Latest ArticlesChinese herbal medicines (CHMs) play an increasingly important role in the field of medicine and affects public health in the world. Although more and more strict has been employed to ensure the quality and safety of CHMs, pesticide residues in CHMs remain a serious issue and are the bottleneck for the global development of CHMs. In this work, we applied molecularly imprinted membrane electrospray mass spectrometry (MIM-ESI MS) for rapid detecting 4 classes of pesticide residues in CHMs, including organophosphorus (OPP), carbamates, pyrethroids and neonicotinoids in CHMs. Compared with our previous ambient ionization method MESI, MIM-ESI is capable of achieving a ~50-fold increase in the detection limit of conventional analytical methods owing to the specificity recognition and unique enrichment of MIM. The optimal experimental conditions were determined, and the method was further validated for its sensitivity and specificity. Our data showed that MIM-ESI MS is applicable for the direct quantitation of pesticide residues in CHMs. This detection technology may help to ensure the quality of CHMs in the future.
Developing an excellent photocatalysis system to remove pesticides from water is an urgent problem in current environment purification field. Herein, a Z-scheme WO3/g-C3N4 photocatalyst was prepared by a facile in-situ calcination method, and the photocatalytic activity was investigated for degradation of nitenpyram (NTP) under visible light. The optimal Z-scheme WO3/g-C3N4 photocatalyst displayed the highest rate constant (0.036 min−1), which is about 1.7 and 25 times higher than that of pure g-C3N4 and WO3, respectively. The improvement of photocatalytic performance is attributed to fast transfer of photogenerated carriers in the Z-scheme structure, which are testified by electron spin resonance (ESR) experiments, photocurrent and electrochemical impedance spectra (EIS) measurements. Moreover, the effects of typical water environmental factors on the degradation NTP were systematically studied. And the possible degradation pathways of NTP were deduced by the intermediates detected by high-performance liquid chromatography-mass spectrometry (HPLC-MS). This work will not only contribute to understand the degradation mechanism of pesticides in real water environmental condition, but also promote the development of new technologies for pesticide pollution control as well as environmental remediation.
MicroRNAs are a class of important biomarkers, and the simultaneous detection of multiple miRNAs can provide valuable information about many diseases and biological processes. Amplification-free determination has been developed for the analysis of multiple miRNAs because of its characteristic low cost and high fidelity. Herein, a method for the amplification-free analysis and simultaneous detection of multiple miRNAs based on a so-called pico-HPLC-LIF system is described. In this process, a bare open capillary with an inner diameter of 680 nm is used as a separation column for a sample volume of several hundreds of femtoliters (300 fL), followed by separation and detection. The technique has a zeptomolar limit of detection. The method was applied to detect cellular miRNA from adenocarcinomic human alveolar basal epithelial (A549) cell extracts, and the simultaneous detection of the mir-182, miR-155, and let-7a was achieved. The results showed that the expression of mir-182 and miR-155 was up-regulated and that of let-7a was down-regulated in A549 cells. This method for multiple miRNAs detection is expected to have broad applications in miRNA-based disease diagnosis, prognosis, treatment, and monitoring.
A novel GO modified g-C3N4 nanosheets/flower-like BiOBr hybrid photocatalyst is fabricated by a facile method. The characterization results reveal that wrinkled GO is deposited between g-C3N4 nanosheets and flower-like BiOBr forming a Z-scheme heterojunction. As a mediator, plicate GO plays a positive role in prompting photogenerated electrons transferring through its sizeable 2D/2D contact surface area. The g-C3N4/GO/BiOBr hybrid displays a superior photocatalytic ability to g-C3N4 and BiOBr in photodegrading tetracycline (TC), whose removal efficiency could reach 96% within 2 h. Besides, g-C3N4/GO/BiOBr composite can reduce Cr(Ⅵ), and simultaneously treat TC and Cr(Ⅵ) combination contaminant under the visible light. The g-C3N4/GO/BiOBr ternary composite also exhibits satisfactory stability and reusability after four cycling experiments. Further, a feasible mechanism related to the photocatalytic process of g-C3N4/GO/BiOBr is put forward. This study offers a ternary hybrid photocatalyst with eco-friendliness and hopeful application in water pollution.
A label-free and sensitive electrochemical biosensing strategy for a hepatocellular carcinoma biomarker of miRNA-122 has been proposed based on hybridization induced ion-barrier effect on the electroactive sensing interface. First, a bifunctional electroactive electrode with the nanocomposite of Prussian blue (PB) and gold nanoparticles (AuNPs) was prepared through a two-step electrodeposition process. The PB endows the electrode excellent K+-dependent voltammetric signal and the AuNPs act as the matrix for the self-assembly immobilization of the thiolated probe DNA. Upon specific hybridization of probe DNA with the target miRNA-122, the formed double duplex induced the ion-barrier effect, which blocked the diffusion of the K + from the bulk solution to the electrode surface. As a result, the voltammetric signal of the PB on the electrode was surpressed, and thus the target miRNA-122 was monitored. The sensing assay showed that the miRNA-122 could be analyzed in the concentration range from 0.1 fmol/L to 1.0 nmol/L, with a detection limit of 0.021 fmol/L. The practical applicability of the biosensor was also verified by the spiking serum assay.
