Latest ArticlesA novel and efficient copper-catalyzed decarboxylative alkynylselenation of indoles with Se powder and propiolic acids has been developed. The outstanding advantages of this protocol not only nicely avoid the use of prefabricated arylselenation reagent and address the facile over-selention issues, but also enrich the chemistry of selenium powder. Importantly, this reaction could be extended to pyrrole, and the practical utility of this transformation has been demonstrated in gram-scale synthesis and late-stage indolylselenation of Clofibrate-derived propiolic acid.
Protein-based drugs have received extensive attention in the field of drug research in recent years. However, protein-based drug activity is difficult to maintain during oral delivery, which limits its application. This study developed bifunctional oral lipid polymer hybrid nanoparticles (R8-PEG-PPNPs) that deliver superoxide dismutase (SOD) for the treatment of ulcerative colitis (UC). R8-PEG-PPNPs was composed of PCADK, PLGA, lecithin, and co-modified with stearic acid-octa-arginine and polyethylene glycol. The nanoparticles (NPs) are uniformly dispersed with a complete spherical structure. In vitro stability and release studies showed that R8-PEG-PPNPs exhibited good stability and protection. In vitro cell culture experiments demonstrated that R8-PEG-PPNPs as carriers have no significant toxic effects on cells at concentration below 1000 µg/mL and promote cellular uptake. In experiments with ulcerative colitis mice, R8-PEG- PPNPs were able to enhance drug absorption by intestinal epithelial cells and accumulate effectively at the site of inflammation. Its therapeutic effect further demonstrates that R8-PEG-PPNPs are a promising delivery system for oral delivery of protein-based drugs.
Carbon dots (CDs) with intriguing fluorescent property, good biocompatibility, high stability, easy interaction with substrates, are burgeoning carbon nanoparticles with large potential in various applications. Incorporating CDs into the polymer matrix is becoming a popular strategy to endow the complex with new functions. Herein, the green-synthesized CDs was integrated into the mixture of gelatin (derived from waste fish scale) and chitosan, and a multifunctional bio-nanocomposite (defined as Gelatin/Chitosan/CDs) film was developed, which showed the excellent antibacterial, antioxidant, pH-sensitivity, UV shielding, and blue-emission properties. The effects of different concentrations of CDs on the physical, mechanical, structural, and functional activity of bio-nanocomposite film were tested. Compared with the Gelatin/Chitosan film, the Gelatin/Chitosan/CDs film with an optimum addition of 20% CDs showed the enhanced antibacterial, antioxidant as well as UV shielding activities. More importantly, it was used as an effective packaging material for fish meat preservation, reducing the loss of nutritional quality consumption, extending the shelf life of food. Besides, the bio-nanocomposite films also possessed the anti-counterfeiting and pH-responsive properties due to the strong fluorescent emission of CDs, and had the great potential in developing the intelligent packaging materials. Our work shed new light on the new application of CDs and the synthesis of bio-nanocomposite film in food industry.
Lithium–sulfur (Li–S) batteries exhibit outstanding energy density and material sustainability. Enormous effects have been devoted to the sulfur cathode to address redox kinetics and polysulfide intermediates shuttle. Recent attentions are gradually turning to the protection of the lithium metal anodes, since electrochemical performances of Li–S batteries are closely linked to the working efficiency of the anode side, especially in pouch cells that adopt stringent test protocols. This Perspective article summarizes critical issues encountered in the lithium metal anode, and outlines possible solutions to achieve efficient working lithium anode in Li–S batteries. The lithium metal anode in Li–S batteries shares the common failure mechanisms of volume fluctuation, nonuniform lithium flux, electrolyte corrosion and lithium pulverization occurring in lithium metal batteries with oxide cathodes, and also experiences unique polysulfide corrosion and massive lithium accumulation. These issues can be partially addressed by developing three-dimensional scaffold, exerting quasi-solid reaction, tailoring native solid electrolyte interphase (SEI) and designing artificial SEI. The practical evaluation of Li–S batteries highlights the importance of pouch cell platform, which is distinguished from coin-type cells in terms of lean electrolyte-to-sulfur ratio, thin lithium foil, as well as sizable total capacity and current that are loaded on pouch cells. This Perspective underlines the development of practically efficient working lithium metal anode in Li–S batteries.
During cancer treatment, chemotherapeutic drugs always result in severe side-effects and drug resistance. Therefore, combining cheomtherapy with other therapeutic modalities, such as photodynamic therapy (PDT) and designing an activable platform is promising for precise and efficient anticancer treatment. Herein, we report a "pro-drug-photosensitizer" agent, LMB-S-CPT, bearing a disulfide bond as the glutathione (GSH)-activatable linker. LMB-S-CPT can be selectively activated by GSH to release activated drug, camptothecin (CPT), for chemotherapy and activated photosensitizer, methylene blue (MB), for PDT. LMB-S-CPT exhibits excellent tumor-activatable performance when injected into tumor-bearing mice, as well as specific cancer therapy with negligible toxic side effects. The activatable pro-drug-photosensitizer offers a new strategy for chemo-photodynamic therapy and displays precise, selective and excellent antitumor effect.
