Latest ArticlesWith the rapid development of economy, industrial and agricultural pollutants have caused great damage to the ecological environment and the normal development of organisms, posing a serious threat to global public health. Therefore, rapid and sensitive detection of pollutants is very important for environmental safety and people’s health. A stable multi-response fluorescence sensor (RhB@1) with dual emission characteristics was constructed by embedding RhB guest molecules in Zn-MOF using a simple one-pot method. XRD, IR, XPS, Raman and other characterization methods were used to demonstrate the formation of composite materials. The sensor has two fluorescence emission peaks at 415 nm and 575 nm under the excitation of 316 nm. It has high sensitivity and low detection limit (7.94 and 7.82 nmol/L, respectively) in the detection of fluazinam (FLU) and Fe3+. The mechanism of fluorescence quenching may be due to the synergistic effect of IFE and PET. Outstandingly, when ascorbate acid (AA) was added to the quenching system of Fe3+ and RhB@1, its fluorescence gradually recovered, forming the unique “on-off-on” sensor. Therefore, RhB@1 has a fast fluorescence response and good stability, making it potentially useful in practical application and biosensors. More significantly, using Fe3+ and AA as chemical input signals, a binary intelligent logic gate device has been developed based on the “on-off-on” response mode of RhB@1, which extends the application of logic gate switching devices in the chemical field. In addition, a visual portable test paper with good selectivity and high sensitivity was developed, which can be used for rapid detection of FLU, showing its broad application prospect.
Catalyzed by cerium ammonium nitrate (CAN), the oxidative cracking reaction of alkenes occurred to produce carbonyls in good yields under mild conditions. The reaction employed molecular oxygen (O2) as the safe and clean oxidant. The catalyst dosage was reduced to as low as 0.5 mol%, while no additive was required. Thus, it may afford a generally green synthetic approach for introducing oxygen into organic molecules as well as the biomass degradation and the resource recycling from the C=C bond-containing waste polymers. X-ray photoelectron spectroscopy (XPS) analysis and control experiments demonstrated that the process proceeded via a single electron transfer (SET) reaction-initiated free radical reaction mechanism. In the process, both Ce and NO3− acted as the oxygen carrier to promote the oxidation reaction. The application of the abundantly existed nitrate in CAN was found to be the key for reducing the catalyst loading.
The synthesis methods of α-fluoro-arylketones were well-established through electrophilic/nucleophilic fluorination and transition metal catalyzed cross-coupling. However, due to the site selectivity and substrate restriction, only a few cases have been developed to afford α-alkyl-α-fluoro-alkylketones. Herein, we report a general and efficient method of preparing diverse α-alkyl-α-fluoro-alkylketones via nickel-catalyzed reductive coupling reaction of monofluoroalkyl triflates with low-cost industrial raw material alkyl carboxylic acids. These transformations demonstrate high efficiency, mild conditions, and excellent functional group compatibility. This strategy provides a general and efficient method for the synthesis of α-alkyl-α-fluoro-alkylketones.
Dry eye disease (DED) is a multifactorial chronic inflammatory disease of the ocular surface with complex and unclear etiology. The development of reliable detection tools for the pathology of DED will benefit its treatment, but it is still lacking. In parallel, it has been discovered recently that viscosity changes are involved in inflammation processes. In this regard, we constructed a fluorescent probe V5 with an asymmetric donor-acceptor-donor (D-A-D) feature after rational structural modulation for viscosity detection during DED progression. The probe manifested a remarkable fluorescence enhancement (110 folds) in highly viscous conditions without interferences from polarity and reactive species. Specifically, no aggregation effect of the probe was found in glycerol. Moreover, viscosity increment in human corneal epithelial cells (HCECs) induced by hyperosmosis and inflammation was monitored, and ferroptosis in HCECs also led to the viscosity elevation. A reactive oxygen species (ROS)-dependent viscosity changes during DED progression is demonstrated. Finally, viscosity change in corneal epithelial cell layer from mice treated by scopolamine was also visualized for the first time. We anticipate this work can provide a new lens to the pathogenesis study and diagnosis of DED and other ophthalmic diseases using fluorescence methods.
