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Sample records for membrane phospholipid composition

  1. Characterization of phospholipid composition and its control in the plasma membrane of developing soybean root

    International Nuclear Information System (INIS)

    Whitman, C.E.

    1985-01-01

    The phospholipid composition of plasma membrane enriched fractions from developing soybean root and several mechanisms which may regulate it have been examined. Plasma membrane vesicles were isolated from meristematic and mature sections of four-day-old dark grown soybean roots (Glycine max [L.] Merr. Cult. Wells II). Analysis of lipid extracts revealed two major phospholipid classes: phosphatidylcholine and phosphatidylethanolamine. Minor phospholipid classes were phosphatidylinositol, phosphatidylserine, phosphatidylgylcerol and diphosphatidylgylcerol. Phospholipid composition was similar at each developmental stage. Fatty acids of phosphatidylcholine and phosphatidylethanolamine were 16:0, 18:0, 18:2, and 18:3. Fatty acid composition varied with both phospholipid class and the developmental stage of the root. The degradation of phosphatidylcholine by endogenous phospholipase D during membrane isolation indicated that this enzyme might be involved in phospholipid turnover within the membrane. Phospholipase D activity was heat labile and increasing the pH of the enzyme assay from 5.3 to 7.8 resulted in 90% inhibition of activity. The turnover of fatty acids within the phospholipids of the plasma membrane was studied. Mature root sections were incubated with [1- 14 C] acetate, 1 mM Na acetate and 50 μg/ml chloramphenicol. Membrane lipid extracts analyzed for phospholipid class and acyl chain composition revealed that the long incubation times did not alter the phospholipid composition of the plasma membrane enriched fraction

  2. Eccentric contractions affect muscle membrane phospholipid fatty acid composition in rats

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Therkildsen, K J; Jørgensen, T B

    2001-01-01

    This study investigated if prior eccentric contractions, and thus mechanical strain and muscle damage, exert an effect on the muscle membrane phospholipid fatty acid composition in rats, and whether a possible effect could be attenuated by dietary supplements. Twenty-three rats were randomised...... muscle, was excised from both legs. In the muscles stimulated to contract eccentrically, compared to the control muscles, the proportion of arachidonic acid, C20:4,n-6 (17.7 +/- 0.6; 16.4 +/- 0.4% of total fatty acids, respectively) and docosapentanoeic acid, C22:5,n-3 (2.9 +/- 0.1 and 2.7 +/- 0.......1% of total fatty acids, respectively) was uniformly higher across groups (P acids) compared to the control leg (38.2 +/- 0...

  3. Eccentric contractions affect muscle membrane phospholipid fatty acid composition in rats

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Therkildsen, K J; Jørgensen, T B

    2001-01-01

    This study investigated if prior eccentric contractions, and thus mechanical strain and muscle damage, exert an effect on the muscle membrane phospholipid fatty acid composition in rats, and whether a possible effect could be attenuated by dietary supplements. Twenty-three rats were randomised...... to three groups who received chow with added fish oil (n = 8), vitamin C (n = 8) or no supplement (n = 7). After 3 weeks of feeding, calf muscles on one side were stimulated electrically during anaesthesia causing eccentric contractions. Two days later the white gastrocnemius, a part of the stimulated calf...... muscle, was excised from both legs. In the muscles stimulated to contract eccentrically, compared to the control muscles, the proportion of arachidonic acid, C20:4,n-6 (17.7 +/- 0.6; 16.4 +/- 0.4% of total fatty acids, respectively) and docosapentanoeic acid, C22:5,n-3 (2.9 +/- 0.1 and 2.7 +/- 0...

  4. Membrane phospholipid fatty acid composition regulates cardiac SERCA activity in a hibernator, the Syrian hamster (Mesocricetus auratus.

    Directory of Open Access Journals (Sweden)

    Sylvain Giroud

    Full Text Available Polyunsaturated fatty acids (PUFA have strong effects on hibernation and daily torpor. Increased dietary uptake of PUFA of the n-6 class, particularly of Linoleic acid (LA, C18:2 n-6 lengthens torpor bout duration and enables animals to reach lower body temperatures (T(b and metabolic rates. As previously hypothesized, this well-known influence of PUFA may be mediated via effects of the membrane fatty acid composition on sarcoplasmic reticulum (SR Ca(2+-ATPase 2a (SERCA in the heart of hibernators. We tested the hypotheses that high proportions of n-6 PUFA in general, or specifically high proportions of LA (C18:2 n-6 in SR phospholipids (PL should be associated with increased cardiac SERCA activity, and should allow animals to reach lower minimum T(b in torpor. We measured activity of SERCA from hearts of hibernating and non-hibernating Syrian hamsters (Mesocricetus auratus in vitro at 35 °C. Further, we determined the PL fatty acid composition of the SR membrane of these hearts. We found that SERCA activity strongly increased as the proportion of LA in SR PL increased but was negatively affected by the content of Docosahexaenoic acid (DHA; C22:6 n-3. SR PL from hibernating hamsters were characterized by high proportions of LA and low proportions of DHA. As a result, SERCA activity was significantly higher during entrance into torpor and in torpor compared to inter-bout arousal. Also, animals with increased SERCA activity reached lower T(b during torpor. Interestingly, a subgroup of hamsters which never entered torpor but remained euthermic throughout winter displayed a phenotype similar to animals in summer. This was characterized by lower proportions of LA and increased proportions of DHA in SR membranes, which is apparently incompatible with torpor. We conclude that the PUFA composition of SR membranes affects cardiac function via modulating SERCA activity, and hence determines the minimum T(b tolerated by hibernators.

  5. Effects of acclimation temperature on thermal tolerance and membrane phospholipid composition in the fruit fly Drosophila melanogaster

    Czech Academy of Sciences Publication Activity Database

    Overgaard, J.; Tomčala, Aleš; Sorensen, J. G.; Holmstrup, M.; Krogh, P. H.; Šimek, Petr; Košťál, Vladimír

    2008-01-01

    Roč. 54, č. 3 (2008), s. 619-629 ISSN 0022-1910 R&D Projects: GA ČR GA206/07/0269 Institutional research plan: CEZ:AV0Z50070508 Keywords : homeoviscous adaptation * membrane phospholipid * PE Subject RIV: ED - Physiology Impact factor: 2.155, year: 2008

  6. Membrane phospholipid composition may contribute to exceptional longevity of the naked mole-rat (Heterocephalus glaber): a comparative study using shotgun lipidomics.

    Science.gov (United States)

    Mitchell, Todd W; Buffenstein, Rochelle; Hulbert, A J

    2007-11-01

    Phospholipids containing highly polyunsaturated fatty acids are particularly prone to peroxidation and membrane composition may therefore influence longevity. Phospholipid molecules, in particular those containing docosahexaenoic acid (DHA), from the skeletal muscle, heart, liver and liver mitochondria were identified and quantified using mass-spectrometry shotgun lipidomics in two similar-sized rodents that show an approximately 9-fold difference in maximum lifespan. The naked mole rat is the longest-living rodent known with a maximum lifespan of >28 years. Total phospholipid distribution is similar in tissues of both species; DHA is only found in phosphatidylcholines (PC), phosphatidylethanolamines (PE) and phosphatidylserines (PS), and DHA is relatively more concentrated in PE than PC. Naked mole-rats have fewer molecular species of both PC and PE than do mice. DHA-containing phospholipids represent 27-57% of all phospholipids in mice but only 2-6% in naked mole-rats. Furthermore, while mice have small amounts of di-polyunsaturated PC and PE, these are lacking in naked mole-rats. Vinyl ether-linked phospholipids (plasmalogens) are higher in naked mole-rat tissues than in mice. The lower level of DHA-containing phospholipids suggests a lower susceptibility to peroxidative damage in membranes of naked mole-rats compared to mice. Whereas the high level of plasmalogens might enhance membrane antioxidant protection in naked mole-rats compared to mice. Both characteristics possibly contribute to the exceptional longevity of naked mole-rats and may indicate a special role for peroxisomes in this extended longevity.

  7. Tropical to sub-polar gradient in phospholipid composition suggests adaptive tuning of biological membrane function in drosophilds

    Czech Academy of Sciences Publication Activity Database

    Slotsbo, S.; Sorensen, J. G.; Holmstrup, M.; Košťál, Vladimír; Kellermann, V.; Overgaard, J.

    2016-01-01

    Roč. 30, č. 5 (2016), s. 759-768 ISSN 0269-8463 Institutional support: RVO:60077344 Keywords : cold tolerance * Drosophila * phospholipid fatty acid composition Subject RIV: ED - Physiology Impact factor: 5.630, year: 2016 http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.12568/abstract

  8. Molecular dynamics simulation of a phospholipid membrane

    NARCIS (Netherlands)

    Egberts, Egbert; Marrink, Siewert-Jan; Berendsen, Herman J.C.

    We present the results of molecular dynamics (MD) simulations of a phospholipid membrane in water, including full atomic detail. The goal of the simulations was twofold: first we wanted to set up a simulation system which is able to reproduce experimental results and can serve as a model membrane in

  9. Effects of acclimation temperature on thermal tolerance and membrane phospholipid composition in the fruit fly Drosophila melanogaster

    DEFF Research Database (Denmark)

    Overgaard, Johannes; Tomcala, Ales; Sørensen, Jesper G

    2008-01-01

    and the composition of membrane GPLs in adult Drosophila melanogaster. Long-term cold survival was significantly improved by low acclimation temperature. After 60h at 0 degrees C, more than 80% of the 15 degrees C-acclimated flies survived while none of the 25 degrees C-acclimated flies survived. Cold shock tolerance...... acclimation temperature and correlated with the changes in GPL composition in membranes of adult D. melanogaster. Udgivelsesdato: 2008-Mar...

  10. Novicidin interactions with phospholipid membranes

    DEFF Research Database (Denmark)

    Balakrishnan, Vijay Shankar

    Antimicrobial peptides target bacterial cell membranes and are considered as potential antibiotics. Their interactions with cell membranes are studied using different approaches. This thesis comprises of the biophysical investigations on the antimicrobial peptide Novicidin, interacting...... with liposomes. The lipid-induced changes in the peptide due to membrane binding, and the peptide-induced changes in the membrane properties were investigated using various spectroscopic and calorimetric methods, and the structural and thermodynamic aspects of peptide-lipid interactions are discussed. This helps...... in understanding not only the antimicrobial nature of Novicidin, but also sheds light on the membrane-peptide interactions....

  11. Computer simulations of phospholipid - membrane thermodynamic fluctuations

    DEFF Research Database (Denmark)

    Pedersen, U.R.; Peters, Günther H.j.; Schröder, T.B.

    2008-01-01

    This paper reports all-atom computer simulations of five phospholipid membranes, DMPC, DPPC, DMPG, DMPS, and DMPSH, with a focus on the thermal equilibrium fluctuations of volume, energy, area, thickness, and order parameter. For the slow fluctuations at constant temperature and pressure (defined...

  12. Cholesterol autoxidation in phospholipid membrane bilayers

    International Nuclear Information System (INIS)

    Sevanian, A.; McLeod, L.L.

    1987-01-01

    Lipid peroxidation in unilamellar liposomes of known cholesterol-phospholipid composition was monitored under conditions of autoxidation or as induced by a superoxide radical generating system, gamma-irradiation or cumene hydroperoxide. Formation of cholesterol oxidation products was indexed to the level of lipid peroxidation. The major cholesterol oxidation products identified were 7-keto-cholesterol, isomeric cholesterol 5,6-epoxides, isomeric 7-hydroperoxides and isomeric 3,7-cholestane diols. Other commonly encountered products included 3,5-cholestadiene-7-one and cholestane-3 beta, 5 alpha, 6 beta-triol. Superoxide-dependent peroxidation required iron and produced a gradual increase in 7-keto-cholesterol and cholesterol epoxides. Cholesterol oxidation was greatest in liposomes containing high proportions of unsaturated phospholipid to cholesterol (4:1 molar ratio), intermediate with low phospholipid to cholesterol ratios (2:1) and least in liposomes prepared with dipalmitoylphosphatidylcholine and cholesterol. This relationship held regardless of the oxidizing conditions used. Cumene hydroperoxide-dependent lipid peroxidation and/or more prolonged oxidations with other oxidizing systems yielded a variety of products where cholesterol-5 beta,6 beta-epoxide, 7-ketocholesterol and the 7-hydroperoxides were most consistently elevated. Oxyradical initiation of lipid peroxidation produced a pattern of cholesterol oxidation products distinguishable from the pattern derived by cumene hydroperoxide-dependent peroxidation

  13. Phospholipid composition and longevity: lessons from Ames dwarf mice.

    Science.gov (United States)

    Valencak, Teresa G; Ruf, Thomas

    2013-12-01

    Membrane fatty acid (FA) composition is correlated with longevity in mammals. The "membrane pacemaker hypothesis of ageing" proposes that animals which cellular membranes contain high amounts of polyunsaturated FAs (PUFAs) have shorter life spans because their membranes are more susceptible to peroxidation and further oxidative damage. It remains to be shown, however, that long-lived phenotypes such as the Ames dwarf mouse have membranes containing fewer PUFAs and thus being less prone to peroxidation, as would be predicted from the membrane pacemaker hypothesis of ageing. Here, we show that across four different tissues, i.e., muscle, heart, liver and brain as well as in liver mitochondria, Ames dwarf mice possess membrane phospholipids containing between 30 and 60 % PUFAs (depending on the tissue), which is similar to PUFA contents of their normal-sized, short-lived siblings. However, we found that that Ames dwarf mice membrane phospholipids were significantly poorer in n-3 PUFAs. While lack of a difference in PUFA contents is contradicting the membrane pacemaker hypothesis, the lower n-3 PUFAs content in the long-lived mice provides some support for the membrane pacemaker hypothesis of ageing, as n-3 PUFAs comprise those FAs being blamed most for causing oxidative damage. By comparing tissue composition between 1-, 2- and 6-month-old mice in both phenotypes, we found that membranes differed both in quantity of PUFAs and in the prevalence of certain PUFAs. In sum, membrane composition in the Ames dwarf mouse supports the concept that tissue FA composition is related to longevity.

  14. Nonenzymatic Reactions above Phospholipid Surfaces of Biological Membranes: Reactivity of Phospholipids and Their Oxidation Derivatives

    Science.gov (United States)

    Solís-Calero, Christian; Ortega-Castro, Joaquín; Frau, Juan; Muñoz, Francisco

    2015-01-01

    Phospholipids play multiple and essential roles in cells, as components of biological membranes. Although phospholipid bilayers provide the supporting matrix and surface for many enzymatic reactions, their inherent reactivity and possible catalytic role have not been highlighted. As other biomolecules, phospholipids are frequent targets of nonenzymatic modifications by reactive substances including oxidants and glycating agents which conduct to the formation of advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs). There are some theoretical studies about the mechanisms of reactions related to these processes on phosphatidylethanolamine surfaces, which hypothesize that cell membrane phospholipids surface environment could enhance some reactions through a catalyst effect. On the other hand, the phospholipid bilayers are susceptible to oxidative damage by oxidant agents as reactive oxygen species (ROS). Molecular dynamics simulations performed on phospholipid bilayers models, which include modified phospholipids by these reactions and subsequent reactions that conduct to formation of ALEs and AGEs, have revealed changes in the molecular interactions and biophysical properties of these bilayers as consequence of these reactions. Then, more studies are desirable which could correlate the biophysics of modified phospholipids with metabolism in processes such as aging and diseases such as diabetes, atherosclerosis, and Alzheimer's disease. PMID:25977746

  15. Impact of Membrane Phospholipid Alterations in Escherichia coli on Cellular Function and Bacterial Stress Adaptation.

    Science.gov (United States)

    Rowlett, Veronica W; Mallampalli, Venkata K P S; Karlstaedt, Anja; Dowhan, William; Taegtmeyer, Heinrich; Margolin, William; Vitrac, Heidi

    2017-07-01

    Bacteria have evolved multiple strategies to sense and rapidly adapt to challenging and ever-changing environmental conditions. The ability to alter membrane lipid composition, a key component of the cellular envelope, is crucial for bacterial survival and adaptation in response to environmental stress. However, the precise roles played by membrane phospholipids in bacterial physiology and stress adaptation are not fully elucidated. The goal of this study was to define the role of membrane phospholipids in adaptation to stress and maintenance of bacterial cell fitness. By using genetically modified strains in which the membrane phospholipid composition can be systematically manipulated, we show that alterations in major Escherichia coli phospholipids transform these cells globally. We found that alterations in phospholipids impair the cellular envelope structure and function, the ability to form biofilms, and bacterial fitness and cause phospholipid-dependent susceptibility to environmental stresses. This study provides an unprecedented view of the structural, signaling, and metabolic pathways in which bacterial phospholipids participate, allowing the design of new approaches in the investigation of lipid-dependent processes involved in bacterial physiology and adaptation. IMPORTANCE In order to cope with and adapt to a wide range of environmental conditions, bacteria have to sense and quickly respond to fluctuating conditions. In this study, we investigated the effects of systematic and controlled alterations in bacterial phospholipids on cell shape, physiology, and stress adaptation. We provide new evidence that alterations of specific phospholipids in Escherichia coli have detrimental effects on cellular shape, envelope integrity, and cell physiology that impair biofilm formation, cellular envelope remodeling, and adaptability to environmental stresses. These findings hold promise for future antibacterial therapies that target bacterial lipid biosynthesis

  16. Training affects muscle phospholipid fatty acid composition in humans

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Wu, B J; Willer, Mette

    2001-01-01

    on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk......, the phospholipid fatty acid contents of oleic acid 18:1(n-9) and docosahexaenoic acid 22:6(n-3) were significantly higher in the trained (10.9 +/- 0.5% and 3.2 +/- 0.4% of total fatty acids, respectively) than the untrained leg (8.8 +/- 0.5% and 2.6 +/- 0.4%, P fatty acids...... was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P

  17. Pollen viability and membrane lipid composition

    NARCIS (Netherlands)

    Bilsen, van D.G.J.L.

    1993-01-01

    In this thesis membrane lipid composition is studied in relation to pollen viability during storage. Chapter 1 reviews pollen viability, membranes in the dry state and membrane changes associated with cellular aging. This chapter is followed by a study of age-related changes in phospholipid

  18. Mechanics and dynamics of triglyceride-phospholipid model membranes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi I.; Duelund, Lars; Qvortrup, Klaus

    2011-01-01

    We demonstrate here that triolein alters the mechanical properties of phospholipid membranes and induces extraordinary conformational dynamics. Triolein containing membranes exhibit fluctuations up to size range of 100µm and with the help of these are e.g. able to squeeze through narrow passages...... with larger lamellar distances observed in the TOPOPC membranes. These findings suggest repulsion between adjacent membranes. We provide a comprehensive discussion on the possible explanations for the observed mechanics and dynamics in the TOPOPC system and on their potential cellular implications....

  19. Training affects muscle phospholipid fatty acid composition in humans

    DEFF Research Database (Denmark)

    Helge, Jørn Wulff; Wu, B J; Willer, Mette

    2001-01-01

    was significantly lower in the trained (11.1 +/- 0.9) than the untrained leg (13.1 +/- 1.2, P muscle triacylglycerol fatty acid composition. Citrate synthase activity was increased by 17% in the trained compared with the untrained leg (P diet plays......Training improves insulin sensitivity, which in turn may affect performance by modulation of fuel availability. Insulin action, in turn, has been linked to specific patterns of muscle structural lipids in skeletal muscle. This study investigated whether regular exercise training exerts an effect...... on the muscle membrane phospholipid fatty acid composition in humans. Seven male subjects performed endurance training of the knee extensors of one leg for 4 wk. The other leg served as a control. Before, after 4 days, and after 4 wk, muscle biopsies were obtained from the vastus lateralis. After 4 wk...

  20. Daily and Seasonal Rhythms in Human Mucosa Phospholipid Fatty Acid Composition.

    Science.gov (United States)

    Ruf, Thomas; Arnold, Walter

    2015-08-01

    Fatty acids (FAs) can exert important physiological effects: for example, as precursors of eicosanoids, as signaling molecules, and, in particular, as parts of phospholipids, the major constituents of cell membranes. Animals can remodel cell membranes in terms of their FA composition in response to environmental conditions, and even endothermic mammals exhibit seasonal cycles in the FA makeup of membranes. Previous evidence pointed to the existence of both seasonal and daily cycles in phospholipid composition of human cell membranes. Therefore, we used a noninvasive method to collect human mucosa cells over 1 year in 20 healthy subjects, and we determined seasonal and daily rhythmicity of phospholipid FA content. Our results show that significant daily rhythms were detectable in 11 of 13 FAs and were largely synchronous among subjects. Also, these daily rhythms showed stable phase relationships between different FAs within subjects. In contrast, yearly rhythms in phospholipid FA content were statistically significant in only ~50% of subjects and were asynchronous between subjects. These results support the view that while human physiology is still dominated by geophysical sunrise and sunset, resulting in strong daily cycles, seasonal rhythms are less well defined, at least in Western societies. We suggest that the main physiological function underlying rhythms in cell membrane composition is the regulation of the activity of transmembrane proteins, such as ion pumps, which can be strongly affected by the fatty acyl chains of phospholipids in the surrounding membrane bilayer. Hence, among a multitude of other functions, cycles in membrane FA composition may be involved in generating the daily rhythm of metabolic rate. Rhythms in certain membrane FAs, namely polyunsaturated and monounsaturated FAs that are known to affect health, could be also involved in daily and seasonal rhythms of diseases and death. © 2015 The Author(s).

  1. Identification of unusual phospholipid fatty acyl compositions of Acanthamoeba castellanii.

    Science.gov (United States)

    Palusinska-Szysz, Marta; Kania, Magdalena; Turska-Szewczuk, Anna; Danikiewicz, Witold; Russa, Ryszard; Fuchs, Beate

    2014-01-01

    Acanthamoeba are opportunistic protozoan pathogens that may lead to sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba followed by aggressive treatment regimen. The plasma membrane of Acanthamoeba consists of 25% phospholipids (PL). The presence of C20 and, recently reported, 28- and 30-carbon fatty acyl residues is characteristic of amoeba PL. A detailed knowledge about this unusual PL composition could help to differentiate Acanthamoeba from other parasites, e.g. bacteria and develop more efficient treatment strategies. Therefore, the detailed PL composition of Acanthamoeba castellanii was investigated by 31P nuclear magnetic resonance spectroscopy, thin-layer chromatography, gas chromatography, high performance liquid chromatography and liquid chromatography-mass spectrometry. Normal and reversed phase liquid chromatography coupled with mass spectrometric detection was used for detailed characterization of the fatty acyl composition of each detected PL. The most abundant fatty acyl residues in each PL class were octadecanoyl (18∶0), octadecenoyl (18∶1 Δ9) and hexadecanoyl (16∶0). However, some selected PLs contained also very long fatty acyl chains: the presence of 28- and 30-carbon fatty acyl residues was confirmed in phosphatidylethanolamine (PE), phosphatidylserine, phosphatidic acid and cardiolipin. The majority of these fatty acyl residues were also identified in PE that resulted in the following composition: 28∶1/20∶2, 30∶2/18∶1, 28∶0/20∶2, 30∶2/20∶4 and 30∶3/20∶3. The PL of amoebae are significantly different in comparison to other cells: we describe here for the first time unusual, very long chain fatty acids with Δ5-unsaturation (30∶35,21,24) and 30∶221,24 localized exclusively in specific phospholipid classes of A. castellanii protozoa that could serve as specific biomarkers for the presence of these

  2. Identification of unusual phospholipid fatty acyl compositions of Acanthamoeba castellanii.

    Directory of Open Access Journals (Sweden)

    Marta Palusinska-Szysz

    Full Text Available Acanthamoeba are opportunistic protozoan pathogens that may lead to sight-threatening keratitis and fatal granulomatous encephalitis. The successful prognosis requires early diagnosis and differentiation of pathogenic Acanthamoeba followed by aggressive treatment regimen. The plasma membrane of Acanthamoeba consists of 25% phospholipids (PL. The presence of C20 and, recently reported, 28- and 30-carbon fatty acyl residues is characteristic of amoeba PL. A detailed knowledge about this unusual PL composition could help to differentiate Acanthamoeba from other parasites, e.g. bacteria and develop more efficient treatment strategies. Therefore, the detailed PL composition of Acanthamoeba castellanii was investigated by 31P nuclear magnetic resonance spectroscopy, thin-layer chromatography, gas chromatography, high performance liquid chromatography and liquid chromatography-mass spectrometry. Normal and reversed phase liquid chromatography coupled with mass spectrometric detection was used for detailed characterization of the fatty acyl composition of each detected PL. The most abundant fatty acyl residues in each PL class were octadecanoyl (18∶0, octadecenoyl (18∶1 Δ9 and hexadecanoyl (16∶0. However, some selected PLs contained also very long fatty acyl chains: the presence of 28- and 30-carbon fatty acyl residues was confirmed in phosphatidylethanolamine (PE, phosphatidylserine, phosphatidic acid and cardiolipin. The majority of these fatty acyl residues were also identified in PE that resulted in the following composition: 28∶1/20∶2, 30∶2/18∶1, 28∶0/20∶2, 30∶2/20∶4 and 30∶3/20∶3. The PL of amoebae are significantly different in comparison to other cells: we describe here for the first time unusual, very long chain fatty acids with Δ5-unsaturation (30∶35,21,24 and 30∶221,24 localized exclusively in specific phospholipid classes of A. castellanii protozoa that could serve as specific biomarkers for the presence of

  3. Bacillus subtilis alters the proportion of major membrane phospholipids in response to surfactin exposure.

    Science.gov (United States)

    Uttlová, Petra; Pinkas, Dominik; Bechyňková, Olga; Fišer, Radovan; Svobodová, Jaroslava; Seydlová, Gabriela

    2016-12-01

    Surfactin, an anionic lipopeptide produced by Bacillus subtilis, is an antimicrobial that targets the cytoplasmic membrane. Nowadays it appears increasingly apparent that the mechanism of resistance against these types of antibiotics consists of target site modification. This prompted us to investigate whether the surfactin non-producing strain B. subtilis 168 changes its membrane composition in response to a sublethal surfactin concentration. Here we show that the exposure of B. subtilis to surfactin at concentrations of 350 and 650 μg/ml (designated as SF350 and SF650, respectively) leads to a concentration-dependent growth arrest followed by regrowth with an altered growth rate. Analysis of the membrane lipid composition revealed modifications both in the polar head group and the fatty acid region. The presence of either surfactin concentration resulted in a reduction in the content of the major membrane phospholipid phosphatidylglycerol (PG) and increase in phosphatidylethanolamine (PE), which was accompanied by elevated levels of phosphatidic acid (PA) in SF350 cultures. The fatty acid analysis of SF350 cells showed a marked increase in non-branched high-melting fatty acids, which lowered the fluidity of the membrane interior measured as the steady-state fluorescence anisotropy of DPH. The liposome leakage of carboxyfluorescein-loaded vesicles resembling the phospholipid composition of surfactin-adapted cells showed that the susceptibility to surfactin-induced leakage is strongly reduced when the PG/PE ratio decreases and/or PA is included in the target bilayer. We concluded that the modifications of the phospholipid content of B. subtilis cells might provide a self-tolerance of the membrane active surfactin. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Chitosan cushioned phospholipid membrane and its application in imaging ellipsometry based-biosensor

    International Nuclear Information System (INIS)

    Zhang Yibang; Chen Yanyan; Jin Gang

    2011-01-01

    Chitosan cushion can support the air stability of phospholipid membrane, but the problem of serum solubility of phospholipid membrane prevents it from use in serum detection applications. Poly (ethylene glycol) (PEG) shielding promises both stability and non-specific adsorption resistance for phospholipid membrane. An air stable phospholipid membrane microarray has been successfully fabricated on chitosan modified silicon wafer. We have demonstrated the potential application of PEGylated phospholipid membrane in imaging ellipsometry-based protein biosensor. Because of the strong resistance against non-specific adsorption of serum, antigens are immobilized onto the membrane surface through chemical activation and further bind their antibodies without using blocking agent. Taking advantage of the multiple and parallel reaction capabilities of microfluidic reactor system, we have assayed the binding by varying both the density of antigen on the membrane surface and the concentration of antibody in solution.

  5. Interaction of tachykinins with phospholipid membranes: A neutron diffraction study

    Science.gov (United States)

    Darkes, Malcolm J. M.; Davies, Sarah M. A.; Bradshaw, Jeremy P.

    Tachykinins are a group of peptides which bind to G-protein-coupled receptors. Receptor affinity appears to depend on different secondary structures of tachykinin which share the same hydrophobic carboxy-terminal sequence, FXGLM. Receptor activation is thought to be due to the carboxy-terminal submerging into the bilayer and the amino-terminal binding on the surface. Binding of tachykinins to phospholipid bilayers may take place both on the aqueous membrane surface and in the hydrophobic region. The two-state equilibrium appears to depend on the surface charge of the membrane. Deuterating substance P and neurokinin A at their carboxy-terminals, our results show two populations of label for each peptide. One is very close to the water-hydrocarbon interface, the other some 13 Å deeper. We report that the bilayer location of the two tachykinins is remarkably similar, thereby inferring that receptor specifity must be controlled by finer levels of structure.

  6. Lipid chain saturation and the cholesterol in the phospholipid membrane affect the spectroscopic properties of lipophilic dye nile red

    Science.gov (United States)

    Halder, Animesh; Saha, Baishakhi; Maity, Pabitra; Kumar, Gopinatha Suresh; Sinha, Deepak Kumar; Karmakar, Sanat

    2018-02-01

    We have studied the effect of composition and the phase state of phospholipid membranes on the emission spectrum, anisotropy and lifetime of a lipophilic fluorescence probe nile red. Fluorescence spectrum of nile red in membranes containing cholesterol has also been investigated in order to get insights into the influence of cholesterol on the phospholipid membranes. Maximum emission wavelength (λem) of nile red in the fluid phase of saturated and unsaturated phospholipids was found to differ by 10 nm. The λem was also found to be independent of chain length and charge of the membrane. However, the λem is strongly dependent on the temperature in the gel phase. The λem and rotational diffusion rate decrease, whereas the anisotropy and lifetime increase markedly with increasing cholesterol concentration for saturated phosoholipids, such as, dimyristoyl phosphatidylcholine (DMPC) in the liquid ordered phase. However, these spectroscopic properties do not alter significantly in case of unsaturated phospholipids, such as, dioleoyl phosphatidylcholine (DOPC) in liquid disordered phase. Interestingly, red edge excitation shift (REES) in the presence of lipid-cholesterol membranes is the direct consequences of change in rotational diffusion due to motional restriction of lipids in the presence of cholesterol. This study provides correlations between the membrane compositions and fluorescence spectral features which can be utilized in a wide range of biophysical fields as well the cell biology.

  7. The influence of ergosterol on the phase behaviour of phospholipid membranes

    Science.gov (United States)

    Hsueh, Ya-Wei

    2005-03-01

    Lipids in biological membranes form domains having distinct physical properties. Defined mixtures of lipids and sterols are of interest to ascertain the fundamental interactions governing these lipids in the absence of other cell membrane components. We study the effect of ergosterol (an important component of fungal plasma membranes) on the physical properties of phospholipid multibilayers using deuterium nuclear magnetic resonance (^2H NMR). In the ^2H NMR experiments the sn-1 chain was perdeuterated and NMR spectra were taken as a function of temperature and ergosterol concentration. It is found that domains of different composition and phase state are present in membranes. The phase diagram constructed from the NMR spectra will be discussed.

  8. Magnetic field alignable domains in phospholipid vesicle membranes containing lanthanides.

    Science.gov (United States)

    Beck, Paul; Liebi, Marianne; Kohlbrecher, Joachim; Ishikawa, Takashi; Rüegger, Heinz; Zepik, Helmut; Fischer, Peter; Walde, Peter; Windhab, Erich

    2010-01-14

    Magnetic fields were applied as a structuring force on phospholipid-based vesicular systems, using paramagnetic lanthanide ions as magnetic handles anchored to the vesicle membrane. Different vesicle formulations were investigated using small angle neutron scattering (SANS) in a magnetic field of up to 8 T, cryo-transmission electron microscopy (cryo-TEM), (31)P NMR spectroscopy, dynamic light scattering (DLS), and permeability measurements with a fluorescent water-soluble marker (calcein). The investigated vesicle formulations consisted usually of 80 mol % of the phospholipid 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 20 mol % of a chelator lipid (DMPE-DTPA; 1,2-dimyristoyl-sn-glycero-3-phosphoethanolamine-diethylenetriaminepentaacetate) with complexed lanthanide ions (Tm(3+), Dy(3+), or La(3+)), and the total lipid concentration was 15 mM. Vesicles containing the paramagnetic lanthanide Tm(3+) or Dy(3+) exhibited a temperature-dependent response to magnetic fields, which can be explained by considering the formation of lipid domains, which upon reaching a critical size become alignable in a magnetic field. The features of this "magnetic field alignable domain model" are as follows: with decreasing temperature (from 30 to 2.5 degrees C) solid domains, consisting mainly of the higher melting phospholipid (DMPE-DTPA.lanthanide), begin to form and grow in size. The domains assemble the large magnetic moments conferred by the lanthanides and orient in magnetic fields. The direction of alignment depends on the type of lanthanide used. The domains orient with their normal parallel to the magnetic field with thulium (Tm(3+)) and perpendicular with dysprosium (Dy(3+)). No magnetic field alignable domains were observed if DMPE-DTPA is replaced either by POPE-DTPA (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoethanolamine-diethylenetriamine-pentaacetate) or by DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine).

  9. The influence of membrane stress on phase separation and domain shape in phospholipid vesicles

    Science.gov (United States)

    Chen, Dong; Santore, Maria

    2012-02-01

    Phase separation of mixed phospholipid bilayers is of interest due to the potential role of phospholipid rafts in cell adhesion and signaling. Studies of membrane dynamics and the phase diagram itself typically neglect the role of tension, though it is expected that imposition of moderate membrane tensions might mildly shift the phase separation temperature, as anticipated by Clausius Clapeyron. We show here, using a simple binary system (DOPC/DPPC), a more dramatic effect: The tension imposed on giant unilamellar phospholipid vesicles can alter the phase and the domain shape, completely changing the composition of the liquid and solid phases, their proportions, and the transition temperature. The example in this talk demonstrates how striped or patchy hexagonal phases can develop, depending on thermal history and tension. Different incorporation of tracers into the ordered phases suggests fundamental differences in their structure at the molecular level. Rapid quenching and low tensions favor hexagonal patches while increased tension and slower quenching favors a striped phase. For this reason it is believed that the patches contain corrugations such that the structure of the ordered phase is metastable.

  10. Efficient replacement of plasma membrane outer leaflet phospholipids and sphingolipids in cells with exogenous lipids.

    Science.gov (United States)

    Li, Guangtao; Kim, JiHyun; Huang, Zhen; St Clair, Johnna R; Brown, Deborah A; London, Erwin

    2016-12-06

    Our understanding of membranes and membrane lipid function has lagged far behind that of nucleic acids and proteins, largely because it is difficult to manipulate cellular membrane lipid composition. To help solve this problem, we show that methyl-α-cyclodextrin (MαCD)-catalyzed lipid exchange can be used to maximally replace the sphingolipids and phospholipids in the outer leaflet of the plasma membrane of living mammalian cells with exogenous lipids, including unnatural lipids. In addition, lipid exchange experiments revealed that 70-80% of cell sphingomyelin resided in the plasma membrane outer leaflet; the asymmetry of metabolically active cells was similar to that previously defined for erythrocytes, as judged by outer leaflet lipid composition; and plasma membrane outer leaflet phosphatidylcholine had a significantly lower level of unsaturation than phosphatidylcholine in the remainder of the cell. The data also provided a rough estimate for the total cellular lipids residing in the plasma membrane (about half). In addition to such lipidomics applications, the exchange method should have wide potential for investigations of lipid function and modification of cellular behavior by modification of lipids.

  11. Seasonal changes in minor membrane phospholipid classes, sterols and tocopherols in overwintering insect, Pyrrhocoris apterus.

    Science.gov (United States)

    Koštál, Vladimír; Urban, Tomáš; Rimnáčová, Lucie; Berková, Petra; Simek, Petr

    2013-09-01

    Ectotherm animals including insects are known to undergo seasonal restructuring of the cell membranes in order to keep their functionality and/or protect their structural integrity at low body temperatures. Studies on insects so far focused either on fatty acids or on composition of molecular species in major phospholipid classes. Here we extend the scope of analysis and bring results on seasonal changes in minor phospholipid classes, lysophospholipids (LPLs), free fatty acids, phytosterols and tocopherols in heteropteran insect, Pyrrhocoris apterus. We found that muscle tissue contains unusually high amounts of LPLs. Muscle and fat body tissues also contain high amounts of β-sitosterol and campesterol, two phytosterols derived from plant food, while only small amounts of cholesterol are present. In addition, two isomers (γ and δ) of tocopherol (vitamin E) are present in quantities comparable to, or even higher than phytosterols in both tissues. Distinct seasonal patterns of sterol and tocopherol concentrations were observed showing a minimum in reproductively active bugs in summer and a maximum in diapausing, cold-acclimated bugs in winter. Possible adaptive meanings of such changes are discussed including: preventing the unregulated transition of membrane lipids from functional liquid crystalline phase to non-functional gel phase; decreasing the rates of ion/solute leakage; silencing the activities of membrane bound enzymes and receptors; and counteracting the higher risk of oxidative damage to PUFA in winter membranes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Flip-flop of phospholipids in proteoliposomes reconstituted from detergent extract of chloroplast membranes: kinetics and phospholipid specificity.

    Directory of Open Access Journals (Sweden)

    Archita Rajasekharan

    Full Text Available Eukaryotic cells are compartmentalized into distinct sub-cellular organelles by lipid bilayers, which are known to be involved in numerous cellular processes. The wide repertoire of lipids, synthesized in the biogenic membranes like the endoplasmic reticulum and bacterial cytoplasmic membranes are initially localized in the cytosolic leaflet and some of these lipids have to be translocated to the exoplasmic leaflet for membrane biogenesis and uniform growth. It is known that phospholipid (PL translocation in biogenic membranes is mediated by specific membrane proteins which occur in a rapid, bi-directional fashion without metabolic energy requirement and with no specificity to PL head group. A recent study reported the existence of biogenic membrane flippases in plants and that the mechanism of plant membrane biogenesis was similar to that found in animals. In this study, we demonstrate for the first time ATP independent and ATP dependent flippase activity in chloroplast membranes of plants. For this, we generated proteoliposomes from Triton X-100 extract of intact chloroplast, envelope membrane and thylakoid isolated from spinach leaves and assayed for flippase activity using fluorescent labeled phospholipids. Half-life time of flipping was found to be 6 ± 1 min. We also show that: (a intact chloroplast and envelope membrane reconstituted proteoliposomes can flip fluorescent labeled analogs of phosphatidylcholine in ATP independent manner, (b envelope membrane and thylakoid reconstituted proteoliposomes can flip phosphatidylglycerol in ATP dependent manner, (c Biogenic membrane ATP independent PC flipping activity is protein mediated and (d the kinetics of PC translocation gets affected differently upon treatment with protease and protein modifying reagents.