The development of organic materials with white-light emission and thermally activated delayed fluorescence (TADF) properties in the solid state remain a challenge. Herein, a series of white-light-emitting organic luminogens have been developed and are found to show aggregation-induced delayed fluorescence (AIDF) characteristics. The AIDF emitters present dual-emission consisted of prompt fluorescence and TADF in the crystalline state. Their white-light emissions can be easily tuned by altering the chemical structure and connecting position of the heterocyclic aromatic substituent. Under the stimuli of mechanical force and solvent vapor, the compounds exhibit remarkable and reversible mechanochromism, in which their emission colors are switchable between white and yellow. Upon grinding, they also display linearly tunable luminescence colors, as well as force-induced TADF enhancement, which may be associated with the more compact molecular packing and the restriction of intramolecular motions. The results from time-resolved emission scanning and theoretical calculation suggest that the dual-emission of the AIDF luminogens likely results from the twisted intramolecular charge transfer transitions of the molecules, and the reversible mechanochromism properties probably stem from the interconversion of the quasi-axial and the quasi-equatorial conformations.
Rechargeable aqueous zinc-ion batteries have attracted extensive interest because of low cost and high safety. However, the relationship between structure change of cathode and the zinc ion storage mechanism is still complex and challenging. Herein, open-structured ferric vanadate (Fe2V4O13) has been developed as cathode material for aqueous zinc-ion batteries. Intriguingly, two zinc ion storage mechanism can be observed simultaneously for the Fe2V4O13 electrode, i.e., classical intercalation/deintercalation storage mechanism in the tunnel structure of Fe2V4O13, and reversible phase transformation from ferric vanadate to zinc vanadate, which is verified by combined studies using various in-situ and ex-situ techniques. As a result, the Fe2V4O13 cathode delivers a high discharge capacity of 380 mAh/g at 0.2 A/g, and stable cyclic performance up to 1000 cycles at 10 A/g in the operating window of 0.2–1.6 V with 2 mol/L Zn(CF3SO3)2 aqueous solution. Moreover, the assembled Fe2V4O13//Zn flexible quasi-solid-state battery also exhibits a relatively high mechanical strength and good cycling stability. The findings reveal a new perspective of zinc ion storage mechanism for Fe2V4O13, which may also be applicable to other vanadate cathodes, providing a new direction for the investigation and design of zinc-ion batteries.
Black phosphorus (BP) has attracted an ever-growing interest due to its unique anisotropic two-dimensional structure, impressive photoelectronic properties and attractive application potential. However, the tools for bandgap engineering and passivation via covalent modification of BP nanosheets remain limited to diazonium salt and nucleophilic addition methods, so that developing new modification strategies for BP nanosheets is crucial to explore its physical and chemical properties and enrich the toolbox for functionalization. Herein, we report the covalent modification of liquid-phase exfoliated BP nanosheets based on a rational analysis of BP structure. The modification of BP is achieved via carbene, a highly reactive organic mediate. The carbene modification improves the solubility and stability of BP nanosheets. Detailed microscopic and spectroscopic characterizations including infrared spectra, Raman spectra, X-ray photoelectron spectra, SEM and TEM were conducted to provide insights for the reaction. The proof of the existence of covalent bonds between BP nanosheets and organic moieties confirms the successful modification. Moreover, theoretical calculations were conducted to unveil the reaction mechanism of the two different types of bonds and the chemical property of two-dimensional BP.
The production of graphene oxide with less acid is beneficial to reduce the costs and lower the impact on the environment, but it is still a great challenge. In this work, a relatively simple, safe method for synthesizing graphene oxide with much less acid (decrease ~40%) is proposed. With assistance of the heat absorbed from environment and reaction system, the temperature of reaction system of low acid can be well controlled. More interestingly, the graphite can be completely oxidized into graphite oxide by using much less acid, with lowering the production of high-concentration aqueous waste acid (> 1 mol/L, decrease ~40%). A series of characterizations show that the prepared graphene oxide has similar yield and functional groups compared with that of using the conventional method. This work provides a safe and environmentally friendly choice for the large-scale production of graphene oxide and its derivative materials.
Buchwald-Hartwig amination of 5, 15-dibromo and 5, 10-dibromo Ni(Ⅱ)porphyrins with 5-amino Ni(Ⅱ)porphyrin gave linear and bent trimers 4Ni and 5Ni with a central quinodiimine-type Ni(Ⅱ)porphyrinoid. The structures of 4Ni and 5Ni have been confirmed by X-ray diffraction analysis in both cases. The formation of unusual products 4Ni and 5Ni has been ascribed to facile oxidation of 5, 15- and 5, 10-amino Ni(Ⅱ) porphyrin unit. Reduction of 4Ni and 5Ni under proper conditions gave NH-bridged Ni(Ⅱ)porphyrin trimers 4Ni-2H and 5Ni-2H in high yields. Trimers 4Ni and 5Ni exhibit the lowest energy band as compared with 4Ni-2H and 5Ni-2H. Especially the bent trimer 5Ni exhibits a broad absorption tail beyond 1400 nm.
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