Photodynamic therapy (PDT) has shown great application potential in cancer treatment and the important manifestation of PDT in the inhibition of tumors is the activation of immunogenic cell death (ICD) effects. However, the strategy is limited in the innate hypoxic tumor microenvironment. There are two key elements for the realization of enhanced PDT: specific cellular uptake and release of the photosensitizer in the tumor, and a sufficient amount of oxygen to ensure photodynamic efficiency. Herein, self-oxygenated biomimetic nanoparticles (CS@M NPs) co-assembled by photosensitizer prodrug (Ce6-S-S-LA) and squalene (SQ) were engineered. In the treatment of triple negative breast cancer (TNBC), the oxygen carried by SQ can be converted to reactive oxygen species (ROS). Meanwhile, glutathione (GSH) consumption during transformation from Ce6-S-S-LA to chlorin e6 (Ce6) avoided the depletion of ROS. The co-assembled (CS NPs) were encapsulated by homologous tumor cell membrane to improve the tumor targeting. The results showed that the ICD effect of CS@M NPs was confirmed by the significant release of calreticulin (CRT) and high mobility group protein B1 (HMGB1), and it significantly activated the immune system by inhibiting the hypoxia inducible factor-1alpha (HIF-1α)-CD39-CD73-adenosine a2a receptor (A2AR) pathway, which not only promoted the maturation of dendritic cells (DC) and the presentation of tumor specific antigens, but also induced effective immune infiltration of tumors. Overall, the integrated nanoplatform implements the concept of multiple advantages of tumor targeting, reactive drug release, and synergistic photodynamic therapy-immunotherapy, which can achieve nearly 90% tumor suppression rate in orthotopic TNBC models.
Metal/nucleophilic Lewis base dual catalysis has been recognized as a reliable and promising strategy for finishing ideal organic synthesis over the past decades. The new strategy can usually achieve some chemical reactions that cannot be realized by the traditionally mono-catalytic system, dramatically expanding the synthetic utility of chemical transformations by leveraging additional activation modes. Thus considerable progress has been made in the synthesis of a wide range of heterocyclic and biologically active compounds by using the combination of diversely metal/nucleophilic Lewis base dual catalysts, including metal/phosphine, metal/N-heterocyclic carbene (NHC) and metal/tertiary amine dual catalysis systems. In this review, we describe a comprehensive and updated advance of metal/nucleophilic Lewis base dual catalytic annualtion reactions, meanwhile, the related mechanism and the application of these annulation strategies in natural product total synthesis will be highlighted in detail.
Compartmentalization in the biological world brings excellent efficiency and specificity to the formation of complex compounds, inspiring supramolecular chemists to continuously search for defined spaces that can mimic such natural binding sites. Bowl-shaped cavitands built up from resorcinarenes (RA) present rigid and preorganized concave surfaces, which are capable of mimicking the molecular recognition properties of enzymes. The versatile scaffold of RA endows the cavitand with terrific variety and excellent binding behavior. This review provides a comprehensive overview over the structural modification to date in the high attention field of RA-based cavitands development. Different strategies for synthesizing diverse cavitands, such as small cavity cavitands, wider cavity cavitands, deep cavity cavitands, biscavitands, and asymmetric cavitands, are discussed in details. Furthermore, insights into their applications including catalysis, separations and sensing are provided.
