High-Entropy Oxide Derived from Metal-Organic Framework as a Bifunctional Electrocatalyst for Efficient Urea Oxidation and Oxygen Evolution Reactions.

High-entropy oxides (HEOs) offer unique features through a combination of incompatible metal cations to a single crystalline lattice. Owing to their special characteristics such as abundant cation compositions, high entropy stabilization, chemical and thermal stability, and lattice distortion effect, they have drawn ever-increasing attention for various applications. However, very few studies have been reported for catalytic application, and developing HEOs with large surface areas for efficient catalytic application is still in infancy. Herein, we design nanostructured HEO of (FeNiCoCrCu)3O4 using metal-organic frameworks (MOFs) as sacrificial templates to achieve a large surface area, high density of exposed active sites, and more oxygen vacancies. Single-crystalline phase HEOs with surface area as large as 206 m2 g-1 are produced and further applied as bifunctional electrocatalysts for the urea oxidation reaction (UOR) and oxygen evolution reaction (OER). Benefiting from enhanced oxygen vacancies and a large surface area with abundant exposed active sites, the optimized HEO exhibited excellent electrocatalytic activity toward UOR with a very low potential of 1.35 V at the current density of 10 mA cm-2 and showed long-term stability for 36 h operation, making a significant catalytic performance over previously reported HEOs. Moreover, the HEO demonstrated an efficient catalytic performance toward OER with a low overpotential of 270 mV at 10 mA cm-2 and low Tafel slope of 49 mV dec-1. The excellent catalytic activity is ascribed to the starting MOF precursor and favorable high-entropy effect.

Silver-enhanced fluorescence of bimetallic Au/Ag nanoclusters as ultrasensitive sensing probe for the detection of folic acid.

Folic acid (FA) is the natural form of water-soluble vitamins widely found in most plants and animal products and its deficiency leads to several human body abnormalities. The advancements of metal nanoclusters are highly increasing due to their molecule-like optical properties and attractive applications. Because of increasingly demand of noble metal nanoclusters as sensing templates, different synthesis methods have been developed for facile synthesis of noble metal nanoclusters. Herein, red-emitting fluorescent bovine serum albumin (BSA)-capped Au-Ag bimetallic NCs are facilely synthesized through green one-pot synthetic approach. The effect of silver on the fluorescence properties of Au NCs was investigated and it was found that introduction of silver can enhance the fluorescence intensity. The fluorescence intensity of the as-prepared Au-Ag nanoclusters gets quenched in the presence of folic acid in an aqueous medium and it was used as ultrasensitive sensing probe for FA detection. The developed Au-Ag NCs-based sensing probe shows linear response in the wide range of 0-100 µM and the detection limit is as low as 0.47 nM. Its applicability has also been confirmed successfully in real human serum, urine and FA tablet samples. Due to the high stability, sensitivity and selectivity, the developed bimetallic cluster sensing system is highly promising to be applied in the pharmaceutical and clinical laboratories.

Pd-Doping-Induced Oxygen Vacancies in One-Dimensional Tungsten Oxide Nanowires for Enhanced Acetone Gas Sensing.

Metal oxide semiconductors (MOS) with different nanostructures have been widely used as gas sensing materials due to the tunable interface structures and properties. However, further improvement of the sensing sensitivity and selectivity is still challenging in this area. Constructing appropriate heterogeneous interface structures and oxygen vacancies is one of the important strategies to tune the sensing properties of MOS. In the present study, interfacial heterostructures in PdxW18O49 nanowires (PdxW18O49 NWs) were fabricated and manipulated by doping different Pd contents through a simple hydrothermal process. Relevant characterization proved that the structure and composition of the one-dimensional (1D) nanomaterial can be effectively changed by Pd doping. It was found that the oxygen vacancy concentration increases first with the increase of Pd content, and when the Pd content increases to 7.18% (Pd7.18%W18O49 NWs), the oxygen vacancy content reaches the maximum (52.5%). If the Pd content continues to increase, the oxygen vacancy ratio decreases. The gas sensing investigations illustrated that the PdxW18O49 NWs exhibited enhanced sensing properties than pure W18O49 NWs toward acetone. Among the as-prepared catalysts, the Pd7.18%W18O49 NWs showed the best sensing response and the fastest response-recovery speeds (5 and 10 s, respectively) at a working temperature of 175 °C. In addition, this 1D nanostructure with fabricated heterostructures also delivers a good sensing selectivity and a wide detection range from 100 ppb to 300 ppm, with maintaining excellent performance in the presence of high concentrations of ethanol and carbon dioxide. The excellent gas sensing behavior could be attributed to the generated oxygen vacancies and the heterostructures upon Pd doping. This study offers a novel strategy for the design of high-performance gas sensors for ppb-level acetone sensing.

