Assessment of the hemolysis and endothelial cell cytotoxicity induced by residual linear alkylbenzene sulfonates on pharmaceutical rubber stoppers based on HPLC‐ESI‐MS

This study was designed to develop a high‐performance liquid chromatographic–electrospray ionization–mass spectrometry (HPLC‐ESI‐MS) method for quantitative determination of residual surfactant linear alkylbenzene sulfonate (LAS) compounds on pharmaceutical rubber stoppers. An HPLC‐ESI‐MS method was developed for separation and determination of five LAS homologs (C10–C14) under gradient conditions using methanol and ammonium acetate as mobile phases. Hemolysis activity of residual LAS compounds was analyzed by spectrophotometry. Expression of interleukin (IL)‐6 and tumor necrosis factor (TNF)‐α in human umbilical vein endothelial cells (HUVECs) after LAS compound treatment was examined by enzyme‐linked sorbent assay. LAS compounds were well separated and determined by the established gradient conditions. The linear range was 0.05–8 µg/mL with correlation coefficients ≥0.997. Recoveries were from 73 to 134% and the relative standard deviation was <13.7%. There was a correlation between hemolysis rate and LAS compounds concentration when it was ≥0.8 µg/cm². LAS compounds decreased the viability of HUVECs and promoted the production of IL‐6 and TNF‐α. The developed analytical method was successful for quantitative determination of residual LAS compounds on pharmaceutical rubber stoppers and it is important to monitor and control the amount of LAS compounds on rubber stoppers. Copyright © 2015 John Wiley & Sons, Ltd.     

Nanoparticle‐Assisted Alignment of Carbon Nanotubes on DNA Origami

Aligning carbon nanotubes (CNTs) is a key challenge for fabricating CNT‐based electronic devices. Herein, we report a spherical nucleic acid (SNA) mediated approach for the highly precise alignment of CNTs at prescribed sites on DNA origami. We find that the cooperative DNA hybridization occurring at the interface of SNA and DNA‐coated CNTs leads to an approximately five‐fold improvement of the positioning efficiency. By combining this with the intrinsic positioning addressability of DNA origami, CNTs can be aligned in parallel with an extremely small angular variation of within 10°. Moreover, we demonstrate that the parallel alignment of CNTs prevents incorrect logic functionality originating from stray conducting paths formed by misaligned CNTs. This SNA‐mediated method thus holds great potential for fabricating scalable CNT arrays for nanoelectronics.     

Qualitative and quantitative analysis of arctiin and arctigenin in Arctium tomentosum Mill. by high-performance thin-layer chromatography

A sensitive, reliable and rapid high-performance thin-layer chromatography (HPTLC) method for the determination of arctiin and arctigenin in Arctium tomentosum Mill. was established. A. tomentosum Mill. extract was used for chromatographic analysis. The ratio of chloroform and methanol was 48:5 as mobile phase. Temperature is 20–23 °C and humidity is less than 30%. The scanning wavelength is 280 nm. The results showed that arctiin had a good linear relationship in the range of 0.5315–5.8465 μg, r = 0.9982; arctigenin had a good linear relationship in the range of 0.5654–6.2194 μg, r = 0.9951. Precision analysis showed that the RSD < 3.0%. The stability study showed that the sample was stable within 24 h at room temperature, RSD < 2.0%. The average recoveries were 103.07 ± 1.57% and 98.55 ± 2.71%, respectively. The antioxidant activity of Arctium tomentosum Mill. was also identified. The results showed that the antioxidant component identified by thin-layer chromatography–1, 1-diphenyl-2-trinitrophenylhydrazine (TLC-DPPH) was arctigenin not arctiin. The proposed HPTLC is a simple and accurate method for the qualitative and quantitative analysis of arctiin and arctigenin in Arctium tomentosum Mill. from different areas.

     

Facile microfluidic fabrication of monodispersed self-coupling microcavity with fine tunability

Whispering gallery mode (WGM) resonators have received extensive attention because of their nonlinear optical application in lasers and sensors. Optical microcavities are excellent candidates for constructing powerful microlasers and label-free biosensors, owing to their low optical losses and small size. However, most of these microcavity syntheses rely on sophisticated fabrication methods and cannot be manipulated easily. To achieve facile and versatile microcavity fabrication, we present a robust microfluidics method for monodispersed self-coupling optical microcavity fabrication with a fine tunability. The microcavity polydispersity was less than 3%. The optical microcavity size could be varied from 10 to 30 µm with a steady quality factor (Q) of approximately 1000. The lowest laser threshold that we obtained was 0.82 µJ with a microcavity size of 20 µm. The doped fluorescent dye concentration can be tuned precisely from 0.001 to 0.05 wt% to explore an optimized fluorescent background. The experimental results and theoretical simulation match well in terms of Q and the electrometric resonance field intensity. Compared with previous precise and practical fabrication methods, we have demonstrated a facile approach for versatile optical microcavity fabrication. This method can vary the microcavity materials, size, doped fluorescent dye concentration, WGM resonance spectrum, Q factor, and laser threshold easily to adapt to various circumstances and specific applications.     

