Simultaneous determination of atropine,scopolamine, and anisodamine from Hyoscyamus niger L. in rat plasma by high‐performance liquid chromatography with tandem mass spectrometry and its application to a pharmacokinetics study

In order to investigate the pharmacokinetics of tropane alkaloids in Hyoscyamus niger L., a sensitive and specific high‐performance liquid chromatography with tandem mass spectrometry method for the simultaneous determination of atropine, scopolamine, and anisodamine in rat plasma is developed and fully validated, using homatropine as an internal standard. The separation of the four compounds was carried out on a BDS Hypersil? C₁₈ column using a mobile phase consisting of acetonitrile and water (containing 10 mmol ammonium acetate). Calibration curves were linear from 0.2 to 40 ng/mL for atropine, scopolamine, and from 0.08 to 20 ng/mL for anisodamine. The precision of three analytes was <5.89% and the accuracy was between ?1.04 to 2.94%. This method is successfully applied to rat pharmacokinetics analysis of the three tropane alkaloids after oral administration of H. niger extract. The maximum concentration of these three tropane alkaloids was reached within 15 min, and the maximum concentrations were 31.36 ± 7.35 ng/mL for atropine, 49.94 ± 2.67 ng/mL for scopolamine, and 2.83 ± 1.49 ng/mL for anisodamine. The pharmacokinetic parameters revealed areas under the curve of 22.76 ± 5.80, 16.80 ± 3.08, and 4.31 ± 1.21 ng/h mL and mean residence times of 2.08 ± 0.55, 1.19 ± 0.45, and 3.28 ± 0.78 h for atropine, scopolamine, and anisodamine, respectively.     

Application of capillary electrophoresis for the early diagnosis of cancer

Early diagnosis is the key to the effective treatment of cancer. The detection of cancer biomarkers plays a critical role not only in cancer early diagnosis, but also in classification and staging tumor progression, or assessment prognosis and treatment response. Currently, various molecular diagnostic techniques have been developed for cancer biomarker studies, with many of the more effective approaches requiring a separation step before detection. Capillary electrophoresis (CE) can perform rapid and efficient separation with small samples, which is well-suited for analysis of both small- and macro- molecule biomarkers in complex samples. CE has different separation modes and can couple to different detectors into a variety of platforms, such as conducting studies on DNA/ RNA point mutation, protein misexpression, and metabolite abnormality. Similarly, microchip capillary electrophoresis (MCE) appears as a very important biomarker screening platform with the merits of high throughput, integration, and miniaturization, which makes it a promising clinical tool. By hyphenated different detectors, or integrated with immunoassay, PCR/LDR and related technologies, MCE can be constructed into diverse platforms used in genomics, proteomics, and metabolomics study for biomarkers discovery. The multiplex biomarker screening approach via CE- or MCE-based platforms is becoming a trend. This paper focuses on studies of cancer biomarkers via CE/MCE platforms, based on the studies published over the past 3 years. Some recent CE applications in the field of cancer study, such as cancer theranostics, are introduced.     

双萘酰亚胺衍生物用于检测水溶液中的苦味酸

设计合成了一个新的双1,8-萘酰亚胺衍生物(Bis-Nph), 并通过核磁共振波谱和高分辨质谱鉴定了其结构. Bis-Nph呈现出典型的分子内电荷转移(ICT)和聚集诱导增强发射(AIEE). 该化合物可以作为荧光探针检测水溶液中的苦味酸(2,4,6-三硝基苯酚, TNP), 检出限为5.8×10^-7 mol/L. 作用机制为TNP的质子转移到Bis-Nph, 有效地阻断了其ICT发射, 使荧光发生显著猝灭. 另外, Bis-Nph的细胞毒性较低, 可做成试纸进行TNP的快速检测.     

Effect of Freeze-Thaw Cycles on the Oxidation of Protein and Fat and Its Relationship with the Formation of Heterocyclic Aromatic Amines and Advanced Glycation End Products in Raw Meat

The aim of this research was to investigate the effect of the number of freeze–thaw cycles (0, 1, 3, 5, and 7) on porcine longissimus protein and lipid oxidation, as well as changes in heterocyclic aromatic amines (HAAs) and advanced glycation end products (AGEs) and their precursors. We analyzed the relationship among HAAs, AGEs, oxidation, and precursors and found the following results after seven freeze–thaw cycles. The HAAs, Norharman and Harman, were 20.33% and 16.67% higher, respectively. The AGEs, Nε-carboxyethyllysine (CEL) and Nε-carboxymethyllysine (CML), were 11.81% and 14.02% higher, respectively. Glucose, creatine, and creatinine were reduced by 33.92%, 5.93%, and 1.12%, respectively after seven freeze–thaw cycles. Norharman was significantly correlated with thiobarbituric acid reactive substances (TBARS; r² = 0.910) and glucose (r² = −0.914). Harman was significantly correlated to TBARS (r² = 0.951), carbonyl (r² = 0.990), and glucose (r² = −0.920). CEL was correlated to TBARS (r² = 0.992) and carbonyl (r² = 0.933). These changes suggest that oxidation and the Maillard reaction during freeze–thaw cycles promote HAA and AGE production in raw pork.     

