金属│固体电解质│含水凝胶│石墨体系的研究

应用点缺陷模型和双层模型分析了金属│固体电解质│含水凝胶│石墨体系贮藏和放电时金属表面氧化膜的变化.在固体电解质含有微量水分的情况下,微量水分有助于金属表面形成松层,但由于水分子与紧密钝化膜的持续作用,金属表面松层厚度会不断增长,孔率降低,使得电池的电压和放电电流下降.松层的孔率强烈影响膜溶解行为,与紧密钝化膜的电学特性一样,松层也是一种半导体.     

Study on the discrete dielectrophoresis for particle–cell separation

This paper presents the application of the discrete dielectrophoretic force to separate polystyrene particles from red blood cells. The separation process employs a simple microfluidic device that is composed of interdigitated electrodes and a microchannel. The discrete dielectrophoretic force is generated by adjusting the duty cycle of the applied voltage. The electrodes make a tilt angle with the microchannel to change the moving direction of the red blood cells. By adjusting the voltage magnitude and duty cycle, we investigate the deflection of red blood cells and the variation of cell velocity along electrode edge under positive dielectrophoresis. The experiments with polystyrene particles show that the enrichment of the particles is greater than 150 times. The maximum separation efficiency is 97% for particle-to-cell number ratio equal to 1:2000 in the sample having high cell concentration. Using the appropriate applied voltage magnitude and duty cycle, the discrete dielectrophoretic force can prevent the clogging of microchannel while successfully separating the particles from the cells with high enrichment and efficiency. The proposed principle can be readily applied to dielectrophoresis-based devices for biomedical sample preparation or diagnosis such as the separation of rare or infected cells from a blood sample.     

Tetrameric RGD induces clustering of integrin αvβ3 on the melanoma cell surface and decreases cell viability

The recombinant hybrid protein SR15 composed of streptavidin fused with RGD peptide is obtained. The ability of this protein to recognize human melanoma cells (MeWo line) is demonstrated. Types of expressed RGD-binding integrins in the cells of this line are identified. It is found that the recombinant hybrid protein SR15 binds to integrin αvβ3 on the surface of human melanoma cells. The binding to the protein SR15 results in clustering of αvβ3 receptors on the surface of MeWo cells, internalization of the recombinant protein, and an almost twofold decrease in cell viability.     

Conjugated polymers based on new thienylene – PPV derivatives for solar cell applications

Two π-conjugated monomers based on bis-(1-cyano-2-thienyl-vinylene)phenylene derivatives were synthesized by Knoevenagel condensation. Both monomers are found to form electroactive polymers upon electrochemical oxidation. The withdrawing effect due to the cyano-substituent allows for the reversible n-doping of the polymer. Thus, the band gap E_g was measured using electrochemical techniques and compared with that obtained by UV–VIS–NIR spectroscopy. Based on the measured band gap of 1.87 and 1.58 eV, these polymers appear to be interesting candidates for solar-cell applications.     

An extensive review of studies on mycobacterium cell wall polysaccharide-related oligosaccharides – part I: Synthetic studies on arabinofuranosyl oligosaccharides

Abstract

Lipoarabinomannan (LAM), mannosyl LAM (ManLAM), and mycolyl-arabinogalactan (mAG) are unique and ubiquitous cell wall constituents of Mycobacterium tuberculosis (M. tb), the bacterium causing tuberculosis (TB), one of the deadliest diseases worldwide. It has been well documented that LAM, ManLAM, and mAG play an important role in mycobacterial infections and in the elicitation of specific immune responses against M. tb in the host. Therefore, LAM, ManLAM, mAG, and related molecules are attractive targets for the development of novel diagnostic and therapeutic strategies for TB. Accordingly, great research efforts have been spent on the chemical synthesis and biological studies of mycobacterium-related arabinofuranosyl oligosaccharides and their mimetics and conjugates. This article provides an extensive review about the progresses in this area. Due to the page limit of the journal, this review is published separately in three parts. Part I is focused on various glycosylation methods or strategies and protection tactics for stereoselective and stereospecific construction of α- and β-arabinofuranosyl linkages, as well as their applications to the synthesis of simple to highly complex mycobacterium-related arabinofuranosyl oligosaccharides containing only α-linked or both α- and β-linked arabinofuranosyl residues.     

Synthesis of an external β-turn based on the GLDV motif of cell adhesion proteins

The (3S,6S,10S)-7/5 bicyclic lactam 4, designed as an external turn constraint, was synthesised by a new stereoselective route involving Eschenmoser condensation. Calculated preferred conformations compare well with the preferred solid state conformation, obtained by X-ray crystallography. The lactam 4 was not a turn mimic in its own right but could be used as an external constraint to prepare the cyclic peptide 29 containing the integrin recognition motif GLDV. High-resolution NMR measurements were consistent with this compound having a single backbone conformation.     