Monitoring of Intracellular Vesicles in Cultured Neurons at Different Growth Stages Using Intracellular Vesicle Electrochemical Cytometry

The exploration of intracellular vesicles plays crucial roles for neuronal activity assessment. Neurons at different growth stages may possess distinct neuronal activity, including vesicular content and release kinetics. Here, we monitored the vesicular content and its release kinetics in neurons at different growth stages by intracellular vesicle electrochemical cytometry. We found that the neurotransmitters content of vesicles changed to be increased and the vesicle release process became longer as the neurons grew. Further, we demonstrated that the vesicular adsorption and rupture modes changed from the dominant simple event to simple and complex event coexisting mode. We speculate that this work provides a new strategy for the neuronal activity assessment or real- time cell activity analysis.     

车前草中黄酮类成分结构和性质的理论研究

采用密度泛函理论中ωB97XD/6-311+G(2d,p)方法对车前草中的黄酮类化合物进行量化计算研究, 探讨了该类化合物的构效关系. 首先研究了13种车前草中提取的黄酮类化合物(1~13)和已成药的二氢杨梅素(14)的几何结构、 谱学性质及电子结构, 再运用概念密度泛函理论进行反应指数分析, 最后利用药代动力学平台开展了成药性评价. 根据几何结构的分析结果初步推测14种黄酮类化合物的抗氧化能力强弱顺序为10>12≈ 7>13>6>4>14≈9≈8>11>5>3≈2>1. 核磁共振拟合结果表明, 利用该方法得到的核磁位移理论值与实验值吻合度较高(R²>0.95). 分子表面静电势图显示, 14种黄酮类化合物的静电势的极小值点都位于羰基氧附近, 极大值点都位于羟基氢附近, 且B环上对位羟基的极大值>C环和A环羟基极大值. 全局反应性描述符结果显示, 化合物1, 2, 4, 11和12的化学势较低, 电负性、 亲电指数和硬度较高, 说明这5种化合物的稳定性和反应性较好. 通过局部反应性描述符进一步预测了14种黄酮类化合物的亲核/亲电反应位点. 药代动力学结果显示, 化合物1, 3, 4, 6, 12和13的成药性和药代动力学活性较好. 研究结果表明, 化合物4和12最有成药潜力, 可进行更深入的实验研究.     

以实践应用为导向的石墨烯非共价功能化

石墨烯的湿法化学修饰,主要包括共价及非共价两种,是目前广泛采用的宏量功能化策略,亦是解决其易团聚充分发挥纳米性能的重要修饰方法。 非共价功能化因可同时保持原有及引入物质的物化性质,并可充分发挥协同作用,近年来已受到比共价修饰更多的研究关注,并已在生物科学与技术、可持续能源储存及转化、医疗和复合材料等诸多领域得到了广泛的应用。在这里,我们精心遴选了近三年的文献,综述了以应用为导向的石墨烯非共价功能化的构建策略,期望文中涉及的湿法组装策略能为进一步构建性能提升的新材料提供参考。     

Crystal structure and NMR study of a bisperoxovanadium complex [NH4][VO(O2)2(ima)]

A novel bisperoxovanadium complex, [NH₄][VO(O₂)₂(ima)] (1) (ima = imidazole-4-carboxamide), was synthesized by the reaction of NH₄VO₃ and ima in the presence of H₂O₂, and the structure was characterized by single-crystal X-ray technology. The adjacent [NH₄][VO(O₂)₂(ima)] monomers further constructed a 3-D supramolecular framework through intra- and intermolecular hydrogen bonding interactions. The composition of the title complex solution was explored using a combination of multinuclear (¹H, ¹³C and ⁵¹V) magnetic resonance, heteronuclear single quantum coherence (HSQC), and variable temperature NMR in a 0.15 mol L^?1 NaCl/D₂O solution that mimics physiological conditions. According to NMR experimental results, a pair of isomers (Isomers A and B) are observed in aqueous solution, which are attributed to different types of coordination modes between the metal center and the ligands; Isomer B (the main product) has the same coordination structure as the crystal structure of [NH₄][VO(O₂)₂(ima)]. The ⁵¹V NMR experiment together with single-crystal X-ray diffraction results indicated that Isomer A is the hexa-coordinated peroxovanadium species while Isomer B is the hepta-coordinated species.