stability after undergoing long-time storage for one year and 360 h exposure under 460 nm blue light. The G-CDs@PVB film was used as color-conversion materials in green-emitting light-emitting diode (LED) application, exhibiting a Commission internationale de l'Eclairage (CIE) chromaticity coordinate of (0.21, 0.44). The film was also used in CD-based liquid crystal display (CD-LCD) application, achieving a color gamut value of 85%. This work will offer a working basis for the synthesis of high-performance CDs as well as their application in displays.
Electrocatalytic nitrogen reduction reaction (NRR) is considered as an attractive approach for ammonia synthesis under mild conditions. A bottleneck of NRR is the exploration of efficient catalysts for accelerating reaction kinetics, among which heterogeneous structures possessing distinct atomic arrangement could modify electronic structure, and therefore altering their NRR activity. Here, we report a facile strategy for fabricating hetero-phase metal oxides derived from metal organic framework that are further integrated with Au nanoparticles as NRR catalysts. The phase composition of zirconia can be easily adjusted by simply changing the reaction temperature, where the monoclinic and tetragonal phases with the roughly close proportions have a distinct interface, leading to a strong interaction between Au and ZrO2. The enhanced interaction renders Au to be more electropositive and facilitates stronger binding to N2. As a result, a remarkable ammonia yield of 22.32 µg h−1 mgcat.−1 and a Faradaic efficiency of 31.92% can be achieved at low overpotential. This work is expected to pave the way for the design of heterogeneous structures and the exploration of hetero-phase nanostructures in boosting the electrocatalytic NRR.
Thirty-one new 10,12-disubstituted aloperine derivatives were subtly constructed through a selective oxidation on the 10-α-C–H induced by sulfonyl and a nucleophilic substitution with the stereoselectivity and scalability. Of them, compound 6b displayed a moderate anti-human coronavirus OC43 (HCoV-OC43) potency and blocked the viral entry stage through a host mechanism of action. Using chemoproteomic techniques, both transmembrane serine protease 2 (TMPRSS2) and scavenger receptor class B type 1 (SR-B1) proteins, which act as host cofactors of viral entry, were identified to be the direct targets of 6b against HCoV-OC43. Furthermore, 6b may deactivate the TMPRSS2 by inducing a change in protein conformation, rather than binding to its catalytic center, thus suppressing the viral membrane fusion. Accordingly, our study provided key scientific data for the development of aloperine derivatives into a new class of antiviral candidates against human β-coronavirus, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).
Copper phthalocyanine (CuPc) is adopted as an electrolyte additive to stabilize lithium anode for lithium-sulfur (Li-S) batteries. CuPc with a planar molecular structure and lithiophilic N-containing group, is likely to be adsorbed on the surface of Li anode to form a coating layer, which can restrict the direct contact between Li anode and solvents, and guide the uniform deposition of Li+ ions. The Li||Li symmetric cells demonstrate a stable cycle performance, and Li||Cu cells show high Coulombic efficiencies. In Li-S batteries, the formed stable solid-electrolyte interface (SEI) film containing copper sulfides can protect Li anode from the polysulfide corrosion and side reactions with the electrolyte, leading to the compact and smooth surface morphology of Li anode. Therefore, the Li-S batteries with CuPc additive deliver much higher capacity, better cycle performance and rate capability as compared to the one without CuPc additive.
Dendritic cell (DC)-targeted delivery of mRNA is a prominent method to boost the efficacy of mRNA tumor vaccines. The targeting ligands are often modified on nanocarriers by polyethylene glycol (PEG) linker in mRNA delivery systems. Whether the PEG linker length influences the targeting delivery efficiency of mRNA nanocarrier in vivo remains unclear. Here, we designed and constructed DC-targeted mRNA delivery systems modified by mannose via different PEG linker lengths (100/400/1000/2000) (MPn-LPX). The top candidate MP400-LPX (the linker was PEG400) showed the optimal mRNA expression and antigen presentation owing to the highly efficient uptake by DCs. Furthermore, MP400-LPX could better inhibited tumor growth and extended survival in the E.G7-OVA lymphoma and TC-1 cervical tumor mouse model. Collectively, these results demonstrated that PEG400 was the optimal linker for the PEGylated DC-targeted mRNA vaccines. Our findings provided a new platform for the rational design of targeted mRNA nanovaccines with shorter-length PEG.
Conversion of CO2 into high-value products using electrochemical CO2 reduction (ECR) technology is an effective way to alleviate global warming and reach carbon neutrality. The oxygen vacancies in heterogenous catalysis are generally considered as a powerful method to enhance the performance of ECR by promoting CO2 adsorption and activation. However, the extent of defects in oxygen vacancies-activity relation has rarely been studied. Herein, we prepared Cu–Cd bimetallic catalysts with adjustable oxygen defect degree by controlling the amount of cadmium addition. Fourier transform infrared spectroscopy characterization results reveal that the formation of oxygen vacancies is attributed to the asymmetric stretching of Cu–O by the addition of cadmium. Electrochemical results show that the oxygen defect degree can modulate the selectivity of ECR products. A low degree of oxygen defects (CuO) is generally associated with lower product Faraday efficiency (FEC2/FEC1 ≈ 114%), but overabundant oxygen vacancies (CuO2.625–CdO0.375) are not entirely favorable to improving ECR activity (FEC2/FEC1 ≈ 125%) and single selectivity, while an appropriate degree of oxygen vacancies (CuO2.75–CdO0.25) can facilitate the ECR process toward single product selective production (FEC2/FEC1 ≈ 296%). The theoretical calculation showed that the O vacancy formed on CuO and the interface between CdO and CuO were conducive to enhancing the formation of *COOH intermediate and promoting the generation of ethylene products. This study provides a new approach and insight into the selective production of single products for future industrial applications of ECR.
