Latest ArticlesA new cooperative nickel reductive catalysis and N,N-dimethylformamide-mediated strategy for umpolung C–S radical reductive cross coupling of S-(trifluoromethyl)arylsulfonothioates with alkyl halides to produce alkyl aryl thioethers is described. This reaction features excellent selectivity, wide functionality tolerance, broad substrate scope, and facile late-stage modification of biologically relevant molecules. Mechanistic studies recognize initial generation of an amidyl radical anion via thermoinduced reduction of DMF with Sn, followed by umpolung reduction and single electron transfer of the nucleophilic sulfonyl moiety to form a sulphydryl radical and engage the Ni0/NiⅠ/NiⅢ/NiⅠ catalytic cycle.
Chemotherapy combined with photodynamic therapy has emerged as a promising strategy for cancer treatment. However, simultaneously delivering chemotherapeutic drugs and photosensitizers and precisely adjusting the ratio of the two components as needed remains a challengeable task. Herein, novel supramolecular nanoparticles (donated as BODIPY-CPT-NPs) for chemo-photodynamic combination cancer therapy are constructed from a glutathione-responsive camptothecin-based prodrug, BODIPY photosensitizer, and dimacrocyclic host molecule through orthogonal host-guest recognitions and co-assembly. With this strategy, the ratio of prodrugs and photosensitizers in nanoparticles can be easily and precisely controlled as needed. Benefiting from the strong host-guest interactions and stable self-assembly, the nanoparticles exhibit excellent stability and photobleaching resistance. Furthermore, camptothecin can be released from nanoparticles for chemotherapy in the presence of reduction agent and single oxygen can be efficiently generated for PDT with light irradiation. The combined effects of the BODIPY-CPT-NPs have been verified in CT26 and HeLa cancer cells.
Fluorescent materials that respond to multiple stimuli have broad applications ranging from sensing and bioimaging to information encryption. Herein, we report the design and synthesis of a single-fluorophore-based amphiphile DCSO, which shows temperature-, solvent-, humidity-, and radiation-dependent fluorescence. DCSO consists of a dicyanostilbene (DCS) group as a rigid hydrophobic core with oligo(ethylene glycol) (OEG) chains at both ends as a flexible hydrophilic periphery. The DCS group acts as a highly efficient fluorophore, while the OEG chain endows the molecule with thermo-responsiveness. Fluorescent colors can vary from blue to green to yellow in response to external stimuli. On the basis of light radiation, we demonstrate that this system can be applied to time-dependent information encryption, in which the correct information can only be read at a specific time under irradiation. This work further demonstrates the usefulness and application of single-fluorophore-based luminescent materials with multiple stimuli-responsive functions.
The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction (OER) is a prerequisite for efficient water electrolysis. Herein, we develop a broccoli-like Ni3S2@NiFePx (Ni3S2@NFP) catalyst on nickel foam (NF) via a sequential two-step layer-by-layer assembly electrodeposition method. X-ray diffraction, in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition. The reconstruction of double layer Ni3S2@NFP facilitates the formation of the active (oxy)hydroxides, which is modulated by the dual anionic layer with mixed sulfate and phosphate ions. As a result, the obtained Ni3S2@NFP electrode exhibits low overpotential (329 mV) and long-term durability (~500 h) for OER at current density of 500 mA/cm2. Moreover, the self-supported Ni3S2@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device (AEMWE). This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance.
CRISPR/Cas system has been utilized to rationally manipulate intracellular genes, and it has been engineered as versatile and efficient gene editing tools with precise site-specificity and excellent targeting ability for therapeutics, diagnostics, and bioimaging. Here, the evolution and application of CRISPR/Cas systems were sketched chronologically. Landmark works were exemplified to illustrate the design principles of CRISPR/Cas systems. Furthermore, the delivery vectors of CRISPR/Cas system especially DNA nanomaterials-based vectors were categorized and illuminated. DNA nanomaterials are suitable for CRISPR/Cas system delivery via base pairing due to its sequence programmability and biocompatibility. Then the applications of CRISPR/Cas in diagnosis and genomic imaging were highlighted. At the end of the review, the challenges and opportunities of CRISPR/Cas systems were deeply discussed. We envision that the grant advances on CRISPR/Cas systems will promote the development of interdisciplinary fields in chemistry, biology and medicine.
Fe-NX/C electrocatalysts have aroused extensive interest in accelerating sluggish oxygen reduction reaction (ORR) kinetics as potential alternatives to platinum catalysts in rechargeable Zn-air batteries (ZABs). However, the low density and poor accessibility of Fe-NX sites have severely restricted the electrocatalytic performance of Fe-NX/C. Herein, Fe, N co-doped ordered mesoporous carbon fiber bundles are prepared through a ligand-assisted strategy with nitrogen-rich 1,10-phenanthroline as space isolation agent. 1,10-Phenanthroline reveals a six-membered heterocyclic structure containing abundant nitrogen species to tightly coordinate with Fe ions, which is conducive to achieving high-density Fe-NX sites. Meanwhile, the adoption of SBA-15 as hard-templates enables the catalysts with highly ordered channels and large specific surface areas, improving the accessibility of Fe-NX sites. The optimal catalyst (PDA-Fe-900) demonstrates a positive half-wave potential of 0.84 V (vs. RHE) in alkaline solution, outperforming the commercial Pt/C (0.83 V). In addition, PDA-Fe-900 delivers comparable ORR performance to commercial Pt/C in acidic electrolyte. Impressively, when PDA-Fe-900 is employed as an air cathode, it achieves large power densities of 163.0 mW/cm2 in liquid-state ZAB and 116.6 mW/cm2 in the flexible solid-state ZAB. This work provides an efficient ligand-assisted pathway for fabricating catalysts with dense and accessible Fe-NX sites as high-performance ORR electrocatalysts for ZABs.