  13. Employment of Voltammetry in Studies of Transport Processes across Artificial Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Šestáková, Ivana; Navrátil, Tomáš; Josypčuk, Bohdan

    2016-01-01

    Roč. 28, č. 11 (2016), s. 2754-2759 ISSN 1040-0397 Institutional support: RVO:61388955 Keywords : phospholipid membrane * cadmium * calcium ionophore (calcimycin) Subject RIV: CG - Electrochemistry Impact factor: 2.851, year: 2016

  14. Polyarylether composition and membrane

    Science.gov (United States)

    Hung, Joyce; Brunelle, Daniel Joseph; Harmon, Marianne Elisabeth; Moore, David Roger; Stone, Joshua James; Zhou, Hongyi; Suriano, Joseph Anthony

    2010-11-09

    A composition including a polyarylether copolymer is provided. The copolymer includes a polyarylether backbone; and a sulfonated oligomeric group bonded to the polyarylether suitable for use as a cation conducting membrane. Method of bonding a sulfonated oligomeric group to the polyarylether backbone to form a polyarylether copolymer. The membrane may be formed from the polyarylether copolymer composition. The chain length of the sulfonated oligomeric group may be controlled to affect or control the ion conductivity of the membrane.

  15. Rooster sperm plasma membrane protein and phospholipid organization and reorganization attributed to cooling and cryopreservation

    Science.gov (United States)

    Cholesterol to phospholipid ratio is used as a representation for membrane fluidity, and predictor of cryopreservation success but results are not consistent across species and ignore the impact of membrane proteins. Therefore, this research explored the modulation of membrane fluidity and protein ...

  16. Effect of Structure on the Interactions between Five Natural Antimicrobial Compounds and Phospholipids of Bacterial Cell Membrane on Model Monolayers

    Directory of Open Access Journals (Sweden)

    Stella W. Nowotarska

    2014-06-01

    Full Text Available Monolayers composed of bacterial phospholipids were used as model membranes to study interactions of the naturally occurring phenolic compounds 2,5-dihydroxybenzaldehyde and 2-hydroxy-5-methoxybenzaldehyde, and the plant essential oil compounds carvacrol, cinnamaldehyde, and geraniol, previously found to be active against both Gram-positive and Gram-negative pathogenic microorganisms. The lipid monolayers consist of 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (DPPE, 1,2-dihexa- decanoyl-sn-glycero-3-phospho-(1'-rac-glycerol (DPPG, and 1,1',2,2'-tetratetradecanoyl cardiolipin (cardiolipin. Surface pressure–area (π-A and surface potential–area (Δψ-A isotherms were measured to monitor changes in the thermodynamic and physical properties of the lipid monolayers. Results of the study indicated that the five compounds modified the three lipid monolayer structures by integrating into the monolayer, forming aggregates of antimicrobial –lipid complexes, reducing the packing effectiveness of the lipids, increasing the membrane fluidity, and altering the total dipole moment in the monolayer membrane model. The interactions of the five antimicrobial compounds with bacterial phospholipids depended on both the structure of the antimicrobials and the composition of the monolayers. The observed experimental results provide insight into the mechanism of the molecular interactions between naturally-occurring antimicrobial compounds and phospholipids of the bacterial cell membrane that govern activities.

  17. Daptomycin resistance in enterococci is associated with distinct alterations of cell membrane phospholipid content.

    Directory of Open Access Journals (Sweden)

    Nagendra N Mishra

    Full Text Available The lipopeptide antibiotic, daptomycin (DAP interacts with the bacterial cell membrane (CM. Development of DAP resistance during therapy in a clinical strain of Enterococcus faecalis was associated with mutations in genes encoding enzymes involved in cell envelope homeostasis and phospholipid metabolism. Here we characterized changes in CM phospholipid profiles associated with development of DAP resistance in clinical enterococcal strains.Using two clinical strain-pairs of DAP-susceptible and DAP-resistant E. faecalis (S613 vs. R712 and E. faecium (S447 vs. R446 recovered before and after DAP therapy, we compared four distinct CM profiles: phospholipid content, fatty acid composition, membrane fluidity and capacity to be permeabilized and/or depolarized by DAP. Additionally, we characterized the cell envelope of the E. faecium strain-pair by transmission electron microscopy and determined the relative cell surface charge of both strain-pairs.Both E. faecalis and E. faecium mainly contained four major CM PLs: phosphatidylglycerol (PG, cardiolipin, lysyl-phosphatidylglycerol (L-PG and glycerolphospho-diglycodiacylglycerol (GP-DGDAG. In addition, E. faecalis CMs (but not E. faecium also contained: i phosphatidic acid; and ii two other unknown species of amino-containing PLs. Development of DAP resistance in both enterococcal species was associated with a significant decrease in CM fluidity and PG content, with a concomitant increase in GP-DGDAG. The strain-pairs did not differ in their outer CM translocation (flipping of amino-containing PLs. Fatty acid content did not change in the E. faecalis strain-pair, whereas a significant decrease in unsaturated fatty acids was observed in the DAP-resistant E. faecium isolate R446 (vs S447. Resistance to DAP in E. faecium was associated with distinct structural alterations of the cell envelope and cell wall thickening, as well as a decreased ability of DAP to depolarize and permeabilize the CM

  18. Modulation of the molecular arrangement in artificial and biological membranes by phospholipid-shelled microbubbles.

    Science.gov (United States)

    Carugo, Dario; Aron, Miles; Sezgin, Erdinc; Bernardino de la Serna, Jorge; Kuimova, Marina K; Eggeling, Christian; Stride, Eleanor

    2017-01-01

    The transfer of material from phospholipid-coated microbubbles to cell membranes has been hypothesized to play a role in ultrasound-mediated drug delivery. In this study, we employed quantitative fluorescence microscopy techniques to investigate this phenomenon in both artificial and biological membrane bilayers in an acoustofluidic system. The results of the present study provide strong evidence for the transfer of material from microbubble coatings into cell membranes. Our results indicate that transfer of phospholipids alters the organization of molecules in cell membranes, specifically the lipid ordering or packing, which is known to be a key determinant of membrane mechanical properties, protein dynamics, and permeability. We further show that polyethylene-glycol, used in many clinical microbubble formulations, also has a major impact on both membrane lipid ordering and the extent of lipid transfer, and that this occurs even in the absence of ultrasound exposure. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  19. Effects of Chain Length and Saturability of Fatty Acids on Phospholipids and Proteins in Plasma Membranes of Bovine Mammary Gland.

    Science.gov (United States)

    Yan, Qiongxian; Tang, Shaoxun; Han, Xuefeng; Bamikole, Musibau Adungbe; Zhou, Chuanshe; Kang, Jinhe; Wang, Min; Tan, Zhiliang

    2016-12-01

    Free fatty acids (FFAs) in plasma are essential substrates for de novo synthesis of milk fat, or directly import into mammary cells. The physico-chemical properties of mammary cells membrane composition affected by FFAs with different chain lengths and saturability are unclear yet. Employing GC, FTIR and fluorescence spectroscopy, the adsorption capacity, phospholipids content, membrane proteins conformation, lipid peroxidation product, and free sulfhydryl of plasma membranes (PMs) interacted with different FFAs were determined. The mammary cells PMs at 38 and 39.5 °C showed different adsorption capacities: acetic acid (Ac) > stearic acid (SA) > β-hydroxybutyric acid (BHBA) > trans10, cis12 CLA. In the FTIR spectrum, the major adsorption peaks appeared at 2920 and 2850 cm -1 for phospholipids, and at 1628 and 1560 cm -1 for membrane proteins. The intensities of PMs-FFAs complexes were varied with the FFAs species and their initial concentrations. The β-sheet and turn structures of membrane proteins were transferred into random coil and α-helix after BHBA, SA and trans10, cis12 CLA treatments compared with Ac treatment. The quenching effects on the fluorescence of endogenous membrane protein, 1, 8-ANS, NBD-PE, and DHPE entrapped in PMs by LCFA were different from those of short chain FFAs. These results indicate that the adsorption of FFAs could change membrane protein conformation and polarity of head group in phospholipids. This variation of the mammary cells PMs was regulated by carbon chain length and saturability of FFAs.

  20. Slow Phospholipid Exchange between a Detergent-Solubilized Membrane Protein and Lipid-Detergent Mixed Micelles: Brominated Phospholipids as Tools to Follow Its Kinetics.

    Science.gov (United States)

    Montigny, Cédric; Dieudonné, Thibaud; Orlowski, Stéphane; Vázquez-Ibar, José Luis; Gauron, Carole; Georgin, Dominique; Lund, Sten; le Maire, Marc; Møller, Jesper V; Champeil, Philippe; Lenoir, Guillaume

    2017-01-01

    Membrane proteins are largely dependent for their function on the phospholipids present in their immediate environment, and when they are solubilized by detergent for further study, residual phospholipids are critical, too. Here, brominated phosphatidylcholine, a phospholipid which behaves as an unsaturated phosphatidylcholine, was used to reveal the kinetics of phospholipid exchange or transfer from detergent mixed micelles to the environment of a detergent-solubilized membrane protein, the paradigmatic P-type ATPase SERCA1a, in which Trp residues can experience fluorescence quenching by bromine atoms present on phospholipid alkyl chains in their immediate environment. Using dodecylmaltoside as the detergent, exchange of (brominated) phospholipid was found to be much slower than exchange of detergent under the same conditions, and also much slower than membrane solubilization, the latter being evidenced by light scattering changes. The kinetics of this exchange was strongly dependent on temperature. It was also dependent on the total concentration of the mixed micelles, revealing the major role for such exchange of the collision of detergent micelles with the detergent-solubilized protein. Back-transfer of the brominated phospholipid from the solubilized protein to the detergent micelle was much faster if lipid-free DDM micelles instead of mixed micelles were added for triggering dissociation of brominated phosphatidylcholine from the solubilized protein, or in the additional presence of C12E8 detergent during exchange, also emphasizing the role of the chemical nature of the micelle/protein interface. This protocol using brominated lipids appears to be valuable for revealing the possibly slow kinetics of phospholipid transfer to or from detergent-solubilized membrane proteins. Independently, continuous recording of the activity of the protein can also be used in some cases to correlate changes in activity with the exchange of a specific phospholipid, as shown here

  1. Analysis of the induction of the myelin basic protein binding to the plasma membrane phospholipid monolayer

    International Nuclear Information System (INIS)

    Zhang Lei; Hao Changchun; Feng Ying; Gao Feng; Lu Xiaolong; Li Junhua; Sun Runguang

    2016-01-01

    Myelin basic protein (MBP) is an essential structure involved in the generation of central nervous system (CNS) myelin. Myelin shape has been described as liquid crystal structure of biological membrane. The interactions of MBP with monolayers of different lipid compositions are responsible for the multi-lamellar structure and stability of myelin. In this paper, we have designed MBP-incorporated model lipid monolayers and studied the phase behavior of MBP adsorbed on the plasma membrane at the air/water interface by thermodynamic method and atomic force microscopy (AFM). By analyzing the pressure–area ( π – A ) and pressure–time ( π – T ) isotherms, univariate linear regression equation was obtained. In addition, the elastic modulus, surface pressure increase, maximal insertion pressure, and synergy factor of monolayers were detected. These parameters can be used to modulate the monolayers binding of protein, and the results show that MBP has the strongest affinity for 1,2-dipalmitoyl-sn-glycero-3- phosphoserine (DPPS) monolayer, followed by DPPC/DPPS mixed and 1,2-dipalmitoyl-sn-glycero-3-phospho-choline (DPPC) monolayers via electrostatic and hydrophobic interactions. AFM images of DPPS and DPPC/DPPS mixed monolayers in the presence of MBP (5 nM) show a phase separation texture at the surface pressure of 20 mN/m and the incorporation of MBP put into the DPPC monolayers has exerted a significant effect on the domain structure. MBP is not an integral membrane protein but, due to its positive charge, interacts with the lipid head groups and stabilizes the membranes. The interaction between MBP and phospholipid membrane to determine the nervous system of the disease has a good biophysical significance and medical value. (special topic)

  2. Phospholipid Membrane Protection by Sugar Molecules during Dehydration—Insights into Molecular Mechanisms Using Scattering Techniques

    Directory of Open Access Journals (Sweden)

    Ben Kent

    2013-04-01

    Full Text Available Scattering techniques have played a key role in our understanding of the structure and function of phospholipid membranes. These techniques have been applied widely to study how different molecules (e.g., cholesterol can affect phospholipid membrane structure. However, there has been much less attention paid to the effects of molecules that remain in the aqueous phase. One important example is the role played by small solutes, particularly sugars, in protecting phospholipid membranes during drying or slow freezing. In this paper, we present new results and a general methodology, which illustrate how contrast variation small angle neutron scattering (SANS and synchrotron-based X-ray scattering (small angle (SAXS and wide angle (WAXS can be used to quantitatively understand the interactions between solutes and phospholipids. Specifically, we show the assignment of lipid phases with synchrotron SAXS and explain how SANS reveals the exclusion of sugars from the aqueous region in the particular example of hexagonal II phases formed by phospholipids.

  3. Relation between various phospholipase actions on human red cell membranes and the interfacial phospholipid pressure in monolayers

    NARCIS (Netherlands)

    Demel, R.A.; Geurts van Kessel, W.S.M.; Zwaal, R.F.A.; Roelofsen, B.; Deenen, L.L.M. van

    1975-01-01

    The action of purified phospholipases on monomolecular films of various interfacial pressures is compared with the action on erythrocyte membranes. The phospholipases which cannot hydrolyse phospholipids of the intact erythrocyte membrane, phospholipase C from Bacillus cereus, phospholipase A2 from

  4. Increased Binding of Calcium Ions at Positively Curved Phospholipid Membranes

    Czech Academy of Sciences Publication Activity Database

    Magarkar, Aniket; Jurkiewicz, Piotr; Allolio, Christoph; Hof, Martin; Jungwirth, Pavel

    2017-01-01

    Roč. 8, č. 2 (2017), s. 518-523 ISSN 1948-7185 R&D Projects: GA ČR(CZ) GA16-01074S; GA ČR(CZ) GAP207/12/0919 Grant - others:AV ČR(CZ) AP1102 Program:Akademická prémie - Praemium Academiae Institutional support: RVO:61388963 ; RVO:61388955 Keywords : molecular dynamics * fluorescence spectroscopy * calcium * phospholipids Subject RIV: CF - Physical ; Theoretical Chemistry ; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Physical chemistry ; Physical chemistry (UFCH-W) Impact factor: 9.353, year: 2016

  5. Effect of heavy water on phospholipid membranes: experimental confirmation of molecular dynamics simulations

    Czech Academy of Sciences Publication Activity Database

    Beranová, Lenka; Humpolíčková, Jana; Sýkora, Jan; Benda, Aleš; Cwiklik, Lukasz; Jurkiewicz, Piotr; Gröbner, G.; Hof, Martin

    Roč. 14, č. 42 ( 2012 ), s. 14516-14522 ISSN 1463-9076 R&D Projects: GA AV ČR GEMEM/09/E006; GA ČR GBP208/12/G016 Institutional support: RVO:61388955 Keywords : phospholipid membranes * biophysics * physical chemistry Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.829, year: 2012

  6. Seasonal changes in minor membrane phospholipid classes, sterols and tocopherols in overwintering insect, Pyrrhocoris apterus

    Czech Academy of Sciences Publication Activity Database

    Košťál, Vladimír; Urban, T.; Řimnáčová, Lucie; Berková, Petra; Šimek, Petr

    2013-01-01

    Roč. 59, č. 9 (2013), s. 934-941 ISSN 0022-1910 R&D Projects: GA MŠk LH12103; GA MZd(CZ) NT11513 Institutional support: RVO:60077344 Keywords : seasonal membrane restructuring * phospholipids * lysophospholipids Subject RIV: ED - Physiology Impact factor: 2.500, year: 2013 http://www.sciencedirect.com/science/article/pii/S0022191013001406#

  7. Correlated volume-energy fluctuations of phospholipid membranes: A simulation study

    DEFF Research Database (Denmark)

    Pedersen, Ulf. R.; Peters, Günther H.J.; Schröder, Thomas B.

    2010-01-01

    This paper reports all-atom computer simulations of five phospholipid membranes (DMPC, DPPC, DMPG, DMPS, and DMPSH) with focus on the thermal equilibrium fluctuations of volume, energy, area, thickness, and chain order. At constant temperature and pressure, volume and energy exhibit strong...

  8. Membrane phospholipids and radiation-induced death of mammalian cells

    International Nuclear Information System (INIS)

    Wolters, H.

    1987-01-01

    Radiation-induced cell killing is generally believed to be a consequence of residual DNA damage or damage that is mis-repaired. However, besides this DNA damage, damage to other molecules or structures of the cell may be involved in the killing. Especially membranes have been suggested as a determinant in cellular radiosensitivity. In this thesis experiments are described, dealing with the possible involvement of membranes in radiation-induced killing of mammalian cells. A general treatise of membrane structure is followed by information concerning deleterious effects of radiation on membranes. Consequences of damage to structure and function of membranes are reviewed. Thereafter evidence relating to the possible involvement of membranes in radiation-induced cell killing is presented. (Auth.)

  9. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    The purpose of the present study was to examine the short-term effect of dietary specific structured triacylglycerols (MLM, M = 8:0, L = 18:2n-6), LLL and MMM on the fatty acid composition of brush border membrane (BBM) phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Rats were...... fatty acids in the two phospholipid pools. Minor effects on BBM-PC and BBM-PE fatty acid profiles (mole-%) were observed. The present study demonstrated for the first time incorporation of C-13-labeled 18:2n-6 into BBM-PC 2 hours and 6 hours after intragastric administration of L*L*L* or ML...

  10. (CryoTransmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

    Directory of Open Access Journals (Sweden)

    Annette Meister

    2017-10-01

    Full Text Available Lipid membranes can incorporate amphiphilic or polyphilic molecules leading to specific functionalities and to adaptable properties of the lipid bilayer host. The insertion of guest molecules into membranes frequently induces changes in the shape of the lipid matrix that can be visualized by transmission electron microscopy (TEM techniques. Here, we review the use of stained and vitrified specimens in (cryoTEM to characterize the morphology of amphiphilic and polyphilic molecules upon insertion into phospholipid model membranes. Special emphasis is placed on the impact of novel synthetic amphiphilic and polyphilic bolalipids and polymers on membrane integrity and shape stability.

  11. An averaged polarizable potential for multiscale modeling in phospholipid membranes

    DEFF Research Database (Denmark)

    Witzke, Sarah; List, Nanna Holmgaard; Olsen, Jógvan Magnus Haugaard

    2017-01-01

    is underlined for the description of larger assemblies of lipids, that is, membranes. In conclusion, we find that specially developed polarizable parameters are needed for embedding calculations in membranes, while common non-polarizable point-charge force fields usually perform well enough for structural...

  12. Phospholipids in Milk Fat: Composition, Biological and Technological Significance, and Analytical Strategies

    Directory of Open Access Journals (Sweden)

    Giovanna Contarini

    2013-01-01

    Full Text Available Glycerophospholipids and sphingolipids are quantitatively the most important phospholipids (PLs in milk. They are located on the milk fat globule membrane (MFGM and in other membranous material of the skim milk phase. They include principally phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine, while sphingomyelin is the dominant species of sphingolipids There is considerable evidence that PLs have beneficial health effects, such as regulation of the inflammatory reactions, chemopreventive and chemotherapeutic activity on some types of cancer, and inhibition of the cholesterol absorption. PLs show good emulsifying properties and can be used as a delivery system for liposoluble constituents. Due to the amphiphilic characteristics of these molecules, their extraction, separation and detection are critical points in the analytical approach. The extraction by using chloroform and methanol, followed by the determination by high pressure liquid chromatography (HPLC, coupled with evaporative light scattering (ELSD or mass detector (MS, are the most applied procedures for the PL evaluation. More recently, nuclear magnetic resonance spectrometry (NMR was also used, but despite it demonstrating high sensitivity, it requires more studies to obtain accurate results. This review is focused on milk fat phospholipids; their composition, biological activity, technological properties, and significance in the structure of milk fat. Different analytical methodologies are also discussed.

  13. Structure refinement and membrane positioning of selectively labeled OmpX in phospholipid nanodiscs

    Energy Technology Data Exchange (ETDEWEB)

    Hagn, Franz, E-mail: franz.hagn@tum.de; Wagner, Gerhard, E-mail: gerhard-wagner@hms.harvard.edu [Harvard Medical School, Department of Biological Chemistry and Molecular Pharmacology (United States)

    2015-04-15

    NMR structural studies on membrane proteins are often complicated by their large size, taking into account the contribution of the membrane mimetic. Therefore, classical resonance assignment approaches often fail. The large size of phospholipid nanodiscs, a detergent-free phospholipid bilayer mimetic, prevented their use in high-resolution solution-state NMR spectroscopy so far. We recently introduced smaller nanodiscs that are suitable for NMR structure determination. However, side-chain assignments of a membrane protein in nanodiscs still remain elusive. Here, we utilized a NOE-based approach to assign (stereo-) specifically labeled Ile, Leu, Val and Ala methyl labeled and uniformly {sup 15}N-Phe and {sup 15}N-Tyr labeled OmpX and calculated a refined high-resolution structure. In addition, we were able to obtain residual dipolar couplings (RDCs) of OmpX in nanodiscs using Pf1 phage medium for the induction of weak alignment. Back-calculated NOESY spectra of the obtained NMR structures were compared to experimental NOESYs in order to validate the quality of these structures. We further used NOE information between protonated lipid head groups and side-chain methyls to determine the position of OmpX in the phospholipid bilayer. These data were verified by paramagnetic relaxation enhancement (PRE) experiments obtained with Gd{sup 3+}-modified lipids. Taken together, this study emphasizes the need for the (stereo-) specific labeling of membrane proteins in a highly deuterated background for high-resolution structure determination, particularly in large membrane mimicking systems like phospholipid nanodiscs. Structure validation by NOESY back-calculation will be helpful for the structure determination and validation of membrane proteins where NOE assignment is often difficult. The use of protein to lipid NOEs will be beneficial for the positioning of a membrane protein in the lipid bilayer without the need for preparing multiple protein samples.

  14. Mass spectrometric study of rhamnolipid biosurfactants and their interactions with cell membrane phospholipids

    Directory of Open Access Journals (Sweden)

    Pashynska V. A.

    2009-12-01

    Full Text Available Aim. To examine the formation of supramolecular complexes of biogenous rhamnolipids with membrane phospholipids that is considered as a molecular mechanism of the biosurfactants antimicrobial action. Method. In the present work rhamnolipid biosurfactant samples produced by Pseudomonas sp. PS-17 strain have been investigated by electrospray ionization mass spectrometry for the first time. Results. As a result of the study, characteristic mass spectra of the rhamnolipid samples were obtained, that can be used as reference spectra for mass spectrometric identification of the compounds in any biological or industrial samples. At the next stage of the experiments the pair systems, containing the biosurfactants and a membrane phospholipid dipalmitoylphosphatidylcholine, have been tested. The cationized noncovalent complexes of the rhamnolipids with the phospholipid were observed in the spectra. Conclusions. The results obtained testify to the consideration that rhamnolipids (similar to other membranotropic agents can form stable supramolecular complexes with membrane phospholipids that are able to evoke the biosurfactants antimicrobial action. A great potential of electrospray ionization mass spectrometry for the biosurfactants identification and study has been demonstrated in the work.

  15. Field-effect detection using phospholipid membranes -Topical Review

    Directory of Open Access Journals (Sweden)

    Chiho Kataoka-Hamai and Yuji Miyahara

    2010-01-01

    Full Text Available The application of field-effect devices to biosensors has become an area of intense research interest. An attractive feature of field-effect sensing is that the binding or reaction of biomolecules can be directly detected from a change in electrical signals. The integration of such field-effect devices into cell membrane mimics may lead to the development of biosensors useful in clinical and biotechnological applications. This review summarizes recent studies on the fabrication and characterization of field-effect devices incorporating model membranes. The incorporation of black lipid membranes and supported lipid monolayers and bilayers into semiconductor devices is described.

  16. Perforin rapidly induces plasma membrane phospholipid flip-flop.

    Directory of Open Access Journals (Sweden)

    Sunil S Metkar

    Full Text Available The cytotoxic cell granule secretory pathway is essential for host defense. This pathway is fundamentally a form of intracellular protein delivery where granule proteases (granzymes from cytotoxic lymphocytes are thought to diffuse through barrel stave pores generated in the plasma membrane of the target cell by the pore forming protein perforin (PFN and mediate apoptotic as well as additional biological effects. While recent electron microscopy and structural analyses indicate that recombinant PFN oligomerizes to form pores containing 20 monomers (20 nm when applied to liposomal membranes, these pores are not observed by propidium iodide uptake in target cells. Instead, concentrations of human PFN that encourage granzyme-mediated apoptosis are associated with pore structures that unexpectedly favor phosphatidylserine flip-flop measured by Annexin-V and Lactadherin. Efforts that reduce PFN mediated Ca influx in targets did not reduce Annexin-V reactivity. Antigen specific mouse CD8 cells initiate a similar rapid flip-flop in target cells. A lipid that augments plasma membrane curvature as well as cholesterol depletion in target cells enhance flip-flop. Annexin-V staining highly correlated with apoptosis after Granzyme B (GzmB treatment. We propose the structures that PFN oligomers form in the membrane bilayer may include arcs previously observed by electron microscopy and that these unusual structures represent an incomplete mixture of plasma membrane lipid and PFN oligomers that may act as a flexible gateway for GzmB to translocate across the bilayer to the cytosolic leaflet of target cells.

  17. Composition and metabolism of phospholipids of human leukocytes.

    Science.gov (United States)

    Marinetti, G V; Cattieu, K

    1982-10-01

    Human mononuclear (MN) and polymorphonuclear (PMN) leukocytes were analyzed for their phospholipid, triglyceride, cholesterol and fatty acid content. The phospholipid/cholesterol ratio was 1.24 for both cells. MN cells contain more phosphatidylcholine (PC), but less phosphatidylserine (PS), Phosphatidylethanolamine (PE) and sphingomyelin (SPH) than PMN cells when expressed as percent of total phospholipid. When expressed on the basis of lipid content per cell, MN cells contain less PS, PE and SPH but more triglyceride than PMN cells. PMN cells incorporate palmitic, stearic, linoleic and linolenic acids into their phospholipids, triglycerides or cholesterol esters. The incorporation into triglycerides was highest for all fatty acids. Of the phospholipids, the incorporation was highest into PC. Labeled fatty acids also were found in proteins which had been delipidized by exhaustive extraction with organic solvents. These represent tightly or covalently bound fatty acids. The incorporation [3H] palmitic acid into this protein fraction is stimulated by insulin.

  18. Solvent accessible surface area (ASA) of simulated phospholipid membranes

    DEFF Research Database (Denmark)

    Tuchsen, E.; Jensen, Morten Østergaard; Westh, P.

    2003-01-01

    The membrane-solvent interface has been investigated through calculations of the solvent accessible surface area (ASA) for simulated membranes of DPPC and POPE. For DPPC at 52 degreesC we found an ASA of 126 +/- 8 Angstrom(2) per lipid molecule, equivalent to twice the projected lateral area......, even the most exposed parts of the PC head-group show average ASAs of less than half of its maximal or 'fully hydrated' value. The average ASA of a simulated POPE membrane was 96 +/- 7 Angstrom(2) per lipid. The smaller value than for DPPC reflects much lower ASA of the ammonium ion, which is partially...... compensated by increased exposure of the ethylene and phosphate moieties. The ASA of the polar moieties Of (PO4, NH3 and COO) constitutes 65% of the total accessible area for POPE, making this interface more polar than that of DPPC. It is suggested that ASA information can be valuable in attempts...

  19. Role of Intra- and Inter-mitochondrial Membrane Contact Sites in Yeast Phospholipid Biogenesis.

    Science.gov (United States)

    Tamura, Yasushi; Endo, Toshiya

    2017-01-01

    Eukaryotic cells exhibit intracellular compartments called organelles wherein various specialized enzymatic reactions occur. Despite the specificity of the characteristic functions of organelles, recent studies have shown that distinct organelles physically connect and communicate with each other to maintain the integrity of their functions. In yeast, multiple inter- and intramitochondrial membrane contact sites (MCSs) were identified to date and were proposed to be involved in phospholipid biogenesis. In the present article, we focus on inter- and intra-organellar MCSs involving mitochondria and their tethering factors, such as the ERMES (endoplasmic reticulum (ER)-mitochondria encounter structure) complex and EMC (conserved ER membrane protein complex) between mitochondria and the ER, vCLAMP (vacuole and mitochondria patch) between mitochondria and vacuoles, and the MICOS (mitochondrial contact site) complex between the mitochondrial outer and inner membranes (MOM and MIM). All of these membrane-tethering factors were proposed to be involved in phospholipid biogenesis. Furthermore, the existence of functional interconnections among multiple organelle contact sites is suggested. In the present article, we summarize the latest discoveries in regard to MCSs and MCS-forming factors involving mitochondria and discuss their molecular functions, with particular focus on phospholipid metabolism in yeast.

  20. Changes of murine sperm phospholipid composition during epididymal maturation determined by MALDI-TOF mass spectrometry.

    Science.gov (United States)

    Pyttel, S; Nimptsch, A; Böttger, J; Zschörnig, K; Jakop, U; Wegener, J; Müller, K; Paasch, U; Schiller, J

    2014-08-01

    After leaving the testis, spermatozoa undergo several important steps of biochemical maturation during the passage through the epididymis, increasing their motility and fertilizing ability. These changes comprise (among others) the modification of the phospholipid composition of the sperm membrane. This process is thought to be important for the achievement of motility and fertilizing capacity. The lipids of the sperm membrane are characterized by a significant content of unsaturated fatty acyl residues, resulting in a high sensitivity against oxidative stress. This is evidenced by the appearance of lysolipids, for example, lysophosphatidylcholine, which acts like a detergent and is normally present in only very small amounts in biological membranes. The epididymis represents a tubular system comprising three main parts (caput, corpus, and cauda), through which the spermatozoa are consecutively transported undergoing distinct maturation stages. Using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, we established three striking differences in the lipid composition of murine spermatozoa from the different epididymal regions: in comparison to the caput sperm, sperm from the cauda are characterized by (1) a higher degree of unsaturation (PC 18:0/22:5 and 18:0/22:6 vs. 18:0/20:4 and 18:0/18:1), (2) an enhanced plasmalogen content, and (3) an enhanced content of lysolipids. These changes are likely to be of physiological relevance and potentially useful as diagnostic markers of sperm maturation and acquisition of motility. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Influence of membrane composition on its flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Gerbelli, B.B.; Teixeira da Silva, E.R.; Oliveira, C.L.P.; Oliveira, E.A. [Universidade de Sao Paulo (USP), SP (Brazil)

    2012-07-01

    Full text: Lamellar phases and vesicles composed of lipids have been used as model systems to investigate biological process related to cell membrane as well as promising carriers for drugs and gene therapy. The composition of the membrane determines its three dimensional shape and its properties such as rigidity and compressibility which play an important role on membrane fusion, protein adhesion, interactions between proteins, etc. We present systematic study of a lamellar system composed mainly of lecithin which is a biocompatible phospholipid and simusol, which is a mixture of fatty acids that acts as a cosurfactant introducing flexibility to the membrane. Using X ray scattering we determine the lamellar periodicity as a function of the hydration for different formulations of the membrane; ranging from 100 % to 50 % mass fraction of lecithin. The X-ray spectra are fitted using a 4 Gaussian model [1]that allows us to determine the lamellar periodicity and the Caille parameter [2]. The ideal swelling law relating the membrane volume fraction ({phi}{sub m}) to the lamellar periodicity (D) is given by {phi}{sub m} ={delta}{sub m}/D, where {delta}{sub m} is the thickness membrane, however, when steric interactions are dominant with respect to electrostatic and van der Waals interactions, deviations from this behavior are expected [3]. We present experimental data illustrating the swelling behavior for the membrane compositions and the respective behavior of the hydration limit, membrane Luzzati [4], of the Caille parameter and qualitative interpretation of the interaction forces the systems studying the parameter membrane square amplitude fluctuation[5]. [1] Private communication with Prof. Dr. Cristiano Luis Pinto de Oliveira. [2] Caille A. et all, Acad. Sci. Paris B274 (1972) 891. [3] E. Kurtisovski et all, PRL 98, 258103 (2007). [4] Nagle et all, Curr Opin Struct Biol. 2000 Aug;10(4):474-80. [5] H. I. Petrache. Structure and interactions of fluid phospholipids

  2. Composition and physical state of phospholipids in calanoid copepods from India and Norway

    Digital Repository Service at National Institute of Oceanography (India)

    Farkas, T.; Storebakken, T.; Bhosle, N.B.

    The fatty acid composition and physical state of isolated phospholipids obtained from marine copepods collected on the Southwest coast of India (Calanus spp.) and the west coast of Norway (Calanus finmarchicus) were investigated to compare...

  3. Phospholipid synthesis participates in the regulation of diacylglycerol required for membrane trafficking at the Golgi complex.

    Science.gov (United States)

    Sarri, Elisabet; Sicart, Adrià; Lázaro-Diéguez, Francisco; Egea, Gustavo

    2011-08-12

    The lipid metabolite diacylglycerol (DAG) is required for transport carrier biogenesis at the Golgi, although how cells regulate its levels is not well understood. Phospholipid synthesis involves highly regulated pathways that consume DAG and can contribute to its regulation. Here we altered phosphatidylcholine (PC) and phosphatidylinositol synthesis for a short period of time in CHO cells to evaluate the changes in DAG and its effects in membrane trafficking at the Golgi. We found that cellular DAG rapidly increased when PC synthesis was inhibited at the non-permissive temperature for the rate-limiting step of PC synthesis in CHO-MT58 cells. DAG also increased when choline and inositol were not supplied. The major phospholipid classes and triacylglycerol remained unaltered for both experimental approaches. The analysis of Golgi ultrastructure and membrane trafficking showed that 1) the accumulation of the budding vesicular profiles induced by propanolol was prevented by inhibition of PC synthesis, 2) the density of KDEL receptor-containing punctated structures at the endoplasmic reticulum-Golgi interface correlated with the amount of DAG, and 3) the post-Golgi transport of the yellow fluorescent temperature-sensitive G protein of stomatitis virus and the secretion of a secretory form of HRP were both reduced when DAG was lowered. We confirmed that DAG-consuming reactions of lipid synthesis were present in Golgi-enriched fractions. We conclude that phospholipid synthesis pathways play a significant role to regulate the DAG required in Golgi-dependent membrane trafficking.

  4. Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma

    DEFF Research Database (Denmark)

    Ask, Kristine Skoglund; Bardakci, Turgay; Parmer, Marthe Petrine

    2016-01-01

    Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic...... solvent used as supported liquid membranes (SLMs), and into 50μL aqueous acceptor solutions. The acceptor solutions were subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using in-source fragmentation and monitoring the m/z 184→184 transition for investigation...

  5. Perimicrovillar membrane assembly: the fate of phospholipids synthesised by the midgut of Rhodnius prolixus

    Directory of Open Access Journals (Sweden)

    Paula Rego Bittencourt-Cunha

    2013-06-01

    Full Text Available In this study, we describe the fate of fatty acids that are incorporated from the lumen by the posterior midgut epithelium of Rhodnius prolixus and the biosynthesis of lipids. We also demonstrate that neutral lipids (NL are transferred to the haemolymphatic lipophorin (Lp and that phospholipids remain in the tissue in which they are organised into perimicrovillar membranes (PMMs. 3H-palmitic acid added at the luminal side of isolated midguts of R. prolixus females was readily absorbed and was used to synthesise phospholipids (80% and NL (20%. The highest incorporation of 3H-palmitic acid was on the first day after a blood meal. The amounts of diacylglycerol (DG and triacylglycerol synthesised by the tissue decreased in the presence of Lp in the incubation medium. The metabolic fates of 3H-lipids synthesised by the posterior midgut were followed and it was observed that DG was the major lipid released to Lp particles. However, the majority of phospholipids were not transferred to Lp, but remained in the tissue. The phospholipids that were synthesised and accumulated in the posterior midgut were found to be associated with Rhodnius luminal contents as structural components of PMMs.

  6. Composite membrane with integral rim

    Science.gov (United States)

    Routkevitch, Dmitri; Polyakov, Oleg G

    2015-01-27

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  7. Adsorption and binding dynamics of graphene-supported phospholipid membranes using the QCM-D technique.

    Science.gov (United States)

    Meléndrez, D; Jowitt, T; Iliut, M; Verre, A F; Goodwin, S; Vijayaraghavan, A

    2018-02-01

    We report on the adsorption dynamics of phospholipid membranes on graphene-coated substrates using the quartz crystal microbalance with dissipation monitoring (QCM-D) technique. We compare the lipid vesicle interaction and membrane formation on gold and silicon dioxide QCM crystal surfaces with their graphene oxide (GO) and reduced (r)GO coated counterparts, and report on the different lipid structures obtained. We establish graphene derivative coatings as support surfaces with tuneable hydrophobicity for the formation of controllable lipid structures. One structure of interest formed is lipid monolayer membranes which were formed on rGO, which are otherwise challenging to produce. We also demonstrate and monitor biotin-avidin binding on such a membrane, which will then serve as a platform for a wide range of biosensing applications. The QCM-D technique could be extended to both fundamental studies and applications of other covalent and non-covalent interactions in 2-dimensional materials.

  8. Parallel artificial liquid membrane extraction as an efficient tool for removal of phospholipids from human plasma.

    Science.gov (United States)

    Ask, Kristine Skoglund; Bardakci, Turgay; Parmer, Marthe Petrine; Halvorsen, Trine Grønhaug; Øiestad, Elisabeth Leere; Pedersen-Bjergaard, Stig; Gjelstad, Astrid

    2016-09-10

    Generic Parallel Artificial Liquid Membrane Extraction (PALME) methods for non-polar basic and non-polar acidic drugs from human plasma were investigated with respect to phospholipid removal. In both cases, extractions in 96-well format were performed from plasma (125μL), through 4μL organic solvent used as supported liquid membranes (SLMs), and into 50μL aqueous acceptor solutions. The acceptor solutions were subsequently analysed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using in-source fragmentation and monitoring the m/z 184→184 transition for investigation of phosphatidylcholines (PC), sphingomyelins (SM), and lysophosphatidylcholines (Lyso-PC). In both generic methods, no phospholipids were detected in the acceptor solutions. Thus, PALME appeared to be highly efficient for phospholipid removal. To further support this, qualitative (post-column infusion) and quantitative matrix effects were investigated with fluoxetine, fluvoxamine, and quetiapine as model analytes. No signs of matrix effects were observed. Finally, PALME was evaluated for the aforementioned drug substances, and data were in accordance with European Medicines Agency (EMA) guidelines. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Regulation of biliary cholesterol secretion is independent of hepatocyte canalicular membrane lipid composition: a study in the diosgenin-fed rat model

    NARCIS (Netherlands)

    Nibbering, C. P.; Groen, A. K.; Ottenhoff, R.; Brouwers, J. F.; vanBerge-Henegouwen, G. P.; van Erpecum, K. J.