Porphyrins and their derivatives are excellent photosensitizers in photodynamic therapy (PDT). The modification of porphyrin molecules into metal-organic cages (MOCs) is a viable strategy to improve their bioavailability. In this work, MOC C66 based on porphyrin was synthesised by a one-pot self-assembly method. The three-dimensional structure of the metal-organic cage ameliorated the aggregation and self-quenching of porphyrins and increased the molar absorption coefficient in the visible light region, which enhanced the reactive oxygen species (ROS) yield of porphyrins and effectively improved the efficiency of photodynamic therapy. ROS generation ability tests in solution confirmed the improved reactive oxygen capacity of the cage, which showed greater phototoxicity to HeLa and MCF-7 cells in vitro, suggesting a new strategy for future modifications of the simple synthesis of porphyrins as photosensitizers.
Rhodium(Ⅲ)-catalyzed CH couplings of arenes with alkenes are among the most powerful methods for CC bond formation. For these transformations, subtle manipulation of ancillary ligands can lead to dramatic changes in reactivity and selectivity. However, detailed mechanistic studies concerning the ligand effects are rare. In this study, we investigated the origin of ligand-controlled product-selectivity in rhodium(Ⅲ)-catalyzed CH couplings of arenes with alkenes, using a series of well-defined [CpXRhⅢ] complexes that feature electronically or sterically distinct CpX (Cp (η5-C5H5), CpCF3 (η5-C5Me4CF3) and Cp* (η5-C5Me5)) ligands. A combination of experimental and theoretical investigations showed that (i) rhodium hydride species containing the electron rich Cp* ligand can undergo reinsertion of the alkene, thereby allowing rhodium-walking, (ii) rhodium hydride species involving the electron-deficient Cp or CpCF3 ligands prefer reductive elimination rather than alkene insertion. These findings offer valuable insights on future rational catalyst design for selective arene–alkene cross coupling reactions.
Multifunctional drug delivery systems (DDSs) have shown great prospects in overcoming the heterogeneous barrier of delivery drugs to the complex tumor microenvironment (TME). In this study, multifunctional AS/Ge-pNAB microgels with dual-active targeting, triple environment responsiveness, and fluorescence imaging capability were prepared through a straightforward procedure. This was aimed to improve the antitumor therapeutic application of gambogic acid (GA) based on the biological characteristics of TME. The microgels have a uniform double-layer structure with aptamer in the outer layer which helps in recognizing receptors on the tumor cells. The GA loaded nano-herb exhibited environment-responsive drug release profiles under acidic pH, reductant and high temperature. The nano-herb significantly improved the accumulation of GA in tumor sites through the synergistic combination of the enhanced permeability and retention effect and dual-ligand mediated internalization. Then, it accelerated intracellular drug release and killed tumor cells. Therefore, the nano-herb had specific therapeutic effects on the tumor in vitro and in vivo as they remarkably inhibited tumor growth while depicting optimal biosafety and lower levels of off-target toxicity. Overall, these findings demonstrate the great potential of the multifunctional AS/Ge-pNAB microgels for precisely targeted GA delivery and open a new avenue for the facile preparation of multifunctional DDSs.
Saccharides are a sort of ubiquitous and vital molecules within the whole life. However, the application of saccharides analysis with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is restricted by their low ionization efficiency and the instability of the sialic acid fraction. Derivatization strategy based on nonreductive amination provides a good solution, however, this is often time consuming and may result in sample loss due to removal of excessive derivatization reagents. Herein, hydralazine (HZN) was utilized as a reactive matrix for labeling reducing saccharides directly on MALDI target which eliminated tedious sample preparation and avoided sample loss. After optimization, effective and reproducible on-MALDI-target derivatization of neutral and acidic saccharides was achieved in both positive and negative modes. Compared with 2,5-dihydroxybenzoic acid (DHB) and 9-aminoacridine (9-AA), HZN improved the detection sensitivity of reducing saccharides and provided more abundant fragment ions in MS/MS analysis. Moreover, 26 kinds of neutral glycans and 5 kinds of sialic glycans were identified from ovalbumin (OVA) and bovine fetuin, respectively. Combined with the statistical models, this strategy could be used to distinguish and predict samples of 6 brands of beer, and discriminate 2 kinds of beer fermentation modes. In addition, HZN was applied for quantitative analysis of glucose in urine samples, and the obtained urine glucose concentrations of diabetic patients were consistent with the clinical test results, showing the potential of qualitative and quantitative analysis of reducing saccharides in complex samples.
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