Interfacial heterojunction construction by introducing Pd into W18O49 nanowires to promote the visible light-driven photocatalytic degradation of environmental organic pollutants.

Photocatalytic degradation of organic dyes by sunlight can greatly simplify the catalytic devices and save the cost. The development of photocatalysts for organic pollutants degradation driven by sunlight at room temperature still faces serious challenges. In this work, we developed a novel Pd-W18O49 nanowire photocatalyst for high efficiency, high stability, and sunlight-induced degradation of methylene blue and neutral red. It was found that after Pd introducing, the band gap energy of W18O49 nanowires lowers from 2.77 to 2.44 eV, which can accelerate the electron jump from the valence band to the conduction band, resulting in the efficient separation of electrons and holes. Meanwhile, with Pd introducing to the W18O49 nanowires, interfacial heterojunction with the Schottky barrier is formed, which can reduce the rate of electron-hole recombination. The catalytic results show that the obtained Pd-W18O49 nanowires demonstrate enhanced photodegradation capacity in comparison with W18O49 nanowires. Especially, with Pd-W18O49 nanowires (10 mg) as photocatalyst, 98.4% of methylene blue and 96.1% of neutral red can be decomposed within 40 min under sunlight irradiation. Besides, the photocatalytic degradation pathways of methylene blue and neutral red on the Pd-W18O49 nanowires are also proposed. This study provides a good strategy for the design and preparation of highly efficient 1D heterojunction-based photocatalysts for the degradation of environmental organic pollutants.

"Turn-off" sensing probe based on fluorescent gold nanoclusters for the sensitive detection of hemin.

Balanced level of hemin in the body is fundamentally important for normal human organ function. Therefore, environmentally benign, stable, and fluorescent metal nanoclusters (NCs) for selective and sensitive detection of hemin have been investigated and reported. Herein, highly orange red emissive gold NCs are successfully synthesized using glutathione as a reducing and stabilizing agent (GSH-Au NCs). The clusters are characterized using various techniques like Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-vis spectroscopy, and fluorescence spectrometer. The fluorescence intensity of as-synthesized Au NCs strongly quenched upon addition of different concentrations of hemin. The decrease in fluorescence intensity of GSH-Au NCs has been applied for determination of hemin concentration in the linear range from 1 to 25 nM with a low limit of detection (LOD) of 0.43 nM. The method was also successfully applied for quantification of hemin in human serum sample. In view of this reality, the system can be considered as a possible strategy and excellent platform for determination of hemin in various areas of application.

Recent advances in formic acid electro-oxidation: from the fundamental mechanism to electrocatalysts.

Direct formic acid fuel cells have attracted significant attention because of their low fuel crossover, high safety, and high theoretical power density among all the proton-exchange membrane fuel cells. Much effort has been devoted to the study of formic acid oxidation, including the reaction processes and electrocatalysts. However, as a model reaction, the anodic electro-oxidation process of formic acid is still not very clear, especially regarding the confirmation of the intermediates, which is not helpful for the design and synthesis of high-performance electrocatalysts for formic acid oxidation or conducive to understanding the reaction mechanisms of other small fuel molecules. Herein, we briefly review the recent advances in investigating the mechanism of formic acid electro-oxidation and the basic design concepts of formic acid oxidation electrocatalysts. Rather than an exhaustive overview of all aspects of this topic, this mini-review mainly outlines the progress of this field in recent years.

Melognine, a novel monoterpenoid indole alkaloid from Melodinus fusiformis that induce apoptosis in BT549 cells.

A novel monoterpenoid indole alkaloid, melognine (1) possessing an unprecedented skeleton with a 6/6/5/5/6/6 hexatomic rearranged ring system was isolated from the stems of Melodinus fusiformis. The structure with absolute configuration of 1 was established by extensive spectroscopic analyses and quantum ECD calculations. Melognine showed significant cytotoxicity on human breast cancer BT549 cells with an IC50 value of 1.49 µM by MTT assay. Further mechanism of action study indicated that melognine demonstrated the ability to induce apoptosis by activation of caspase-3 and p53, and downregulation of Bcl-2 in BT549 cells.

New butenolides with anti-inflammatory activity from Balanophora fungosa.