    2001-01-01

    Phosphatidylcholine (PC) and sphingomyelin (SM) are the major phospholipids on the outer leaflet of the hepatocyte canalicular membrane. Since cholesterol preferentially associates with SM in detergent-resistant microdomains, we hypothesized that canalicular membrane lipid composition could modulate

  10. Proceedings of the users meeting on structure and phase transition of phospholipid membrane

    Energy Technology Data Exchange (ETDEWEB)

    Hatta, Ichiro [Nagoya Univ. (Japan). School of Engineering; Amemiya, Yoshiyuki [eds.

    1994-06-01

    On the occasion that the persons of three groups that have carried out the research on the structure and the phase transition of phospholipid membranes have carried out the experiment successively, the users meeting was held on November 1, 1993 at National Laboratory for High Energy Physics. Lectures were given on the L{sub {beta}I} structure of DPPC/alcohol system, the self gathering and intermolecular cooperation phenomenon of glycero phospholipid, the phase transition of DEPE/water system, the structure of DMPA/polylysine, the development of X-ray television, the ripple structure of DMPC/cholesterol system and the simultaneous measurement of X-ray diffraction/DSC. To have the chance like this is very meaningful because sufficient discussion can be done among usually busy researchers at the synchrotron radiation experiment facility. (K.I.).

  11. Effect of artificial and natural phospholipid membranes on rate of sperm whale oxymyoglobin autooxidation.

    Science.gov (United States)

    Postnikova, G B; Shekhovtsova, E A

    2013-03-01

    We were the first to show that MbO2 deoxygenation in the cell occurs only upon interaction of myoglobin with mitochondrial membrane, which must be accompanied by changes in the heme cavity conformation of the protein and its affinity for the ligand. Under aerobic conditions, some changes in the equilibrium O2 dissociation constant (Kdis) can be detected by changes of the rate of MbO2 autooxidation, i.e. spontaneous turning it into metMb (kox), as far as a direct correlation between Kdis and kox is experimentally shown. In this work, we studied the effect on MbO2 autooxidation rate of phospholipid liposomes from neutral soybean phosphatidylcholine (lecithin) and from negatively charged 1-palmitoyl-2-oleylphosphatidylglycerol (POPG) at various phospholipid/MbO2 ratios from 25 : 1 to 100 : 1, and also the effect of rat liver mitochondria at concentration of 1 and 2 mg/ml mitochondrial protein (at 22 and 37°C). In all cases, kox was found to increase due to interaction of the protein with phospholipid membranes. The effect of negatively charged liposomes from POPG on kox is significantly greater than that of neutral lecithin liposomes. At the POPG/MbO2 molar ratio of 25 : 1, MbO2 autooxidation rate is almost 25-fold increased compared to the control, whereas in the presence of 50-fold molar excess of lecithin, kox is only ~10 times higher (10 mM buffer, pH 7.2, 22°C). With the same phospholipid/MbO2 ratio of 100 : 1, kox is 7 times higher for the POPG than for lecithin liposomes. In the presence of mitochondria inhibited by antimycin A, kox grows proportionally to their concentration (about 10-fold per 1 mg/ml of mitochondrial protein), and practically does not change after adding superoxide dismutase in the reaction mixture. The kox value decreases markedly at high ionic strength, thus suggesting an important role of coulombic electrostatics in the myoglobin-mitochondrial interaction. The increase in the autooxidation rate of MbO2 (and hence its Kdis) due to the

  12. Cell membrane-inspired phospholipid polymers for developing medical devices with excellent biointerfaces

    Directory of Open Access Journals (Sweden)

    Yasuhiko Iwasaki

    2012-01-01

    Full Text Available This review article describes fundamental aspects of cell membrane-inspired phospholipid polymers and their usefulness in the development of medical devices. Since the early 1990s, polymers composed of 2-methacryloyloxyethyl phosphorylcholine (MPC units have been considered in the preparation of biomaterials. MPC polymers can provide an artificial cell membrane structure at the surface and serve as excellent biointerfaces between artificial and biological systems. They have also been applied in the surface modification of some medical devices including long-term implantable artificial organs. An MPC polymer biointerface can suppress unfavorable biological reactions such as protein adsorption and cell adhesion – in other words, specific biomolecules immobilized on an MPC polymer surface retain their original functions. MPC polymers are also being increasingly used for creating biointerfaces with artificial cell membrane structures.

  13. A Conserved Endoplasmic Reticulum Membrane Protein Complex (EMC) Facilitates Phospholipid Transfer from the ER to Mitochondria

    Science.gov (United States)

    Tavassoli, Shabnam; Wong, Andrew K. O.; Choudhary, Vineet; Young, Barry P.; Loewen, Christopher J. R.; Prinz, William A.

    2014-01-01

    Mitochondrial membrane biogenesis and lipid metabolism require phospholipid transfer from the endoplasmic reticulum (ER) to mitochondria. Transfer is thought to occur at regions of close contact of these organelles and to be nonvesicular, but the mechanism is not known. Here we used a novel genetic screen in S. cerevisiae to identify mutants with defects in lipid exchange between the ER and mitochondria. We show that a strain missing multiple components of the conserved ER membrane protein complex (EMC) has decreased phosphatidylserine (PS) transfer from the ER to mitochondria. Mitochondria from this strain have significantly reduced levels of PS and its derivative phosphatidylethanolamine (PE). Cells lacking EMC proteins and the ER–mitochondria tethering complex called ERMES (the ER–mitochondria encounter structure) are inviable, suggesting that the EMC also functions as a tether. These defects are corrected by expression of an engineered ER–mitochondrial tethering protein that artificially tethers the ER to mitochondria. EMC mutants have a significant reduction in the amount of ER tethered to mitochondria even though ERMES remained intact in these mutants, suggesting that the EMC performs an additional tethering function to ERMES. We find that all Emc proteins interact with the mitochondrial translocase of the outer membrane (TOM) complex protein Tom5 and this interaction is important for PS transfer and cell growth, suggesting that the EMC forms a tether by associating with the TOM complex. Together, our findings support that the EMC tethers ER to mitochondria, which is required for phospholipid synthesis and cell growth. PMID:25313861

  14. Membrane phospholipid augments cytochrome P4501a enzymatic activity by modulating structural conformation during detoxification of xenobiotics.

    Directory of Open Access Journals (Sweden)

    Manik C Ghosh

    Full Text Available Cytochrome P450 is a superfamily of membrane-bound hemoprotein that gets involved with the degradation of xenobiotics and internal metabolites. Accumulated body of evidence indicates that phospholipids play a crucial role in determining the enzymatic activity of cytochrome P450 in the microenvironment by modulating its structure during detoxification; however, the structure-function relationship of cytochrome P4501A, a family of enzymes responsible for degrading lipophilic aromatic hydrocarbons, is still not well defined. Inducibility of cytochrome P4501A in cultured catfish hepatocytes in response to carbofuran, a widely used pesticide around the world, was studied earlier in our laboratory. In this present investigation, we observed that treating catfish with carbofuran augmented total phospholipid in the liver. We examined the role of phospholipid on the of cytochrome P4501A-marker enzyme which is known as ethoxyresorufin-O-deethylase (EROD in the context of structure and function. We purified the carbofuran-induced cytochrome P4501A protein from catfish liver. Subsequently, we examined the enzymatic activity of purified P4501A protein in the presence of phospholipid, and studied how the structure of purified protein was influenced in the phospholipid environment. Membrane phospholipid appeared to accelerate the enzymatic activity of EROD by changing its structural conformation and thus controlling the detoxification of xenobiotics. Our study revealed the missing link of how the cytochrome P450 restores its enzymatic activity by changing its structural conformation in the phospholipid microenvironment.

  15. Temperature Dependence of Triplet–Triplet Annihilation Upconversion in Phospholipid Membranes

    Science.gov (United States)

    2017-01-01

    Understanding the temperature dependency of triplet–triplet annihilation upconversion (TTA-UC) is important for optimizing biological applications of upconversion. Here the temperature dependency of red-to-blue TTA-UC is reported in a variety of neutral PEGylated phospholipid liposomes. In these systems a delicate balance between lateral diffusion rate of the dyes, annihilator aggregation, and sensitizer self-quenching leads to a volcano plot, with the maximum upconversion intensity occurring near the main order–disorder transition temperature of the lipid membrane. PMID:28059523

  16. Association between Erythrocyte Membrane Phospholipid Fatty Acids and Sleep Disturbance in Chinese Children and Adolescents.

    Science.gov (United States)

    Tang, Jun; Yan, Yinkun; Zheng, Ju-Sheng; Mi, Jie; Li, Duo

    2018-03-12

    The relationship between circulating fatty acid (FA) composition and childhood sleep disturbance remains largely unclear. We aimed to investigate the association of erythrocyte membrane FA composition with prevalence of sleep disturbance in Chinese children and adolescents. A cross-sectional survey was conducted among 2337 school-aged children and adolescents who completed a clinical assessment in Beijing, China. Presence of sleep disturbance was self-reported or parent-reported by questionnaires. Erythrocyte FAs were measured by gas chromatography, and desaturase activities were estimated by FA ratios. Multivariable-adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for sleep disturbance across FA quartiles were calculated by a logistical regression model. We found higher proportions of erythrocyte phospholipid 24:0, 24:1n-9, and lower proportions of total n-3 polyunsaturated FA (PUFA), 22:5n-3 and 22:6n-3 in participants with sleep disturbance compared with those without. In the logistical regression models, significant inverse associations were found for total n-3 PUFA, 22:5n-3 and 22:6n-3, the highest versus lowest quartile ORs and 95% CIs were 0.57 (0.40, 0.82), 0.67 (0.47, 0.97) and 0.69 (0.49, 0.96), respectively. For per 1 SD difference of proportion, OR and 95% CI of prevalence of sleep disturbance was 0.91 (0.86, 0.97) for total n-3 PUFA, 0.90 (0.82, 0.98) for 22:5n-3, and 0.92 (0.86, 0.99) for 22:6n-3, respectively. No significant association was found for saturated fatty acids, monounsaturated fatty acids, n-6 polyunsaturated fatty acids or FA ratios. The present study suggested that erythrocyte n-3 PUFAs, especially 22:5n-3 and 22:6n-3, are inversely associated with prevalence of sleep disturbance in Chinese children and adolescents.

  17. Layered plasma polymer composite membranes

    Science.gov (United States)

    Babcock, Walter C.

    1994-01-01

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is .gtoreq.2 and is the number of selective layers.

  18. Nanoscale investigation of the interaction of colistin with model phospholipid membranes by Langmuir technique, and combined infrared and force spectroscopies.

    Science.gov (United States)

    Freudenthal, Oona; Quilès, Fabienne; Francius, Grégory; Wojszko, Kamila; Gorczyca, Marcelina; Korchowiec, Beata; Rogalska, Ewa

    2016-11-01

    Colistin (Polymyxin E), an antimicrobial peptide, is increasingly put forward as salvage for severe multidrug-resistant infections. Unfortunately, colistin is potentially toxic to mammalian cells. A better understanding of the interaction with specific components of the cell membranes may be helpful in controlling the factors that may enhance toxicity. Here, we report a physico-chemical study of model phospholipid (PL) mono- and bilayers exposed to colistin at different concentrations by Langmuir technique, atomic force microscopy (AFM) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). The effect of colistin on chosen PL monolayers was examined. Insights into the topographical and elastic changes in the PL bilayers within time after peptide injection are presented via AFM imaging and force spectra. Finally, changes in the PL bilayers' ATR-FTIR spectra as a function of time within three bilayer compositions, and the influence of colistin on their spectral fingerprint are examined together with the time-evolution of the Amide II and νCO band integrated intensity ratios. Our study reveals a great importance in the role of the PL composition as well as the peptide concentration on the action of colistin on PL model membranes. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Membrane potential of cells and its regulation during aging. 1. Report: the role of energetic metabolism and plasma membrane phospholipid contents.

    Science.gov (United States)

    Frolkis, V V; Tanin, S A; Gorban, E N; Bogatskaya, L N; Sabko, V E

    1987-01-01

    Age-dependent changes in the polarization of the plasma membranes (PM) of various cell types and the mechanisms responsible for its regulation were studied in the experiments on the adult (6-8 months) and old (28-32 months) Wistar male rats. The relationship was found between the specificity of cellular function and the pattern of changes in resting potential (RP) and action potential (AP). In senility, changes occur in the ratio of different pathways of energy provision of the ionic transport: the contribution made by enzymic reactions to the mechanism of maintenance of the PM polarization level is diminished. Changes in the PM phospholipid composition influences considerably the character of the PM electric reactions in aging. An anti-oxidant, dibunol (butilated hydroxytoluene, BHT) has appeared to restore many reactions of the cellular PM in the old animals.

  20. Variation of the Detergent-Binding Capacity and Phospholipid Content of Membrane Proteins When Purified in Different Detergents

    Science.gov (United States)

    Ilgü, Hüseyin; Jeckelmann, Jean-Marc; Gachet, María Salomé; Boggavarapu, Rajendra; Ucurum, Zöhre; Gertsch, Jürg; Fotiadis, Dimitrios

    2014-01-01

    Purified membrane proteins are ternary complexes consisting of protein, lipid, and detergent. Information about the amounts of detergent and endogenous phospholipid molecules bound to purified membrane proteins is largely lacking. In this systematic study, three model membrane proteins of different oligomeric states were purified in nine different detergents at commonly used concentrations and characterized biochemically and biophysically. Detergent-binding capacities and phospholipid contents of the model proteins were determined and compared. The insights on ternary complexes obtained from the experimental results, when put into a general context, are summarized as follows. 1), The amount of detergent and 2) the amount of endogenous phospholipids bound to purified membrane proteins are dependent on the size of the hydrophobic lipid-accessible protein surface areas and the physicochemical properties of the detergents used. 3), The size of the detergent and lipid belt surrounding the hydrophobic lipid-accessible surface of purified membrane proteins can be tuned by the appropriate choice of detergent. 4), The detergents n-nonyl-β-D-glucopyranoside and Cymal-5 have exceptional delipidating effects on ternary complexes. 5), The types of endogenous phospholipids bound to membrane proteins can vary depending on the detergent used for solubilization and purification. 6), Furthermore, we demonstrate that size-exclusion chromatography can be a suitable method for estimating the molecular mass of ternary complexes. The findings presented suggest a strategy to control and tune the numbers of detergent and endogenous phospholipid molecules bound to membrane proteins. These two parameters are potentially important for the successul crystallization of membrane proteins for structure determination by crystallographic approaches. PMID:24739165

  1. Variation of the detergent-binding capacity and phospholipid content of membrane proteins when purified in different detergents.

    Science.gov (United States)

    Ilgü, Hüseyin; Jeckelmann, Jean-Marc; Gachet, María Salomé; Boggavarapu, Rajendra; Ucurum, Zöhre; Gertsch, Jürg; Fotiadis, Dimitrios

    2014-04-15

    Purified membrane proteins are ternary complexes consisting of protein, lipid, and detergent. Information about the amounts of detergent and endogenous phospholipid molecules bound to purified membrane proteins is largely lacking. In this systematic study, three model membrane proteins of different oligomeric states were purified in nine different detergents at commonly used concentrations and characterized biochemically and biophysically. Detergent-binding capacities and phospholipid contents of the model proteins were determined and compared. The insights on ternary complexes obtained from the experimental results, when put into a general context, are summarized as follows. 1), The amount of detergent and 2) the amount of endogenous phospholipids bound to purified membrane proteins are dependent on the size of the hydrophobic lipid-accessible protein surface areas and the physicochemical properties of the detergents used. 3), The size of the detergent and lipid belt surrounding the hydrophobic lipid-accessible surface of purified membrane proteins can be tuned by the appropriate choice of detergent. 4), The detergents n-nonyl-β-D-glucopyranoside and Cymal-5 have exceptional delipidating effects on ternary complexes. 5), The types of endogenous phospholipids bound to membrane proteins can vary depending on the detergent used for solubilization and purification. 6), Furthermore, we demonstrate that size-exclusion chromatography can be a suitable method for estimating the molecular mass of ternary complexes. The findings presented suggest a strategy to control and tune the numbers of detergent and endogenous phospholipid molecules bound to membrane proteins. These two parameters are potentially important for the successul crystallization of membrane proteins for structure determination by crystallographic approaches. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  2. Fatty acid composition of total lipids and phospholipids of muscular tissue and brain of rats under the impact of vibration

    Directory of Open Access Journals (Sweden)

    N. M. Kostyshyn

    2016-06-01

    Full Text Available Fatty acids are important structural components of biological membranes, energy substrate of cells involved in fixing phospholipid bilayer proteins, and acting as regulators and modulators of enzymatic activity. Under the impact of vibration oscillations there can occur shifts in the ratio of different groups of fatty acids, and degrees of their saturation may change. The imbalance between saturated, monounsaturated and polyunsaturated fatty acids, which occurs later in the cell wall, disrupts fluidity and viscosity of lipid phase and causes abnormal cellular metabolism. Aim. In order to study the impact of vibration on the level of fatty acids of total lipids in muscular tissue and fatty acid composition of phospholipids in muscles and brain, experimental animals have been exposed to vertical vibration oscillations with different frequency for 28 days. Methods and results. Tissues fragments of hip quadriceps and brain of rats were used for obtaining methyl esters of fatty acids studied by the method of gas-liquid chromatography. It was found that the lipid content, ratio of its separate factions and fatty acid composition in muscular tissue and brain of animals with the action of vibration considerably varies. With the increase of vibration acceleration tendency to increase in absolute quantity of total lipids fatty acids can be observed at the account of increased level of saturated and monounsaturated ones. These processes are caused by activation of self-defense mechanisms of the body under the conditions of deviations from stabilized physiological norm, since adaptation requires certain structural and energy costs. Increase in the relative quantity of saturated and monounsaturated fatty acids in phospholipids of muscles and brain and simultaneous reduction in concentration of polyunsaturated fatty acids are observed. Conclusion. These changes indicate worsening of structural and functional organization of muscles and brain cell membranes of

  3. Composition and metabolism of phospholipids of Fasciola hepatica, the common liver fluk

    NARCIS (Netherlands)

    Oldenborg, V.; Vugt, F. van; Golde, L.M.G. van

    1. 1. The phospholipid composition of Fasciola hepatica, the common liver fluke, was compared to that of the liver of the host animals (rats and cattle). Considerable differences were found: monoacyl-sn-glycero-3-phosphorylcholine, hardly detectable in the liver, was found in significant amounts in

  4. Alterations in lipid composition and fluidity of liver plasma membranes in copper-deficient rats

    Energy Technology Data Exchange (ETDEWEB)

    Lei, K.Y.; Rosenstein, F.; Shi, F.; Hassel, C.A.; Carr, T.P.; Zhang, J. (Univ. of Arizona, Tucson (USA))

    1988-07-01

    In view of the importance of membrane fluidity on cell functions, the influence of phospholipid acyl groups on membrane fluidity, and the changes in lipid metabolism induced by copper (Cu) deficiency, this study was designed to examine the influence of dietary Cu on the lipid composition and fluidity of liver plasma membranes. Male Sprague-Dawley rats were divided into two dietary treatments, namely Cu deficient and Cu adequate. After 8 weeks of treatment, liver plasma membranes were isolated by sucrose density gradient centrifugation. The lipid fluidity of plasma membranes, as assessed by the intramolecular eximer fluorescence of 1,3-di(1-pyrenyl) propane, was significantly depressed by Cu deficiency. In addition, Cu deficiency significantly reduced the content of arachidonic and palmitoleic acids but increased the docosatetraenoic acids of membrane phospholipids. This alteration in unsaturated phospholipid fatty acid composition, especially the large reduction in arachidonic acid, may have contributed to the depressed membrane fluidity. Furthermore, Cu deficiency also markedly altered the fatty acid composition of the triacylglycerols associated with the plasma membranes. Thus, the lipid composition and fluidity of liver plasma membranes are responsive to the animal's Cu status.

  5. Nano silver entrapped in phospholipids membrane: synthesis, characteristics and antibacterial kinetics.

    Science.gov (United States)

    Barani, Hossein; Montazer, Majid; Samadi, Nasrin; Toliyat, Tayebeh

    2011-05-01

    The antimicrobial property of stabilized silver nanoparticles (AgNPs) with phospholipid membrane was investigated on both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacterial strains. The influence of phospholipid concentrations on antibacterial kinetics actions of AgNPs was studied with two different methodologies in order to understand the bactericidal and bacteriostatic effects. The bacterial inactivation of synthesized AgNPs fitted well to the Chick-Watson model with a high regression coefficient, R(2) > 0.91. The antibacterial properties of AgNPs depend on the particle size, stabilizer and lecithin concentrations. Only the stabilized AgNPs that have the K(lec/Ag) values of 1 and 2 presented the inhabitation zone, while unstabilized AgNPs agglomerated quickly, settled on the wells and did not diffuse in agar. In addition, the specific coefficient of lethality depends on the lecithin concentration. An increase in lecithin concentration caused multilayer creation on the AgNPs' surface and reduced the release of AgNPs which led to low bacterial killing rate.

  6. Higher sterol content regulated by CYP51 with concomitant lower phospholipid content in membranes is a common strategy for aluminium tolerance in several plant species.

    Science.gov (United States)

    Wagatsuma, Tadao; Khan, Md Shahadat Hossain; Watanabe, Toshihiro; Maejima, Eriko; Sekimoto, Hitoshi; Yokota, Takao; Nakano, Takeshi; Toyomasu, Tomonobu; Tawaraya, Keitaro; Koyama, Hiroyuki; Uemura, Matsuo; Ishikawa, Satoru; Ikka, Takashi; Ishikawa, Akifumi; Kawamura, Takeshi; Murakami, Satoshi; Ueki, Nozomi; Umetsu, Asami; Kannari, Takayuki

    2015-02-01

    Several studies have shown that differences in lipid composition and in the lipid biosynthetic pathway affect the aluminium (Al) tolerance of plants, but little is known about the molecular mechanisms underlying these differences. Phospholipids create a negative charge at the surface of the plasma membrane and enhance Al sensitivity as a result of the accumulation of positively charged Al(3+) ions. The phospholipids will be balanced by other electrically neutral lipids, such as sterols. In the present research, Al tolerance was compared among pea (Pisum sativum) genotypes. Compared with Al-tolerant genotypes, the Al-sensitive genotype accumulated more Al in the root tip, had a less intact plasma membrane, and showed a lower expression level of PsCYP51, which encodes obtusifoliol-14α-demethylase (OBT 14DM), a key sterol biosynthetic enzyme. The ratio of phospholipids to sterols was higher in the sensitive genotype than in the tolerant genotypes, suggesting that the sterol biosynthetic pathway plays an important role in Al tolerance. Consistent with this idea, a transgenic Arabidopsis thaliana line with knocked-down AtCYP51 expression showed an Al-sensitive phenotype. Uniconazole-P, an inhibitor of OBT 14DM, suppressed the Al tolerance of Al-tolerant genotypes of maize (Zea mays), sorghum (Sorghum bicolor), rice (Oryza sativa), wheat (Triticum aestivum), and triticale (×Triticosecale Wittmark cv. Currency). These results suggest that increased sterol content, regulated by CYP51, with concomitant lower phospholipid content in the root tip, results in lower negativity of the plasma membrane. This appears to be a common strategy for Al tolerance among several plant species. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  7. Co-existence of Gel and Fluid Lipid Domains in Single-component Phospholipid Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Armstrong, Clare L [McMaster University; Barrett, M [McMaster University; Toppozini, L [McMaster University; Yamani, Zahra [Canadian Neutron Beam Centre, National Research Council, Chalk River Laboratorie; Kucerka, Norbert [Canadian Neutron Beam Centre and Comelius University (Slovakia); Katsaras, John [ORNL; Fragneto, Giovanna [Institut Laue-Langevin (ILL); Rheinstadter, Maikel C [McMaster University

    2012-01-01

    Lateral nanostructures in membranes, so-called rafts, are believed to strongly influence membrane properties and functions. The experimental observation of rafts has proven difficult as they are thought to be dynamic structures that likely fluctuate on nano- to microsecond time scales. Using neutron diffraction we present direct experimental evidence for the co-existence of gel and fluid lipid domains in a single-component phospholipid membrane made of DPPC as it undergoes its main phase transition. The coherence length of the neutron beam sets a lower limit for the size of structures that can be observed. Neutron coherence lengths between 30 and 242A used in this study were obtained by varying the incident neutron energy and the resolution of the neutron spectrometer. We observe Bragg peaks corresponding to co-existing nanometer sized structures, both in out-of-plane and in-plane scans, by tuning the neutron coherence length. During the main phase transition, instead of a continuous transition that shows a pseudo-critical behavior, we observe the co-existence of gel and fluid domains.

  8. Binding of the radioprotective agent cysteamine with the phospholipidic membrane headgroup-interface region

    Energy Technology Data Exchange (ETDEWEB)

    Berleur, F.; Roman, V.; Jaskierowicz, D.; Fatome, M.; Leterrier, F.; Ter-Minassian-Saraga, L.; Madelmont, G.

    1985-09-01

    The interaction of the aminothiol radioprotector cysteamine (..beta..-mercaptoethylamine)(CYST) with dipalmitoylphosphatidylcholine (DPPC) artificial membranes has been studied by differential scanning calorimetry (DSC), turbidimetry and spin labeling. This hydrophilic molecule displays a biphasic, concentration-dependent binding to the phospholipidic head groups at neutral pH. In the CYST/DPPC molar ratio 1:160-1:2 (mole/mole) an increasing ordering effect is observed. At high concentrations (over 3:1 ratio), this ordering effect decreases. With the symmetric disulfide dimer cystamine, the biphasic effect is not shown and the membrane rigidity decrease is obtained only at concentration ratio higher than 1:1. The charge repartition of the cysteamine molecule has been shown to be disymmetric, +0.52 e on the NH/sub 3/ group and +0.19 e on the SH extremity, whereas the cystamine molecule is electrostatically symmetrical. These properties could be related to their membrane effects. With cysteamine, at a low concentration, an electrostatic bridging between the negatively charged phosphate groups of the polar heads induces the increase in membrane stability: the molecules behave like a divalent cation. At high concentration a displacement of the slightly charged SH extremity by the amine disrupts the bridges and induces the decrease in rigidity: the drug behaves like a monovalent cation. Due to its symmetric charge and its double length, such an effect is not observed with cystamine. This study could bring further information about the interactions between cysteamine and polyelectrolytic structures (ADN for example) and about the radioprotective properties of this drug.

  9. Binding of monovalent alkali metal ions with negatively charged phospholipid membranes.

    Science.gov (United States)

    Maity, Pabitra; Saha, Baishakhi; Kumar, Gopinatha Suresh; Karmakar, Sanat

    2016-04-01

    We have systematically investigated the effect of various alkali metal ions with negatively charged phospholipid membranes. Size distributions of large unilamellar vesicles have been confirmed using dynamic light scattering. Zeta potential and effective charges per vesicle in the presence of various alkali metal ions have been estimated from the measured electrophoretic mobility. We have determined the intrinsic binding constant from the zeta potential using electrostatic double layer theory. The reasonable and consistent value of the intrinsic binding constant of Na(+), found at moderate NaCl concentration (10-100 mM), indicates that the Gouy-Chapman theory cannot be applied for very high (> 100mM) and very low (concentrations. The isothermal titration calorimetry study has revealed that the net binding heat of interaction of the negatively charged vesicles with monovalent alkali metal ions is small and comparable to those obtained from neutral phosphatidylcholine vesicles. The overall endothermic response of binding heat suggests that interaction is primarily entropy driven. The entropy gain might arise due to the release of water molecules from the hydration layer vicinity of the membranes. Therefore, the partition model which does not include the electrostatic contribution suffices to describe the interaction. The binding constant of Na(+) (2.4 ± 0.1 M(-1)), obtained from the ITC, is in agreement with that estimated from the zeta potential (-2.0 M(-1)) at moderate salt concentrations. Our results suggest that hydration dynamics may play a vital role in the membrane solution interface which strongly affects the ion-membrane interaction. Copyright © 2016 Elsevier B.V. All rights reserved

  10. Improvement of pharmacokinetic and antitumor activity of layered double hydroxide nanoparticles by coating with PEGylated phospholipid membrane.

    Science.gov (United States)

    Yan, Mina; Zhang, Zhaoguo; Cui, Shengmiao; Lei, Ming; Zeng, Ke; Liao, Yunhui; Chu, Weijing; Deng, Yihui; Zhao, Chunshun

    2014-01-01

    Layered double hydroxide (LDH) has attracted considerable attention as a drug carrier. However, because of its poor in vivo behavior, polyethylene glycolylated (PEGylated) phospholipid must be used as a coformer to produce self-assembled core-shell nanoparticles. In the present study, we prepared a PEGylated phospholipid-coated LDH (PLDH) (PEG-PLDH) delivery system. The PEG-PLDH nanoparticles had an average size of 133.2 nm. Their core-shell structure was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy. In vitro liposome-cell-association and cytotoxicity experiments demonstrated its ability to be internalized by cells. In vivo studies showed that PEGylated phospholipid membranes greatly reduced the blood clearance rate of LDH nanoparticles. PEG-PLDH nanoparticles demonstrated a good control of tumor growth and increased the survival rate of mice. These results suggest that PEG-PLDH nanoparticles can be a useful drug delivery system for cancer therapy.

  11. Polyunsaturated Fatty Acid Composition of Maternal Diet and Erythrocyte Phospholipid Status in Chilean Pregnant Women

    Directory of Open Access Journals (Sweden)

    Karla A. Bascuñán

    2014-11-01

    Full Text Available Chilean diets are characterized by a low supply of n-3 polyunsaturated fatty acids (n-3 PUFA, which are critical nutrients during pregnancy and lactation, because of their role in brain and visual development. DHA is the most relevant n-3 PUFA in this period. We evaluated the dietary n-3 PUFA intake and erythrocyte phospholipids n-3 PUFA in Chilean pregnant women. Eighty healthy pregnant women (20–36 years old in the 3rd–6th month of pregnancy were included in the study. Dietary assessment was done applying a food frequency questionnaire, and data were analyzed through the Food Processor SQL® software. Fatty acids of erythrocyte phospholipids were assessed by gas-liquid chromatography. Diet composition was high in saturated fat, low in mono- and PUFA, high in n-6 PUFA (linoleic acid and low in n-3 PUFA (alpha-linolenic acid and DHA, with imbalance in the n-6/n-3 PUFA ratio. Similar results were observed for fatty acids from erythrocyte phospholipids. The sample of Chilean pregnant women showed high consumption of saturated fat and low consumption of n-3 PUFA, which is reflected in the low DHA content of erythrocyte phospholipids. Imbalance between n-6/n-3 PUFA could negatively affect fetal development. New strategies are necessary to improve n-3 PUFA intake throughout pregnancy and breast feeding periods. Furthermore, it is necessary to develop dietary interventions to improve the quality of consumed foods with particular emphasis on n-3 PUFA.

  12. Polyunsaturated fatty acid composition of maternal diet and erythrocyte phospholipid status in Chilean pregnant women.

    Science.gov (United States)

    Bascuñán, Karla A; Valenzuela, Rodrigo; Chamorro, Rodrigo; Valencia, Alejandra; Barrera, Cynthia; Puigrredon, Claudia; Sandoval, Jorge; Valenzuela, Alfonso

    2014-11-07

    Chilean diets are characterized by a low supply of n-3 polyunsaturated fatty acids (n-3 PUFA), which are critical nutrients during pregnancy and lactation, because of their role in brain and visual development. DHA is the most relevant n-3 PUFA in this period. We evaluated the dietary n-3 PUFA intake and erythrocyte phospholipids n-3 PUFA in Chilean pregnant women. Eighty healthy pregnant women (20-36 years old) in the 3rd-6th month of pregnancy were included in the study. Dietary assessment was done applying a food frequency questionnaire, and data were analyzed through the Food Processor SQL® software. Fatty acids of erythrocyte phospholipids were assessed by gas-liquid chromatography. Diet composition was high in saturated fat, low in mono- and PUFA, high in n-6 PUFA (linoleic acid) and low in n-3 PUFA (alpha-linolenic acid and DHA), with imbalance in the n-6/n-3 PUFA ratio. Similar results were observed for fatty acids from erythrocyte phospholipids. The sample of Chilean pregnant women showed high consumption of saturated fat and low consumption of n-3 PUFA, which is reflected in the low DHA content of erythrocyte phospholipids. Imbalance between n-6/n-3 PUFA could negatively affect fetal development. New strategies are necessary to improve n-3 PUFA intake throughout pregnancy and breast feeding periods. Furthermore, it is necessary to develop dietary interventions to improve the quality of consumed foods with particular emphasis on n-3 PUFA.

  13. Kinase Associated-1 Domains Drive MARK/PAR1 Kinases to Membrane Targets by Binding Acidic Phospholipids

    Energy Technology Data Exchange (ETDEWEB)

    Moravcevic, Katarina; Mendrola, Jeannine M.; Schmitz, Karl R.; Wang, Yu-Hsiu; Slochower, David; Janmey, Paul A.; Lemmon, Mark A. (UPENN-MED)

    2011-09-28

    Phospholipid-binding modules such as PH, C1, and C2 domains play crucial roles in location-dependent regulation of many protein kinases. Here, we identify the KA1 domain (kinase associated-1 domain), found at the C terminus of yeast septin-associated kinases (Kcc4p, Gin4p, and Hsl1p) and human MARK/PAR1 kinases, as a membrane association domain that binds acidic phospholipids. Membrane localization of isolated KA1 domains depends on phosphatidylserine. Using X-ray crystallography, we identified a structurally conserved binding site for anionic phospholipids in KA1 domains from Kcc4p and MARK1. Mutating this site impairs membrane association of both KA1 domains and intact proteins and reveals the importance of phosphatidylserine for bud neck localization of yeast Kcc4p. Our data suggest that KA1 domains contribute to coincidence detection, allowing kinases to bind other regulators (such as septins) only at the membrane surface. These findings have important implications for understanding MARK/PAR1 kinases, which are implicated in Alzheimer's disease, cancer, and autism.

  14. Dissipative Particle Dynamics Simulations for Phospholipid Membranes Based on a Four-To-One Coarse-Grained Mapping Scheme.

    Directory of Open Access Journals (Sweden)

    Xiaoxu Li

    Full Text Available In this article, a new set of parameters compatible with the dissipative particle dynamics (DPD force field is developed for phospholipids. The coarse-grained (CG models of these molecules are constructed by mapping four heavy atoms and their attached hydrogen atoms to one bead. The beads are divided into types distinguished by charge type, polarizability, and hydrogen-bonding capacity. First, we derive the relationship between the DPD repulsive force and Flory-Huggins χ-parameters based on this four-to-one CG mapping scheme. Then, we optimize the DPD force parameters for phospholipids. The feasibility of this model is demonstrated by simulating the structural and thermodynamic properties of lipid bilayer membranes, including the membrane thickness, the area per lipid, the lipid tail orientation, the bending rigidity, the rupture behavior, and the potential of mean force for lipid flip-flop.

  15. Relationship between wettability and lubrication characteristics of the surfaces of contacting phospholipid-based membranes.

    Science.gov (United States)

    Pawlak, Zenon; Petelska, Aneta D; Urbaniak, Wieslaw; Yusuf, Kehinde Q; Oloyede, Adekunle

    2013-04-01

    The wettability of the articular surface of cartilage depends on the condition of its surface active phospholipid overlay, which is structured as multi-bilayer. Based on a hypothesis that the surface of cartilage facilitates the almost frictionless lubrication of the joint, we examined the characteristics of this membrane surface entity in both its normal and degenerated conditions using a combination of atomic force microscopy, contact angle measurement, and friction test methods. The observations have led to the conclusions that (1) the acid-base equilibrium condition influences the lubrication effectiveness of the surface of cartilage and (2) the friction coefficient is significantly dependent on the hydrophobicity of the surface of the tissue, thereby confirming the hypothesis tested in this paper. Both wettability angle and interfacial energy were obtained for varying conditions of the cartilage surface both in its wet, dry and lipid-depleted conditions. The interfacial energy also increased with mole fraction of the lipid species reaching an asymptotic value after 0.6. Also, the friction coefficient was found to decrease to an asymptotic level as the wettability angle increased. The result reveal that the interfacial energy increased with pH till pH = 4.0, and then decreased from pH = 4.0 to reach equilibrium at pH = 7.0.

  16. Freezing point depression of water in phospholipid membranes: a solid-state NMR study.

    Science.gov (United States)

    Lee, Dong-Kuk; Kwon, Byung Soo; Ramamoorthy, Ayyalusamy

    2008-12-02

    Lipid-water interaction plays an important role in the properties of lipid bilayers, cryoprotectants, and membrane-associated peptides and proteins. The temperature at which water bound to lipid bilayers freezes is lower than that of free water. Here, we report a solid-state NMR investigation on the freezing point depression of water in phospholipid bilayers in the presence and absence of cholesterol. Deuterium NMR spectra at different temperatures ranging from -75 to + 10 degrees C were obtained from fully (2)H2O-hydrated POPC (1-palmitoyl-2-oleoylphosphatidylcholine) multilamellar vesicles (MLVs), prepared with and without cholesterol, to determine the freezing temperature of water and the effect of cholesterol on the freezing temperature of water in POPC bilayers. Our 2H NMR experiments reveal the motional behavior of unfrozen water molecules in POPC bilayers even at temperatures significantly below 0 degrees C and show that the presence of cholesterol further lowered the freezing temperature of water in POPC bilayers. These results suggest that in the presence of cholesterol the fluidity and dynamics of lipid bilayers can be retained even at very low temperatures as exist in the liquid crystalline phase of the lipid. Therefore, bilayer samples prepared with a cryoprotectant like cholesterol should enable the performance of multidimensional solid-state NMR experiments to investigate the structure, dynamics, and topology of membrane proteins at a very low temperature with enhanced sample stability and possibly a better sensitivity. Phosphorus-31 NMR data suggest that lipid bilayers can be aligned at low temperatures, while 15N NMR experiments demonstrate that such aligned samples can be used to enhance the signal-to-noise ratio of is 15N chemical shift spectra of a 37-residue human antimicrobial peptide, LL-37.

  17. Structure determination of membrane proteins in their native phospholipid bilayer environment by rotationally aligned solid-state NMR spectroscopy.