Protein adsorption and cell adhesion on polyurethane/Pluronic® surface with lotus leaf-like topography

Lotus leaf-like polyurethane/Pluronic^® F-127 surface was fabricated via replica molding using a natural lotus leaf as the template. Water contact angle measurements showed that both the hydrophobicity of the unmodified polyurethane (PU) surface and the hydrophilicity of the PU/Pluronic^® surface were enhanced by the construction of lotus leaf-like topography. Protein adsorption on the PU/Pluronic^® surface without topographic modification was significantly lower than on the PU surface. Adsorption was further reduced when lotus leaf-like topography was constructed on the PU/Pluronic^® surface. Cell culture experiments with L929 cells showed that adhesion on the PU/Pluronic^® surface with lotus leaf-like topography was low and adherent cells were spherical and of low viability. The PU/Pluronic^® surface with lotus leaf-like topography thus appears to be resistant to nonspecific protein adsorption and to cell adhesion, and these effects derive from the both chemical composition and topography. The results suggest a new strategy based on surface topography for the design of antifouling materials.     

Sensitive detection of human breast cancer cells based on aptamer–cell–aptamer sandwich architecture

Breast cancer is one of the most critical threats to the health of women, and the development of new methods for early diagnosis is urgently required, so this paper reports a method to detect Michigan cancer foundation-7 (MCF-7) human breast cancer cells with considerable sensitivity and selectivity by using electrochemical technique. In this method, a mucin 1 (MUC1)-binding aptamer is adopted to recognize MCF-7 human breast cancer cells, while enzyme labeling is employed to produce amplified catalytic signals. The molecular recognition and the signal amplification are elaborately integrated by fabricating an aptamer–cell–aptamer sandwich architecture on an electrode surface, thus a biosensor for the detection of MCF-7 is fabricated based on the architecture. The detection range can be from 100 to 1 × 10⁷ cells, and the detection limit can be as low as 100 cells. The method is also cost-effective and conveniently operated, implying potential help for the development of early diagnosis of breast cancer.     

Aluminum enhances the toxic effects of amyloid β-peptide on cell membranes and a molecular model

Abstract  

The amyloid β-peptide (Aβ) and aluminum are found, among other components, in the senile plaques of patients with Alzheimer’s disease. Aggregated Aβ and aluminum are toxic to neurons but the mechanism of accumulation and toxicity remains poorly understood. It has been proposed that Aβ and aluminum toxicity results from Aβ– and aluminum–membrane interactions. It was therefore of interest to study the effect that Aβ and aluminum could have on cell membranes. Thus, the interactions of Aβ(1-40), Aβ(1-42), and Al(III) with the human erythrocyte membrane and a molecular model of the erythrocyte membrane were examined by electron microscopy and X-ray diffraction, respectively. The molecular model consisted of bilayers built up of dimyristoylphosphatidylcholine and dimyristoylphosphatidylethanolamine, phospholipid classes located in the outer and inner monolayers of most cell membranes, respectively. Aβ(1-40) and Aβ(1-42) in the presence of Al(III) altered the erythrocyte membrane morphology and the structure of dimyristoylphosphatidylcholine bilayers, effects that were different and stronger than those induced by Aβ and Al(III) separately.     

Zn│纳米TiO2-聚苯胺二次电池的充放电性能

以 1 0mol/L硫酸为介质 ,于 0 8V恒电位下 ,在纳米TiO2 (Nano TiO2 )膜电极上实现了苯胺 (Aniline)的电化学聚合 ,借助透射电镜、X射线衍射、红外光谱等对制得的Nano TiO2 /聚苯胺 (Nano TiO2 /PANI)复合膜进行了表征。用Nano TiO2 │PANI作为二次电池的正极 ,Zn为负极 ,在不同的电流密度下对Zn│Nano TiO2 PANI二次电池的充放电性能进行了研究。结果表明 ,二次电池首次充电容量可达 98 0 4mA·h/g ,充放电效率为 91 6 7% ,充放电曲线平稳     

Zn│纳米TiO2-聚苯胺二次电池的充放电性能

以1.0 mol/L硫酸为介质,于0.8 V恒电位下,在纳米TiO2(Nano-TiO2)膜电极上实现了苯胺(Aniline)的电化学聚合,借助透射电镜、 X射线衍射、红外光谱等对制得的Nano-TiO2/聚苯胺(Nano-TiO2/PANI)复合膜进行了表征. 用Nano-TiO2│PANI作为二次电池的正极,Zn为负极,在不同的电流密度下对Zn│Nano-TiO2-PANI二次电池的充放电性能进行了研究. 结果表明,二次电池首次充电容量可达98.04 mA·h/g,充放电效率为91.67%,充放电曲线平稳.     

Study on Conductivity Detection for Capillary Electrophoresis──Design of a new type of miniature conductance cell

IntroductionSineHjerenintroduceditinl967,capillaryelectrophoresis(CE)hasbecomeapowerfulanalyticaltool.Becauseithasidealdetectionlimits,smallsampleintIoductionandhighseparationefficiency,CEhasbeenappliedinmanyareasincludingchemistry,biology,medicineandenvironmentalscience,etc.InCEtechnique,owingtoextremelysmallsampleintroductionandverythincapillaries,thedetectorsmustpossessthefeaturesofhigh-sensitivity,high-reso1ution,rapidresponseandon-line.Forthisreason,developingdetectivemethodsisaveryim…     

A selective and sensitive off–on probe for palladium and its application for living cell imaging

A new rhodamine B derivative T1 has been rationally synthesized and displayed selective Pd(Ⅱ)-amplified absorbance and fluorescence emission above 540 nm in methanol–water. Upon the addition of Pd(Ⅱ), the spirolactam ring was unfolded and a 1:1 metal-ligand complex formed, which can be used for ‘‘naked-eyes" detection. In addition, fluorescence imaging experiments of Pd~(2+) in HepG2 living cells showed its valuable application in biological systems.     