Two new butenolides, balanolides A (1) and B (1), were isolated from the aerial parts of the parasitic plant Balanophora fungosa. Their structures were established by comprehensive spectroscopic analysis and quantum chemical ECD calculation. The new butenolides were evaluated for their inhibitory effects against nitric oxide (NO) production in LPS-induced RAW 264.7 macrophage cells. Compounds 1 and 2 displayed moderate anti-inflammatory activity with IC50values of 11.8 and 12.9 µM, respectively.

Insights into the Mo-Doping Effect on the Electrocatalytic Performance of Hierarchical CoxMoyS Nanosheet Arrays for Hydrogen Generation and Urea Oxidation.

Energy-efficient, low-cost, and highly durable catalysts for the electrochemical hydrogen evolution reaction (HER) and urea oxidation reaction (UOR) are extremely important for related sustainable energy systems. In the present work, hierarchical coassembled cobalt molybdenum sulfide nanosheets deposited on carbon cloth (CC) were synthesized as catalysts for hydrogen evolution and urea oxidation. By adjusting the doping amount of Mo, 2D nanosheets with different morphologies and compositions (CoxMoyS-CC) can be obtained. The as-prepared nanosheet materials with abundant active sites exhibit superior properties on the electrochemical HER and UOR in alkaline medium. Significantly, the Mo-doping concentration and composition of the formed nanosheets have large effects on the electrocatalytic activity. The fabricated nanosheets with optimal Mo doping (Co3Mo1S-CC) illustrate the best catalytic properties for the HER in N2-saturated 1.0 M KOH. A small overpotential (85 mV) is needed to meet the current density of 10 mA/cm2. This study indicates that the doping of an appropriate amount of molybdenum into CoS2 nanosheets can efficiently improve the catalytic performance. Also, the nanosheet catalyst exhibits an extremely high electrocatalytic activity for the UOR, and the electrochemical results indicate that a relatively low cell voltage of 1.50 V is needed to obtain the current density of 10 mA/cm2. The present work demonstrates the potential application of CoMoS nanosheets in the energy electrocatalysis area and the insights into performance-boosting through heteroatom doping and optimization of the composition and structure.

A Review: The Triterpenoid Saponins and Biological Activities of Lonicera Linn.

Lonicera Linn. is an important genus of the family Caprifoliaceae comprising of approximately 200 species, and some species of which have been usually used in traditional Chinese medicine for thousands of years. Some species of this genus can also be used in functional foods, cosmetics and other applications. The saponins, as one of most important bioactive components of the Lonicera Linn. genus, have attracted the attention of the scientific community. Thus, a comprehensive and systematic review on saponins from the genus is indispensable. In this review, 87 saponins and sapogenin from the genus of Lonicera Linn., together with their pharmacological activities including hepatoprotective, anti-inflammatory, anti-bacterial, anti-allergic, anti-tumor, and immunomodulatory effects, and hemolytic toxicity were summarized.

Cytotoxic aspidosperma-type alkaloids from Melodinus suaveolens.

Four new aspidosperma-type alkaloids, melosuavines J-M (1-4) were isolated from the leaves of Melodinus suaveolens. Their structures with absolute configurations were elucidated by extensive HRESIMS and NMR spectroscopic analysis, as well as ECD calculations and Mosher's method. Their cytotoxic activities against four human cancer cell lines were also evaluated.

Tanshinone IIA: A Review of its Anticancer Effects.

Tanshinone IIA (Tan IIA) is a pharmacologically lipophilic active constituent isolated from the roots and rhizomes of the Chinese medicinal herb Salvia miltiorrhiza Bunge (Danshen). Tan IIA is currently used in China and other neighboring countries to treat patients with cardiovascular system, diabetes, apoplexy, arthritis, sepsis, and other diseases. Recently, it was reported that tan IIA could have a wide range of antitumor effects on several human tumor cell lines, but the research of the mechanism of tan IIA is relatively scattered in cancer. This review aimed to summarize the recent advances in the anticancer effects of tan IIA and to provide a novel perspective on clinical use of tan IIA.

Melosuavine I, an apoptosis-inducing bisindole alkaloid from Melodinus suaveolens.

A new bisindole alkaloid, melosuavine I (1) possessing an aspidosperma-aspidosperma dimeric skeleton, was isolated from the leaves of Melodinus suaveolens. The structure with absolute configuration of 1 was elucidated by a combination of MS, NMR and computational methods. MTT assays indicated that 1 exhibited significant cytotoxicity on human breast cancer BT549 cells with an IC50 value of 0.89 µM. Further study showed that 1 inhibited BT549 cell proliferation by inducing apoptosis through activation of caspase 3 and p53, and down-regulation of Bcl-2.