    Science.gov (United States)

    Opella, Stanley J

    2013-09-17

    One of the most important topics in experimental structural biology is determining the structures of membrane proteins. These structures represent one-third of all of the information expressed from a genome, distinguished by their locations within the phospholipid bilayer of cells, organelles, or enveloped viruses. Their highly hydrophobic nature and insolubility in aqueous media means that they require an amphipathic environment. They have unique functions in transport, catalysis, channel formation, and signaling. Researchers are particularly interested in G-protein coupled receptors (GPCRs) because they modulate many biological processes, and about half of the approximately 800 of these proteins within the human genome are or can be turned into drug receptors that affect a wide range of diseases. Because of experimental difficulties, researchers have studied membrane proteins using a wide variety of artificial media that mimic membranes, such as mixed organic solvents or detergents. More sophisticated mimics include bilayer discs (bicelles) and the lipid cubic phase (LCP), but both of these contain a very large detergent component, which can disrupt the stability and function of membrane proteins. To have confidence in the resulting structures and their biological functions and to avoid disrupting these delicate proteins, the structures of membrane proteins should be determined in their native environment of liquid crystalline phospholipid bilayers under physiological conditions. This Account describes a recently developed general method for determining the structures of unmodified membrane proteins in phospholipid bilayers by solid-state NMR spectroscopy. Because it relies on the natural, rapid rotational diffusion of these proteins about the bilayer normal, this method is referred to as rotationally aligned (RA) solid-state NMR. This technique elaborates on oriented sample (OS) solid-state NMR, its complementary predecessor. These methods exploit the power of

  18. Dynamics of bio-membranes investigated by neutron spin echo: Effects of phospholipid conformations and presence of lidocaine

    Science.gov (United States)

    Yi, Zheng

    Bio-membranes of the natural living cells are made of bilayers of phospholipids molecules embedded with other constituents, such as cholesterol and membrane proteins, which help to accomplish a broad range of functions. Vesicles made of lipid bilayers can serve as good model systems for bio-membranes. Therefore these systems have been extensively characterized and much is known about their shape, size, porosity and functionality. In this dissertation we report the studies of the effects of the phosoholipid conformation, such as hydrocarbon number and presence of double bond in hydrophobic tails on dynamics of phospholipids bilayers studied by neutron spin echo (NSE) technique. We have investigated how lidocaine, the most medically used local anesthetics (LA), influence the structural and dynamical properties of model bio-membranes by small angle neutron scattering (SANS), NSE and differential scanning calorimetry (DSC). To investigate the influence of phospholipid conformation on bio-membranes, the bending elasticities kappac of seven saturated and monounsaturated phospholipid bilayers were investigated by NSE spectroscopy. kappa c of phosphatidylcholines (PCS) in liquid crystalline (L alpha) phase ranges from 0.38x10-19 J for 1,2-Dimyristoyl- sn-Glycero-3-Phosphocholine (14:0 PC) to 0.64x10-19 J for 1,2-Dieicosenoyl-sn-Glycero-3-Phosphocholine (20:1 PC). It was confirmed that when the area modulus KA varies little with chain unsaturation or length, the elastic ratios (kappac/ KA)1/2 of bilayers varies linearly with lipid hydrophobic thickness d. For the study of the influence of LA on bio-membranes, SANS measurements have been performed on 14:0 PC bilayers with different concentrations of lidocaine to determine the bilayer thickness dL as a function of the lidocaine concentration. NSE has been used to study the influence of lidocaine on the bending elasticity of 14:0 PC bilayers in Lalpha and ripple gel (Pbeta') phases. Our results confirmed that the molecules of

  19. Yeast PAH1-encoded phosphatidate phosphatase controls the expression of CHO1-encoded phosphatidylserine synthase for membrane phospholipid synthesis.

    Science.gov (United States)

    Han, Gil-Soo; Carman, George M

    2017-08-11

    The PAH1 -encoded phosphatidate phosphatase (PAP), which catalyzes the committed step for the synthesis of triacylglycerol in Saccharomyces cerevisiae , exerts a negative regulatory effect on the level of phosphatidate used for the de novo synthesis of membrane phospholipids. This raises the question whether PAP thereby affects the expression and activity of enzymes involved in phospholipid synthesis. Here, we examined the PAP-mediated regulation of CHO1 -encoded phosphatidylserine synthase (PSS), which catalyzes the committed step for the synthesis of major phospholipids via the CDP-diacylglycerol pathway. The lack of PAP in the pah1 Δ mutant highly elevated PSS activity, exhibiting a growth-dependent up-regulation from the exponential to the stationary phase of growth. Immunoblot analysis showed that the elevation of PSS activity results from an increase in the level of the enzyme encoded by CHO1 Truncation analysis and site-directed mutagenesis of the CHO1 promoter indicated that Cho1 expression in the pah1 Δ mutant is induced through the inositol-sensitive upstream activation sequence (UAS INO ), a cis -acting element for the phosphatidate-controlled Henry (Ino2-Ino4/Opi1) regulatory circuit. The abrogation of Cho1 induction and PSS activity by a CHO1 UAS INO mutation suppressed pah1 Δ effects on lipid synthesis, nuclear/endoplasmic reticulum membrane morphology, and lipid droplet formation, but not on growth at elevated temperature. Loss of the DGK1 -encoded diacylglycerol kinase, which converts diacylglycerol to phosphatidate, partially suppressed the pah1 Δ-mediated induction of Cho1 and PSS activity. Collectively, these data showed that PAP activity controls the expression of PSS for membrane phospholipid synthesis. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  20. The effect of N-stearoylethanolamine on liver phospholipid composition of rats with insulin resistance caused by alimentary obesity

    Directory of Open Access Journals (Sweden)

    O. V. Onopchenko

    2014-02-01

    Full Text Available We used alimentary obesity-induced insulin resistance (IR model in rats to investigate the influence of N-stearoylethanolamine on the content of phospholipids and their fatty acid composition. Our results show that prolonged high-fat diet triggers considerable aberrations in the composition of main phospholipids in the liver and can be one of the causes of IR in rats. In particular, the increase of phosphatidylcholine, phosphatidylethanolamine and significant decrease of other phospholipids: lysophosphatidylcholine, lysophosphatidylethanolamine, sphingomyelin, phosphatidylinositol, phosphatidylserine and diphosphaglicerol were observed. The levels of monounsaturated (erucic, nervonic, oleic and polyunsaturated (eicosatrienoic, docosatrienoic, arachidonic fatty acids were increased; meanwhile the content of diunsaturated acids was decreased. The NSE administration (50 mg/kg of body weight caused restoration of the phospholipids content in the liver of rats with diet-induced IR that highly correlated with the decrease in plasma insulin level and the improvement of insulin sensitivity. Moreover, the effect of NSE was accompanied by the normalization of fatty acids composition of phospholipids that could be related to modulating influen­ce of NSE on the activity of the main fatty acid desaturases. It is known that the imbalance in phospholipid composition of the rat liver causes substantial metabolic alterations that are associated with the development of IR. Accordingly, the compensations of the imbalance by NSE can help to restore insulin sensitivity, inhibit the development of obesity, IR and type 2 diabetes.

  1. Fatty acid composition of human follicular fluid phospholipids and fertilization rate in assisted reproductive techniques.

    Science.gov (United States)

    Shaaker, Maghsod; Rahimipour, Ali; Nouri, Mohammad; Khanaki, Korosh; Darabi, Masoud; Farzadi, Laya; Shahnazi, Vahideh; Mehdizadeh, Amir

    2012-01-01

    Fatty acids are known to be critically important in multiple biological functions. Phospholipid fatty acids of follicular fluid, an important microenvironment for the development of oocytes, may contribute to the women's fertility and the efficacy of assisted reproduction techniques. The aim of this study was to investigate the effect of fatty acid composition of follicular fluid phospholipids on women undergoing assisted reproductive techniques. Follicular fluid samples were obtained from 100 patients, referred to Tabriz Alzahra Hospital. Seventy-nine subjects underwent in vitro fertilization (IVF) and the remaining 21 underwent intracytoplasmic sperm injection (ICSI). Total lipid of follicular fluid was extracted and fatty acids were analyzed by gas-liquid chromatography. Saturated fatty acids (SFA, P = 0.002) and the ratio of SFA to polyunsaturated fatty acids (P = 0.001) were correlated negatively with a number of mature oocytes after age adjustment. Linoleic acid (P = 0.006) was positively correlated, while the level of arachidonic acid was negatively correlated with fertility percentage after adjustment for body mass index, sperm count, sperm motility. Since phospholipids are one of the major components of lipid metabolism, the results of this study highlight the importance of this component in follicular fluid lipid metabolism. Consequently, it is proposed as an index in determination of the rate of success in assisted reproductive techniques such as IVF/ICSI.

  2. Composition, structure and properties of POPC–triolein mixtures. Evidence of triglyceride domains in phospholipid bilayers

    DEFF Research Database (Denmark)

    Duelund, Lars; Jensen, Grethe Vestergaard; Hannibal-Bach, Hans Kristian

    2013-01-01

    We have in this study investigated the composition, structure and spectroscopical properties of multilamellar vesicles composed of a phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), and up to 10mol% of triolein (TO), a triglyceride. We found in agreement with previous result......% TO contained pure TO domains. These observations are consistent with an earlier MD simulation study by us and our co-workers suggesting triglycerides to be located in lens shaped, blister-like domains between the two lipid bilayer leaflets (Khandelia et al. (2010) [26])....

  3. Osmoelastic coupling in biological structures: decrease in membrane fluidity and osmophobic association of phospholipid vesicles in response to osmotic stress.

    Science.gov (United States)

    Yamazaki, M; Ohnishi, S; Ito, T

    1989-05-02

    Poly(ethylene glycol)- (PEG-) induced change in membrane fluidity and aggregation of phospholipid vesicles were studied. A threshold concentration of PEG was required to induce the aggregation. This concentration increased with a decrease in the molecular weight of PEG, e.g., from 5% (w/w) with PEG 6000 (PEG with an average molecular weight of 7500) to more than 30% (w/w) with PEG 200. The aggregation was reversible upon dilution of PEG if the initial PEG concentration was smaller than a certain value, e.g., 22% (w/w) for PEG 6000. Addition of PEG caused a decrease in membrane fluidity of the vesicles detected by fluorescence anisotropy of diphenylhexatriene and by electron spin resonance of a spin-labeled fatty acid. The anisotropy change of diphenylhexatriene fluidity change had an inflection point at approximately 5% (w/w) of PEG 6000, which might suggest that the aggregation would make the decrease of membrane fluidity smaller. Transfer of lipid molecules between phospholipid vesicles was enhanced by the PEG-induced aggregation. The enhancement occurred not only upon direct addition of PEG to the suspending medium, but also upon dialysis of the vesicle suspension against a high concentration of PEG. All these features are consistent with osmoelastic coupling in the phospholipid membranes and the subsequent osmophobic association of the vesicles. The imbalance of osmolarity between the region adjacent to the vesicle surface (exclusion layer) and the bulk aqueous phase, which results from the preferential exclusion of PEG from the exclusion layer in the case of direct addition of PEG, exerts an osmotic stress on the vesicles.(ABSTRACT TRUNCATED AT 250 WORDS)

  4. Effect of polyunsaturated fatty acids and phospholipids on [3H]-vitamin E incorporation into pulmonary artery endothelial cell membranes

    International Nuclear Information System (INIS)

    Sekharam, K.M.; Patel, J.M.; Block, E.R.

    1990-01-01

    Vitamin E, a dietary antioxidant, is presumed to be incorporated into the lipid bilayer of biological membranes to an extent proportional to the amount of polyunsaturated fatty acids or phospholipids in the membrane. In the present study we evaluated the distribution of incorporated polyunsaturated fatty acids (PUFA) and phosphatidylethanolamine (PE) in various membranes of pulmonary artery endothelial cells. We also studied whether incorporation of PUFA or PE is responsible for increased incorporation of [3H]-vitamin E into the membranes of these cells. Following a 24-hr incubation with linoleic acid (18:2), 18:2 was increased by 6.9-, 9.2-, and 13.2-fold in plasma, mitochondrial, and microsomal membranes, respectively. Incorporation of 18:2 caused significant increases in the unsaturation indexes of mitochondrial and microsomal polyunsaturated fatty acyl chains (P less than .01 versus control in both membranes). Incubation with arachidonic acid (20:4) for 24 hr resulted in 1.5-, 2.3-, and 2.4-fold increases in 20:4 in plasma, mitochondrial, and microsomal membranes, respectively. The unsaturation indexes of polyunsaturated fatty acyl chains of mitochondrial and microsomal membranes also increased (P less than .01 versus control in both membranes). Although incubations with 18:2 or 20:4 resulted in several-fold increases in membrane 18:2 or 20:4 fatty acids, incorporation of [3H]-vitamin E into these membranes was similar to that in controls. Following a 24-hr incubation with PE, membrane PE content was significantly increased, and [3H]-vitamin E incorporation was also increased to a comparable degree, i.e., plasma membrane greater than mitochondria greater than microsomes. Endogenous vitamin E content of the cells was not altered because of increased incorporation of PE and [3H]-vitamin E

  5. Composite membranes and methods for making same

    Science.gov (United States)

    Routkevitch, Dmitri; Polyakov, Oleg G

    2012-07-03

    Composite membranes that are adapted for separation, purification, filtration, analysis, reaction and sensing. The composite membranes can include a porous support structure having elongate pore channels extending through the support structure. The composite membrane also includes an active layer comprising an active layer material, where the active layer material is completely disposed within the pore channels between the surfaces of the support structure. The active layer is intimately integrated within the support structure, thus enabling great robustness, reliability, resistance to mechanical stress and thermal cycling, and high selectivity. Methods for the fabrication of composite membranes are also provided.

  6. Protection of DPPC phospholipid liposomal membrane against radiation oxidative damage by antioxidants

    Energy Technology Data Exchange (ETDEWEB)

    Marathe, D.L.; Pandey, B.N.; Mishra, K.P [Bhabha Atomic Research Centre, Mumbai (India)

    2000-05-01

    Investigations in our laboratory on egg lecithin liposomes have recently showed a marked protection against damage by gamma radiation when cholesterol was present in the composition of vesicles suggesting a role of bilayer molecular architecture in the mechanism of free radical mediated lipid peroxidation. Present study was designed to determine the changes in bilayer permeability in DPPC unilamelar vesicles after exposure to gamma radiation by monitoring the leakage of pre-loaded carboxyfluorescein (CF), a marker loaded in aqueous interior of vesicle and fluidity alterations in the bilayer using fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH), a membrane bilayer probe. It was found that radiation doses of an order of magnitude higher were required to produce detectable changes in vesicles of DPPC than in the vesicles of egg lecithin suggesting a modulating role of chemical nature of composition in the membrane radiation sensitivity. It was significant to find that the leakage of CF from and incorporation of DPH into vesicle bilayer showed similar response pattern to radiation doses (0.1-6 kGy) which was also found to be dose rate dependent. Presence of antioxidants; alpha-tocopherol (0.15 mole %) in the bilayer membrane or ascorbic acid (0.1 mM) in the aqueous region significantly protected DPPC vesicles from radiation damage as determined from DPH uptake kinetics suggesting involvement of reactive free radicals of lipids as well as water radicals in the mechanism of membrane peroxidative damage. The magnitude of protection was found to increase with the increasing concentration of both these antioxidants but comparisons showed that {alpha}-tocopherol was far more effective in protecting the vesicles than ascorbic acid. These results contribute to our understanding of the mechanism of radiation oxidative damage and its modification by radical scavenging and/or organizational modulation which emphasize the importance of structure and composition of

  7. Drosophila TRF2 and TAF9 regulate lipid droplet size and phospholipid fatty acid composition.

    Science.gov (United States)

    Fan, Wei; Lam, Sin Man; Xin, Jingxue; Yang, Xiao; Liu, Zhonghua; Liu, Yuan; Wang, Yong; Shui, Guanghou; Huang, Xun

    2017-03-01

    The general transcription factor TBP (TATA-box binding protein) and its associated factors (TAFs) together form the TFIID complex, which directs transcription initiation. Through RNAi and mutant analysis, we identified a specific TBP family protein, TRF2, and a set of TAFs that regulate lipid droplet (LD) size in the Drosophila larval fat body. Among the three Drosophila TBP genes, trf2, tbp and trf1, only loss of function of trf2 results in increased LD size. Moreover, TRF2 and TAF9 regulate fatty acid composition of several classes of phospholipids. Through RNA profiling, we found that TRF2 and TAF9 affects the transcription of a common set of genes, including peroxisomal fatty acid β-oxidation-related genes that affect phospholipid fatty acid composition. We also found that knockdown of several TRF2 and TAF9 target genes results in large LDs, a phenotype which is similar to that of trf2 mutants. Together, these findings provide new insights into the specific role of the general transcription machinery in lipid homeostasis.

  8. Model mass spectrometric study of competitive interactions of antimicrobial bisquaternary ammonium drugs and aspirin with membrane phospholipids

    Directory of Open Access Journals (Sweden)

    Vekey K.

    2013-03-01

    Full Text Available The aim of the study is to reveal molecular mechanisms of possible activity modulation of antimicrobial bis-quaternary ammonium compounds (BQAC and aspirin (ASP through noncovalent competitive complexation under their combined introduction into the model systems with membrane phospholipids. Methods. Binary and triple systems containing either decamethoxinum or ethonium, or thionium and aspirin, as well as dipalmitoyl-phosphatidylcholine (DPPC have been investigated by electrospray ionization mass spectrometry. Results. Basing on the analysis of associates recorded in the mass spectra, the types of nonocovalent complexes formed in the systems studied were determined and the supposed role of the complexation in the BQAC and ASP activity modulation was discussed. The formation of associates of BQAC dications with ASP anion is considered as one of the possible ways of deactivation of ionic forms of the medications. The formation of stable complexes of BQAC with DPPC and ASP with DPPC in binary systems as well as the complexes distribution in triple-components systems BQAC:ASP:DPPC point to the existence of competition between drugs of these two types for the binding to DPPC. Conclusions. The results obtained point to the competitive complexation in the model molecular systems containing the BQAC, aspirin and membrane phospholipids. The observed phenomenon testifies to the possibility of modulating the activity of bisquaternary antimicrobial agents and aspirin under their combined usage, due to the competition between the drugs for binding to the target membrane phospholipid molecules and also due to the formation of stable noncovalent complexes between BQAC and ASP.

  9. PHOSPHOLIPIDS FROM PUMPKIN (Cucurbita moschata (Duch. Poir SEED KERNEL OIL AND THEIR FATTY ACID COMPOSITION

    Directory of Open Access Journals (Sweden)

    Tri Joko Raharjo

    2011-07-01

    Full Text Available The phospholipids (PL of pumpkin (Cucurbita moschata (Duch Poir seed kernel and their fatty acid composition were investigated. The crude oil was obtained by maceration with isopropanol followed by steps of extraction yielded polar lipids. The quantitative determination of PLs content of the dried pumpkin seed kernel and their polar lipids were calculated based on the elemental phosphorus (P contents which was determined by means of spectrophotometric methods. PL classes were separated from polar lipids via column chromatography. The fatty acid composition of individual PL was identified by gas chromatography-mass spectrometry (GC-MS. The total of PL in the pumpkin seed kernels was 1.27% which consisted of phosphatidylcholine (PC, phosphatidylserine (PS and phosphatidyletanolamine (PE. The predominant fatty acids of PL were oleic and palmitic acid in PC and PE while PS's fatty acid were dominantly consisted of oleic acid and linoleic acid.

  10. Regulation of TMEM16A/ANO1 and TMEM16F/ANO6 ion currents and phospholipid scrambling by Ca2+and plasma membrane lipid.

    Science.gov (United States)

    Schreiber, Rainer; Ousingsawat, Jiraporn; Wanitchakool, Podchanart; Sirianant, Lalida; Benedetto, Roberta; Reiss, Karina; Kunzelmann, Karl

    2018-01-15

    TMEM16 proteins can operate as Ca 2+ -activated Cl - channels or scramble membrane phospholipids, which are both highly relevant mechanisms during disease. Overexpression of TMEM16A and TMEM16F were found to be partially active at 37°C and at resting intracellular Ca 2+ concentrations. We show that TMEM16 Cl - currents and phospholipid scrambling can be activated by modification of plasma membrane phospholipids, through reactive oxygen species and phospholipase A2. While phospholipids and Cl - ions are likely to use the same pore within TMEM16F, TMEM16A only conducts Cl - ions. Lipid regulation of TMEM16 proteins is highly relevant during inflammation and regulated cell death such as apoptosis and ferroptosis. TMEM16/anoctamin (ANO) proteins form Ca 2+ -activated ion channels or phospholipid scramblases. We found that both TMEM16A/ANO1 and TMEM16F/ANO6 produced Cl - currents when activated by intracellular Ca 2+ , but only TMEM16F was able to expose phosphatidylserine to the outer leaflet of the plasma membrane. Mutations within TMEM16F or TMEM16A/F chimeras similarly changed Cl - currents and phospholipid scrambling, suggesting the same intramolecular pathway for Cl - and phospholipids. When overexpressed, TMEM16A and TMEM16F produced spontaneous Cl - currents at 37°C even at resting intracellular Ca 2+ levels, which was abolished by inhibition of phospholipase A2 (PLA 2 ). Connversely, activation of PLA 2 or application of active PLA 2 , as well as lipid peroxidation induced by reactive oxygen species (ROS) using staurosporine or tert-butyl hydroperoxide, enhanced ion currents by TMEM16A/F and in addition activated phospholipid scrambling by TMEM16F. Thus, TMEM16 proteins are activated by an increase in intracellular Ca 2+ , or independent of intracellular Ca 2+ , by modifications occurring in plasma and intracellular membrane phospholipids. These results may help to explain why regions distant to the TMEM16 pore and the Ca 2+ binding sites control Cl

  11. Membrane-surfactant interactions. The role of surfactant in mitochondrial complex III-phospholipid-Triton X-100 mixed micelles

    International Nuclear Information System (INIS)

    Valpuesta, J.M.; Arrondo, J.L.; Barbero, M.C.; Pons, M.; Goni, F.M.

    1986-01-01

    Complex III (ubiquinol-cytochrome c reductase) was purified from beef heart mitochondria in the form of protein-phospholipid-Triton X-100 mixed micelles (about 1:80:100 molar ratio). Detergent may be totally removed by sucrose density gradient centrifugation, and the resulting lipoprotein complexes retain full enzyme activity. In order to understand the role of surfactant in the mixed micelles, and the interaction of Triton X-100 with integral membrane proteins and phospholipid bilayers, both the protein-lipid-surfactant mixed micelles and the detergent-free lipoprotein system were examined from the point of view of particle size and ultrastructure, enzyme activity, tryptophan fluorescence quenching, 31P NMR, and Fourier transform infrared spectroscopy. The NMR and IR spectroscopic studies show that surfactant withdrawal induces a profound change in phospholipid architecture, from a micellar to a lamellar-like phase. However, electron microscopic observations fail to reveal the existence of lipid bilayers in the absence of detergent. We suggest that, under these conditions, the lipid:protein molar ratio (80:1) is too low to permit the formation of lipid bilayer planes, but the relative orientation and mobility of phospholipids with respect to proteins is similar to that of the lamellar phase. Protein conformational changes are also detected as a consequence of surfactant removal. Fourier transform infrared spectroscopy indicates an increase of peptide beta-structure in the absence of Triton X-100; changes in the amide II/amide I intensity ratio are also detected, although the precise meaning of these observations is unclear

  12. Phospholipid classes and fatty acid composition of ewe’s and goat’s milk

    Directory of Open Access Journals (Sweden)

    Zancada, L.

    2013-06-01

    Full Text Available The content, distribution of individual species, and the fatty acid composition of phospholipids (PL from ewe’s and goat’s milk were analyzed. The binding of enterotoxigenic and uropathogenic Escherichia coli strains to PL and the inhibition of bacterial hemagglutination by PL were addressed using high performance thin-layer chromatography-overlay assays and microtiter plates, respectively. Ovine and caprine milk contained more PL than bovine milk but less than human milk. The profile of individual PL was similar, including sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol in both ovine and caprine milk. Regarding the fatty acid composition, a high content of long-chain fatty acids (more than C16 and unsaturated fatty acids, with C18:1 as the most abundant was found in ovine and caprine milk PL. Ovine milk has longer and less saturated fatty acids while caprine milk has shorter and more saturated ones. Neither the adhesion of any bacterial strains assayed to the individual PL from ovine or caprine milk nor the inhibition of bacterial hemagglutination by PL were observed. These are important constituents of the milk fat globule membrane, but it seems that they do not play a role in the defence of new-borns against bacteria if the results obtained are taken into account.Se ha analizado el contenido, distribución de las especies individuales y la composición en ácidos grasos de los fosfolípidos (FL de la leche de oveja y de cabra. Se ha estudiado también la unión de cepas enterotoxigénicas y uropatogénicas de Escherichia coli a estos compuestos y el efecto de los FL sobre la hemaglutinación provocada por estas bacterias mediante inmunodetección en placa y ensayos en placas multipocillo, respectivamente. La leche de oveja y de cabra contiene más FL que la de vaca, pero menos que la leche humana. El perfil de FL individuales es similar en la leche de oveja y de cabra e incluye

  13. Surface-Dependent Transitions during Self-Assembly of Phospholipid Membranes on Mica, Silica, and Glass

    Czech Academy of Sciences Publication Activity Database

    Beneš, Martin; Billy, D.; Benda, Aleš; Speijer, H.; Hof, Martin; Hermens, W. T.

    2004-01-01

    Roč. 20, č. 23 (2004), s. 10129-10137 ISSN 0743-7463 R&D Projects: GA MŠk LN00A032 Institutional research plan: CEZ:AV0Z4040901 Keywords : silica and glass * phospholipid * surface-dependent Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.295, year: 2004

  14. Conformations of double-headed, triple-tailed phospholipid oxidation lipid products in model membranes

    DEFF Research Database (Denmark)

    Hermetter, Albin; Kopec, Wojciech; Khandelia, Himanshu

    2013-01-01

    Products of phospholipid oxidation can produce lipids with a carbonyl moiety at the end of a shortened lipid acyl tail, such as 1-palmitoyl-2-(5-oxovaleroyl)-sn-glycero-3-phosphocholine (POVPC). The carbonyl tail of POVPC can covalently bond to the free tertiary amine of a phosphatidylethanolamin...

  15. Fatty acid composition and phospholipid types used in infant formulas modifies the establishment of human gut bacteria in germ-free mice

    DEFF Research Database (Denmark)

    Bennike, Rikke Mette Guldhammer; Licht, Tine Rask; Hellgren, Lars

    2017-01-01

    Human milk fat contains high concentrations of medium-chained fatty acids (MCFA) and triacylglycerols emulsified by a sphingomyelin-rich phospholipid membrane (milk phospholipids, MPL). Infant formula comprises mainly long-chained fatty acids (LCFA) emulsified with dairy proteins and soy lecithin...

  16. Daptomycin-resistant Enterococcus faecalis diverts the antibiotic molecule from the division septum and remodels cell membrane phospholipids.

    Science.gov (United States)

    Tran, Truc T; Panesso, Diana; Mishra, Nagendra N; Mileykovskaya, Eugenia; Guan, Ziqianq; Munita, Jose M; Reyes, Jinnethe; Diaz, Lorena; Weinstock, George M; Murray, Barbara E; Shamoo, Yousif; Dowhan, William; Bayer, Arnold S; Arias, Cesar A

    2013-07-23

    Treatment of multidrug-resistant enterococci has become a challenging clinical problem in hospitals around the world due to the lack of reliable therapeutic options. Daptomycin (DAP), a cell membrane-targeting cationic antimicrobial lipopeptide, is the only antibiotic with in vitro bactericidal activity against vancomycin-resistant enterococci (VRE). However, the clinical use of DAP against VRE is threatened by emergence of resistance during therapy, but the mechanisms leading to DAP resistance are not fully understood. The mechanism of action of DAP involves interactions with the cell membrane in a calcium-dependent manner, mainly at the level of the bacterial septum. Previously, we demonstrated that development of DAP resistance in vancomycin-resistant Enterococcus faecalis is associated with mutations in genes encoding proteins with two main functions, (i) control of the cell envelope stress response to antibiotics and antimicrobial peptides (LiaFSR system) and (ii) cell membrane phospholipid metabolism (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase). In this work, we show that these VRE can resist DAP-elicited cell membrane damage by diverting the antibiotic away from its principal target (division septum) to other distinct cell membrane regions. DAP septal diversion by DAP-resistant E. faecalis is mediated by initial redistribution of cell membrane cardiolipin-rich microdomains associated with a single amino acid deletion within the transmembrane protein LiaF (a member of a three-component regulatory system [LiaFSR] involved in cell envelope homeostasis). Full expression of DAP resistance requires additional mutations in enzymes (glycerophosphoryl diester phosphodiesterase and cardiolipin synthase) that alter cell membrane phospholipid content. Our findings describe a novel mechanism of bacterial resistance to cationic antimicrobial peptides. The emergence of antibiotic resistance in bacterial pathogens is a threat to public health

  17. Engineered Asymmetric Composite Membranes with Rectifying Properties.

    Science.gov (United States)

    Wen, Liping; Xiao, Kai; Sainath, Annadanam V Sesha; Komura, Motonori; Kong, Xiang-Yu; Xie, Ganhua; Zhang, Zhen; Tian, Ye; Iyoda, Tomokazu; Jiang, Lei

    2016-01-27

    Asymmetric composite membranes with rectifying properties are developed by grafting pH-stimulus-responsive materials onto the top layer of the composite structure, which is prepared by two novel block copolymers using a phase-separation technique. This engineered asymmetric composite membrane shows potential applications in sensors, filtration, and nanofluidic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Herpes simplex viruses activate phospholipid scramblase to redistribute phosphatidylserines and Akt to the outer leaflet of the plasma membrane and promote viral entry

    OpenAIRE

    Cheshenko, Natalia; Pierce, Carl; Herold, Betsy C.

    2018-01-01

    Herpes simplex virus (HSV) entry is associated with Akt translocation to the outer leaflet of the plasma membrane to promote a complex signaling cascade. We hypothesized that phospholipid scramblase-1 (PLSCR1), a calcium responsive enzyme that flips phosphatidylserines between membrane leaflets, might redistribute Akt to the outside during entry. Confocal imaging, biotinylation of membrane proteins and flow cytometric analysis demonstrated that HSV activates PLSCR1 and flips phosphatidylserin...

  19. Testosterone replacement therapy improves erythrocyte membrane lipid composition in hypogonadal men.

    Science.gov (United States)

    Angelova, Petya; Momchilova, Albena; Petkova, Diana; Staneva, Galya; Pankov, Roumen; Kamenov, Zdravko

    2012-09-01

    The aim of this study was to investigate the effects of testosterone replacement therapy (TRT) on erythrocyte membrane (EM) lipid composition and physico-chemical properties in hypogonadal men. EM isolated from three patients before and after TRT with injectable testosterone undecanoate or testosterone gel were used for analysis of the phospholipid and fatty acid composition, cholesterol/phospholipid ratio, membrane fluidity, ceramide level and enzyme activities responsible for sphingomyelin metabolism. TRT induced increase of phosphatidylethanolamine (PE) in the EMs and sphingomyelin. Reduction of the relative content of the saturated palmitic and stearic fatty acids and a slight increase of different unsaturated fatty acids was observed in phosphatidylcholine (PC). TRT also induced decrease of the cholesterol/total phospholipids ratio and fluidization of the EM. The TRT induced increase of PE content and the reduction of saturation in the PC acyl chains induced alterations in the structure of EM could result in higher flexibility of the erythrocytes. The increase of the SM-metabolizing enzyme neutral sphingomyelinase, which regulates the content of ceramide in membranes has a possible impact on the SM signaling pathway. We presume that the observed effect of TRT on the composition and fluidity of the EM contributes for improvement of blood rheology and may diminish the thrombosis risk. Larger studies are needed to confirm the findings of this pilot study.

  20. Supported Phospholipid Membranes Formation at a Gel Electrode and Transport of Divalent Cations across them

    Czech Academy of Sciences Publication Activity Database

    Navrátil, Tomáš; Šestáková, Ivana; Mareček, Vladimír

    2011-01-01

    Roč. 6, č. 1 (2011), s. 6032-6046 ISSN 1452-3981 R&D Projects: GA AV ČR IAA400400806; GA ČR GAP206/11/1638 Institutional research plan: CEZ:AV0Z40400503 Keywords : gel * agar * phospholipids Subject RIV: CG - Electrochemistry Impact factor: 3.729, year: 2011 http://www.electrochemsci.org/list11.htm

  1. Influence of Development and Dietary Phospholipid Content and Composition on Intestinal Transcriptome of Atlantic Salmon (Salmo salar.

    Directory of Open Access Journals (Sweden)

    Christian De Santis

    Full Text Available The inclusion of intact phospholipids in the diet is essential during larval development and can improve culture performance of many fish species. The effects of supplementation of dietary phospholipid from marine (krill or plant (soy lecithin sources were investigated in Atlantic salmon, Salmo salar. First feeding fry were fed diets containing either krill oil or soybean lecithin supplying phospholipid at 2.6%, 3.2%, 3.6% and 4.2% of diet. Fish were sampled at ~ 2.5 g (~1,990°day post fertilization, dpf and ~10 g (2,850°dpf. By comparison of the intestinal transcriptome in specifically chosen contrasts, it was determined that by 2,850°dpf fish possessed a profile that resembled that of mature and differentiated intestinal cell types with a number of changes specific to glycerophospholipid metabolism. It was previously shown that intact phospholipids and particularly phosphatidylcholine are essential during larval development and that this requirement is associated with the inability of enterocytes in young fry to endogenously synthesize sufficient phospholipid for the efficient export of dietary lipid. In the immature phase (~1,990°dpf, the dietary phospholipid content as well as its class composition impacted on several biochemical and morphological parameters including growth, but these differences were not associated with differences in intestinal transcriptomes. The results of this study have made an important contribution to our understanding of the mechanisms associated with lipid transport and phospholipid biosynthesis in early life stages of fish.

  2. Morphological and physical analysis of natural phospholipids-based biomembranes.

    Directory of Open Access Journals (Sweden)

    Adrien Jacquot

    Full Text Available BACKGROUND: Liposomes are currently an important part of biological, pharmaceutical, medical and nutritional research, as they are considered to be among the most effective carriers for the introduction of various types of bioactive agents into target cells. SCOPE OF REVIEW: In this work, we study the lipid organization and mechanical properties of biomembranes made of marine and plant phospholipids. Membranes based on phospholipids extracted from rapeseed and salmon are studied in the form of liposome and as supported lipid bilayer. Dioleylphosphatidylcholine (DOPC and dipalmitoylphosphatidylcholine (DPPC are used as references to determine the lipid organization of marine and plant phospholipid based membranes. Atomic force microscopy (AFM imaging and force spectroscopy measurements are performed to investigate the membranes' topography at the micrometer scale and to determine their mechanical properties. MAJOR CONCLUSIONS: The mechanical properties of the membranes are correlated to the fatty acid composition, the morphology, the electrophoretic mobility and the membrane fluidity. Thus, soft and homogeneous mechanical properties are evidenced for salmon phospholipids membrane containing various polyunsaturated fatty acids. Besides, phase segregation in rapeseed membrane and more important mechanical properties were emphasized for this type of membranes by contrast to the marine phospholipids based membranes. GENERAL SIGNIFICANCE: This paper provides new information on the nanomechanical and morphological properties of membrane in form of liposome by AFM. The originality of this work is to characterize the physico-chemical properties of the nanoliposome from the natural sources containing various fatty acids and polar head.

  3. Composition and functionality of whey protein phospholipid concentrate and delactosed permeate.

    Science.gov (United States)

    Levin, M A; Burrington, K J; Hartel, R W

    2016-09-01

    Whey protein phospholipid concentrate (WPPC) and delactosed permeate (DLP) are 2 coproducts of cheese whey processing that are currently underused. Past research has shown that WPPC and DLP can be used together as a functional dairy ingredient in foods such as ice cream, soup, and caramel. However, the scope of the research has been limited to 1 WPPC supplier. The objective of this research was to fully characterize a range of WPPC. Four WPPC samples and 1 DLP sample were analyzed for chemical composition and functionality. This analysis showed that WPPC composition was highly variable between suppliers and lots. In addition, the functionality of the WPPC varies depending on the supplier and testing pH, and cannot be correlated with fat or protein content because of differences in processing. The addition of DLP to WPPC affects functionality. In general, WPPC has a high water-holding capacity, is relatively heat stable, has low foamability, and does not aid in emulsion stability. The gel strength and texture are highly dependent on the amount of protein. To be able to use these 2 dairy products, the composition and functionality must be fully understood. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  4. Ceramic nanostructure materials, membranes and composite layers

    NARCIS (Netherlands)

    Burggraaf, A.J.; Keizer, Klaas; van Hassel, B.A.

    1989-01-01

    Synthesis methods to obtain nanoscale materials will be briefly discussed with a focus on sol-gel methods. Three types of nanoscale composites (powders, membranes and ion implanted layers) will be discussed and exemplified with recent original research results. Ceramic membranes with a thickness of

  5. Terahertz dielectric relaxation of biological water confined in model membranes made of lyotropic phospholipids

    NARCIS (Netherlands)

    Paparo, D.; Tielrooij, K.J.; Bakker, H.J.; Bonn, M.

    2009-01-01

    Understanding water-membrane interactions is a fundamental issue in biophysics since these interactions are at the basis of many key molecular processes occurring in membranes. The hydrogen-bond network of water molecules is highly dynamic and its dynamical structure influences membrane fluidity and

  6. Composite perfluorohydrocarbon membranes, their preparation and use

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Yong; Bikson, Benjamin

    2017-04-04

    Composite porous hydrophobic membranes are prepared by forming a perfluorohydrocarbon layer on the surface of a preformed porous polymeric substrate. The substrate can be formed from poly (aryl ether ketone) and a perfluorohydrocarbon layer can be chemically grafted to the surface of the substrate. The membranes can be utilized for a broad range of fluid separations, such as microfiltration, nanofiltration, ultrafiltration as membrane contactors for membrane distillation and for degassing and dewatering of fluids. The membranes can further contain a dense ultra-thin perfluorohydrocarbon layer superimposed on the porous poly (aryl ether ketone) substrate and can be utilized as membrane contactors or as gas separation. membranes for natural gas treatment and gas dehydration.

  7. Dietary Selenium or Zinc Supplementation Restores Brain Lipid Composition and Membrane Fluidity in Protein-Undernourished Rats.

    Science.gov (United States)

    Adebayo, Olusegun L; Salau, Bamidele A; Sandhir, Rajat; Adenuga, Gbenga A

    2016-01-01

    Studies have shown that protein undernutrition (PU) modifies the membrane lipid composition in the intestine and liver, as well as in plasma and other areas. However, there is limited information on the effect of PU on synaptosomal membrane lipid composition and fluidity and the protective role of selenium (Se) and zinc (Zn), which is a major focus of the present study. For 10 weeks, rats were fed diets containing 16% casein, which constituted the adequate protein diet, or 5% casein, representing the PU diet. The animals were supplemented with Se and Zn at a concentration of 0.15 and 227 mg L-1, respectively, in drinking water for 3 weeks. The results showed a significant increase in total lipids, glycolipids, triglycerides, cholesterol, and the cholesterol/phospholipid (Chol/PL) ratio, and a significant reduction in phospholipids and membrane fluidity. Se and Zn supplementation to PU rats, however, significantly lowered total lipids, glycolipids, triglycerides, cholesterol, and the Chol/PL ratio, while phospholipids and membrane fluidity were significantly restored. It is concluded that a perturbed lipid composition induced by PU affects the membrane structure and fluidity, which in turn influences membrane functions. The study suggests that Se and Zn supplementation might be beneficial in restoring the lipid dyshomeostasis associated with PU. © 2017 S. Karger AG, Basel.