Visible-light heterogeneous photocatalyst with high activity and selectivity is crucial for the development of organic transformations, but remains a formidable challenge. Herein, a simple and effective strategy was developed to integrate tetrazine moiety, a visible light active unit, into robust metal-organic frameworks (2D MOF-1(M), M = Co, Mn, Zn, and 3D MOF-2(Co)). MOF-1 series are isomorphous 2D porous frameworks, and MOF-2(Co) displays 3D porous framework. Interestingly, benefiting from the oxidative active species of O2•−, these MOFs all exhibit obviously highly enhanced photocatalytic activities toward the straightforward condensation of o-aminothiophenol and aromatic aldehydes at room temperature in EtOH under visible-white-light irradiation. Notably, compared to 3D MOF, the 2D layered MOF-1(Co) exhibited more excellent catalytic activity with a wide range of substrates possessing preeminent tolerance of steric hindrance. Most impressively, MOF-1(Co) can be recycled at least five times without significant loss of catalytic activity or crystallinity, exhibiting excellent stability and reusability. This study sheds light on the wide-ranging prospects of visible light active 2D MOFs as green photocatalysts for the preparation of fine chemicals.
The rechargeable Li-O2 battery endowed with high theoretical specific energy density has sparked intense research interest as a promising energy storage system. However, the intrinsic high activity of Li anode, especially to moisture, usually leads to inferior electrochemical performance of Li-O2 battery in humid environments, hindering its widespread application. To settle the trouble of poor moisture tolerance, fabricating a water-proof layer on the Li-metal anode could be an effective tactic. Herein, a facile strategy for constructing an ibuprofen-based protective layer on the Li anode has been proposed to realize highly rechargeable Li-O2 battery in humid atmosphere. Due to the in-situ reaction between ibuprofen reagent and metallic Li, the protective layer with a thickness of ~30 μm has been uniformly deposited on the surface of Li anode. Particularly, the protective layer, consisting of a large amount of hydrophobic alkyl group and benzene ring, can significantly resist water ingress and enhance the electrochemical stability of Li anode. As a result, the Li-O2 battery based on the protected Li anode achieves a long cycle life of 210 h (21 cycles at 1000 mAh/g, 200 mA/g) in highly moist atmosphere with relative humidity (RH) of 68%. This convenient and efficient strategy offers novel design concept of water-resistant metal anode, and paves the way to the promising future prospect for the high-energy Li-O2 battery implementing in the ambient atmosphere.
Triple-negative breast cancer (TNBC) lacks specific regimens for targeted therapy. Repeat chemotherapy promotes the evolution of TNBC into highly chemo-resistant tumors that metastasize to multiple organs simultaneously. Herein, polyacrylic acid-coated ultrasmall superparamagnetic iron-oxide nanoparticles (PAA@IONs) and dual-targeting doxorubicin liposomes achieved chemo–immunotherapy through intermittent administration. They inhibited tumor-drug resistance and multiorgan-specific metastasis significantly by targeting tumors and the microenvironment. We deciphered an immunosuppressive pre-metastatic niche and discovered that PAA@IONs could target tumors, tumor-draining lymph nodes (TDLNs), the liver, bone, and lungs. They promoted the polarization of macrophages into M1 macrophages in these organs and tissues. This action remodeled the immunosuppressive microenvironment and induced a sustained immune response, thereby reducing organ-specific metastasis. Overcoming the disadvantages of doxorubicin-induced cardiotoxicity as well as low tumor specificity, dual peptide-modified liposomes could target CD206 and CD13 simultaneously, and reverse chemo-resistance. These properties resulted in a significant decrease in the numbers of myeloid-derived suppressor cells (MDSCs) and cancer stem cells (CSCs) in the liver, lungs, and bone, thereby reducing protein expression of Ki-67 in TDLNs, and dramatically increasing the number of cluster of differentiation (CD)8+T cells and CD8+ T cell/T-regulatory-cell ratio in tumors and TDLNs (P < 0.0001). Compared with the control (P < 0.05 and P < 0.01, respectively) or free drug (P < 0.0001 and P < 0.01, respectively), multi-organ metastases were suppressed significantly, tumor-growth rate reduced, and survival prolonged. Our drug-delivery system overcame TNBC chemo-resistance and inhibited multiorgan-specific metastases. It circumvents the lack of effective therapeutic targets, the problem of patient selection due to a low mutation rate, and can simultaneously offer the possibility of avoiding surgery and considerable postoperative complications.
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