The peroxisome proliferator-activated receptor (PPARδ) agonists are reported to improve insulin sensitivity, reduce glucose levels, and alleviate dysfunctional lipid metabolism in animal models of type 2 diabetes mellitus. However, the underlying mechanisms remain incompletely understood. Metabolism plays an essential role in the biological system. Monitoring of metabolic changes in response to disease conditions or drug treatment is critical for better understanding of the pathophysiological mechanisms. In this study, metabolic profiling analysis by gas chromatography-mass spectrometry integrated with targeted analysis by liquid chromatography-mass spectrometry was carried out in plasma samples of db/db diabetic mice after six-week treatment of PPARδ agonist GW501516. GW501516 treatment significantly altered levels of metabolites, such as branched-chain amino acids (BCAAs), BCAA metabolites (3-hydroxyisobutyric acid and 3-hydroxyisovaleric acid), long-chain fatty acids, uric acid and ketone bodies (3-hydroxybutyric acid and 2-hydroxybutyric acid) which are all associated with the impaired systemic insulin sensitivity. The present results indicate the beneficial effect of PPARδ agonist in alleviating insulin resistance of diabetic mice by favorably modulating metabolic profile, thus providing valuable information in understanding the therapeutic potential of PPARδ agonists in correcting metabolic dysfunction in diabetes.
With regard to the reaction of higher alcohol synthesis (HAS), the optimizations of activity and selectivity towards C2+ alcohol are restricted by the improper equilibrium in two different CO activation pathways and chain growth capacity. Herein, we find that delibrately controlling the compositions of catalysts is an effective strategy to achieve the equilibrium of CO activation pathways and promote the chain growth. As a result, the optimized Cu0.25Co0.75 alloy catalyst can achieve a large proportion of higher alcohol in alcohol products (C2+OH/MeOH = 4.40), together with high CO conversion of 71.27% and space-time-yield of 147.65 g kg−1 h−1. The mechanistic studies suggest that the good performance of Cu0.25Co0.75 catalyst is attributed to the synergistic effect between alloyed Cu and Co.
Noble-metal-free photocatalysts with high and stable performance provide an environmentally-friendly and cost-efficient route for green organic synthesis. In this work, CdS nanoparticles with small particle size and different amount were successfully deposited on the surface of covalent organic frameworks (COFs). The deposition of suitable content of CdS on COFs could not only modify the light adsorption ability and the intrinsic electronic properties, but also enhance the photocatalytic activity and cycling performance of CdS for the selective oxidation of aromatic alcohols under visible light. Especially, COF/CdS-3 exhibited the highest yield (97.1%) of benzaldehyde which is approximately 2.5 and 15.9 times as that of parental CdS and COF, respectively. The results show that the combination of CdS and COF can improve the utilization of visible light and the separation of photo-generated charge carriers, and COF with the π-conjugated system as supports for CdS nanoparticles could provide efficient electron transport channels and improve the photocatalytic performance. Therefore, this kind of COF-supported photocatalysts with accelerated photo-induced electrons and charge-carrier separation between semiconductors possesses great potentials in future green organic synthesis.
A highly-active, metal-free, carbon-based oxygen reduction reaction (ORR) cathode, i.e., graphitized N-doped carbon felt (GNCF), was prepared, for the first time, by in-situ modifying the doping species of polyacrylonitrile (PAN)-based carbon felt (CF) via a facile annealing process in Ar atmosphere. It was applied for dramatically enhanced organics degradation and electricity generation in a photocatalytic fuel cell (PFC) system. The GNCF showed enhanced specific surface area, improved graphitization and raised ratio of graphitic N, therefore resulting in excellently improved ORR performance compared to the CF. When applying the GNCF as a cathode in a PFC system, the proposed PFC showed significant improvement in degrading various model organic conta minants and outputing electricity simultaneously when compared with the PFC with CF. For instance, the apparent rate constant and electricity output efficiency showed ~10.6 times and ~7.2 times, respectively, improvement when using rhoda mine B as model waste. Further improved performance was also achieved by aeration of air or O2 due to the further enhanced ORR. The proposed PFC was also efficient in a wide pH, and kept outstanding stability in long-term utilization.
Aqueous supercapacitors (SCs) have attracted more and more attention for their safety, fast charge/discharge capability and ultra-long life. However, the application of aqueous SCs is limited by the low working voltage due to the narrow electrochemical stability window (ESW) of water. Herein, we report a new "water in salt" (WIS) electrolyte by dissolving potassium bis (fluorosulfonyl) amide (KFSI) in water with an ultra-high mass molar concentration of 37 mol/kg. The highly concentrated electrolyte can achieve a wide ESW of 2.8 V. The WIS electrolyte enables a safe carbon-based symmetrical supercapacitor to operate stably at 2.3 V with an ultra-long cycle life and excellent rate performance. The energy density reaches 20.5 Wh/kg at 2300 W/kg, and the capacity retention is 83.5% after 50, 000 cycles at a current density of 5 A/g. This new electrolyte will be a promising candidate for future high-voltage aqueous supercapacitors.
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