  8. The origin of phospholipids of the enveloped bacteriophage phi6

    International Nuclear Information System (INIS)

    Laurinavicius, Simonas; Kaekelae, Reijo; Bamford, Dennis H.; Somerharju, Pentti

    2004-01-01

    The phospholipid class and molecular species compositions of bacteriophage phi6 and its host Pseudomonas syringae were determined quantitatively using TLC and liquid-chromatography/electrospray ionization mass-spectrometry. In addition, the fatty acid compositions of the phospholipids were analyzed by gas-chromatography/mass-spectrometry. The phage contained significantly more phosphatidylglycerol (PG) and less phosphatidylethanolamine (PE) than the host cytoplasmic (CM) and outer (OM) membranes. In addition, the phospholipid molecular species composition of the viral membrane differed from those of the host membranes, but resembled that of CM more than OM as shown by principal component analysis (PCA). The membrane of phi6 contained more 34:1 and 34:2, and less 32:1 PE and PG molecular species than the host CM or OM. Also, phi6 contained negligible amounts of saturated phospholipid molecular species. These data provide the first biochemical evidence suggesting that phi6 obtains its lipids from the CM. This process is not unselective, but certain phospholipid species are preferentially incorporated in the phage membrane. Common factors leading to similar enrichment of PG in every membrane-containing bacterial virus system studied so far (phi6, PM2, PRD1, PR4, Bam35) are discussed

  9. Ceria Based Composite Membranes for Oxygen Separation

    DEFF Research Database (Denmark)

    Gurauskis, Jonas; Ovtar, Simona; Kaiser, Andreas

    2014-01-01

    Mixed ionic-electronic conducting membranes for oxygen gas separation are attracting a lot of interest due to their promising potential for the pure oxygen and the syngas production. Apart from the need for a sufficiently high oxygen permeation fluxes, the prolonged stability of these membranes...... under the large oxygen potential gradients at elevated temperatures is decisive for the future applications. The gadolinium doped cerium oxide (CGO) based composite membranes are considered as promising candidates due to inherent stability of CGO phase. The CGO matrix is a main oxygen ion transporter......; meanwhile the primary role of a secondary phase in this membrane is to compensate the low electronic conductivity of matrix at intended functioning conditions. In this work thin film (15-20 μm) composite membranes based on CGO matrix and LSF electronic conducting phase were fabricated and evaluated...

  10. Phospholipid Composition in Synthetic Surfactants Is Important for Tidal Volumes and Alveolar Stability in Surfactant-Treated Preterm Newborn Rabbits.

    Science.gov (United States)

    Calkovska, Andrea; Linderholm, Bim; Haegerstrand-Björkman, Marie; Pioselli, Barbara; Pelizzi, Nicola; Johansson, Jan; Curstedt, Tore

    2016-01-01

    The development of synthetic surfactants for the treatment of lung pulmonary diseases has been going on for many years. To investigate the effects of phospholipid mixtures combined with SP-B and SP-C analogues on lung functions in an animal model of respiratory distress syndrome. Natural and synthetic phospholipid mixtures with/without SP-B and/or SP-C analogues were instilled in ventilated premature newborn rabbits. Lung functions were evaluated. Treatment with Curosurf or phospholipids from Curosurf combined with SP-B and SP-C analogues gave similar results. Treatment with phospholipids from adult rabbit lungs or liver combined with dipalmitoylphosphatidylcholine (DPPC) and palmitoyloleoylphosphatidylglycerol (POPG) gave tidal volumes (VT) well above physiological levels, but alveolar stability at end-expiration was only achieved when these phospholipids were combined with analogues of SP-B and SP-C. Treatment with egg yolk-PC mixed with DPPC with and without POPG gave small VT, but after addition of both analogues VT was only somewhat lower and lung gas volumes (LGV) similar to those obtained with Curosurf. Substitution of egg yolk-PC (≥99% PC) with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1-palmitoyl-2-linoleoyl-sn-glycero-3-phosphocholine, and combining them with DPPC, POPG and 2% each of the SP-B and SP-C analogue gave a completely synthetic surfactant with similar effects on VT and LGV as Curosurf. Phospholipid composition is important for VT while the SP-B and SP-C analogues increase alveolar stability at end-expiration. Synthetic surfactant consisting of unsaturated and saturated phosphatidylcholines, POPG and the analogues of SP-B and SP-C has similar activity as Curosurf regarding VT and LGV in an animal model using preterm newborn rabbits ventilated without positive end-expiratory pressure. © 2016 S. Karger AG, Basel.

  11. Softening of phospholipid membranes by the adhesion of silica nanoparticles - as seen by neutron spin-echo (NSE)

    Science.gov (United States)

    Hoffmann, Ingo; Michel, Raphael; Sharp, Melissa; Holderer, Olaf; Appavou, Marie-Sousai; Polzer, Frank; Farago, Bela; Gradzielski, Michael

    2014-05-01

    The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon

  12. Testing the limits of model membrane simulations-bilayer composition and pressure scaling.

    Science.gov (United States)

    Ivanova, Nikoleta; Ivanova, Anela

    2018-03-30

    Studying transfer of bioactive compounds across cell membranes by simulations attracts growing attention. To perform such calculations accurately, it is necessary to verify the validity of computational protocols established for description of unperturbed lipid bilayers also with translocating substances present. The current work reports the results from 1 μs long atomistic molecular dynamics simulations of two types of model plasma membranes-one built of a single phospholipid (DPPC) and one constructed of four types of phospholipids-in the presence of a drug-peptide complex experimentally known to cross cell membranes. The influence of membrane composition and of applied pressure scaling algorithm on the simulations outcome is analyzed with particular focus on membrane structure and on complex-lipid interactions during the initial penetration stage. It is found that the mixed composition of the membrane is important for correct assessment of the interactions with the complex both from purely structural perspective and because of the uneven charge distribution. The structure of the mixed lipid bilayer is affected more markedly by the pressure scaling algorithm. When the pressure is isotropically scaled, lipids are distributed almost homogeneously along the membrane in liquid ordered state. On semi-isotropic scaling, the lipid tails undergo significant rearrangement and a long-range ordered state is established. This results in "freezing" of the membrane and expulsion of the complex. The statistical analysis of the MD data points to the conclusion that a mixed-lipid membrane model with isotropic pressure scaling would be more suitable for describing the process of complex translocation across neoplastic membranes. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  13. Synthesis of Carbon Nanotube (CNT Composite Membranes

    Directory of Open Access Journals (Sweden)

    Dusan Losic

    2010-12-01

    Full Text Available Carbon nanotubes are attractive approach for designing of new membranes for advanced molecular separation because of their unique transport properties and ability to mimic biological protein channels. In this work the synthetic approach for fabrication of carbon nanotubes (CNTs composite membranes is presented. The method is based on growth of multi walled carbon nanotubes (MWCNT using chemical vapour deposition (CVD on the template of nanoporous alumina (PA membranes. The influence of experimental conditions including carbon precursor, temperature, deposition time, and PA template on CNT growth process and quality of fabricated membranes was investigated. The synthesis of CNT/PA composites with controllable nanotube dimensions such as diameters (30–150 nm, and thickness (5–100 µm, was demonstrated. The chemical composition and morphological characteristics of fabricated CNT/PA composite membranes were investigated by various characterisation techniques including scanning electron microscopy (SEM, energy-dispersive x-ray spectroscopy (EDXS, high resolution transmission electron microscopy (HRTEM and x-ray diffraction (XRD. Transport properties of prepared membranes were explored by diffusion of dye (Rose Bengal used as model of hydrophilic transport molecule.

  14. Transverse and lateral distribution of phospholipids and glycolipids in the membrane of the bacterium Micrococcus luteus

    International Nuclear Information System (INIS)

    de Bony, J.; Lopez, A.; Gilleron, M.; Welby, M.; Laneelle, G.; Rousseau, B.; Beaucourt, J.P.; Tocanne, J.F.

    1989-01-01

    The photodimerization of anthracene was used to investigate the transverse and lateral distribution of lipids in the membrane of the Gram-positive bacterium Micrococcus luteus. 9-(2-Anthryl)nonanoic acid (9-AN) is incorporated at a high rate into various membrane lipids of M. luteus. On irradiation of intact bacteria at 360 nm, anthracene-labeled lipids form stable photodimers which can be extracted and separated by thin-layer chromatography. We present here the results of a study on the distribution of two major lipids, phosphatidylglycerol (PG) and dimannosyldiacylglycerol (DMDG), within each leaflet of the membrane lipid bilayer. After metabolic incorporation of a tritiated derivative of 9-AN in M. luteus, the radioactivity associated with the photodimers issued from PG and DMDG was counted. In the bacterial membrane, the ratio of PG-DMDG heterodimer with respect to PG-PG and DMDG-DMDG homodimers is around half of what should be obtained for a homogeneous mixture of the two lipids. In order to find out whether this was due to an asymmetric distribution of the two lipids between the two membrane leaflets or a heterogeneous distribution of the two lipids within the same membrane leaflet, the transverse distribution of PG and DMDG was also investigated. This was carried out by following the kinetics of oxidation of the two lipids by periodic acid in the membrane of M. luteus protoplasts. PG predominated slightly in the outer layer (60%), while DMDG was found to be symmetrically distributed between the two leaflets. By itself, this lipid asymmetry cannot account for the lipid distribution determined from the photodimerization experiments. This indicates that PG and DMDG are not homogeneously distributed in the plane of the bacterial membrane

  15. Softening of phospholipid membranes by the adhesion of silica nanoparticles--as seen by neutron spin-echo (NSE).

    Science.gov (United States)

    Hoffmann, Ingo; Michel, Raphael; Sharp, Melissa; Holderer, Olaf; Appavou, Marie-Sousai; Polzer, Frank; Farago, Bela; Gradzielski, Michael

    2014-06-21

    The interactions between nanoparticles and vesicles are of significant interest both from a fundamental as well as from a practical point of view, as vesicles can serve as a model system for cell membranes. Accordingly the effect of nanoparticles that bind to the vesicle bilayer is very important with respect to understanding their biological impact and also may shed some light on the mechanisms behind the effect of nanotoxicity. In this study we have investigated the influence of small adsorbed silica nanoparticles (SiNPs) on the structure of zwitterionic DOPC vesicles. By a combination of SANS, cryo-TEM, and DLS, we observed that the SiNPs are bound to the outer vesicle surface without significantly affecting the vesicle structure. Most interestingly, by means of neutron spin-echo (NSE) local bilayer fluctuations were studied and one finds a small but marked decrease of the membrane rigidity upon binding of the nanoparticles. This surprising finding may be a relevant aspect for the further understanding of the effects that nanoparticles have on phospholipid bilayers.

  16. The Effect of Meal Frequency on the Fatty Acid Composition of Serum Phospholipids in Patients with Type 2 Diabetes.

    Science.gov (United States)

    Kahleova, Hana; Malinska, Hana; Kazdova, Ludmila; Belinova, Lenka; Tura, Andrea; Hill, Martin; Pelikanova, Terezie

    2016-01-01

    Fatty acids are important cellular constituents that can affect many metabolic processes relevant for the development of diabetes and its complications. We previously demonstrated a positive effect of eating just 2 meals a day, breakfast and lunch, compared to 6 small meals. The aim of this secondary analysis was to explore the effect of meal frequency on the fatty acid composition of serum phospholipids in subjects with type 2 diabetes (T2D). In a randomized, crossover study, we assigned 54 patients with T2D to follow one of 2 regimens of a hypocaloric diet (-500 kcal/day), each for 12 weeks: 6 meals (A6) or 2 meals a day, breakfast and lunch (B2). The diet in both regimens had the same macronutrient and energy content. The fatty acid composition of serum phospholipids was measured at weeks 0, 12, and 24, using gas liquid chromatography. Insulin sensitivity was derived as an oral glucose insulin sensitivity (OGIS) index. Saturated fatty acids (mainly myristic and palmitic acids) decreased (p meal frequency affects the fatty acid composition of serum phospholipids. The B2 regimen had more marked positive effects, with saturated fatty acids and the ratio of saturated to unsaturated fatty acids decreasing more. The increase in linoleic acid could partly explain the insulin-sensitizing effect of B2 in T2D.

  17. Reorganization of Azospirillum brasilense cell membrane is mediated by lipid composition adjustment to maintain optimal fluidity during water deficit.

    Science.gov (United States)

    Cesari, A B; Paulucci, N S; Biasutti, M A; Reguera, Y B; Gallarato, L A; Kilmurray, C; Dardanelli, M S

    2016-01-01

    We study the Azospirillum brasilense tolerance to water deficit and the dynamics of adaptive process at the level of the membrane. Azospirillum brasilense was exposed to polyethylene glycol (PEG) growth and PEG shock. Tolerance, phospholipids and fatty acid (FA) composition and membrane fluidity were determined. Azospirillum brasilense was able to grow in the presence of PEG; however, its viability was reduced. Cells grown with PEG showed membrane fluidity similar to those grown without, the lipid composition was modified, increasing phosphatidylcholine and decreasing phosphatidylethanolamine amounts. The unsaturation FAs degree was reduced. The dynamics of the adaptive response revealed a decrease in fluidity 20 min after the addition of PEG, indicating that the PEG has a fluidizing effect on the hydrophobic region of the cell membrane. Fluidity returned to initial values after 60 min of PEG exposure. Azospirillum brasilense is able to perceive osmotic changes by changing the membrane fluidity. This effect is offset by changes in the composition of membrane phospholipid and FA, contributing to the homeostasis of membrane fluidity under water deficit. This knowledge can be used to develop new Azospirillum brasilense formulations showing an adapted membrane to water deficit. © 2015 The Society for Applied Microbiology.

  18. Hybrid Nano composite Membranes for PEMFC Applications

    International Nuclear Information System (INIS)

    Niepceron, F.

    2008-03-01

    This work aims at validating a new concept of hybrid materials for the realization of proton exchange membranes, an essential constituent of PEM fuel cells. The originality of this nano-composite hybrid concept corresponds to a separation of the membrane's properties. We investigated the preparation of composite materials based on an inert, relatively low cost, polymer matrix (PVDF-HFP) providing the mechanical stability embedding inorganic fillers providing the necessary properties o f proton-conduction and water retention. The first step of this work consisted in the modification of fumed silica to obtain a proton-conducting filler. An ionic exchange capacity (CEI) equal to 3 meq/g was obtained by the original grafting of sodium poly(styrene-sulfonate) chains from the surface of particles. Nano-composite hybrid membranes PVDF-HFP/functionalized silica were accomplished by a film casting process. The coupling of the morphological and physicochemical analyses validated the percolation of the inorganic phase for 30 wt.% of particles. Beyond 40 % of loading, measured protonic conductivity is higher than the reference membrane Nafion 112. Finally, these membranes presented high performances, above 0.8 W/cm 2 , in single-cell fuel cell tests. A compromise is necessary according to the rate of loading between performances in fuel cell and mechanical properties of the membrane. 50 % appeared as best choice with, until 90 C, a remarkable thermal stability of the performances. (author)

  19. Contribution of hydrogen bonding to lipid-lipid interactions in membranes and the role of lipid order: effects of cholesterol, increased phospholipid unsaturation, and ethanol.

    Science.gov (United States)

    Slater, S J; Ho, C; Taddeo, F J; Kelly, M B; Stubbs, C D

    1993-04-13

    It is proposed that increased phospholipid unsaturation in membranes and perturbation by agents such as ethanol weaken interlipid hydrogen bonding involving water and that the process is independent of effects on lipid order. To investigate this, the rates of phospholipid desorption, as a measure of the strength of interlipid interactions, from "donor" lipid vesicles was determined. This was accomplished using (7-nitrobenzo-2-oxa-1,3-diazole-4-yl)aminohexanoate (C6-NBD) labeled phospholipids, the rate of desorption being followed from changes in fluorescence with time. The rates of desorption of the NBD-phospholipids from phosphatidylcholine (PC) donor vesicles was in the order phosphatidylcholine (PC) > phosphatidylserine (PS) > phosphatidylethanolamine (PE), the slower rates in the PS and PE reflecting direct interlipid hydrogen bonding. For PC, the interlipid hydrogen bonding was restricted to the "hydration layer", the network of hydrogen-bonded water molecules extending between phospholipid head groups. The rate of C6-NBD-PC desorption was elevated with higher levels of donor PC sn-2 unsaturation, due the increased head group spacing weakening the lipid-lipid interactions that occur via the hydration layer. Ethanol also increased the rate of NBD-phospholipid desorption from donor PC vesicles in the order PC > PS > PE, showing that PC interactions, here limited to the weaker hydrogen-bonded water molecule network, were more susceptible compared to stronger, direct interlipid hydrogen bonds involving PE and PS. The relative magnitude of the ethanol-induced increase in the desorption rate was amplified with higher levels of donor lipid sn-2 unsaturation. Cholesterol had little effect on the rate of phospholipid desorption.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. The cooperative interaction between vitamin E and vitamin C in suppression of peroxidation of membrane phospholipids

    Energy Technology Data Exchange (ETDEWEB)

    Leung, H.W.; Vang, M.J.; Mavis, R.D.

    1981-01-01

    The time course of peroxidation of rat liver microsomes by FeSO/sub 4/ in the presence of ascorbate showed a delay in the onset of peroxidation compared to the time course when NADPH replaced ascorbate as the electron donor. The delay was consistent with an antioxidant function of ascorbate, possibly mediated through endogenous vitamin E. In order to further investigate the cooperation between ascorbate and vitamin E in suppressing lipid peroxidation, a liposomal system containing polyunsaturated phospholipids was used. Peroxidation was initated by ferrous iron at pH 5, where spontaneous oxidation of Fe/sup 2 +/ did not occur and the antioxidant properties of ascorbic acid could be characterized independently of its pro-oxidant properties as a reducer of Fe/sup 3 +/. Ascorbic acid alone at concentrations of 30-100 ..mu..M delayed peroxidation by 20 min and at higher concentrations prevented peroxidation for 60 min. Physiological levels of vitamin E decreased peroxidation at early time points but the vitamin was apparently consumed during the course of the incubation. The presence of both vitamin C and vitamin E produced suppression of peroxidation at early time points (0-20 min) which was approximately the sum of the individual inhibitions. At longer time points, however, the mixture of antioxidants was much more effective than the sum of both vitamins alone. This suggests that interaction between these antioxidants yields an enhanced delivery of antioxidant protection.

  1. Efficient internalization of TAT peptide in zwitterionic DOPC phospholipid membrane revealed by neutron diffraction.

    Science.gov (United States)

    Chen, Xiaochao; Liu, Shutao; Deme, Bruno; Cristiglio, Viviana; Marquardt, Drew; Weller, Richard; Rao, Pingfan; Wang, Yunqiang; Bradshaw, Jeremy

    2017-05-01

    The aim of this study is to investigate the interactions between TAT peptides and a neutral DOPC bilayer by using neutron lamellar diffraction. The distribution of TAT peptides and the perturbation of water distribution across the DOPC bilayer were revealed. When compared to our previous study on an anionic DOPC/DOPS bilayer (X. Chen et al., Biochim Biophys Acta. 2013. 1828 (8), 1982-1988), a much deeper insertion of TAT peptides was found in the hydrophobic core of DOPC bilayer at a depth of 6.0Å from the center of the bilayer, a position close to the double bond of fatty acyl chain. We conclude that the electrostatic attractions between the positively charged TAT peptides and the negatively charged headgroups of phospholipid are not essential for the direct translocation. Furthermore, the interactions of TAT peptides with the DOPC bilayer were found to vary in a concentration-dependent manner. A limited number of peptides first associate with the phosphate moieties on the lipid headgroups by using the guanidinium ions pairing. Then the energetically favorable water defect structures are adopted to maintain the arginine residues hydrated by drawing water molecules and lipid headgroups into the bilayer core. Such bilayer deformations consequently lead to the deep intercalation of TAT peptides into the bilayer core. Once a threshold concentration of TAT peptide in the bilayer is reached, a significant rearrangement of bilayer will happen and steady-state water pores will form. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Interaction of melittin with mixed phospholipid membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylserine studied by deuterium NMR

    Energy Technology Data Exchange (ETDEWEB)

    Dempsey, C.; Bitbol, M.; Watts, A. (Oxford Univ. (England))

    1989-08-08

    The interaction of bee venom melittin with mixed phospholipid bilayers composed of dimyristoylphosphatidylcholine deuterated in the {alpha}- and {beta}-methylenes of the choline head group (DMPC-d{sub 4}) and dimyristoylphosphatidylserine deuterated in the {alpha}-methylene and {beta}-CH positions of the serine head group (DMPS-d{sub 3}) was studied in ternary mixtures by using deuterium NMR spectroscopy. The changes in the deuterium quadrupole splittings of the head-group deuteriomethylenes of DMPC-d{sub 4} induced by DMPS in binary mixtures were systematically reversed by increasing concentrations of melittin, so that at a melittin concentration of 4 mol % relative to total lipid the deuterium NMR spectrum from DMPC-d{sub 4} in the ternary mixture was similar to the spectrum from pure DMPC-d{sub 4} bilayers. The absence of deuterium NMR signals arising from melittin-bound DMPS in ternary mixtures containing DMPS-d{sub 3} indicates that the reversal by melittin of the effects of DMPS on the quadrupole splittings of DMPC-d{sub 4} results from the response of the choline head group to the net surface charge rather than from phase separation of melittin-DMPS complexes. The similarity in the effects of the two cationic but otherwise dissimilar peptides indicates that the DMPS head group responds to the surface charge resulting from the presence in the bilayer of charged amphiphiles, in a manner analogous to the response of the choline head group of phosphatidylcholine to the bilayer surface charge. The presence of DMPS greatly stabilized DMPC bilayers with respect to melittin-induced micellization, indicating that the latter effect of melittin may not be important for the hemolytic activity of the peptide.

  3. Interaction of melittin with mixed phospholipid membranes composed of dimyristoylphosphatidylcholine and dimyristoylphosphatidylserine studied by deuterium NMR

    International Nuclear Information System (INIS)

    Dempsey, C.; Bitbol, M.; Watts, A.

    1989-01-01

    The interaction of bee venom melittin with mixed phospholipid bilayers composed of dimyristoylphosphatidylcholine deuterated in the α- and β-methylenes of the choline head group (DMPC-d 4 ) and dimyristoylphosphatidylserine deuterated in the α-methylene and β-CH positions of the serine head group (DMPS-d 3 ) was studied in ternary mixtures by using deuterium NMR spectroscopy. The changes in the deuterium quadrupole splittings of the head-group deuteriomethylenes of DMPC-d 4 induced by DMPS in binary mixtures were systematically reversed by increasing concentrations of melittin, so that at a melittin concentration of 4 mol % relative to total lipid the deuterium NMR spectrum from DMPC-d 4 in the ternary mixture was similar to the spectrum from pure DMPC-d 4 bilayers. The absence of deuterium NMR signals arising from melittin-bound DMPS in ternary mixtures containing DMPS-d 3 indicates that the reversal by melittin of the effects of DMPS on the quadrupole splittings of DMPC-d 4 results from the response of the choline head group to the net surface charge rather than from phase separation of melittin-DMPS complexes. The similarity in the effects of the two cationic but otherwise dissimilar peptides indicates that the DMPS head group responds to the surface charge resulting from the presence in the bilayer of charged amphiphiles, in a manner analogous to the response of the choline head group of phosphatidylcholine to the bilayer surface charge. The presence of DMPS greatly stabilized DMPC bilayers with respect to melittin-induced micellization, indicating that the latter effect of melittin may not be important for the hemolytic activity of the peptide

  4. Composition and metabolism of phospholipids in Octopus vulgaris and Sepia officinalis hatchlings.

    Science.gov (United States)

    Reis, Diana B; Acosta, Nieves G; Almansa, Eduardo; Tocher, Douglas R; Andrade, José P; Sykes, António V; Rodríguez, Covadonga

    2016-10-01

    The objective of the present study was to characterise the fatty acid (FA) profiles of the major phospholipids, of Octopus vulgaris and Sepia officinalis hatchlings, namely phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE); and to evaluate the capability of both cephalopod species on dietary phospholipid remodelling. Thus, O. vulgaris and S. officinalis hatchlings were in vivo incubated with 0.3μM of L-∝-1-palmitoyl-2-[1-(14)C]arachidonyl-PC or L-∝-1-palmitoyl-2-[1-(14)C]arachidonyl-PE. Octopus and cuttlefish hatchlings phospholipids showed a characteristic FA profiles with PC presenting high contents of 16:0 and 22:6n-3 (DHA); PS having high 18:0, DHA and 20:5n-3 (EPA); PI a high content of saturated FA; and PE showing high contents of DHA and EPA. Interestingly, the highest content of 20:4n-6 (ARA) was found in PE rather than PI. Irrespective of the phospholipid in which [1-(14)C]ARA was initially bound (either PC or PE), the esterification pattern of [1-(14)C]ARA in octopus lipids was similar to that found in their tissues with high esterification of this FA into PE. In contrast, in cuttlefish hatchlings [1-(14)C]ARA was mainly recovered in the same phospholipid that was provided. These results showed a characteristic FA profiles in the major phospholipids of the two species, as well as a contrasting capability to remodel dietary phospholipids, which may suggest a difference in phospholipase activities. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Effect of acute nitrogen dioxide exposure on the composition of fatty acid associated with phospholipids in alveolar lavage

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, T.; Noguchi, T.; Kikuno, M.; Kubota, K.

    1984-01-01

    In vivo exposure of rats to 10 ppm nitrogen dioxide (NO/sub 2/) for 12 h caused changes in fatty acids composition of alveolar lavage phospholipids. Among the fatty acid species, the relative ratio of palmitic acid, myristic acid and palmitoleic acid increased significantly. While the relative ratio of stearic acid, oleic acid, linoleic acid and arachidonic acid decreased significantly. Both the increase in the incorporation of palmitic acid in phosphatidylcholine which would be released into the alveoli and the increase in the release of phosphatidylcholine into the alveoli may account for the changes in the fatty acid composition of the present findings. 12 references, 2 figures, 1 table.

  6. Effect of acute nitrogen dioxide exposure on the composition of fatty acid associated with phospholipids in alveolar lavage

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, T.; Noguchi, T.; Kikuno, M.; Kubota, K.

    1984-01-01

    In vivo exposure of rats to 10 ppm nitrogen dioxide (NO/sub 2/) for 12 h caused changes in fatty acids composition of alveolar lavage phospholipids. Among the fatty acid species, the relative ratio of palmitic acid, myristic acid and palmitoleic acid increased significantly. While the relative ratio of stearic acid, oleic acid, linoleic acid and arachidonic acid decreased significantly. Both the increase in the incorporation of palmitic acid in phosphatidylcholine which would be released into the alveoli and the increase in the release of phosphatidylcholine into the alveoli may account for the changes in the fatty acid composition of the present findings.

  7. Butter making from caprine creams: effect of washing treatment on phospholipids and milk fat globule membrane proteins distribution.

    Science.gov (United States)

    Lamothe, Sophie; Robitaille, Gilles; St-Gelais, Daniel; Britten, Michel

    2008-11-01

    A washing treatment was applied to caprine cream before churning in order to improve phospholipids and MFGM protein purification from buttermilk and butter serum. Cream obtained from a first separation was diluted with water and separated a second time using pilot plant equipment. Regular and washed creams were churned to produce buttermilk and butter, from which butter serum was extracted. The washing treatment allowed a significant decrease of the casein content. As a result, the phospholipids-to-protein ratios in washed buttermilk and butter serum were markedly increased by 2.1 and 1.7-folds respectively, which represents an advantage for the production of phospholipids concentrates. However, when compared with bovine cream, lower phospholipids-to-protein ratios were observed when the washing treatment was applied to caprine cream. A higher concentration of MFGM protein and a lower retention of phospholipids during washing treatment are responsible for the lower phospholipids-to-protein ratios in buttermilk and butter serum obtained from caprine cream. The phospholipids distribution in the butter making process was similar to the one obtained from bovine regular and washed cream. Phospholipids were preferentially concentrated in the butter serum rather than the buttermilk fraction. This simple approach permitted the production of caprine and bovine butter sera extracts containing up to 180 and 240 g phospholipids/kg sera, respectively, on a dry basis.

  8. Polymer-SnO2 composite membranes

    DEFF Research Database (Denmark)

    Nørgaard, Casper Frydendal; Skou, Eivind Morten

    When designing sulfonic acid based ionomers, high ion exchange capacity (IEC) comes at the expense of the mechanical properties. With too high IEC, the membrane will excessively swell or even dissolve in water. Therefore a suitable compromise must be found between high charge carrier concentration...... and adequate mechanical properties. It has been demonstrated that this compromise can be found at higher IEC when the mechanical properties are improved by increasing crystallinity, increasing molecular weight, crosslinking or reinforcement of the membrane by dispersion of interacting particles therein....... This work utilizes the latter approach and makes use of particles of tin dioxide (SnO2). Polymer-SnO2 composite membranes were successfully prepared using an ion-exchange method. SnO2 was incorporated into membranes by ion-exchange in solutions of SnCl2 ∙ 2 H2O in methanol, followed by oxidation to SnO2...

  9. Interactions of Borneol with DPPC Phospholipid Membranes: A Molecular Dynamics Simulation Study

    Directory of Open Access Journals (Sweden)

    Qianqian Yin

    2014-11-01

    Full Text Available Borneol, known as a “guide” drug in traditional Chinese medicine, is widely used as a natural penetration enhancer in modern clinical applications. Despite a large number of experimental studies on borneol’s penetration enhancing effect, the molecular basis of its action on bio-membranes is still unclear. We carried out a series of coarse-grained molecular dynamics simulations with the borneol concentration ranging from 3.31% to 54.59% (v/v, lipid-free basis to study the interactions of borneol with aDPPC(1,2-dipalmitoylsn-glycero-3-phosphatidylcholine bilayer membrane, and the temperature effects were also considered. At concentrations below 21.89%, borneol’s presence only caused DPPC bilayer thinning and an increase in fluidity; A rise in temperature could promote the diffusing progress of borneol. When the concentration was 21.89% or above, inverted micelle-like structures were formed within the bilayer interior, which led to increased bilayer thickness, and an optimum temperature was found for the interaction of borneol with the DPPC bilayer membrane. These findings revealed that the choice of optimal concentration and temperature is critical for a given application in which borneol is used as a penetration enhancer. Our results not only clarify some molecular basis for borneol’s penetration enhancing effects, but also provide some guidance for the development and applications of new preparations containing borneol.

  10. Effect of spermine on the activity of synaptosomal plasma membrane Ca(2+)-ATPase reconstituted in neutral or acidic phospholipids.

    Science.gov (United States)

    Palacios, Javier; Sepúlveda, M Rosario; Salvador, J M; Mata, Ana M

    2003-04-01

    The activity of purified plasma membrane Ca(2+)-ATPase (PMCA) from pig brain was inhibited by spermine (a naturally occurring and highly abundant polycation in brain). The level of inhibition was dependent on the phospholipid used for reconstitution as well as on the intact or truncated state of the enzyme. An IC(50) value of 12.5 mM spermine was obtained for both, the intact protein plus calmodulin and the trypsin-digested protein, reconstituted in phosphatidylcholine (PC). In the absence of calmodulin the intact Ca(2+)-ATPase gave an IC(50) of 27 mM. This form was more sensitive to spermine inhibition when it was reconstituted with phosphatidylserine (PS), showing an IC(50) value of 2.5 mM spermine. However, the truncated form was less responsive to spermine inhibition, having an IC(50) value of 12.5 mM. Spermine has no effect on the affinity of the PMCA for Ca(2+) or ATP, but its effect on the protein is pH-dependent. It is suggested that spermine could bind to negatively charged residues on the ATPase with different accessibility, depending on the structural rearrangement of the protein. Further, when the protein is reconstituted in PS, spermine also binds to the lipid.

  11. Antioxidant effect of 4-nerolidylcatechol and α-tocopherol in erythrocyte ghost membranes and phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, K.S.; Silva, A.H.M.; Mendanha, S.A. [Instituto de Física, Universidade Federal de Goiás, Goiânia, GO (Brazil); Rezende, K.R. [Laboratório de Biofarmácia e Farmacocinética de Substâncias Bioativas, Faculdade de Farmácia, Universidade Federal de Goiás, Goiânia, GO (Brazil); Alonso, A. [Instituto de Física, Universidade Federal de Goiás, Goiânia, GO (Brazil)

    2013-09-06

    4-Nerolidylcatechol (4-NC) is found in Pothomorphe umbellata root extracts and is reported to have a topical protective effect against UVB radiation-induced skin damage, toxicity in melanoma cell lines, and antimalarial activity. We report a comparative study of the antioxidant activity of 4-NC and α-tocopherol against lipid peroxidation initiated by two free radical-generating systems: 2,2′-azobis(2-aminopropane) hydrochloride (AAPH) and FeSO{sub 4}/H{sub 2}O{sub 2}, in red blood cell ghost membranes and in egg phosphatidylcholine (PC) vesicles. Lipid peroxidation was monitored by membrane fluidity changes assessed by electron paramagnetic resonance spectroscopy of a spin-labeled lipid and by the formation of thiobarbituric acid-reactive substances. When lipoperoxidation was initiated by the hydroxyl radical in erythrocyte ghost membranes, both 4-NC and α-tocopherol acted in a very efficient manner. However, lower activities were observed when lipoperoxidation was initiated by the peroxyl radical; and, in this case, the protective effect of α-tocopherol was lower than that of 4-NC. In egg PC vesicles, malondialdehyde formation indicated that 4-NC was effective against lipoperoxidation initiated by both AAPH and FeSO{sub 4}/H{sub 2}O{sub 2}, whereas α-tocopherol was less efficient in protecting against lipoperoxidation by AAPH, and behaved as a pro-oxidant for FeSO{sub 4}/H{sub 2}O{sub 2}. The DPPH (2,2-diphenyl-1-picrylhydrazyl) free-radical assay indicated that two free radicals were scavenged per 4-NC molecule, and one free radical was scavenged per α-tocopherol molecule. These data provide new insights into the antioxidant capacity of 4-NC, which may have therapeutic applications for formulations designed to protect the skin from sunlight irradiation.

  12. Biophysical study of resin acid effects on phospholipid membrane structure and properties

    DEFF Research Database (Denmark)

    Jagalski, Vivien; Barker, Robert; Topgaard, Daniel

    2016-01-01

    Hydrophobic resin acids (RAs) are synthesized by conifer trees as part of their defense mechanisms. One of the functions of RAs in plant defense is suggested to be the perturbation of the cellular membrane. However, there is a vast diversity of chemical structures within this class of molecules......, and there are no clear correlations to the molecular mechanisms behind the RA's toxicity. In this study we unravel the molecular interactions of the three closely related RAs dehydroabietic acid, neoabietic acid, and the synthetic analogue dichlorodehydroabietic acid with dipalmitoylphosphatidylcholine (DPPC) model...... are correlated with the physical chemical properties of the RA and their toxicity....

  13. Contribution of the Tyr-1 in Plantaricin149a to Disrupt Phospholipid Model Membranes

    Directory of Open Access Journals (Sweden)

    Georgina Tonarelli

    2013-06-01

    Full Text Available Plantaricin149a (Pln149a is a cationic antimicrobial peptide, which was suggested to cause membrane destabilization via the carpet mechanism. The mode of action proposed to this antimicrobial peptide describes the induction of an amphipathic α-helix from Ala7 to Lys20, while the N-terminus residues remain in a coil conformation after binding. To better investigate this assumption, the purpose of this study was to determine the contributions of the Tyr1 in Pln149a in the binding to model membranes to promote its destabilization. The Tyr to Ser substitution increased the dissociation constant (KD of the antimicrobial peptide from the liposomes (approximately three-fold higher, and decreased the enthalpy of binding to anionic vesicles from −17.2 kcal/mol to −10.2 kcal/mol. The peptide adsorption/incorporation into the negatively charged lipid vesicles was less effective with the Tyr1 substitution and peptide Pln149a perturbed the liposome integrity more than the analog, Pln149S. Taken together, the peptide-lipid interactions that govern the Pln149a antimicrobial activity are found not only in the amphipathic helix, but also in the N-terminus residues, which take part in enthalpic contributions due to the allocation at a lipid-aqueous interface.

  14. Hybrid, Nanoscale Phospholipid/Block Copolymer Vesicles

    Directory of Open Access Journals (Sweden)

    Bo Liedberg

    2013-09-01

    Full Text Available Hybrid phospholipid/block copolymer vesicles, in which the polymeric membrane is blended with phospholipids, display interesting self-assembly behavior, incorporating the robustness and chemical versatility of polymersomes with the softness and biocompatibility of liposomes. Such structures can be conveniently characterized by preparing giant unilamellar vesicles (GUVs via electroformation. Here, we are interested in exploring the self-assembly and properties of the analogous nanoscale hybrid vesicles (ca. 100 nm in diameter of the same composition prepared by film-hydration and extrusion. We show that the self-assembly and content-release behavior of nanoscale polybutadiene-b-poly(ethylene oxide (PB-PEO/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC hybrid phospholipid/block copolymer vesicles can be tuned by the mixing ratio of the amphiphiles. In brief, these hybrids may provide alternative tools for drug delivery purposes and molecular imaging/sensing applications and clearly open up new avenues for further investigation.

  15. A Novel High Mechanical Property PLGA Composite Matrix Loaded with Nanodiamond-Phospholipid Compound for Bone Tissue Engineering.

    Science.gov (United States)

    Zhang, Fan; Song, Qingxin; Huang, Xuan; Li, Fengning; Wang, Kun; Tang, Yixing; Hou, Canglong; Shen, Hongxing

    2016-01-20

    A potential bone tissue engineering material was produced from a biodegradable polymer, poly(lactic-co-glycolic acid) (PLGA), loaded with nanodiamond phospholipid compound (NDPC) via physical mixing. On the basis of hydrophobic effects and physical absorption, we modified the original hydrophilic surface of the nanodiamond (NDs) with phospholipids to be amphipathic, forming a typical core-shell structure. The ND-phospholipid weight ratio was optimized to generate sample NDPC50 (i.e., ND-phospholipid weight ratio of 100:50), and NDPC50 was able to be dispersed in a PLGA matrix at up to 20 wt %. Compared to a pure PLGA matrix, the introduction of 10 wt % of NDPC (i.e., sample NDPC50-PF10) resulted in a significant improvement in the material's mechanical and surface properties, including a decrease in the water contact angle from 80 to 55°, an approximately 100% increase in the Young's modulus, and an approximate 550% increase in hardness, thus closely resembling that of human cortical bone. As a novel matrix supporting human osteoblast (hFOB1.19) growth, NDPC50-PFs with different amounts of NDPC50 demonstrated no negative effects on cell proliferation and osteogenic differentiation. Furthermore, we focused on the behaviors of NDPC-PFs implanted into mice for 8 weeks and found that NDPC-PFs induced acceptable immune response and can reduce the rapid biodegradation of PLGA matrix. Our results represent the first in vivo research on ND (or NDPC) as nanofillers in a polymer matrix for bone tissue engineering. The high mechanical properties, good in vitro and in vivo biocompatibility, and increased mineralization capability suggest that biodegradable PLGA composite matrices loaded with NDPC may potentially be useful for a variety of biomedical applications, especially bone tissue engineering.

  16. Nanofiber Composite Membranes for Alkaline Fuel Cells: Generation of Compositional, Morphological, and Functional Property Relationships

    Science.gov (United States)

    2015-12-01

    properties of nanofiber composite anion-exchange membranes for alkaline fuel cells. A new membrane fabrication strategy, utilizing polymer fiber...Approved for Public Release; Distribution Unlimited Final Report: Nanofiber Composite Membranes for Alkaline Fuel Cells: Generation of Compositional...Park, NC 27709-2211 nanofibers, electrospinning, composite membranes, alkaline fuel cells REPORT DOCUMENTATION PAGE 11. SPONSOR/MONITOR’S REPORT NUMBER

  17. Comparative characteristics of membrane-active single-chained ether phospholipids: PAF and lyso-PAF in Langmuir monolayers.