In recent years, vanadate has attracted the attention of researchers for its application in electrode materials due to its high specific capacity and layered crystal structure. Herein, a typical manganese vanadium oxides (MnV2O6) product is efficient synthesis via a simple one-step hydrothermal method at 200 ℃ for 16 h. The as-prepared MnV2O6 sample is found to be the unique one-dimensional fan-like superstructure consist of several nanorods. From a microcosmic point of view, VO6 octahedra sheets are connected by sharing edges which provides highly-open framework for rapid the intercalation and deintercalation of guest ions Therefore, stable MnV2O6 was prepared and used as a cathode material in aqueous zinc ion batteries, which displayed favorable specific discharge capacity, excellent coulombic efficiency and well cycling performance.
Base pair mismatch has been regarded as the main source of DNA point mutations, where minor short-lived tautomers were usually involved. However, the detection and characterization of these unnatural species pose challenges to existing techniques. Here, by using systematic structural and ultrafast resonance Raman (RR) spectral analysis for the four possible conformers of guanine-cytosine base pairs, the prominent marker Raman bands were identified. We found that the hydrogen bonding vibrational region from 2300 cm−1 to 3700 cm−1 is ideal for the identification of these short live species. The marker bands provide direct evidence for the existence of the tautomer species, thus offering an effective strategy to detect the short-lived minor species. Ultrafast resonance Raman spectroscopy would be a powerful tool to provide direct evidence of critical dynamical details of complex systems involving protonation or tautomerization.
Benefitting from the tunable heterogeneous interface and electronic interaction, metal-polymer-based hybrid composites have attracted wide attention. It is highly desired to develop advanced synthesis methodology and understand the structure-performance relationship. Herein, with the aniline oligomer as the key enabler, we resolve the inferior dynamics issue in the Ag+-aniline reaction system, and successfully fabricate a sub-micron anisotropic eccentric Ag@polyaniline (PANI) particle (an average size up to 340 nm) at room temperature. We demonstrate the synergy mechanism of polyvinyl pyrrolidone and in-situ generated PANI for modifying the dynamic reaction interface. We further clarify the H+ concentration and the surfactant types serve as main descriptors to tune the reaction dynamics. Besides, by applying other aniline oligomers, a series of similar eccentric structures can also be obtained, indicative of the good applicability of our strategy. Such a sub-micron eccentric structure furnishes the Ag@PANI composites with sound performance for microwave absorption, as demonstrated by a minimum reflection loss (RL) value of −35 dB with an effective absorption bandwidth of 3.7 GHz. This study provides an inspiring scope/concept of eccentric microstructure engineering for better meeting the demands in the high-tech military, energy, environment fields, and beyond.
Covalent organic frameworks (COFs) are promising crystalline materials for the light-driven hydrogen evolution reaction (HER) due to their tunable chemical structures and energy band gaps. However, deeply understanding corresponding mechanism is still challenging due to the multiple components and complicated electron transfer and reduction paths involved in photocatalytic HER. Here, the photocatalytic HER investigation has been reported based on three COFs catalysts, 1–3, which are prepared by benzo[1, 2-b: 3, 4-b': 5, 6-b']trithiophene-2, 5, 8-trialdehyde to react with C3 symmetric triamines including tris(4-aminophenyl)amine, 1, 3, 5-tris(4-aminophenyl)benzene, and (1, 3, 5-tris-(4-aminophenyl)triazine, respectively. As the isostructural hexagonal honeycomb-type COF of 2 and 3 reported previously, the crystal structure of 1 has been carefully correlated through the powder X-ray diffraction study with the help of theoretical simulations. 1 shows highly porous framework with Brunauer-Emmett-Teller surface area of 1249 m2/g. Moreover, the introduction of ascorbic acid into the photocatalytic system of COFs achieves the hydrogen evolution rate of 3.75, 12.16 and 20.2 mmol g–1 h–1 for 1–3, respectively. The important role of ascorbic acid in photocatalysis of HER is disclosed to protonate the imine linkages of these COFs, leading to the obvious absorbance red-shift and the improved charge separation efficiency together with reduced resistance in contrast to pristine materials according to the spectroscopic and electronic characterizations. These innovations of chemical and physical properties for these COFs are responsible for their excellent photocatalytic performance. These results elucidate that tiny modifications of COFs structures is able to greatly tune their band structures as well as catalytic properties, therefore providing an available approach for optimizing COFs functionalities.
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