Enantioselective Diels–Alder reactions with left-handed G-quadruplex DNA-based catalysts

Since the discovery of left-handed G-quadruplex (L-G4) structure formed by natural DNA, there has been a growing interest in its potential functions. This study utilised it to catalyse enantioselective Diels-Alder reactions, considering its different optical rotation compared to an ordinary G4. It was determined that when L-G4 was used with a combination of copper(II) ions, there was a good enantioselectivity (?52% ee) without further addition of ligands. When further consideration was given by adding G4 ligands, G4 was further stabilised, even obtaining a better enantioselectivity (up to ?80% ee). Moreover, when using ligands that have regulatory effects on G4, the ee value can be adjusted. In this work, a minimal left-handed G4 was reported. A follow-up study was also conducted, which recovers that the minimal left-handed G4 remains its catalytic effect and enantioselectivity, but is not so effective as the former case. This indicates that a complete G4 structure is relatively conducive to chiral catalysis.     

Redox Modulation of the Reactivity and Regioselectivity in Diels–Alder Reaction of Metallofullerene La@C82 with Cyclopentadiene

Modulation of the reactivity of metallofullerenes is critical for production of metallofullerene derivatives with desired properties and functionalities. In this study, we investigate the effects of reduction and oxidation on the reactivity and regioselectivity in Diels–Alder reaction of metallofullerene La@C₈₂ by means of density functional theory calculations. Because of the enhanced electron-deficiency characteristic upon oxidation, the oxidized metallofullerene exhibits higher thermodynamic and kinetic reactivity as compared with neutral La@C₈₂. The regioselectivity in the reaction of La@C₈₂ with cylcopentadiene is remarkably changed after oxidation of the metallofullerene, which is explained in terms of the changes in the geometrical structure and the electronic structure of the metallofullerene. Quantitative analysis based on the activation-strain model demonstrates that the low activation energy barrier for the reaction of the cation La@C₈₂⁺ with cyclopentadiene originates from small strain energy and large interaction energy between the reactants. Energy decomposition analysis on the transition states of the reactions reveals that the exchange-repulsion interaction energy is one of the critical factors that determine the kinetic reactivity of the metallofullerene. This study not only provides new theoretical insights on how to modulate the reactivity of metallofullerenes, but also offers guideline for future experimental synthesis of new metallofullerene derivatives.     

A novel electrochemiluminescence glucose biosensor based on platinum nanoflowers/graphene oxide/glucose oxidase modified glassy carbon electrode

A novel electrochemiluminescence (ECL) biosensor based on platinum nanoflowers (PtNFs)/graphene oxide (GO)/glucose oxidase (GODx) was discovered for glucose detection. PtNFs/GO was synthesized using a nontoxic, rapid, one-pot and template-free method and characterized by transmission electron microscopy (TEM) and high-resolution TEM techniques. The as-prepared PtNFs/GO with clean surface and multiporous structure was used to assemble GODx to form a glucose biosensor. Based on ECL results, the PtNFs/GO/GODx film-modified electrode displayed a high electrocatalytic activity towards the oxidation of glucose, which generated hydrogen peroxide (H₂O₂) to react with the luminol radicals thus enhanced the luminol ECL. Under the optimized conditions, two linear regions of ECL intensity to glucose concentration were valid in the range from 5 to 80 μmol/L (r?=?0.9957) and 80 to 1,000 μmol/L (r?=?0.9909) with a detection limit (S/N?=?3) of 2.8 μmol/L. In order to verify the reliability, the thus-fabricated biosensor was applied to determine the glucose concentration in glucose injection, glucose functional drink, and blood serum. The results indicated that the proposed biosensor presented good characteristics in terms of high sensitivity and good reproducibility for glucose determination, promising the applicability of this sensor in practical analysis.     

Fast and Selective Semihydrogenation of Alkynes by Palladium Nanoparticles Sandwiched in Metal–Organic Frameworks

The semihydrogenation of alkynes into alkenes rather than alkanes is of great importance in the chemical industry. Unfortunately, state-of-the-art heterogeneous catalysts hardly achieve high turnover frequencies (TOFs) simultaneously with almost full conversion, excellent selectivity, and good stability. Here, we used metal–organic frameworks (MOFs) containing Zr metal nodes (“UiO”) with tunable wettability and electron-withdrawing ability as activity accelerators for the semihydrogenation of alkynes catalyzed by sandwiched palladium nanoparticles (Pd NPs). Impressively, the porous hydrophobic UiO support not only leads to an enrichment of phenylacetylene around the Pd NPs but also renders the Pd surfaces more electron-deficient, which leads to a remarkable catalysis performance, including an exceptionally high TOF of 13835 h⁻¹, 100 % phenylacetylene conversion 93.1 % selectivity towards styrene, and no activity decay after successive catalytic cycles. The strategy of using molecularly tailored supports is universal for boosting the selective semihydrogenation of various terminal and internal alkynes.     

二维导电金属有机骨架材料

金属有机骨架(MOFs)是由金属离子或簇与有机配体以配位键组装而成的晶态多孔材料,其高的孔隙率及功能可设计性使其广泛应用于各种领域.然而,传统MOFs多数电导率非常低,这严重制约了其在电学相关领域的发展.近年来,导电金属有机骨架尤其是二维导电金属有机骨架(2D ECMOFs)材料因其结构中独特的π-π堆积及π-d共轭作...     

Photocatalytic Carboxylation of Phenyl Halides with CO2 by Metal-Organic Frameworks Materials

In this work,important commercial pharmaceutical intermediates,phenylpropionic acid compounds,are successfully obtained by catalyzing the reaction of carbon dioxide with phenyl halides using MOF-5,a typical metal-organic framework(MOF)material.The influence of temperature,pressure,catalyst type and light on the reaction is investigated,and a 90.3%selectivity towards fluorophenylpropionic acid is reached.Significantly,the catalysts are effective for varied benzyl compounds containing different substituent groups.The catalysts are stable and remain active after three cycles.