    Science.gov (United States)

    Flasiński, Michał; Broniatowski, Marcin; Wydro, Paweł; Dynarowicz-Łątka, Patrycja

    2012-03-15

    1-O-Octadecyl-2-acetyl-sn-glycero-3-phosphocholine (PAF) and its deacetylated precursor (lyso-PAF) are membrane-active single-chained ether phospholipids, which play an important signaling role in different physiological processes. There is strong evidence that one of the possible mechanisms of PAF and lyso-PAF activity is connected with their direct influence on biomembranes. Although both lipids have very similar structure, their biological activity is very different and in some cases even antagonistic. Unfortunately, there is a lack of the studies correlating these observations with the molecular structure of both compounds. Therefore, we decided to apply model systems and advanced physicochemical methods to explore this subject and look for the reasons of the observed discrepancies. As a model system, we prepared Langmuir monolayers of PAF and lyso-PAF at the air/water interface. The physicochemical characteristic of the model membranes under different experimental conditions was performed with the application of the Langmuir monolayer technique, Brewster angle microscopy, and the methods based on synchrotron radiation scattering (XR and GIXD). Both compounds form stable Langmuir monolayers, in which the lipid molecules are strongly immersed into the water subphase. The monolayers have expanded character, meaning that the hydrophobic tails are considerably tilted and disordered. Similarly to biochemical studies, also in our model systems, profound differences in the properties of PAF and lyso-PAF were observed. Contrary to PAF, the lyso-PAF molecules express the propensity to form organized, periodical structures in the model membranes. It is manifested in the phase transition observed in the course of the lyso-PAF π-A isotherm which was correlated with the diffraction signal registered with the application of the GIXD method. The formation of 2D domains of hexagonal ordering of the film forming molecules was observed only for the lyso precursor. The observed

  18. Finite element method (FEM) model of the mechanical stress on phospholipid membranes from shock waves produced in nanosecond electric pulses (nsEP)

    Science.gov (United States)

    Barnes, Ronald; Roth, Caleb C.; Shadaram, Mehdi; Beier, Hope; Ibey, Bennett L.

    2015-03-01

    The underlying mechanism(s) responsible for nanoporation of phospholipid membranes by nanosecond pulsed electric fields (nsEP) remains unknown. The passage of a high electric field through a conductive medium creates two primary contributing factors that may induce poration: the electric field interaction at the membrane and the shockwave produced from electrostriction of a polar submersion medium exposed to an electric field. Previous work has focused on the electric field interaction at the cell membrane, through such models as the transport lattice method. Our objective is to model the shock wave cell membrane interaction induced from the density perturbation formed at the rising edge of a high voltage pulse in a polar liquid resulting in a shock wave propagating away from the electrode toward the cell membrane. Utilizing previous data from cell membrane mechanical parameters, and nsEP generated shockwave parameters, an acoustic shock wave model based on the Helmholtz equation for sound pressure was developed and coupled to a cell membrane model with finite-element modeling in COMSOL. The acoustic structure interaction model was developed to illustrate the harmonic membrane displacements and stresses resulting from shockwave and membrane interaction based on Hooke's law. Poration is predicted by utilizing membrane mechanical breakdown parameters including cortical stress limits and hydrostatic pressure gradients.

  19. Quinoline biodegradation by filamentous fungus Cunninghamella elegans and adaptive modifications of the fungal membrane composition.

    Science.gov (United States)

    Felczak, Aleksandra; Bernat, Przemysław; Różalska, Sylwia; Lisowska, Katarzyna

    2016-05-01

    Quinoline, which belongs to N-heterocyclic compounds, occurs naturally in the environment and is used in numerous industrial processes. The structures of various chemicals, such as dyes and medicines, are based on this compound. Due to that fact, quinoline and its derivatives are widely distributed in environment and can exert toxic effects on organisms from different trophic levels. The ability of the filamentous fungus Cunninghamella elegans IM 1785/21Gp to degrade quinoline and modulate the membrane composition in response to the pollutant was studied. C. elegans IM 1785/21Gp removes quinoline with high efficiency and transforms the pollutant into two novel hydroxylated derivatives, 2-hydroxyquinoline and 3-hydroxyquinoline. Moreover, due to the disruption in the membrane stability by quinoline, C. elegans IM 1785/21Gp modulates the fatty acid composition and phospholipid profile.

  20. Herpes simplex viruses activate phospholipid scramblase to redistribute phosphatidylserines and Akt to the outer leaflet of the plasma membrane and promote viral entry.

    Science.gov (United States)

    Cheshenko, Natalia; Pierce, Carl; Herold, Betsy C

    2018-01-01

    Herpes simplex virus (HSV) entry is associated with Akt translocation to the outer leaflet of the plasma membrane to promote a complex signaling cascade. We hypothesized that phospholipid scramblase-1 (PLSCR1), a calcium responsive enzyme that flips phosphatidylserines between membrane leaflets, might redistribute Akt to the outside during entry. Confocal imaging, biotinylation of membrane proteins and flow cytometric analysis demonstrated that HSV activates PLSCR1 and flips phosphatidylserines and Akt to the outside shortly following HSV-1 or HSV-2 exposure. Translocation was blocked by addition of a cell permeable calcium chelator, pharmacological scramblase antagonist, or transfection with small interfering RNA targeting PLSCR1. Co-immunoprecipitation and proximity ligation studies demonstrated that PLSCR1 associated with glycoprotein L at the outer leaflet and studies with gL deletion viruses indicate that this interaction facilitates subsequent restoration of the plasma membrane architecture. Ionomycin, a calcium ionophore, also induced PLSCR1 activation resulting in Akt externalization, suggesting a previously unrecognized biological phenomenon.

  1. Adaptational changes in cellular phospholipids and fatty acid composition of the food pathogen Listeria monocytogenes as a stress response to disinfectant sanitizer benzalkonium chloride.

    Science.gov (United States)

    Bisbiroulas, P; Psylou, M; Iliopoulou, I; Diakogiannis, I; Berberi, A; Mastronicolis, S K

    2011-03-01

    This study provides a first approach to observing the alterations of the cell membrane lipids in the adaptation response of Listeria monocytogenes to the sanitizer benzalkonium chloride. A thorough investigation of the composition of polar and neutral lipids from L. monocytogenes grown when exposed to benzalkonium chloride is compared to cells optimally grown. The adaptation mechanism of L. monocytogenes in the presence of benzalkonium chloride caused (i) an increase in saturated-chain fatty acids (mainly C(16:0) and C(18:0) ) and unsaturated fatty acids (mainly C(16:1) and C(18:1) ) at the expense of branched-chain fatty acids (mainly C(a-15:0) and C(a-17:0) ) mainly because of neutral fatty acids; (ii) no alteration in the percentage of neutral and polar lipid content among total lipids; (iii) a decrease in lipid phosphorus and (iv) an obvious increase in the anionic phospholipids and a decrease in the amphiphilic phosphoaminolipid. These lipid changes could lead to decreased membrane fluidity and also to modifications of physicochemical properties of cell surface and thus changes in bacterial adhesion to abiotic surfaces. The adaptation and resistance of L. monocytogenes to disinfectants is able to change its physiology to allow growth in food-processing plants. Understanding microbial stress response mechanisms would improve the effective use of disinfectants. © 2011 The Authors. Letters in Applied Microbiology © 2011 The Society for Applied Microbiology.

  2. Effects of phosphonium-based ionic liquids on phospholipid membranes studied by small-angle X-ray scattering

    Czech Academy of Sciences Publication Activity Database

    Kontro, I.; Svedström, K.; Duša, Filip; Ahvenainen, P.; Ruokonen, S. K.; Witos, J.; Wiedmer, S. K.

    2016-01-01

    Roč. 201, DEC (2016), s. 59-66 ISSN 0009-3084 Institutional support: RVO:68081715 Keywords : phospholipids * x-ray scattering Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 3.361, year: 2016

  3. Phospholipid fatty acid composition of microorganisms in pine forest soils of Central Siberia

    Czech Academy of Sciences Publication Activity Database

    Evgrafova, S.Yu.; Šantrůčková, H.; Shibistova, O.B.; Elhottová, Dana; Černá, B.; Zrazhevskaya, G.K.; Lloyd, D.

    2008-01-01

    Roč. 35, č. 5 (2008), s. 452-458 ISSN 1062-3590 Grant - others:Evropská unie(XE) 03-55-1344; Ministry of Education and Science of the Russian Federation(RU) RUX0-002-KR-06 Institutional research plan: CEZ:AV0Z60660521 Keywords : phospholipid fatty acid * microorganisms * pine forest soils Subject RIV: EH - Ecology, Behaviour Impact factor: 0.082, year: 2008

  4. Characterisation of the membrane affinity of an isoniazide peptide conjugate by tensiometry, atomic force microscopy and sum-frequency vibrational spectroscopy, using a phospholipid Langmuir monolayer model.

    Science.gov (United States)

    Hill, Katalin; Pénzes, Csanád Botond; Schnöller, Donát; Horváti, Kata; Bosze, Szilvia; Hudecz, Ferenc; Keszthelyi, Tamás; Kiss, Eva

    2010-10-07

    Tensiometry, sum-frequency vibrational spectroscopy, and atomic force microscopy were employed to assess the cell penetration ability of a peptide conjugate of the antituberculotic agent isoniazide. Isoniazide was conjugated to peptide (91)SEFAYGSFVRTVSLPV(106), a functional T-cell epitope of the immunodominant 16 kDa protein of Mycobacterium tuberculosis. As a simple but versatile model of the cell membrane a phospholipid Langmuir monolayer at the liquid/air interface was used. Changes induced in the structure of the phospholipid monolayer by injection of the peptide conjugate into the subphase were followed by tensiometry and sum-frequency vibrational spectroscopy. The drug penetrated lipid films were transferred to a solid support by the Langmuir-Blodgett technique, and their structures were characterized by atomic force microscopy. Peptide conjugation was found to strongly enhance the cell penetration ability of isoniazide.

  5. Effect of long-term aluminum feeding on lipid/phospholipid profiles of rat brain myelin

    Directory of Open Access Journals (Sweden)

    Dave Kunjan R

    2004-06-01

    Full Text Available Abstract Effect of long-term (90–100 days exposure of rats to soluble salt of aluminum (AlCl3 on myelin lipid profile was examined. The long-term exposure to AlCl3 resulted in a 60 % decrease in the total phospholipid (TPL content while the cholesterol (CHL content increased by 55 %. Consequently the TPL / CHL molar ratio decreased significantly by 62 %. The phospholipid composition of the myelin membrane changed drastically; the proportion of practically all the phospholipid classes decreased by 32 to 60 % except for phosphatidylcholine (PC and phosphatidylethanolamine (PE. Of the latter two, proportion of PC was unchanged while PE increased in proportion by 47 %. Quantitatively, all phospholipid classes decreased by from 42 to 76% with no change in the PE content. However the membrane fluidity was not altered in Al-treated rats. Many of the changes we observe here show striking similarities with the reported phospholipid profiles of Alzheimer brains.

  6. Structural Interpretation of the Large Slowdown of Water Dynamics at Stacked Phospholipid Membranes for Decreasing Hydration Level: All-Atom Molecular Dynamics

    Directory of Open Access Journals (Sweden)

    Carles Calero

    2016-04-01

    Full Text Available Hydration water determines the stability and function of phospholipid membranes as well as the interaction of membranes with other molecules. Experiments and simulations have shown that water dynamics slows down dramatically as the hydration decreases, suggesting that the interfacial water that dominates the average dynamics at low hydration is slower than water away from the membrane. Here, based on all-atom molecular dynamics simulations, we provide an interpretation of the slowdown of interfacial water in terms of the structure and dynamics of water–water and water–lipid hydrogen bonds (HBs. We calculate the rotational and translational slowdown of the dynamics of water confined in stacked phospholipid membranes at different levels of hydration, from completely hydrated to poorly hydrated membranes. For all hydrations, we analyze the distribution of HBs and find that water–lipids HBs last longer than water–water HBs and that at low hydration most of the water is in the interior of the membrane. We also show that water–water HBs become more persistent as the hydration is lowered. We attribute this effect (i to HBs between water molecules that form, in turn, persistent HBs with lipids; (ii to the hindering of the H-bonding switching between water molecules due to the lower water density at the interface; and (iii to the higher probability of water–lipid HBs as the hydration decreases. Our interpretation of the large dynamic slowdown in water under dehydration is potentially relevant in understanding membrane biophysics at different hydration levels.

  7. Ultrastructure and lipid composition of detergent-resistant membranes derived from mammalian sperm and two types of epithelial cells.

    Science.gov (United States)

    van Gestel, Renske A; Brouwers, Jos F; Ultee, Anton; Helms, J Bernd; Gadella, Bart M

    2016-01-01

    Lipid rafts are micro-domains of ordered lipids (Lo phase) in biological membranes. The Lo phase of cellular membranes can be isolated from disordered lipids (Ld phase) after treatment with 1 % Triton  X-100 at 4 °C in which the Lo phase forms the detergent-resistant membrane (DRM) fraction. The lipid composition of DRM derived from Madin-Darby canine kidney (MDCK) cells, McArdle cells and porcine sperm is compared with that of the whole cell. Remarkably, the unsaturation and chain length degree of aliphatic chains attached to phospholipids is virtually the same between DRM and whole cells. Cholesterol and sphingomyelin were enriched in DRMs but to a cell-specific molar ratio. Sulfatides (sphingolipids from MDCK cells) were enriched in the DRM while a seminolipid (an alkylacylglycerolipid from sperm) was depleted from the DRM. Treatment with DRM without affecting the composition and amount of the phospholipid while higher levels disrupted the DRM. The substantial amount of (poly)unsaturated phospholipids in DRMs as well as a low stoichiometric amount of cholesterol suggest that lipid rafts in biological membranes are more fluid and dynamic than previously anticipated. Using negative staining, ultrastructural features of DRM were monitored and in all three cell types the DRMs appeared as multi-lamellar vesicular structures with a similar morphology. The detergent resistance is a result of protein-cholesterol and sphingolipid interactions allowing a relatively passive attraction of phospholipids to maintain the Lo phase. For this special issue, the relevance of our findings is discussed in a sperm physiological context.

  8. Impact of oxidized phospholipids on the structural and dynamic organization of phospholipid membranes: a combined DSC and solid state NMR study

    Czech Academy of Sciences Publication Activity Database

    Wallgren, M.; Beranová, Lenka; Pham, Q. D.; Linh, K.; Lidman, M.; Procek, J.; Cyprych, K.; Kinnunen, P. K. J.; Hof, Martin; Gröbner, G.

    2013-01-01

    Roč. 161, DEC 2013 (2013), s. 499-513 ISSN 1359-6640 R&D Projects: GA AV ČR GEMEM/09/E006 Institutional support: RVO:61388955 Keywords : ACYL-CHAIN REVERSAL * MOLECULAR SIMULATIONS * LIPID-MEMBRANES Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.194, year: 2013

  9. A change in the composition of supramolecular DNA-bound phospholipids in thymus and liver of gamma-irradiated rats

    International Nuclear Information System (INIS)

    Krasichkova, Z.I.; Strazhevskaya, N.B.

    1984-01-01

    The composition of supramolecular DNA (SM DNA)-bound phospholipids (PL) of thymus and liver of intact rats and those 2 min, 2, 6 and 24 h after γ-irradiation (9.7 Gy) was studied. In norm, supramolecular DNA of the thymus was shown to contain 6.7 μg PL/mg DNA, and that of the liver, 6.1 μg PL/mg DNA, the main components of PL being cardiolipin (CL) and phosphatidylethanolamine (PEA). Substantial changes were detected in the PL composition of SM DNA of γ,irradiated rat organs. During the postirradiation period the concentration of PEA and CL in thymus SM DNA changed symbatically and irreversibly decAeased to traces; whereas in SM DNA of the liver, their concentrations changed antibatically and decreased only to a definite level thus maintaining the necessary ''lipid volume''. It was shown that PL were not restored in SM DNA of the radiopesistant liver

  10. Direct interaction between EgFABP1, a fatty acid binding protein from Echinococcus granulosus, and phospholipid membranes.

    Directory of Open Access Journals (Sweden)

    Jorge L Porfido

    Full Text Available Growth and maintenance of hydatid cysts produced by Echinococcus granulosus have a high requirement for host lipids for biosynthetic processes, membrane building and possibly cellular and developmental signalling. This requires a high degree of lipid trafficking facilitated by lipid transporter proteins. Members of the fatty acid binding protein (FABP family have been identified in Echinococcus granulosus, one of which, EgFABP1 is expressed at the tegumental level in the protoscoleces, but it has also been described in both hydatid cyst fluid and secretions of protoscoleces. In spite of a considerable amount of structural and biophysical information on the FABPs in general, their specific functions remain mysterious.We have investigated the way in which EgFABP1 may interact with membranes using a variety of fluorescence-based techniques and artificial small unilamellar vesicles. We first found that bacterial recombinant EgFABP1 is loaded with fatty acids from the synthesising bacteria, and that fatty acid binding increases its resistance to proteinases, possibly due to subtle conformational changes induced on EgFABP1. By manipulating the composition of lipid vesicles and the ionic environment, we found that EgFABP1 interacts with membranes in a direct contact, collisional, manner to exchange ligand, involving both ionic and hydrophobic interactions. Moreover, we observed that the protein can compete with cytochrome c for association with the surface of small unilamellar vesicles (SUVs.This work constitutes a first approach to the understanding of protein-membrane interactions of EgFABP1. The results suggest that this protein may be actively involved in the exchange and transport of fatty acids between different membranes and cellular compartments within the parasite.

  11. Liver phospholipids fatty acids composition in response to different types of diets in rats of both sexes.

    Science.gov (United States)

    Ranković, Slavica; Popović, Tamara; Martačić, Jasmina Debeljak; Petrović, Snježana; Tomić, Mirko; Ignjatović, Đurđica; Tovilović-Kovačević, Gordana; Glibetić, Maria

    2017-05-19

    Dietary intake influence changes in fatty acids (FA) profiles in liver which plays a central role in fatty acid metabolism, triacylglycerol synthesis and energy homeostasis. We investigated the effects of 4-weeks treatment with milk- and fish-based diet, on plasma biochemical parameters and FA composition of liver phospholipids (PL) in rats of both sexes. Adult, 4 months old, Wistar rats of both sexes, were fed with different types of diets: standard, milk-based and fish-based, during 4 weeks. Analytical characterization of different foods was done. Biochemical parameters in plasma were determined. Fatty acid composition was analyzed by gas-chromatography. Statistical significance of FA levels was tested with two-way analysis of variance (ANOVA) using the sex of animals and treatment (type of diet) as factors on logarithmic or trigonometric transformed data. Our results showed that both, milk- and fish-based diet, changed the composition and ratio of rat liver phospholipids FA, in gender-specific manner. Initially present sex differences appear to be dietary modulated. Although, applied diets changed the ratio of total saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and polyunsaturated fatty acids (PUFA), and effects were gender specific. Milk-based diet lowered SFA and elevated MUFA in males and increased PUFA in females vs. standard diet. The same diet decreased n-3, increased n-6 and n-6/n-3 ratio in males. Fish-based diet increased n-3, decreased n-6 and n-6/n-3 ratio vs. standard and milk-based diet in females. However, the ratio of individual FA in liver PL was also dietary-influenced, but with gender specific manner. While in females fish-based diet decreased AA (arachidonic acid) increased level of EPA (eicosapentaenoic acid), DPA (docosapentaenoic acid) and DHA (docosahexaenoic acid), the same diet elevated only DHA levels in males. Gender related variations in FA composition of rat liver PL were observed, and results have shown that

  12. Impact of the β-Lactam Resistance Modifier (−-Epicatechin Gallate on the Non-Random Distribution of Phospholipids across the Cytoplasmic Membrane of Staphylococcus aureus

    Directory of Open Access Journals (Sweden)

    Helena Rosado

    2015-07-01

    Full Text Available The polyphenol (−-epicatechin gallate (ECg inserts into the cytoplasmic membrane (CM of methicillin-resistant Staphylococcus aureus (MRSA and reversibly abrogates resistance to β-lactam antibiotics. ECg elicits an increase in MRSA cell size and induces thickened cell walls. As ECg partially delocalizes penicillin-binding protein PBP2 from the septal division site, reduces PBP2 and PBP2a complexation and induces CM remodelling, we examined the impact of ECg membrane intercalation on phospholipid distribution across the CM and determined if ECg affects the equatorial, orthogonal mode of division. The major phospholipids of the staphylococcal CM, lysylphosphatidylglycerol (LPG, phosphatidylglycerol (PG, and cardiolipin (CL, were distributed in highly asymmetric fashion; 95%–97% of LPG was associated with the inner leaflet whereas PG (~90% and CL (~80% were found predominantly in the outer leaflet. ECg elicited small, significant changes in LPG distribution. Atomic force microscopy established that ECg-exposed cells divided in similar fashion to control bacteria, with a thickened band of encircling peptidoglycan representing the most recent plane of cell division, less distinct ribs indicative of previous sites of orthogonal division and concentric rings and “knobbles” representing stages of peptidoglycan remodelling during the cell cycle. Preservation of staphylococcal membrane lipid asymmetry and mode of division in sequential orthogonal planes appear key features of ECg-induced stress.

  13. Membranolytic Activity of Bile Salts: Influence of Biological Membrane Properties and Composition

    Directory of Open Access Journals (Sweden)

    Alfred Blume

    2007-10-01

    Full Text Available The two main steps of the membranolytic activity of detergents: 1 the partitioning of detergent molecules in the membrane and 2 the solubilisation of the membrane are systematically investigated. The interactions of two bile salt molecules, sodium cholate (NaC and sodium deoxycholate (NaDC with biological phospholipid model membranes are considered. The membranolytic activity is analysed as a function of the hydrophobicity of the bile salt, ionic strength, temperature, membrane phase properties, membrane surface charge and composition of the acyl chains of the lipids. The results are derived from calorimetric measurements (ITC, isothermal titration calorimetry. A thermodynamic model is described, taking into consideration electrostatic interactions, which is used for the calculation of the partition coefficient as well as to derive the complete thermodynamic parameters describing the interaction of detergents with biological membranes (change in enthalpy, change in free energy, change in entropy etc. The solubilisation properties are described in a so-called vesicle-to-micelle phase transition diagram. The obtained results are supplemented and confirmed by data obtained from other biophysical techniques (DSC differential scanning calorimetry, DLS dynamic light scattering, SANS small angle neutron scattering.

  14. Effect of wheatgrass on membrane fatty acid composition during hepatotoxicity induced by alcohol and heated PUFA.

    Science.gov (United States)

    Durairaj, Varalakshmi; Shakya, Garima; Pajaniradje, Sankar; Rajagopalan, Rukkumani

    2014-06-01

    Alcoholism is a broad term used for problems related to alcohol, medically considered as disease, specifically an addictive illness, abuse, and dependence. It is the major cause of liver disease in western countries. Alcoholic liver disease encompasses the hepatic alterations leading to fatty liver, hepatitis, and fibrosis or cirrhosis. Fried food items prepared with repeatedly heated polyunsaturated fatty acid (PUFA) exacerbate the disturbances induced by alcohol. The use of herbs to treat diseases is almost universal. Wheatgrass (WG) is used as a supplemental nutrition because of its unique curative properties. As it has antioxidant property, it prevents cancer, diabetes, and acts as liver cleanser. The present study was undertaken to evaluate the efficacy of WG on preserving membrane integrity in liver damage induced by alcohol and heated PUFA (ΔPUFA).The rats were divided into four groups. The animals in group 1 served as normal (standard diet), group 2 served as hepatotoxic (alcohol + ΔPUFA), group 3 served as treated (alcohol + ΔPUFA + WG), and group 4 served as WG control. The compositions of membrane fatty acid, total phospholipids, phospholipase A, C (PLA and PLC) were analyzed in liver to evaluate the effects of WG. Changes in fatty acid composition, decrease in phospholipids levels, and increase in PLA, PLC were observed in the diseased group. Restoration effect was seen in WG-treated rats. Histopathological observations were in correlation with the biochemical parameters. From the results obtained, we conclude that WG effectively protects the liver against alcohol and ΔPUFA-induced changes in fatty acid composition and preserves membrane integrity.

  15. Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer–leaflet and inter-leaflet coupling

    Science.gov (United States)

    Hill, Reghan J.; Wang, Chih-Ying

    2014-01-01

    A variety of observations—sometimes controversial—have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans–Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans–Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer–leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements—including lipids, integral monotopic and polytopic proteins, and lipid rafts—in supported bilayer membranes. PMID:25002822

  16. Diffusion in phospholipid bilayer membranes: dual-leaflet dynamics and the roles of tracer-leaflet and inter-leaflet coupling.

    Science.gov (United States)

    Hill, Reghan J; Wang, Chih-Ying

    2014-07-08

    A variety of observations-sometimes controversial-have been made in recent decades when attempting to elucidate the roles of interfacial slip on tracer diffusion in phospholipid membranes. Evans-Sackmann theory (1988) has furnished membrane viscosities and lubrication-film thicknesses for supported membranes from experimentally measured lateral diffusion coefficients. Similar to the Saffman and Delbrück model, which is the well-known counterpart for freely supported membranes, the bilayer is modelled as a single two-dimensional fluid. However, the Evans-Sackman model cannot interpret the mobilities of monotopic tracers, such as individual lipids or rigidly bound lipid assemblies; neither does it account for tracer-leaflet and inter-leaflet slip. To address these limitations, we solve the model of Wang and Hill, in which two leaflets of a bilayer membrane, a circular tracer and supports are coupled by interfacial friction, using phenomenological friction/slip coefficients. This furnishes an exact solution that can be readily adopted to interpret the mobilities of a variety of mosaic elements-including lipids, integral monotopic and polytopic proteins, and lipid rafts-in supported bilayer membranes.

  17. Dimeric peptides with three different linkers self-assemble with phospholipids to form peptide nanodiscs that stabilize membrane proteins

    DEFF Research Database (Denmark)

    Larsen, Andreas Nørgård; Sørensen, Kasper Kildegaard; Johansen, Nicolai Tidemand

    2016-01-01

    (SEC), circular dichroism (CD) spectroscopy, small-angle scattering (SAS), static light scattering (SLS) and UV-Vis spectroscopy. For all three beltides, MD and combined small-angle X-ray and -neutron scattering were consistent with a disc structure composed by a phospholipid bilayer surrounded...

  18. Shock-induced poration, cholesterol flip-flop and small interfering RNA transfection in a phospholipid membrane: Multimillion atom, microsecond molecular dynamics simulations

    Science.gov (United States)

    Choubey, Amit

    Biological cell membranes provide mechanical stability to cells and understanding their structure, dynamics and mechanics are important biophysics problems. Experiments coupled with computational methods such as molecular dynamics (MD) have provided insight into the physics of membranes. We use long-time and large-scale MD simulations to study the structure, dynamics and mechanical behavior of membranes. We investigate shock-induced collapse of nanobubbles in water using MD simulations based on a reactive force field. We observe a focused jet at the onset of bubble shrinkage and a secondary shock wave upon bubble collapse. The jet length scales linearly with the nanobubble radius, as observed in experiments on micron-to-millimeter size bubbles. Shock induces dramatic structural changes, including an ice-VII-like structural motif at a particle velocity of 1 km/s. The incipient ice VII formation and the calculated Hugoniot curve are in good agreement with experimental results. We also investigate molecular mechanisms of poration in lipid bilayers due to shock-induced collapse of nanobubbles. Our multimillion-atom MD simulations reveal that the jet impact generates shear flow of water on bilayer leaflets and pressure gradients across them. This transiently enhances the bilayer permeability by creating nanopores through which water molecules translocate rapidly across the bilayer. Effects of nanobubble size and temperature on the porosity of lipid bilayers are examined. The second research project focuses on cholesterol (CHOL) dynamics in phospholipid bilayers. Several experimental and computational studies have been performed on lipid bilayers consisting of dipalmitoylphosphatidylcholine (DPPC) and CHOL molecules. CHOL interleaflet transport (flip-flop) plays an important role in interleaflet coupling and determining CHOL flip-flop rate has been elusive. Various studies report that the rate ranges between milliseconds to seconds. We calculate CHOL flip-flop rates by

  19. Serum phospholipid monounsaturated fatty acid composition and Δ-9-desaturase activity are associated with early alteration of fasting glycemic status.

    Science.gov (United States)

    Cho, Jae Sun; Baek, Seung Han; Kim, Ji Young; Lee, Jong Ho; Kim, Oh Yoen

    2014-09-01

    Because alterations in blood fatty acid (FA) composition by dietary lipids are associated with insulin resistance and related metabolic disorders, we hypothesized that serum phospholipid FA composition would reflect the early alteration of fasting glycemic status, even in people without metabolic syndrome (MetS). To examine this hypothesis, serum phospholipid FA, desaturase activities, fasting glycemic status, and cardiometabolic parameters were measured in study participants (n = 1022; 30-69 years; male, n = 527; female, n = 495; nondiabetics without disease) who were stratified into normal fasting glucose (NFG) and impaired fasting glucose (IFG) groups. Total monounsaturated FA (MUFA), oleic acid (OA; 18:1n-9), dihomo-γ-linolenic acid (DGLA; 20:3n-6), Δ-9-desaturase activity (D9D; 18:1n-9/18:0), and DGLA/linoleic acid (20:3n-6/18:2n-6) in serum phospholipids were significantly higher in IFG subjects than NFG controls. Study subjects were subdivided into 4 groups, based on fasting glucose levels and MetS status. Palmitoleic acid (16:1n-7) was highest in IFG-MetS and lowest in NFG-non-MetS subjects. Oleic acid and D9D were higher in IFG-MetS than in the other 3 groups. Dihomo-γ-linolenic acid and DGLA/linoleic acid were higher in MetS than in non-MetS, regardless of fasting glucose levels. The high-sensitivity C-reactive proteins (hs-CRPs) and 8-epi-prostaglandin-F2α were higher in IFG than in NFG, regardless of MetS status. Oxidized low-density lipoproteins were higher in IFG-MetS than in the other 3 groups. Total MUFAs, OA, and D9D were positively correlated with homeostasis model assessment of insulin resistance, fasting glucose, triglyceride, hs-CRP, and 8-epi-prostaglandin-F2α. Palmitoleic acid was positively correlated with triglyceride and hs-CRP. Lastly, total MUFA, OA, palmitoleic acid, and D9D were associated with early alteration of fasting glycemic status, therefore suggesting that these may be useful markers for predicting the risk of type 2

  20. The Optimization of the Oiling Bath Cosmetic Composition Containing Rapeseed Phospholipids and Grapeseed Oil by the Full Factorial Design

    Directory of Open Access Journals (Sweden)

    Michał Górecki

    2015-04-01

    Full Text Available The proper condition of hydrolipid mantle and the stratum corneum intercellular matrix determines effective protection against transepidermal water loss (TEWL. Some chemicals, improper use of cosmetics, poor hygiene, old age and some diseases causes disorder in the mentioned structures and leads to TEWL increase. The aim of this study was to obtain the optimal formulation composition of an oiling bath cosmetic based on rapeseed phospholipids and vegetable oil with high content of polyunsaturated fatty acids. In this work, the composition of oiling bath form was calculated and the degree of oil dispersion after mixing the bath preparation with water was selected as the objective function in the optimizing procedure. The full factorial design 23 in the study was used. The concentrations of rapeseed lecithin ethanol soluble fraction (LESF, alcohol (E and non-ionic emulsifier (P were optimized. Based on the calculations from our results, the optimal composition of oiling bath cosmetic was: L (LESF 5.0 g, E (anhydrous ethanol 20.0 g and P (Polysorbate 85 1.5 g. The optimization procedure used in the study allowed to obtain the oiling bath cosmetic which gives above 60% higher emulsion dispersion degree 5.001 × 10−5 cm−1 compared to the initial formulation composition with the 3.096 × 10−5 cm−1.

  1. [Optimization on preparation of hawthorn fruit total flavonoids-phospholipid complex using Plackett-Burman design, central composite design and response surface methodology].

    Science.gov (United States)

    Shi, Ya-Jun; Wu, Pin-Jiang; Wei, Ping

    2010-03-01

    To choose the optimal conditions for the formation of the complex with total flavonoids in hawthorn fruit and phospholipid. Solvent evaporation process was used to prepare hawthorn total flavonoids phospholipid complex. The evaluation criterion was the complex ratio. The experiment inspected the significance of influential factor of preparation technology by Plackett-Burman design and optimized significance of factor and level with the central composite design. The binomial and linear equations were fitted to the data of overall desirabilities, and the resulting equation was used to produce 3-D response surface graphs, through which the optimal formulation was predicted. The ratio of total flavonoids to phospholipid, flavonoids concentration and reaction temperature had significant influence on the craft. It was showed that the correlation coefficient of second-order quadratic model was high. The correlation coefficient reached 0.9886. The optimum conditions for the preparation of the complex were as follows: phospholipids/total flavonoids was 3 : 1, the temperature was 40 degrees C and the concentration of principal agent was 10 mg/mL The deviation between the result of the best craft verification test and the binomial fitting equation forecast value was less than 2.0%. Response surface methodology is successfully used to optimize the preparation of total flavonoids in hawthorn phospholipid complex. The optimized process is reliable, stable and available for the industrial production.

  2. Structural properties of lipid reconstructs and lipid composition of normotensive and hypertensive rat vascular smooth muscle cell membranes

    Directory of Open Access Journals (Sweden)

    T.R. Oliveira

    2009-09-01

    Full Text Available Multiple cell membrane alterations have been reported to be the cause of various forms of hypertension. The present study focuses on the lipid portion of the membranes, characterizing the microviscosity of membranes reconstituted with lipids extracted from the aorta and mesenteric arteries of spontaneously hypertensive (SHR and normotensive control rat strains (WKY and NWR. Membrane-incorporated phospholipid spin labels were used to monitor the bilayer structure at different depths. The packing of lipids extracted from both aorta and mesenteric arteries of normotensive and hypertensive rats was similar. Lipid extract analysis showed similar phospholipid composition for all membranes. However, cholesterol content was lower in SHR arteries than in normotensive animal arteries. These findings contrast with the fact that the SHR aorta is hyporeactive while the SHR mesenteric artery is hyperreactive to vasopressor agents when compared to the vessels of normotensive animal strains. Hence, factors other than microviscosity of bulk lipids contribute to the vascular smooth muscle reactivity and hypertension of SHR. The excess cholesterol in the arteries of normotensive animal strains apparently is not dissolved in bulk lipids and is not directly related to vascular reactivity since it is present in both the aorta and mesenteric arteries. The lower cholesterol concentrations in SHR arteries may in fact result from metabolic differences due to the hypertensive state or to genes that co-segregate with those that determine hypertension during the process of strain selection.

  3. Sulfonated carbon black-based composite membranes for fuel cell ...

    Indian Academy of Sciences (India)

    Pristine and composite membranes prepared from SPEEK82 decomposed completely in <1 h, which is undesirable for fuel cell applications. SPEEK60 membrane having wt% of 0.25–0.5 with S–C particles led to higher proton conductivity than that of pristine membrane. No positive effect was observed on the properties of ...

  4. 13C-labeled 18 : 2n-6 recovered in brush border membrane phospholipids short time after administration

    DEFF Research Database (Denmark)

    Vistisen, Bodil; Høy, Carl-Erik

    2004-01-01

    The purpose of the present study was to examine the short-term effect of dietary specific structured triacylglycerols (MLM, M = 8:0, L = 18:2n-6), LLL and MMM on the fatty acid composition of brush border membrane (BBM) phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Rats were...... administered intragastrically a bolus of ML*M, M*LM*, L*L*L* or M*M*M* (* = C-13- labeled fatty acid). Rats were decapitated 2 hours and 6 hours later, and the fatty acid composition and C-13-enrichment of BBM-PC and -PE were determined. C-13-enriched 18:2n-6 was observed in BBM-PC after intragastric...... administration of L*L*L* and ML*M, whereas no C-13-labeled fatty acids were recovered after administration of M*LM* or M*M*M*. Interestingly, no C-13-labeled fatty acids were detected in the BBM-PE fraction. This could be due to a lower turnover of PE than PC and to a different ratio of saturated and unsaturated...

  5. Effects of dietary omega-3 and -6 supplementations on phospholipid fatty acid composition in mice uterus during window of pre-implantation.

    Science.gov (United States)

    Fattahi, Amir; Darabi, Masoud; Farzadi, Laya; Salmassi, Ali; Latifi, Zeinab; Mehdizadeh, Amir; Shaaker, Maghsood; Ghasemnejad, Tohid; Roshangar, Leila; Nouri, Mohammad

    2018-03-01

    Since fatty acid composition of uterus phospholipids is likely to influence embryo implantation, this study was conducted to investigate the effects of dietary omega-3 and -6 fatty acids on implantation rate as well as uterine phospholipid fatty acids composition during mice pre-implantation period. Sixty female mice were randomly distributed into:1) control (standard pellet), 2) omega-3 (standard pellet + 10% w/w of omega-3 fatty acids) and 3) omega-6 (standard pellet + 10% w/w of omega-6 fatty acids). Uterine phospholipid fatty acid composition during the pre-implantation window (days 1-5 of pregnancy) was analyzed using gas-chromatography. The implantation rate on the fifth day of pregnancy was also determined. Our results showed that on days 1, 2 and 3 of pregnancy, the levels of arachidonic acid (ARA) as well as total omega-6 fatty acids were significantly higher and the levels of linolenic acid and total omega-3 fatty acids were statistically lower in the omega-6 group compared to the omega-3 group (p omega-6 fatty acids, and poly-unsaturated fatty acids levels were significantly different between the two dietary supplemented groups (p omega-6 fatty acids, especially ARA, with the implantation rate. The present study showed that diets rich in omega-3 and -6 fatty acids could differently modify uterine phospholipid fatty acid composition and uterine levels of phospholipid ARA, and that the total omega-6 fatty acids had a positive association with the implantation rate. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Sulfonated carbon black-based composite membranes for fuel cell

    Indian Academy of Sciences (India)

    Composite membranes were then prepared using S–C as fillers and sulfonated poly(ether ether ketone) (SPEEK) as polymer matrix with three different sulfonation degrees (DS = 60, 70 and 82%). Structure and properties of the composite membranes were characterized by FTIR, TGA, scanning electron microscopy, proton ...

  7. Surface characterization and biological properties study of silicone rubber membrane grafted with phospholipid as biomaterial via plasma induced graft copolymerization.