Study of the cholesterol extraction capacity of β-cyclodextrin and its derivatives, relationships with their effects on endothelial cell viability and on membrane models

Endothelial cells (HUVEC) were treated with β-cyclodextrin and hydroxypropylated or methylated derivatives solutions in order to quantify their cholesterol extraction capacity. Non-toxic concentrations of cyclodextrins (CDs) were determined following methyl thiazol tetrazolium (MTT) assays, total protein measurements, morphological observations and trypan blue assays. The residual cholesterol content of cells was measured and the extraction power of CDs compared to results obtained by phase solubility diagrams. Cholesterol was extracted with a dose-response relationship, the lowest residual cholesterol content being obtained with β-CD at 10 mM. Low substituted derivatives (Crysmeb^® and hydroxypropyl-β-CD) maintained liposomes integrity (as shown before), were the less cytotoxic and presented the lowest affinity for cholesterol contrary to methylated derivatives with degrees of substitution around 2.     

Antioxidant activity and cytotoxic effect of aviprin and aviprin-3″-O-D-glucopyranoside on LNCaP and HeLa cell lines

Many researchers have shown that plant-derived polyphenolic compounds are helpful nutraceuticals in restraining various disorders such as neoplastic diseases. In this study two linear furanocoumarins, aviprin and aviprin-3″-O-D-glucopyranoside (A3G), were isolated from methanol extract of Prangos uloptera roots. The evaluation of free radical scavenging capacity of the compounds showed that aviprin is a more effective antioxidant than A3G with RC50 of 0.54?mg?mL?1. The biological and antiproliferative activities of the furanocoumarins were examined using human cervical carcinoma HeLa cell line and LNCaP prostatic cell line. Cell membrane integrity and cell viability were evaluated by measuring trypan blue exclusion assay and reduction of the tetrazolium blue compound, respectively. Treating the LNCaP cell line with various concentrations of the furanocoumarins showed that IC?? of aviprin and A3G were 0.4 and 6.6?mg?mL?1, whereas their CC50 values were 0.7 and 11?mg?mL?1, respectively. These results indicated that 42.7% of LNCaP cells were not dead by necrosis. Treating the HeLa cells by the furanocoumarins showed the greater sensitivity of the HeLa cell line than the LNCaP cell line. A morphological analysis and the study of DNA fragmentation provided further some evidence for the inhibition of the LNCaP cell line via apoptosis induction.     

Effect of particulate filler on cell size in membranes formed via liquid–liquid thermally induced phase separation

This paper discusses the effects of adding particulate filler to a system undergoing liquid–liquid thermally induced phase separation (L–L TIPS). While much is known about the growth of droplets in L–L TIPS, little is known about the effect particular fillers have on droplet growth and the final cell size in the resulting microporous membranes. In this work, zeolite particles are shown to have a significant effect on the final cell size of these microporous membranes, the extent of which depends on the particle loading and processing conditions used to form the membrane. Two polymer–diluent–zeolite systems are reported: isotactic polypropylene–diphenyl ether and poly(methyl methacrylate)–cyclohexanol, both with zeolite 4A particles.     

Oscillations of pH at the Fe│H2SO4 interface during anodic dissolution

An unmodified Pt microelectrode and a Pt microelectrode coated with polyaniline were used in conjunction with a scanning electrochemical microscope (SECM) to study anodic dissolution in the Fe│H₂SO₄ system. The concentrations of Fe^2 + (c_Fe2 +) measured with the unmodified microelectrode and the pH values measured with the polyaniline-modified microelectrode were recorded in situ during current oscillations in the Fe│H₂SO₄ system and were found to change periodically at the Fe│H₂SO₄ interface. The changes in c_Fe2 + may be caused by the periodic formation and dissolution of surface film(s), which could be salt films and/or oxide films. If a salt film is formed, it is unlikely to affect the pH. Since the pH changes periodically during the current oscillations, it can be deduced that the surface film is mainly composed of oxide, and that the formation and dissolution of the oxide film play a key role in the current oscillations of the system.     

In situ evaluation of cell cultivation on dynamically changed poly(ε-caprolactone) film caused by enzymatic degradation

In situ evaluation of cell cultivation on degrading poly(ε-caprolactone) (PCL) films was studied.New culture surroundings were constructed for cell growth by using PCL films as substrates and adding Pseudomonas cepacia lipase to accelerate biodegradation of PCL films.MTT experiments for 10 h indicated the low cytotoxicity of lipase solution with concentration up to 0.2 mg/mL for MG-63 cells growth on PCL films.With the optimized lipase concentration and degradation time,we studied cell growth behavior on dy...