    Science.gov (United States)

    Hsiue, G H; Lee, S D; Chang, P C; Kao, C Y

    1998-10-01

    Poly(2-methacryloyloxyethyl phosphorylcholine) (pMPC) was grafted onto the surface of a silicon rubber (SR) membrane (pMPC-SR) by plasma induced grafted copolymerization (PIP). Argon plasma was used to activate the SR surfaces. Determination was also made of the influences of grafted copolymerization reaction time, reaction temperature, and monomer concentration on polymerization yield. The surface properties of SR were characterized by ATR-FTIR, ESCA, and SEM. In those analyses the ATR-FTIR spectra indicated that the pMPC grafted onto the SR surface at 1720 and 3300 cm(-1). The elemental composition and different carbon bindings on the surface of the SR were examined by ESCA. An increasing P1s/C1s value g was obtained in the grafted polymerization yield with a concentration of 0.05-0.5M of MPC in the isolated ethanol solution. The surface morphologies of pMPC-SR differed more than those of control and Ar plasma treated surfaces. The difference could have been caused by the homogeneous graft polymerization of pMPC onto the SR membrane. In the biological analyses, protein adsorption on pMPC-SR surfaces was reduced. The reduced level increased with an increase in the pMPC grafted amount. The epithelial cell attachment and growth onto these samples were suppressed. The blood compatibility for a series of pMPC-SR surfaces was examined by platelet adhesion. Blood platelet morphologies in contact with the high ratio of pMPC-SR surfaces were maintained, meaning that in this case the release reaction for platelets never occurred. Consequently, the high amount of pMPC-SR surface had excellent blood compatibility, further suggesting that prevention of adhesion, activation of platelets, and adsorption of blood protein could be achieved.

  8. Competing intermolecular interactions of artemisinin-type agents and aspirin with membrane phospholipids: Combined model mass spectrometry and quantum-chemical study

    International Nuclear Information System (INIS)

    Pashynska, Vlada; Stepanian, Stepan; Gömöry, Agnes; Vekey, Karoly; Adamowicz, Ludwik

    2015-01-01

    Highlights: • Competitive binding of artemisinin agents and aspirin with phospholipids is shown. • Complexation between the antimalarial drugs and aspirin molecules is also found. • Energetically favorable structures of the model complexes are identified by DFT. • Membranotropic activity of the studied drugs can be modified under joint usage. - Abstract: Study of intermolecular interactions of antimalarial artemisinin-type drugs and aspirin with membrane phospholipids is important in term of elucidation of the drugs activity modification under their joint usage. Combined experimental and computational study of the interaction of dihydroartemisinin, α-artemether, and artesunate with aspirin (ASP) and dipalmitoylphosphatidylcholine (DPPC) is performed by electrospray ionization (ESI) mass spectrometry and by DFT B3LYP/aug-cc-pVDZ methods. The results of the ESI investigation of systems containing artemisinin-type agent, ASP and DPPC, reveal a competition between the antimalarial agents and ASP for binding with DPPC molecules. The complexation between the antimalarial drugs and ASP is also found. Observed phenomena suggest that membranotropic activity of artemisin-type agents and aspirin is modified under their combined usage. To elucidate structure-energy characteristics of the non-covalent complexes studied the model DFT calculations are performed for dihydroartemisinin · ASP complex and complexes of the each drug with phosphatidylcholine head of DPPC in neutral and cationized forms

  9. Competing intermolecular interactions of artemisinin-type agents and aspirin with membrane phospholipids: Combined model mass spectrometry and quantum-chemical study

    Energy Technology Data Exchange (ETDEWEB)

    Pashynska, Vlada, E-mail: vlada@vl.kharkov.ua [B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, Lenin Ave., 47, 61103 Kharkov (Ukraine); Stepanian, Stepan [B.Verkin Institute for Low Temperature Physics and Engineering of the National Academy of Sciences of Ukraine, Lenin Ave., 47, 61103 Kharkov (Ukraine); Gömöry, Agnes; Vekey, Karoly [Institute of Organic Chemistry of Research Centre for Natural Sciences of the Hungarian Academy of Sciences, Magyar tudosok korutja, 2, Budapest H-1117 (Hungary); Adamowicz, Ludwik [University of Arizona, Department of Chemistry and Biochemistry, Tucson, AZ 85721 (United States)

    2015-07-09

    Highlights: • Competitive binding of artemisinin agents and aspirin with phospholipids is shown. • Complexation between the antimalarial drugs and aspirin molecules is also found. • Energetically favorable structures of the model complexes are identified by DFT. • Membranotropic activity of the studied drugs can be modified under joint usage. - Abstract: Study of intermolecular interactions of antimalarial artemisinin-type drugs and aspirin with membrane phospholipids is important in term of elucidation of the drugs activity modification under their joint usage. Combined experimental and computational study of the interaction of dihydroartemisinin, α-artemether, and artesunate with aspirin (ASP) and dipalmitoylphosphatidylcholine (DPPC) is performed by electrospray ionization (ESI) mass spectrometry and by DFT B3LYP/aug-cc-pVDZ methods. The results of the ESI investigation of systems containing artemisinin-type agent, ASP and DPPC, reveal a competition between the antimalarial agents and ASP for binding with DPPC molecules. The complexation between the antimalarial drugs and ASP is also found. Observed phenomena suggest that membranotropic activity of artemisin-type agents and aspirin is modified under their combined usage. To elucidate structure-energy characteristics of the non-covalent complexes studied the model DFT calculations are performed for dihydroartemisinin · ASP complex and complexes of the each drug with phosphatidylcholine head of DPPC in neutral and cationized forms.

  10. Omega-3 supplementation alters mitochondrial membrane composition and respiration kinetics in human skeletal muscle.

    Science.gov (United States)

    Herbst, E A F; Paglialunga, S; Gerling, C; Whitfield, J; Mukai, K; Chabowski, A; Heigenhauser, G J F; Spriet, L L; Holloway, G P

    2014-03-15

    Studies have shown increased incorporation of omega-3 fatty acids into whole skeletal muscle following supplementation, although little has been done to investigate the potential impact on the fatty acid composition of mitochondrial membranes and the functional consequences on mitochondrial bioenergetics. Therefore, we supplemented young healthy male subjects (n = 18) with fish oils [2 g eicosapentaenoic acid (EPA) and 1 g docosahexanoic acid (DHA) per day] for 12 weeks and skeletal muscle biopsies were taken prior to (Pre) and following (Post) supplementation for the analysis of mitochondrial membrane phospholipid composition and various assessments of mitochondrial bioenergetics. Total EPA and DHA content in mitochondrial membranes increased (P respiration, determined in permeabilized muscle fibres, demonstrated no change in maximal substrate-supported respiration, or in the sensitivity (apparent Km) and maximal capacity for pyruvate-supported respiration. In contrast, mitochondrial responses during ADP titrations demonstrated an enhanced ADP sensitivity (decreased apparent Km) that was independent of the creatine kinase shuttle. As the content of ANT1, ANT2, and subunits of the electron transport chain were unaltered by supplementation, these data suggest that prolonged omega-3 intake improves ADP kinetics in human skeletal muscle mitochondria through alterations in membrane structure and/or post-translational modification of ATP synthase and ANT isoforms. Omega-3 supplementation also increased the capacity for mitochondrial reactive oxygen species emission without altering the content of oxidative products, suggesting the absence of oxidative damage. The current data strongly emphasize a role for omega-3s in reorganizing the composition of mitochondrial membranes while promoting improvements in ADP sensitivity.

  11. High performance thin-film composite forward osmosis membrane.

    Science.gov (United States)

    Yip, Ngai Yin; Tiraferri, Alberto; Phillip, William A; Schiffman, Jessica D; Elimelech, Menachem

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 mum) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m(2-)h(-1), while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution.

  12. High Performance Thin-Film Composite Forward Osmosis Membrane

    KAUST Repository

    Yip, Ngai Yin

    2010-05-15

    Recent studies show that osmotically driven membrane processes may be a viable technology for desalination, water and wastewater treatment, and power generation. However, the absence of a membrane designed for such processes is a significant obstacle hindering further advancements of this technology. This work presents the development of a high performance thin-film composite membrane for forward osmosis applications. The membrane consists of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation onto a thin (40 μm) polyester nonwoven fabric. By careful selection of the polysulfone casting solution (i.e., polymer concentration and solvent composition) and tailoring the casting process, we produced a support layer with a mix of finger-like and sponge-like morphologies that give significantly enhanced membrane performance. The structure and performance of the new thin-film composite forward osmosis membrane are compared with those of commercial membranes. Using a 1.5 M NaCl draw solution and a pure water feed, the fabricated membranes produced water fluxes exceeding 18 L m2-h-1, while consistently maintaining observed salt rejection greater than 97%. The high water flux of the fabricated thin-film composite forward osmosis membranes was directly related to the thickness, porosity, tortuosity, and pore structure of the polysulfone support layer. Furthermore, membrane performance did not degrade after prolonged exposure to an ammonium bicarbonate draw solution. © 2010 American Chemical Society.

  13. Dicarboxylic phospholipids and irradiated biomembranes

    International Nuclear Information System (INIS)

    Dousset, Nicole.

    1977-01-01

    It was decided to study the effects of ionizing radiations on biomembranes, with special reference to erythrocytes and liver microsomes representing two kinds of membrane very common in nature. Diacid phospholipids were observed at these membranes and the results are reported in part one of this work. It appeared essential to examine as far as possible the metabolism, in vitro and in animals, of these diacids and to find out whether certain harmful effects of radiations on the proteins (membrane permeability changes and enzyme inactivation) could be due to the action of these newly formed compounds. The study of acid compounds formed under irradiation was limited to nonanal-9-oic acid and azelaic acid. Part two deals with the incorporation of acid and diacid compounds into lipids and the effects of diacid phospholipids on the membrane permeability. A chapter is devoted to the changes in certain enzyme activities brought about by diacid phospholipids [fr

  14. Development of composite membranes of PVA-TEOS doped KOH for alkaline membrane fuel cell

    International Nuclear Information System (INIS)

    Haryadi,; Sugianto, D.; Ristopan, E.

    2015-01-01

    Anion exchange membranes (AEMs) play an important role in separating fuel and oxygen (or air) in the Alkaline Membrane Fuel Cells. Preparation of hybrid organic inorganic materials of Polyvinylalcohol (PVA) - Tetraethylorthosilicate (TEOS) composite membrane doped KOH for direct alcohol alkaline fuel cell application has been investigated. The sol-gel method has been used to prepare the composite membrane of PVA-TEOS through crosslinking step and catalyzed by concentrated of hydrochloric acid. The gel solution was cast on the membrane plastic plate to obtain membrane sheets. The dry membranes were then doped by immersing in various concentrations of KOH solutions for about 4 hours. Investigations of the cross-linking process and the presence of hydroxyl group were conducted by FTIR as shown for frequency at about 1600 cm −1 and 3300 cm −1 respectively. The degree of swelling in ethanol decreased as the KOH concentration for membrane soaking process increased. The ion exchange capacity (IEC) of the membrane was 0.25meq/g. This composite membranes display significant ionic conductivity of 3.23 x 10 −2 S/cm in deionized water at room temperature. In addition, the morphology observation by scanning electron microscope (SEM) of the membrane indicates that soaking process of membrane in KOH increased thermal resistant

  15. Cell signalling and phospholipid metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Boss, W.F.

    1990-01-01

    These studies explored whether phosphoinositide (PI) has a role in plants analogous to its role in animal cells. Although no parallel activity of PI in signal transduction was found in plant cells, activity of inositol phospholipid kinase was found to be modulated by light and by cell wall degrading enzymes. These studies indicate a major role for inositol phospholipids in plant growth and development as membrane effectors but not as a source of second messengers.

  16. Modulation of intestinal brush border membrane chemical composition during postnatal development in rats: effect of gestational diabetes.

    Science.gov (United States)

    Sharma, Ruchi; Chauhan, Shailender Singh; Mahmood, Akhtar

    2012-01-01

    There was a significant increase in fucose (52%), total hexoses (16%) and hexosamine (56%) except sialic acid, which was reduced (77%) in the microvillus membrane of infants born to rat mothers made diabetic by injecting alloxan on day 3 of gestation. Expressed on the protein basis there were a significant increase in membrane, triglyceride, total cholesterol, and phospholipids content of brush border in pups from diabetic group between 5-45 days of postnatal age. Intestinal morphology in diabetic group showed, regression of tubular glands, distorted cellular organization of mucosal cells, reduction in the mucosal cell height and number of secretory goblet cells. These findings suggest that the gestational diabetes affects the sugar and lipid composition of the intestinal brush border membrane in rats during early stages of the postnatal development, which may be associated with compromised tissue functions later in life.

  17. ZirfonR-composite membranes: properties and applications

    International Nuclear Information System (INIS)

    Leysen, R.; Doyen, W.; Adriansen, W.; Vermeiren, Ph.

    1993-01-01

    In this report, the fabrication and the applications of a new type of composite membrane, the zirconium-oxide-polysulphone membrane (registered trade mark name: Zirfon), are described. The investigated Zirfon membranes are fabricated by the film casting technique and are composed of zirconium oxide powder and a polymeric binder, polysulphone. Zirfon membranes have been developed first for use as separators in electrochemical applications (e.g. alkaline water electrolysis and alkaline fuel cells). Besides their applications in electrochemical systems, Zirfon membranes have been tested as separating membranes for several ultrafiltration purposes. The most recent application of Zirfon membranes is their use for the removal of heavy metals in waste streams by means of incorporated bacteria. In this application, micro-organisms are immobilized on the porous structure of the membrane. Potential future applications are in the field of energy production (fuel cells) and the treatment of non-nuclear or nuclear waste water. (A.S.)

  18. Polybenzimidazole and sulfonated polyhedral oligosilsesquioxane composite membranes for high temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    Aili, David; Allward, Todd; Alfaro, Silvia Martinez

    2014-01-01

    Composite membranes based on poly(2,2′(m-phenylene)-5,5́bibenzimidazole) (PBI) and sulfonated polyhedral oligosilsesquioxane (S-POSS) with S-POSS contents of 5 and 10wt.% were prepared by solution casting as base materials for high temperature polymer electrolyte membrane fuel cells. With membranes...... based on pure PBI as a reference point, the composite membranes were characterized with respect to spectroscopic and physicochemical properties. After doping with phosphoric acid, the composite membranes showed considerably improved ex situ proton conductivity under anhydrous as well as under fully...... humidified conditions in the 120-180°C temperature range. The conductivity improvements were also confirmed by in situ fuel cell tests at 160°C and further supported by the electrochemical impedance spectroscopy data based on the operating membrane electrode assemblies, demonstrating the technical...

  19. Membrane distillation : a new approach using composite membranes

    NARCIS (Netherlands)

    Franken, Antonius Christianus Maria

    1988-01-01

    In this thesis several aspects of the membrane distillation process and the thermally driven pervaporation process have been described. Both processes differ essentially from each other as far as their mechanism of separation and their applicability is concerned. From a practical point of view,

  20. The CDC50A extracellular domain is required for forming a functional complex with and chaperoning phospholipid flippases to the plasma membrane.

    Science.gov (United States)

    Segawa, Katsumori; Kurata, Sachiko; Nagata, Shigekazu

    2018-02-09

    Flippases are enzymes that translocate phosphatidylserine (PtdSer) and phosphatidylethanolamine (PtdEtn) from the outer to the inner leaflet in the lipid bilayer of the plasma membrane, leading to the asymmetric distribution of aminophospholipids in the membrane. One mammalian phospholipid flippase at the plasma membrane is ATP11C, a type IV P-type ATPase (P4-ATPase) that forms a heterocomplex with the transmembrane protein CDC50A. However, the structural features in CDC50A that support the function of ATP11C and other P4-ATPases have not been characterized. Here, using error-prone PCR-mediated mutagenesis of human CDC50A cDNA followed by functional screening and deep sequencing, we identified 14 amino acid residues that affect ATP11C's flippase activity. These residues were all located in CDC50A's extracellular domain and were evolutionarily well-conserved. Most of the mutations decreased CDC50A's ability to chaperone ATP11C and other P4-ATPases to their destinations. The CDC50A mutants failed to form a stable complex with ATP11C and could not induce ATP11C's PtdSer-dependent ATPase activity. Notably, one mutant variant could form a stable complex with ATP11C and transfer ATP11C to the plasma membrane, yet the ATP11C complexed with this CDC50A variant had very weak or little PtdSer- or PtdEtn-dependent ATPase activity. These results indicated that the extracellular domain of CDC50A has important roles both in CDC50A's ability to chaperone ATP11C to the plasma membrane and in inducing ATP11C's ATP hydrolysis-coupled flippase activity. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Fatty acid desaturase (FADS gene polymorphisms and insulin resistance in association with serum phospholipid polyunsaturated fatty acid composition in healthy Korean men: cross-sectional study

    Directory of Open Access Journals (Sweden)

    Yang Long In

    2011-04-01

    Full Text Available Abstract Background We investigated the relationship between fatty acid desaturase (FADS gene polymorphisms and insulin resistance (IR in association with serum phospholipid polyunsaturated fatty acid (FA composition in healthy Korean men. Methods Healthy men (n = 576, 30 ~ 79 years old were genotyped for rs174537 near FADS1 (FEN1-10154G>T, FADS2 (rs174575C>G, rs2727270C>T, and FADS3 (rs1000778C>T SNPs. Dietary intake, serum phospholipid FA composition and HOMA-IR were measured. Results Fasting insulin and HOMA-IR were significantly higher in the rs174575G allele carriers than the CC homozygotes, but lower in the rs2727270T allele carriers than the CC homozygotes. The proportion of linoleic acid (18:2ω-6, LA was higher in the minor allele carriers of FEN1-10154G>T, rs174575C>G and rs2727270C>T than the major homozygotes, respectively. On the other hand, the proportions of dihomo-γ-linolenic acid (20:3ω-6, DGLA and arachidonic acid (20:4ω-6, AA in serum phospholipids were significantly lower in the minor allele carriers of FEN1-10154 G>T carriers and rs2727270C>T than the major homozygotes respectively. AA was also significantly lower in the rs1000778T allele carriers than the CC homozygotes. HOMA-IR positively correlated with LA and DGLA and negatively with AA/DGLA in total subjects. Interestingly, rs174575G allele carriers showed remarkably higher HOMA-IR than the CC homozygotes when subjects had higher proportions of DLGA (≥1.412% in total serum phospholipid FA composition (P for interaction = 0.009 or of AA (≥4.573% (P for interaction = 0.047. Conclusion HOMA-IR is associated with FADS gene cluster as well as with FA composition in serum phospholipids. Additionally, HOMA-IR may be modulated by the interaction between rs174575C>G and the proportion of DGLA or AA in serum phospholipids.

  2. Phospholipids composition and molecular species of large yellow croaker ( Pseudosciaena crocea ) roe

    DEFF Research Database (Denmark)

    Liang, Peng; Li, Ruifen; Sun, He

    2018-01-01

    to analyze and identify the PLs fatty acids compositions and classes in the P. crocea roe, respectively. Docosahexaenoic acid (DHA, C22:6) and eicosapentaenoic acid (EPA, C20:5) account for 35.0% and 6.9% of the PLs. Phosphatidylcholines (PC), lysophosphatidylcholines (LPC), phosphatidylethanolamines (PE......-Q-TOF-MS). A total of 92 PLs molecular species was identified, including 49 PCs, 13 PEs, 10 phosphatidic acids (PAs), 13 phosphatidylserines (PSs), 3 phosphatidylglycerols (PGs), 2 sphingomyelins (SMs), and 2 PIs of the P. crocea roe....

  3. Endurance of Nafion-composite membranes in PEFCs operating at ...

    Indian Academy of Sciences (India)

    Reduced gas-crossover, fast fuel-cell-reaction kinetics and superior performance of the PEFCs with Nafion-SiO2 and Nafion-MZP composite membranes in relation to the PEFC with pristine Nafion-1135 membrane support the long-term operational usage of the former in PEFCs. An 8-cell PEFC stack employing Nafion-SiO2 ...

  4. Stable catalyst layers for hydrogen permeable composite membranes

    Science.gov (United States)

    Way, J. Douglas; Wolden, Colin A

    2014-01-07

    The present invention provides a hydrogen separation membrane based on nanoporous, composite metal carbide or metal sulfide coated membranes capable of high flux and permselectivity for hydrogen without platinum group metals. The present invention is capable of being operated over a broad temperature range, including at elevated temperatures, while maintaining hydrogen selectivity.

  5. Influence of phospholipid environment on the phosphatidylethanolamine: ceramide-phosphorylethanolamine transferase activity in rat liver plasma membranes.

    Science.gov (United States)

    Nikolova, M N; Petkova, D H; Koumanov, K S

    1992-03-01

    1. Plasma membranes were treated with phospholipase A2, phospholipase C or phospholipase D. The phosphatidylethanolamine:ceramide-phosphorylethanolamine transferase was deactivated by phospholipase C treatment, whereas phospholipase A2 and phospholipase D did not affect the enzyme. 2. Incorporation of phosphatidylethanolamine and phosphatidylglycerol into partially delipidated plasma membranes resulted in significant stimulation of the transferase, whereas inclusion of sphingomyelin and phosphatidylserine suppressed the enzyme activity. Our results suggest that phosphatidylserine is a regulator of sphingomyelin level in membranes. 3. The activity of phosphatidylethanolamine:ceramide-phosphorylethanolamine transferase was not influenced by the fluidity of its lipid environment.

  6. Effects of static magnetic fields on growth and membrane lipid composition of Salmonella typhimurium wild-type and dam mutant strains.

    Science.gov (United States)

    Mihoub, Mouadh; El May, Alya; Aloui, Amine; Chatti, Abdelwaheb; Landoulsi, Ahmed

    2012-07-02

    This study was carried out to explore the adaptive mechanisms of S. typhimurium particularly, the implication of the Dam methyltransferase in the remodelling of membrane lipid composition to overcome magnetic field stress. With this aim, we focused our analyses on the increase in viable numbers and membrane lipid modifications of S. typhimurium wild-type and dam mutant cells exposed for 10h to static magnetic fields (SMF; 200 mT). For the wild-type strain, exposure to SMF induced a significant decrease (pdam mutant was significantly affected (pdam mutant strains. SMF significantly affected the phospholipid proportions in the two strains. The most affected were those of the acidic phospholipids, cardiolipins (CL). In the dam strain the phospholipid response to SMF followed a globally similar trend as in the wild-type with however lower effects, leading mainly to an unusual accumulation of CL. This would in part explain the different behavior of the wild-type and the dam strain. Results showed a significant increase of membrane cyclic fatty acids Cyc17 and Cyc19 in the wild-type strain but only the Cyc17 in the dam strain and a meaningful increase of the total unsaturated fatty acids (UFAs) to total saturated fatty acids (SFAs) ratios of the exposed cells compared to controls from 3 to 9h (pdam mutants to maintain an optimum level of membrane fluidity under SMF. Copyright © 2012 Elsevier B.V. All rights reserved.

  7. Fabrication of bioinspired composite nanofiber membranes with robust superhydrophobicity for direct contact membrane distillation.

    Science.gov (United States)

    Liao, Yuan; Wang, Rong; Fane, Anthony G

    2014-06-03

    The practical application of membrane distillation (MD) for water purification is hindered by the absence of desirable membranes that can fulfill the special requirements of the MD process. Compared to the membranes fabricated by other methods, nanofiber membranes produced by electrospinning are of great interest due to their high porosity, low tortuosity, large surface pore size, and high surface hydrophobicity. However, the stable performance of the nanofiber membranes in the MD process is still unsatisfactory. Inspired by the unique structure of the lotus leaf, this study aimed to develop a strategy to construct superhydrophobic composite nanofiber membranes with robust superhydrophobicity and high porosity suitable for use in MD. The newly developed membrane consists of a superhydrophobic silica-PVDF composite selective skin formed on a polyvinylidene fluoride (PVDF) porous nanofiber scaffold via electrospinning. This fabrication method could be easily scaled up due to its simple preparation procedures. The effects of silica diameter and concentration on membrane contact angle, sliding angle, and MD performance were investigated thoroughly. For the first time, the direct contact membrane distillation (DCMD) tests demonstrate that the newly developed membranes are able to present stable high performance over 50 h of testing time, and the superhydrophobic selective layer exhibits excellent durability in ultrasonic treatment and a continuous DCMD test. It is believed that this novel design strategy has great potential for MD membrane fabrication.

  8. Lysosomotropic cationic amphiphilic drugs inhibit adipocyte differentiation in 3T3-L1K cells via accumulation in cells and phospholipid membranes, and inhibition of autophagy.

    Science.gov (United States)

    Kagebeck, Patrik; Nikiforova, Violetta; Brunken, Lars; Easwaranathan, Arrabi; Ruegg, Joelle; Cotgreave, Ian; Munic Kos, Vesna

    2018-04-05

    Some cationic amphiphilic drugs (CADs) have been individually reported to interfere with the differentiation of immune system cells, such as macrophages and dendritic cells. To investigate the possible generic nature of this process, in this study we aimed to see whether these drugs are capable of interfering with the differentiation of adipocytes. Further, we investigated whether this feature might be connected to the lysosomotropic character of these drugs, and their disturbance of intracellular membrane trafficking rather than to the individual pharmacologic properties of each drug. Thus, for the selected set of compounds consisting of seven structurally and pharmacologically diverse CADs and three non-CAD controls we have measured the impact on differentiation of 3T3-L1K murine preadipocytes to adipocytes. We conclude that CADs indeed inhibit adipocyte differentiation, as shown morphologically, at the level of lipid droplet formation and on the expression of genetic markers of adipocytes. Furthermore, the intensity of this inhibitory effect was found to strongly positively correlate with the extent of drug accumulation in adipocytes, with their affinity for phospholipid membranes, as well as with their ability to induce phospholipidosis and inhibit autophagy. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Separation of tritiated water from water using composite membranes

    International Nuclear Information System (INIS)

    Duncan, J.; Nelson, D.

    1996-01-01

    Polymeric composite membranes are being developed to remove tritium from contaminated water at DOE sites. Industrial membrane systems are being developed that have proven to be energy efficient, and membrane technologies such as reverse-osmosis have been well developed for desalination and other industrial/municipal applications. Aromatic polyphosphazene membranes are being investigated because they have excellent radiological, thermal, and chemical stability. The FY 1996 effort is directed toward delineating a potential mechanism, providing a statistical approach to data acquisition, refining a mass balance, and designing a staged array module

  10. Performance modeling of direct contact membrane distillation (DCMD) seawater desalination process using a commercial composite membrane

    KAUST Repository

    Lee, Junggil

    2015-01-10

    This paper presents the development of a rigorous theoretical model to predict the transmembrane flux of a flat sheet hydrophobic composite membrane, comprising both an active layer of polytetrafluoroethylene and a scrim-backing support layer of polypropylene, in the direct contact membrane distillation (DCMD) process. An integrated model includes the mass, momentum, species and energy balances for both retentate and permeate flows, coupled with the mass transfer of water vapor through the composite membrane and the heat transfer across the membrane and through the boundary layers adjacent to the membrane surfaces. Experimental results and model predictions for permeate flux and performance ratio are compared and shown to be in good agreement. The permeate flux through the composite layer can be ignored in the consideration of mass transfer pathways at the composite membrane. The effect of the surface porosity and the thickness of active and support layers on the process performance of composite membrane has also been studied. Among these parameters, surface porosity is identified to be the main factor significantly influencing the permeate flux and performance ratio, while the relative influence of the surface porosity on the performance ratio is less than that on flux.

  11. Zeta-potential of fouled thin film composite membrane

    Energy Technology Data Exchange (ETDEWEB)

    Ikeda, K.; Hachisuka, H.; Nakamura, T. [Nitto denko Corp., Ibaraki, (Japan); Kimura, S. [Kogakuin University, Tokyo (Japan). Dept. of Environ. Chemical Engineering; Ueyama, K. [Osaka University, Osaka (Japan). Dept. of Chemical Engineering

    1999-10-01

    The surface zeta-potential of a cross-linked polyamide thin film composite reverse osmosis membrane was measured using an electrophoresis method. It was confirmed that this method could be effectively applied to analyze the fouling of such membranes. It is known that the water flux of membranes drastically decreases as a result of fouling by surfactants. Although the surfactants adsorbed on reverse osmosis membranes could not be detected by conventional methods such as SEM, EDX and FT-IR, their presence could be clarified by the profile measurements of the surface zeta-potential. The profiles of the membrane surface zeta-potentials changed to more positive values in the measured pH range as a result of fouling by cationic or amphoteric surfactants. This measuring method of surface zeta-potentials allowed us to analyze a very small amount of fouling of a thin film composite reverse osmosis membrane. This method could be used to analyze the fouled surface of the thin film composite reverse osmosis membrane which is used for production of ultrapure water and shows a remarkable decrease in flux. It also became clear that this method is easy and effective for the reverse osmosis membrane surface analysis of adsorbed materials such as surfactants. (author)

  12. MICOS and phospholipid transfer by Ups2–Mdm35 organize membrane lipid synthesis in mitochondria

    Science.gov (United States)

    Aaltonen, Mari J.; Friedman, Jonathan R.; Osman, Christof; Salin, Bénédicte; di Rago, Jean-Paul; Nunnari, Jodi

    2016-01-01

    Mitochondria exert critical functions in cellular lipid metabolism and promote the synthesis of major constituents of cellular membranes, such as phosphatidylethanolamine (PE) and phosphatidylcholine. Here, we demonstrate that the phosphatidylserine decarboxylase Psd1, located in the inner mitochondrial membrane, promotes mitochondrial PE synthesis via two pathways. First, Ups2–Mdm35 complexes (SLMO2–TRIAP1 in humans) serve as phosphatidylserine (PS)-specific lipid transfer proteins in the mitochondrial intermembrane space, allowing formation of PE by Psd1 in the inner membrane. Second, Psd1 decarboxylates PS in the outer membrane in trans, independently of PS transfer by Ups2–Mdm35. This latter pathway requires close apposition between both mitochondrial membranes and the mitochondrial contact site and cristae organizing system (MICOS). In MICOS-deficient cells, limiting PS transfer by Ups2–Mdm35 and reducing mitochondrial PE accumulation preserves mitochondrial respiration and cristae formation. These results link mitochondrial PE metabolism to MICOS, combining functions in protein and lipid homeostasis to preserve mitochondrial structure and function. PMID:27241913

  13. Free fatty acids and esters can be immobilized by receptor rich membranes from torpedo marmorata but not phospholipid acyl chains

    NARCIS (Netherlands)

    Rousselet, A.; Devaux, P.F.; Wirtz, K.W.A.

    1979-01-01

    A long chain spin labeled fatty acid and the corresponding ester have been introduced into receptor rich membranes from Torpedo Marmorata. Superimposed to a mobile component, typical of the lipid phase, a strongly immobilized component is seen on the ESR spectra, both at low temperature (−4°C) and

  14. Aggregation of Oligoarginines at Phospholipid Membranes: Molecular Dynamics Simulations, Time-Dependent Fluorescence Shift, and Biomimetic Colorimetric Assays

    Czech Academy of Sciences Publication Activity Database

    Vazdar, Mario; Wernersson, Erik; Khabiri, Morteza; Cwiklik, Lukasz; Jurkiewicz, Piotr; Hof, Martin; Mann, E.; Kolusheva, S.; Jelinek, R.; Jungwirth, Pavel

    2013-01-01

    Roč. 117, č. 39 (2013), s. 11530-11540 ISSN 1520-6106 R&D Projects: GA MŠk LH12001; GA ČR GBP208/12/G016 Institutional support: RVO:61388963 ; RVO:61388955 Keywords : cell penetrating peptides * oligoarginine * molecular dynamics * membranes * fluorescence spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.377, year: 2013

  15. Molecular aspects of the interaction between Mason-Pfizer monkey virus matrix protein and artificial phospholipid membrane

    Czech Academy of Sciences Publication Activity Database

    Junková, P.; Prchal, J.; Spiwok, V.; Pleskot, Roman; Kadlec, Jan; Krásný, L.; Hynek, R.; Hrabal, R.; Ruml, T.

    2016-01-01

    Roč. 84, č. 11 (2016), s. 1717-1727 ISSN 0887-3585 Institutional support: RVO:61388963 Keywords : covalent labelling * mass spectrometry * multiscale molecular dynamics * protein-membrane interaction * phosphatidylinositol-(4,5)-bisphosphate * liposomes Subject RIV: CE - Biochemistry Impact factor: 2.289, year: 2016

  16. Molecular aspects of the interaction between MasonPfizer monkey virus matrix protein and artificial phospholipid membrane

    Czech Academy of Sciences Publication Activity Database

    Junková, P.; Prchal, J.; Spiwok, V.; Pleskot, Roman; Kadlec, J.; Krásný, Libor; Hynek, R.; Hrabal, R.; Ruml, T.

    2016-01-01

    Roč. 84, č. 11 (2016), s. 1717-1727 ISSN 0887-3585 Institutional support: RVO:61389030 ; RVO:61388971 Keywords : d-type retrovirus * force-field * nucleotide-sequence * myristate exposure * plasma-membrane * rhesus monkey Subject RIV: EB - Genetics ; Molecular Biology; EE - Microbiology, Virology (MBU-M) Impact factor: 2.289, year: 2016

  17. Seasonal changes in the composition of storage and membrane lipids in overwintering larvae of the codling moth, Cydia pomonella.

    Science.gov (United States)

    Rozsypal, Jan; Koštál, Vladimír; Berková, Petra; Zahradníčková, Helena; Simek, Petr

    2014-10-01

    The codling moth (Cydia pomonella) is a major insect pest of apples worldwide. It overwinters as a diapausing fifth instar larva. The overwintering is often a critical part of the insect life-cycle in temperate zone. This study brings detailed analysis of seasonal changes in lipid composition and fluidity in overwintering larvae sampled in the field. Fatty acid composition of triacylglycerol (TG) depots in the fat body and relative proportions of phospholipid (PL) molecular species in biological membranes were analyzed. In addition, temperature of melting (Tm) in TG depots was assessed by using differential scanning calorimetry and the conformational order (fluidity) of PL membranes was analyzed by measuring the anisotropy of fluorescence polarization of diphenylhexatriene probe in membrane vesicles. We observed a significant increase of relative proportion of linoleic acid (C18:2n6) at the expense of palmitic acid (C16:0) in TG depots during the larval transition to diapause accompanied with decreasing melting temperature of total lipids, which might increase the accessibility of depot fats for enzymatic breakdown during overwintering. The fluidity of membranes was maintained very high irrespective of developmental mode or seasonally changing acclimation status of larvae. The seasonal changes in PL composition were relatively small. We discuss these results in light of alternative survival strategies of codling moth larvae (supercooling vs. freezing), variability and low predictability of environmental conditions, and other cold tolerance mechanisms such as extending the supercooling capacity and massive accumulation of cryoprotective metabolites. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Permeation of protons, potassium ions, and small polar molecules through phospholipid bilayers as a function of membrane thickness

    Science.gov (United States)

    Paula, S.; Volkov, A. G.; Van Hoek, A. N.; Haines, T. H.; Deamer, D. W.

    1996-01-01

    Two mechanisms have been proposed to account for solute permeation of lipid bilayers. Partitioning into the hydrophobic phase of the bilayer, followed by diffusion, is accepted by many for the permeation of water and other small neutral solutes, but transient pores have also been proposed to account for both water and ionic solute permeation. These two mechanisms make distinctively different predictions about the permeability coefficient as a function of bilayer thickness. Whereas the solubility-diffusion mechanism predicts only a modest variation related to bilayer thickness, the pore model predicts an exponential relationship. To test these models, we measured the permeability of phospholipid bilayers to protons, potassium ions, water, urea, and glycerol. Bilayers were prepared as liposomes, and thickness was varied systematically by using unsaturated lipids with chain lengths ranging from 14 to 24 carbon atoms. The permeability coefficient of water and neutral polar solutes displayed a modest dependence on bilayer thickness, with an approximately linear fivefold decrease as the carbon number varied from 14 to 24 atoms. In contrast, the permeability to protons and potassium ions decreased sharply by two orders of magnitude between 14 and 18 carbon atoms, and leveled off, when the chain length was further extended to 24 carbon atoms. The results for water and the neutral permeating solutes are best explained by the solubility-diffusion mechanism. The results for protons and potassium ions in shorter-chain lipids are consistent with the transient pore model, but better fit the theoretical line predicted by the solubility-diffusion model at longer chain lengths.

  19. Thin Film Composite Membranes: Mechanical and Antifouling Properties

    Directory of Open Access Journals (Sweden)

    Kassim Shaari Norin Zamiah

    2017-01-01

    Full Text Available As compared to membranes produced from pure polymer or pure inorganic materials, a hybrid membrane possesses better mechanical and thermal properties. This paper reported on the effect of incorporating silica nano-precursor (tetraethylorthosilicate as well as glycerol in the formulation of hybrid membrane on the mechanical properties and antifouling properties of the resultant thin film composite membranes. The mechanical properties were measured in terms of tensile strength, tensile strain and elastic modulus. Whereas for antifouling properties, it was evaluated through the measurements of relative flux decay (RFD and relative flux recovery (RFR, along with the permeate flux rate, percentage glycerol permeated and NaCl rejection. Results showed that the presence of silica and glycerol in hybrid membrane’s formulation had increased the tensile strength and elongation of the resultant membranes. In addition to that, the incorporation of glycerol has resulted in thin film composite with better antifouling properties as compared to the thin film composite with barrier layer from the pure polymer blend. Based on its performance, the fabricated thin film composite has a great potential to be used as a pathway for crude glycerol purification due to some advantages over the existing process that employ membrane.

  20. Hybrid polymer composite membrane for an electromagnetic (EM) valveless micropump

    Science.gov (United States)

    Said, Muzalifah Mohd; Yunas, Jumril; Bais, Badariah; Azlan Hamzah, Azrul; Yeop Majlis, Burhanuddin

    2017-07-01

    In this paper, we report on a hybrid membrane used as an actuator in an electromagnetically driven valveless micropump developed using MEMS processes. The membrane structure consists of the combination of a magnetic polymer composite membrane and an attached bulk permanent magnet which is expected to have a compact structure and a strong magnetic force with maintained membrane flexibility. A soft polymeric material made of polydimethylsiloxane (PDMS) is initially mixed with neodymium magnetic particles (NdFeB) to form a magnetic polymer composite membrane. The membrane is then bonded with the PDMS based microfluidic part, developed using soft lithography process. The developed micropump was tested in terms of the actuator membrane deflection capability and the fluidic flow of the injected fluid sample through the microfluidic channel. The experimental results show that the magnetic composite actuator membrane with an attached bulk permanent magnet is capable of producing a maximum membrane deflection of up to 106 µm. The functionality test of the electromagnetic (EM) actuator for fluid pumping purposes was done by supplying an AC voltage with various amplitudes, signal waves and frequencies. A wide range of sample injection rates from a few µl min-1 to tens of nl min-1 was achieved with a maximum flow rate of 6.6 µl min-1. The injection flow rate of the EM micropump can be controlled by adjusting the voltage amplitude and frequency supplied to the EM coil, to control the membrane deflection in the pump chamber. The designed valveless EM micropump has a very high potential to enhance the drug delivery system capability in biomedical applications.

  1. Outer membrane phospholipase A in phospholipid bilayers: a model system for concerted computational and experimental investigations of amino acid side chain partitioning into lipid bilayers.

    Science.gov (United States)

    Fleming, Patrick J; Freites, J Alfredo; Moon, C Preston; Tobias, Douglas J; Fleming, Karen G

    2012-02-01

    Understanding the forces that stabilize membrane proteins in their native states is one of the contemporary challenges of biophysics. To date, estimates of side chain partitioning free energies from water to the lipid environment show disparate values between experimental and computational measures. Resolving the disparities is particularly important for understanding the energetic contributions of polar and charged side chains to membrane protein function because of the roles these residue types play in many cellular functions. In general, computational free energy estimates of charged side chain partitioning into bilayers are much larger than experimental measurements. However, the lack of a protein-based experimental system that uses bilayers against which to vet these computational predictions has traditionally been a significant drawback. Moon & Fleming recently published a novel hydrophobicity scale that was derived experimentally by using a host-guest strategy to measure the side chain energetic perturbation due to mutation in the context of a native membrane protein inserted into a phospholipid bilayer. These values are still approximately an order of magnitude smaller than computational estimates derived from molecular dynamics calculations from several independent groups. Here we address this discrepancy by showing that the free energy differences between experiment and computation become much smaller if the appropriate comparisons are drawn, which suggests that the two fields may in fact be converging. In addition, we present an initial computational characterization of the Moon & Fleming experimental system used for the hydrophobicity scale: OmpLA in DLPC bilayers. The hydrophobicity scale used OmpLA position 210 as the guest site, and our preliminary results demonstrate that this position is buried in the center of the DLPC membrane, validating its usage in the experimental studies. We further showed that the introduction of charged Arg at position 210

  2. Adsorption of Synthetic Cationic Polymers on Model Phospholipid Membranes: Insight from Atomic-Scale Molecular Dynamics Simulations.

    Science.gov (United States)

    Kostritskii, Andrei Yu; Kondinskaia, Diana A; Nesterenko, Alexey M; Gurtovenko, Andrey A

    2016-10-11

    Although synthetic cationic polymers represent a promising class of effective antibacterial agents, the molecular mechanisms behind their antimicrobial activity remain poorly understood. To this end, we employ atomic-scale molecular dynamics simulations to explore adsorption of several linear cationic polymers of different chemical structure and protonation (polyallylamine (PAA), polyethylenimine (PEI), polyvinylamine (PVA), and poly-l-lysine (PLL)) on model bacterial membranes (4:1 mixture of zwitterionic phosphatidylethanolamine (PE) and anionic phosphatidylglycerol (PG) lipids). Overall, our findings show that binding of polycations to the anionic membrane surface effectively neutralizes its charge, leading to the reorientation of water molecules close to the lipid/water interface and to the partial release of counterions to the water phase. In certain cases, one has even an overcharging of the membrane, which was shown to be a cooperative effect of polymer charges and lipid counterions. Protonated amine groups of polycations are found to interact preferably with head groups of anionic lipids, giving rise to formation of hydrogen bonds and to a noticeable lateral immobilization of the lipids. While all the above findings are mostly defined by the overall charge of a polymer, we found that the polymer architecture also matters. In particular, PVA and PEI are able to accumulate anionic PG lipids on the membrane surface, leading to lipid segregation. In turn, PLL whose charge twice exceeds charges of PVA/PEI does not induce such lipid segregation due to its considerably less compact architecture and relatively long side chains. We also show that partitioning of a polycation into the lipid/water interface is an interplay between its protonation level (the overall charge) and hydrophobicity of the backbone. Therefore, a possible strategy in creating highly efficient antimicrobial polymeric agents could be in tuning these polycation's properties through proper

  3. Temperature and metal exposure affect membrane fatty acid composition and transcription of desaturases and elongases in fathead minnow muscle and brain.

    Science.gov (United States)

    Fadhlaoui, Mariem; Pierron, Fabien; Couture, Patrice

    2018-02-01

    In this study, we tested the hypothesis that metal exposure affected the normal thermal response of cell membrane FA composition and of elongase and desaturase gene transcription levels. To this end, muscle and brain membrane FA composition and FA desaturase (fads2, degs2 and scd2) and elongase (elovl2, elovl5 and elovl6) gene transcription levels were analyzed in fathead minnows (Pimephales promelas) acclimated for eight weeks to 15, 25 or 30°C exposed or not to cadmium (Cd, 6μg/l) or nickel (Ni, 450 6μg/l). The response of membrane FA composition to temperature variations or metal exposure differed between muscle and brain. In muscle, an increase of temperature induced a decrease of polyunsaturated FA (PUFA) and an increase of saturated FA (SFA) in agreement with the current paradigm. Although a similar response was observed in brain between 15 and 25°C, at 30°C, brain membrane unsaturation was higher than predicted. In both tissues, metal exposure affected the normal thermal response of membrane FA composition. The transcription of desaturases and elongases was higher in the brain and varied with acclimation temperature and metal exposure but these variations did not generally reflect changes in membrane FA composition. The mismatch between gene transcription and membrane composition highlights that several levels of control other than gene transcription are involved in adjusting membrane FA composition, including post-transcriptional regulation of elongases and desaturases and de novo phospholipid biosynthesis. Our study also reveals that metal exposure affects the mechanisms involved in adjusting cell membrane FA composition in ectotherms. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Solid polymer electrolyte composite membrane comprising laser micromachined porous support

    Science.gov (United States)

    Liu, Han [Waltham, MA; LaConti, Anthony B [Lynnfield, MA; Mittelsteadt, Cortney K [Natick, MA; McCallum, Thomas J [Ashland, MA

    2011-01-11

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 5 microns, are made by laser micromachining and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  5. High performance hydrophilic pervaporation composite membranes for water desalination

    KAUST Repository

    Liang, Bin

    2014-08-01

    A three-layer thin film nanofibrous pervaporation composite (TFNPVC) membrane was prepared by sequential deposition using electrospraying/electrospinning. The poly(vinyl alcohol) (PVA) top barrier layer was first electrosprayed on aluminum foil and its thickness can be easily controlled by adjusting the collecting time. Next a polyacrylonitrile (PAN) nanofibrous scaffold was deposited by electrospinning as a mid-layer support. A nonwoven PET layer is used to complete the composite membrane. The pervaporation desalination performance of TFNPVC membranes was tested using NaCl solutions at 100. Pa and at room temperature. The TFNPVC membranes show excellent desalination performance (high water flux and salt rejection >. 99.5%) for different salt concentrations with virtually no change in performance after 50. h of operation. © 2014 Elsevier B.V.

  6. A theoretical model for gas permeability in a composite membrane

    International Nuclear Information System (INIS)

    Serrano, D. A

    2009-01-01

    We present in this work an analytical expression for permeability in a two-layer composite membrane, which was derived assuming the same hypothesis as those of Adzumi model for permeability in a homogeneous membrane. Whereas in Adzumi model permeability shows a linear dependence on the mean pressure, our model for a composite membrane related permeability to pressure through a rather complex expression, which covers the whole range of flow, from molecular-Knudsen to viscous-Poiseuille regimes. The expression obtained for permeability contained information of membrane structural properties as pore size, porosity and thickness of each layer, as well as gas nature and operational conditions. Our two-layer-model expression turns into Adzumi formula when the structure of the layers approach to each other. [es

  7. Protein kinase C interaction with calcium: a phospholipid-dependent process.

    LENUS (Irish Health Repository)

    Bazzi, M D

    1990-08-21

    The calcium-binding properties of calcium- and phospholipid-dependent protein kinase C (PKC) were investigated by equilibrium dialysis in the presence and the absence of phospholipids. Calcium binding to PKC displayed striking and unexpected behavior; the free proteins bound virtually no calcium at intracellular calcium concentrations and bound limited calcium (about 1 mol\\/mol of PKC) at 200 microM calcium. However, in the presence of membranes containing acidic phospholipids, PKC bound at least eight calcium ions per protein. The presence of 1 microM phorbol dibutyrate (PDBu) in the dialysis buffer had little effect on these calcium-binding properties. Analysis of PKC-calcium binding by gel filtration under equilibrium conditions gave similar results; only membrane-associated PKC bound significant amounts of calcium. Consequently, PKC is a member of what may be a large group of proteins that bind calcium in a phospholipid-dependent manner. The calcium concentrations needed to induce PKC-membrane binding were similar to those needed for calcium binding (about 40 microM calcium at the midpoint). However, the calcium concentration required for PKC-membrane binding was strongly influenced by the phosphatidylserine composition of the membranes. Membranes with higher percentages of phosphatidylserine required lower concentrations of calcium. These properties suggested that the calcium sites may be generated at the interface between PKC and the membrane. Calcium may function as a bridge between PKC and phospholipids. These studies also suggested that calcium-dependent PKC-membrane binding and PKC function could be regulated by a number of factors in addition to calcium levels and diacylglycerol content of the membrane.

  8. Diapause induces remodeling of the fatty acid composition of membrane and storage lipids in overwintering larvae of Ostrinia nubilalis, Hubn. (Lepidoptera: Crambidae).

    Science.gov (United States)

    Vukašinović, Elvira L; Pond, David W; Worland, M Roger; Kojić, Danijela; Purać, Jelena; Popović, Željko D; Grubor-Lajšić, Gordana

    2015-06-01

    Seasonal changes in the FA composition of triacylglycerols and phospholipids prepared from the whole bodies of non-diapausing and diapausing fifth instar larvae of Ostrinia nubilalis, Hubn. (Lepidoptera: Crambidae) were determined to evaluate the role of these lipids in diapause. Substantial changes in the FA composition of triacylglycerols and phospholipids were triggered by diapause development. This led to a significant increase in the overall FA unsaturation (UFAs/SFAs ratio), attributable to an increase in the relative proportion of MUFAs and the concomitant decrease in PUFAs and SFAs. In triacylglycerols, the significant changes in the FAs composition are the result of an increase in the relative proportions of MUFAs, palmitoleic acid (16:1n-7) and oleic acid (18:1n-9), and a concomitant reduction in the composition of SFAs and PUFAs, mainly palmitic acid (16:0) and linoleic acid (18:2n-6), respectively. Changes in the composition of phospholipids were more subtle with FAs contributing to the overall increase of FA unsaturation. Differential scanning calorimetry (DSC) analysis revealed that the melt transition temperatures of total lipids prepared from whole larvae, primarily attributable to the triacylglycerol component, were significantly lower during the time course of diapause compared with non-diapause. These observations were correlated to the FA composition of triacylglycerols, most likely enabling them to remain functional during colder winter conditions. We conclude that O. nubilalis undergoes remodeling of FA profiles of both energy storage triacylglycerols and membrane phospholipids as an element of its overwintering physiology which may improve the ability to cold harden during diapause. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Carbon nanotubes based nafion composite membranes for fuel cell applications

    CSIR Research Space (South Africa)

    Cele, NP

    2009-01-01

    Full Text Available composite membranes. Keywords: Carbon Nanotubes, Conductivity, Fuel Cell, Nafion, Nanocomposite Membranes, Thermal Properties, Water Uptake FUEL CELLS 00, 0000, No. 0, 1–8 ? 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 ORIGINA L RESEAR CH PAPE... used strategies to overcome these drawbacks is the modification of Nafion by using polymer nanocomposite (PNC) technology. PNCs have recently shown a worldwide growth effort especially in the fabrication of high temperature PEM for fuel cells [18...

  10. Biosynthesis of archaeal membrane ether lipids

    NARCIS (Netherlands)

    Jain, Samta; Caforio, Antonella; Driessen, Arnold J. M.

    2014-01-01

    A vital function of the cell membrane in all living organism is to maintain the membrane permeability barrier and fluidity. The composition of the phospholipid bilayer is distinct in archaea when compared to bacteria and eukarya. In archaea, isoprenoid hydrocarbon side chains are linked via an ether

  11. Conformation of the tridimensional structure of 1,2,3,4,6-pentagalloyl-β-D-glucopyranose (PGG) by (1)H NMR, NOESY and theoretical study and membrane interaction in a simulated phospholipid bilayer: a first insight.

    Science.gov (United States)

    Beretta, Giangiacomo; Artali, Roberto; Caneva, Enrico; Maffei Facino, Roberto

    2011-03-01

    1,2,3,4,6-Penta-O-galloyl-β-D-glucopyranose (PGG) is a polyphenolic compound found in substantial amounts in a number of medicinal herbs. We report (i) its conformational analysis by solution NMR and molecular dynamics calculation and (ii) theoretical study of its interaction with a model membrane bilayer. The galloyl groups B and E appear to play important roles in the interaction with the phospholipid bilayer. Copyright © 2011 John Wiley & Sons, Ltd.

  12. Fabrication and characterization of magnetic nanoparticle composite membranes

    Science.gov (United States)

    Cruickshank, Akeem Armand

    To effectively and accurately deliver drugs within the human body, both new designs and components for implantable micropumps are being studied. Designs must ensure high biocompatibility, drug compatibility, accuracy and small power consumption. The focus of this thesis was to fabricate a prototype magnetic nanoparticle membrane for eventual incorporation into a biomedical pump and then determine the relationship between this membrane deflection and applied pneumatic or magnetic force. The magnetic nanoparticle polymer composite (MNPC) membranes in this study were composed of crosslinked polydimethylsiloxane (PDMS) and iron oxide nanoparticles (IONPs). An optimal iron oxide fabrication route was identified and particle size in each batch was approximately 24.6 nm. Once these nanoparticles were incorporated into a membrane (5 wt. %), the nanoparticle formed agglomerates with an average diameter of 2.26 +/-1.23 microm. Comparisons between the 0 and 5 wt. % loading of particles into the membranes indicated that the elastic modulus of the composite decreased with increasing particle concentration. The pressure- central deflection of the membranes could not be predicated by prior models and variation between magnetic and pneumatic pressure-deflection curves was quantified. Attempts to fabricate membranes with above 5 wt. % nanoparticles were not successful (no gelation). Fourier Transform Infrared (FTIR) spectroscopy results suggest that excess oleic acid on the nanoparticles prior to mixing might have prevented crosslinking.

  13. Characteristics of the influence of auxins on physicochemical properties of membrane phospholipids in monolayers at the air/aqueous solution interface.

    Science.gov (United States)

    Flasiński, Michał; Bartosik, Magdalena; Kowal, Sara; Broniatowski, Marcin; Wydro, Paweł

    2015-12-01

    Interactions between representatives of plant hormones and selected membrane lipids have been studied in monolayers at the air/aqueous solutions interface with π-A isotherm analysis, microscopic visualization and grazing incidence X-ray diffraction technique (GIXD). Four phytohormones: indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), 2-naphthoxyacetic acid (BNOA) and 2,4-dichlorophenoxyacetic acid (2,4-D), belonging to the class of auxins differ as regards the chemical structure of the aromatic molecular fragment. The studied phospholipids have been chosen since they are omnipresent in the biological membranes of plant and animal kingdom. Our results revealed that both natural (IAA and IBA) and synthetic (2,4-D and BNOA) phytohormones modify the physicochemical characteristics of the investigated lipid monolayers. Auxins caused strong diminishing of the monolayer condensation, especially for DPPC and SOPE, which may be attributed to the phase transition in these monolayers. In the performed experiments the key step of auxins action occurs when the molecules interact with monolayers in the expanded state-when the space in the lipid head-group region is large enough to accommodate the molecules of water soluble auxins. The application of GIXD technique confirmed that auxin molecules are also present at the interface at higher surface pressure (30 mN/m). The obtained results showed that among the investigated auxins, the largest influence on the lipid monolayers occurred in the case of BNOA, which molecule possesses the largest aromatic fragment. In contrast, 2,4-D, having the smallest aryl group affects the studied lipid systems to the smallest extent. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Binding of diphtheria toxin to phospholipids in liposomes

    Science.gov (United States)

    Alving, Carl R.; Iglewski, Barbara H.; Urban, Katharine A.; Moss, Joel; Richards, Roberta L.; Sadoff, Jerald C.

    1980-01-01

    Diphtheria toxin bound to the phosphate portion of some, but not all, phospholipids in liposomes. Liposomes consisting of dimyristoyl phosphatidylcholine and cholesterol did not bind toxin. Addition of 20 mol% (compared to dimyristoyl phosphatidylcholine) of dipalmitoyl phosphatidic acid, dicetyl phosphate, phosphatidylinositol phosphate, cardiolipin, or phosphatidylserine in the liposomes resulted in substantial binding of toxin. Inclusion of phosphatidylinositol in dimyristol phosphatidylcholine/cholesterol liposomes did not result in toxin binding. The calcium salt of dipalmitoyl phosphatidic acid was more effective than the sodium salt, and the highest level of binding occurred with liposomes consisting only of dipalmitoyl phosphatidic acid (calcium salt) and cholesterol. Binding of toxin to liposomes was dependent on pH, and the pattern of pH dependence varied with liposomes having different compositions. Incubation of diphtheria toxin with liposomes containing dicetyl phosphate resulted in maximal binding at pH 3.6, whereas binding to liposomes containing phosphatidylinositol phosphate was maximal above pH 7. Toxin did not bind to liposomes containing 20 mol% of a free fatty acid (palmitic acid) or a sulfated lipid (3-sulfogalactosylceramide). Toxin binding to dicetyl phosphate or phosphatidylinositol phosphate was inhibited by UTP, ATP, phosphocholine, or p-nitrophenyl phosphate, but not by uracil. We conclude that (a) diphtheria toxin binds specifically to the phosphate portion of certain phospholipids, (b) binding to phospholipids in liposomes is dependent on pH, but is not due only to electrostatic interaction, and (c) binding may be strongly influenced by the composition of adjacent phospholipids that do not bind toxin. We propose that a minor membrane phospholipid (such as phosphatidylinositol phosphate or phosphatidic acid), or that some other phosphorylated membrane molecule (such as a phosphoprotein) may be important in the initial binding of

  15. Binding of Diphtheria Toxin to Phospholipids in Liposomes

    Science.gov (United States)

    Alving, Carl R.; Iglewski, Barbara H.; Urban, Katharine A.; Moss, Joel; Richards, Roberta L.; Sadoff, Jerald C.

    1980-04-01

    Diphtheria toxin bound to the phosphate portion of some, but not all, phospholipids in liposomes. Liposomes consisting of dimyristoyl phosphatidylcholine and cholesterol did not bind toxin. Addition of 20 mol% (compared to dimyristoyl phosphatidylcholine) of dipalmitoyl phosphatidic acid, dicetyl phosphate, phosphatidylinositol phosphate, cardiolipin, or phosphatidylserine in the liposomes resulted in substantial binding of toxin. Inclusion of phosphatidylinositol in dimyristol phosphatidylcholine / cholesterol liposomes did not result in toxin binding. The calcium salt of dipalmitoyl phosphatidic acid was more effective than the sodium salt, and the highest level of binding occurred with liposomes consisting only of dipalmitoyl phosphatidic acid (calcium salt) and cholesterol. Binding of toxin to liposomes was dependent on pH, and the pattern of pH dependence varied with liposomes having different compositions. Incubation of diphtheria toxin with liposomes containing dicetyl phosphate resulted in maximal binding at pH 3.6, whereas binding to liposomes containing phosphatidylinositol phosphate was maximal above pH 7. Toxin did not bind to liposomes containing 20 mol% of a free fatty acid (palmitic acid) or a sulfated lipid (3-sulfogalactosylceramide). Toxin binding to dicetyl phosphate or phosphatidylinositol phosphate was inhibited by UTP, ATP, phosphocholine, or p-nitrophenyl phosphate, but not by uracil. We conclude that (a) diphtheria toxin binds specifically to the phosphate portion of certain phospholipids, (b) binding to phospholipids in liposomes is dependent on pH, but is not due only to electrostatic interaction, and (c) binding may be strongly influenced by the composition of adjacent phospholipids that do not bind toxin. We propose that a minor membrane phospholipid (such as phosphatidylinositol phosphate or phosphatidic acid), or that some other phosphorylated membrane molecule (such as a phosphoprotein) may be important in the initial binding of

  16. The influence of erythrocyte maturity on ion transport and membrane lipid composition in the rat

    Czech Academy of Sciences Publication Activity Database

    Vokurková, Martina; Rauchová, Hana; Dobešová, Zdenka; Loukotová, Jana; Nováková, O.; Kuneš, Jaroslav; Zicha, Josef

    2016-01-01

    Roč. 65, č. 1 (2016), s. 91-99 ISSN 0862-8408 R&D Projects: GA MZd(CZ) NV15-25396A; GA ČR(CZ) GAP304/12/0259 Institutional support: RVO:67985823 Keywords : reticulocytes * immature erythrocytes * mean cellular hemoglobin content * membrane phospholipids * membrane cholesterol Subject RIV: ED - Physiology Impact factor: 1.461, year: 2016

  17. Composite membranes prepared from cation exchange membranes and polyaniline and their transport properties in electrodialysis

    Energy Technology Data Exchange (ETDEWEB)

    Sata, Tshikatsu; Ishii, Yuuko; Kawamura, Kohei; Matsusaki, Koji [Yamaguchi Univ., Ube City, Yamaguchi (Japan). Dept. of Applied Chemistry and Chemical Engineering

    1999-02-01

    A cation exchange membrane was modified with polyaniline by polymerizing aniline with ammonium peroxodisulfate on the membrane surfaces, producing a membrane with polyaniline layers on both surfaces or a membrane with a single polyaniline layer on the surface. The modified membranes, composite membranes, showed sodium ion permselectivity in electrodialysis compared with divalent cations at an optimum polymerization time. The electronic conductivity of dry membranes showed a maximum (ca. 5 {times} 10{sup {minus}3} S/cm) at the same polymerization time as the time to attain a maximum value of the sodium ion permselectivity. Because emeraldine-based polyaniline is conductive and has a cationic charge, the sodium ion permselectivity is based on the difference in the electrostatic repulsion forces of the cationic charge on the membrane surface of a desalting side to divalent cations and sodium ions. In fact, the selective permeation of sodium ions appeared only when the layer faced the desalting side of the membrane, and was affected by dissociation of polyaniline. Further oxidized polyaniline, pernigraniline-based polyaniline, did not affect the permselectivity between cations, and the diffusion coefficient of neutral molecules, urea, increased with increasing polymerization time. Sodium ion permselectivity was maintained with repeated electrodialysis.

  18. Monte Carlo simulations of the distributions of intra- and extra-vesicular ions and membrane associated charges in hybrid liposomes composed of negatively charged tetraether and zwitterionic diester phospholipids

    Directory of Open Access Journals (Sweden)

    István P. Sugár

    2017-04-01

    Full Text Available Here, we model a negatively charged lipid vesicle, composed of a mixture of bipolar tetraether and diester (or diether phospholipid molecules, by a spherical shell that has zero ion permeability. We take into consideration all the charge-charge interactions between intra-vesicular ions, extra-vesicular ions, and membrane lipid associated charges. Monte Carlo simulations result in homogeneous and double-exponential ion distribution, respectively, in the intra- and extra-vesicular space. The extra-vesicular ion concentration close to the membrane surface is proportional to the total amount of the membrane charges (Nm and is independent of the partitioning of the membrane charges between the outer (Nom and inner membrane (Nim surface. This result shows that one should not disregard the effect of the charges on the inner membrane surface when calculating the ion distributions around a charged vesicle. If the partitioning of the membrane charges is not restricted (i.e., lipid flip-flop is allowed, then at different Nm, the Nom/Nim ratio remains constant and the value of Nom/Nim, as a consequence of the interaction between every charges of the model, is close to, but significantly higher than, the ratio of the outer to the inner surface area of the membrane. These results indicate that the amount and the orientation of the negatively-charged tetraether lipids in the membrane are important determinants of membrane properties in tetraether/zwitterionic diester phospholipid liposomes. Finally we compared the results of our discrete charge model and continuous models based on the solutions of the Poisson-Boltzmann equation and pointed out qualitative similarities and sometimes major quantitative differences between these two types of models.

  19. Herpes simplex virus 1 induces de novo phospholipid synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Sutter, Esther [Electron Microscopy, Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Oliveira, Anna Paula de; Tobler, Kurt [Electron microscopy, Institute of Virology, University of Zuerich (Switzerland); Schraner, Elisabeth M. [Electron Microscopy, Institute of Veterinary Anatomy, University of Zuerich (Switzerland); Sonda, Sabrina [Institute of Parasitology, University of Zuerich (Switzerland); Kaech, Andres [Center for Microscopy and Image Analysis, University of Zuerich (Switzerland); Lucas, Miriam S. [Electron Microscopy ETH Zuerich (EMEZ), Swiss Federal Institute of Technology, Zuerich (Switzerland); Ackermann, Mathias [Electron microscopy, Institute of Virology, University of Zuerich (Switzerland); Wild, Peter, E-mail: pewild@access.uzh.ch [Electron Microscopy, Institute of Veterinary Anatomy, University of Zuerich (Switzerland)

    2012-08-01

    Herpes simplex virus type 1 capsids bud at nuclear membranes and Golgi membranes acquiring an envelope composed of phospholipids. Hence, we measured incorporation of phospholipid precursors into these membranes, and quantified changes in size of cellular compartments by morphometric analysis. Incorporation of [{sup 3}H]-choline into both nuclear and cytoplasmic membranes was significantly enhanced upon infection. [{sup 3}H]-choline was also part of isolated virions even grown in the presence of brefeldin A. Nuclei expanded early in infection. The Golgi complex and vacuoles increased substantially whereas the endoplasmic reticulum enlarged only temporarily. The data suggest that HSV-1 stimulates phospholipid synthesis, and that de novo synthesized phospholipids are inserted into nuclear and cytoplasmic membranes to i) maintain membrane integrity in the course of nuclear and cellular expansion, ii) to supply membrane constituents for envelopment of capsids by budding at nuclear membranes and Golgi membranes, and iii) to provide membranes for formation of transport vacuoles.

  20. Production of hydrogen using composite membrane in PEM water electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Santhi priya, E.L.; Mahender, C.; Mahesh, Naga; Himabindu, V. [Centre for Environment, Institute of Science and Technology, Jawaharlal Nehru Technological University Hyderabad, Kukatpally, Hyderabad-500 085, A.P (India); Anjaneyulu, Y. [Director, TLGVRC, JSU Box 18739, JSU, Jackson, MS 32917-0939 (United States)

    2012-07-01

    Electrolysis of water is the best known technology till today to produce hydrogen. The only practical way to produce hydrogen using renewable energy sources is by proton exchange membrane (PEM) water electrolysis. The most commonly used PEM membrane is Nafion. Composite membrane of TiO2 is synthesized by casting method using Nafion 5wt% solution. RuO2 is used as anode and 10 wt% Pd on activated carbon is used as cathode in the water electrolyser system. The performance of this Composite membrane is studied by varying voltage range 1.8 to 2.6V with respect to hydrogen yield and at current density 0.1, 0.2, 0.3, 0.4, and 0.5(A cm-2). This Composite membrane has been tested using in-house fabricated single cell PEM water electrolysis cell with 10cm2 active area at temperatures ranging from 30,45,65 850c and at 1 atmosphere pressure.

  1. AN INORGANIC COMPOSITE MEMBRANE COMPRISING MOLECULAR SIEVE CRYSTALS

    NARCIS (Netherlands)

    Geus, E.R.; Jansen, J.C.; Jaspers, B.C.; Schoonman, J.; Van Bekkum, H.

    1992-01-01

    Abstract of WO 9213631 (A1) Inorganic composite membrane containing molecular sieve crystals, comprising a macroporous support to which molecular sieve crystals and modifications thereof have been applied substantially as a monolayer, said crystals and modifications thereof having been oriented so

  2. Sulfonated carbon black-based composite membranes for fuel cell ...

    Indian Academy of Sciences (India)

    Sci., Vol. 36, No. 4, August 2013, pp. 563–573. c Indian Academy of Sciences. Sulfonated carbon black-based composite membranes for fuel cell applications .... All data were collected from a second heating cycle and glass tran- sition temperatures (Tg) were calculated as a midpoint of thermogram. 2.5d FTIR studies: FTIR ...

  3. Carbon nanotube embedded PVDF membranes: Effect of solvent composition on the structural morphology for membrane distillation

    Science.gov (United States)

    Mapunda, Edgar C.; Mamba, Bhekie B.; Msagati, Titus A. M.

    2017-08-01

    Rapid population increase, growth in industrial and agricultural sectors and global climate change have added significant pressure on conventional freshwater resources. Tapping freshwater from non-conventional water sources such as desalination and wastewater recycling is considered as sustainable alternative to the fundamental challenges of water scarcity. However, affordable and sustainable technologies need to be applied for the communities to benefit from the treatment of non-conventional water source. Membrane distillation is a potential desalination technology which can be used sustainably for this purpose. In this work multi-walled carbon nanotube embedded polyvinylidene fluoride membranes for application in membrane distillation desalination were prepared via non-solvent induced phase separation method. The casting solution was prepared using mixed solvents (N, N-dimethylacetamide and triethyl phosphate) at varying ratios to study the effect of solvent composition on membrane morphological structures. Membrane morphological features were studied using a number of techniques including scanning electron microscope, atomic force microscope, SAXSpace tensile strength analysis, membrane thickness, porosity and contact angle measurements. It was revealed that membrane hydrophobicity, thickness, tensile strength and surface roughness were increasing as the composition of N, N-dimethylacetamide in the solvent was increasing with maximum values obtained between 40 and 60% N, N-dimethylacetamide. Internal morphological structures were changing from cellular structures to short finger-like and sponge-like pores and finally to large macro void type of pores when the amount of N, N-dimethylacetamide in the solvent was changed from low to high respectively. Multi-walled carbon nanotube embedded polyvinylidene fluoride membranes of desired morphological structures and physical properties can be synthesized by regulating the composition of solvents used to prepare the

  4. Method of making sulfur-resistant composite metal membranes

    Science.gov (United States)

    Way, J Douglas [Boulder, CO; Lusk, Mark [Golden, CO; Thoen, Paul [Littleton, CO

    2012-01-24

    The invention provides thin, hydrogen-permeable, sulfur-resistant membranes formed from palladium or palladium-alloy coatings on porous, ceramic or metal supports. Also disclosed are methods of making these membranes via sequential electroless plating techniques, wherein the method of making the membrane includes decomposing any organic ligands present on the substrate, reducing the palladium crystallites on the substrate to reduced palladium crystallites, depositing a film of palladium metal on the substrate and then depositing a second, gold film on the palladium film. These two metal films are then annealed at a temperature between about 200.degree. C. and about 1200.degree. C. to form a sulfur-resistant, composite PdAu alloy membrane.

  5. Endogenous synthesis of n-3 PUFA modifies fatty acid composition of kidney phospholipids and eicosanoid levels in the fat-1 mouse.

    Science.gov (United States)

    Kelton, D; Lysecki, C; Aukema, H; Anderson, B; Kang, J X; Ma, D W L

    2013-09-01

    The goal of the present study was to determine whether endogenous synthesis of n-3 polyunsaturated fatty acids (PUFA) in the fat-1 mouse is comparable to fish oil feeding with respect to kidney n-3 PUFA composition and eicosanoid levels. Wild-type and heterozygous fat-1 mice, capable of synthesizing n-3 PUFA endogenously, were given diets enriched in either n-3 or n-6 PUFA in a 2×2 factorial design and terminated after 12 weeks. Kidney phospholipid fatty acids were analysed by gas chromatography. Kidney eicosanoids were analysed by liquid chromatography tandem mass spectrometry. Relative to control mice fed n-6 PUFA, n-3 PUFA fed and fat-1 mice had higher levels of kidney phospholipid n-3 PUFA, and lower levels of n-6 PUFA and eicosanoids. However, mice fed n-3 PUFA mice had higher levels of n-3 PUFA and lower levels of eicosanoids as compared to fat-1 mice. In conclusion, diet feeding had a greater impact on kidney fatty acid composition and eicosanoid levels than the genetic effect of the fat-1 gene. However, the fat-1 mouse remains a close approximation that can be used as a complementary model to study the role of n-3 PUFA in the kidney. © 2013 Elsevier Ltd. All rights reserved.

  6. The solubilisation of boar sperm membranes by different detergents - a microscopic, MALDI-TOF MS, 31P NMR and PAGE study on membrane lysis, extraction efficiency, lipid and protein composition

    Directory of Open Access Journals (Sweden)

    Müller Karin

    2009-11-01

    Full Text Available Abstract Background Detergents are often used to isolate proteins, lipids as well as "detergent-resistant membrane domains" (DRMs from cells. Different detergents affect different membrane structures according to their physico-chemical properties. However, the effects of different detergents on membrane lysis of boar spermatozoa and the lipid composition of DRMs prepared from the affected sperm membranes have not been investigated so far. Results Spermatozoa were treated with the selected detergents Pluronic F-127, sodium cholate, CHAPS, Tween 20, Triton X-100 and Brij 96V. Different patterns of membrane disintegration were observed by light and electron microscopy. In accordance with microscopic data, different amounts of lipids and proteins were released from the cells by the different detergents. The biochemical methods to assay the phosphorus and cholesterol contents as well as 31P NMR to determine the phospholipids were not influenced by the presence of detergents since comparable amounts of lipids were detected in the organic extracts from whole cell suspensions after exposure to each detergent. However, matrix-assisted laser desorption and ionization time-of-flight mass spectrometry applied to identify phospholipids was essentially disturbed by the presence of detergents which exerted particular suppression effects on signal intensities. After separation of the membrane fractions released by detergents on a sucrose gradient only Triton X-100 and sodium cholate produced sharp turbid DRM bands. Only membrane solubilisation by Triton X-100 leads to an enrichment of cholesterol, sphingomyelin, phosphatidylinositol and phosphatidylethanolamine in a visible DRM band accompanied by a selective accumulation of proteins. Conclusion The boar sperm membranes are solubilised to a different extent by the used detergents. Particularly, the very unique DRMs isolated after Triton X-100 exposure are interesting candidates for further studies regarding the

  7. Cholesterol rules: direct observation of the coexistence of two fluid phases in native pulmonary surfactant membranes at physiological temperatures

    DEFF Research Database (Denmark)

    Bernardino de la Serna, Jorge; Perez-Gil, Jesus; Simonsen, Adam C

    2004-01-01

    Pulmonary surfactant, the lipid-protein material that stabilizes the respiratory surface of the lungs, contains approximately equimolar amounts of saturated and unsaturated phospholipid species and significant proportions of cholesterol. Such lipid composition suggests that the membranes taking p...

  8. Lipid composition of membrane rafts, isolated with and without detergent, from the spleen of a mouse model of Gaucher disease.

    Science.gov (United States)

    Hattersley, Kathryn J; Hein, Leanne K; Fuller, Maria

    2013-12-06

    Biological membranes are composed of functionally relevant liquid-ordered and liquid-disordered domains that coexist. Within the liquid-ordered domains are low-density microdomains known as rafts with a unique lipid composition that is crucial for their structure and function. Lipid raft composition is altered in sphingolipid storage disorders, and here we determined the lipid composition using a detergent and detergent-free method in spleen tissue, the primary site of pathology, in a mouse model of the sphingolipid storage disorder, Gaucher disease. The accumulating lipid, glucosylceramide, was 30- and 50-fold elevated in the rafts with the detergent and detergent-free method, respectively. Secondary accumulation of di- and trihexosylceramide resided primarily in the rafts with both methods. The phospholipids distributed differently with more than half residing in the rafts with the detergent-free method and less than 10% with the detergent method, with the exception of the fully saturated species that were primarily in the rafts. Individual isoforms of sphingomyelin correlated with detergent-free extraction and more than half resided in the raft fractions. However, this correlation was not seen with the detergent extraction method as sphingomyelin species were spread across both the raft and non-raft domains. Therefore caution must be exercised when interpreting phospholipid distribution in raft domains as it differs considerably depending on the method of isolation. Importantly, both methods revealed the same lipid alterations in the raft domains in the spleen of the Gaucher disease mouse model highlighting that either method is appropriate to determine membrane lipid changes in the diseased state. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Nafion®/ODF-silica composite membranes for medium temperature proton exchange membrane fuel cells

    KAUST Repository

    Treekamol, Yaowapa

    2014-01-01

    A series of composite membranes were prepared by dispersing fluorinated polyoxadiazole oligomer (ODF)-functionalized silica nanoparticles in a Nafion matrix. Both melt-extrusion and solvent casting processes were explored. Ion exchange capacity, conductivity, water uptake and dimensional stability, thermal stability and morphology were characterized. The inclusion of functionalized nanoparticles proved advantageous, mainly due to a physical crosslinking effect and better water retention, with functionalized nanoparticles performing better than the pristine silica particles. For the same filler loading, better nanoparticle dispersion was achieved for solvent-cast membranes, resulting in higher proton conductivity. Filler agglomeration, however,was more severe for solvent-castmembranes at loadings beyond 5wt.%. The composite membranes showed excellent thermal stability, allowing for operation in medium temperature PEM fuel cells. Fuel cell performance of the compositemembranesdecreaseswithdecreasing relativehumidity, but goodperformance values are still obtained at 34% RHand 90 °C,with the best results obtained for solvent castmembranes loaded with 10 wt.% ODF-functionalized silica. Hydrogen crossover of the composite membranes is higher than that forpureNafion membranes,possiblydue toporosityresulting fromsuboptimalparticle- matrixcompatibility. © 2013 Crown Copyright and Elsevier BV. All rights reserved.

  10. Milk fat globule membrane and buttermilks: from composition to valorization

    Directory of Open Access Journals (Sweden)

    Vanderghem, C.

    2010-01-01

    Full Text Available Buttermilk, the by-product from butter manufacture, is low cost and available in large quantities but has been considered for many years as invaluable. However, over the last two decades it has gained considerable attention due to its specific composition in proteins and polar lipids from the milk fat globule membrane (MFGM. The aim of this review is to take stock of current buttermilk knowledge. Firstly, the milk fat globule membrane composition and structure are described. Secondly, buttermilk and its associated products are defined according to the milk fat making process. Structure and mean composition of these products are summarized from recent dairy research data and related to technological properties, especially the emulsifying properties provided by MFGM components. Finally, new applications are presented, leading to promising valorizations of buttermilk and its derivate products.

  11. Optimizing Liposomal Cisplatin Efficacy through Membrane Composition Manipulations

    Science.gov (United States)

    Zisman, Natalia; Dos Santos, Nancy; Johnstone, Sharon; Tsang, Alan; Bermudes, David; Mayer, Lawrence; Tardi, Paul

    2011-01-01

    The first liposomal formulation of cisplatin to be evaluated clinically was SPI-077. Although the formulation demonstrated enhanced cisplatin tumor accumulation in preclinical models it did not enhance clinical efficacy, possibly due to limited cisplatin release from the formulation localized within the tumor. We have examined a series of liposomal formulations to address the in vivo relationship between cisplatin release rate and formulation efficacy in the P388 murine leukemia model. The base formulation of phosphatidylcholine: phosphatidylglycerol: cholesterol was altered in the C18 and C16 phospholipid content to influence membrane fluidity and thereby impacting drug circulation lifetime and drug retention. Phase transition temperatures (Tm) ranged from 42–55°C. The high Tm formulations demonstrated enhanced drug retention properties accompanied by low antitumor activity while the lowest Tm formulations released the drug too rapidly in the plasma, limiting drug delivery to the tumor which also resulted in low antitumor activity. A formulation composed of DSPC : DPPC : DSPG : Chol; (35 : 35 : 20 : 10) with an intermediate drug release rate and a cisplatin plasma half-life of 8.3 hours showed the greatest antitumor activity. This manuscript highlights the critical role that drug release rates play in the design of an optimized drug delivery vehicle. PMID:22312548

  12. Mechanical performance of laminated composites incorporated with nanofibrous membranes

    International Nuclear Information System (INIS)

    Liu, L.; Huang, Z.-M.; He, C.L.; Han, X.J.

    2006-01-01

    The effect of non-woven nanofibrous membranes as interlaminar interfaces on the mechanical performance of laminated composites was investigated experimentally. The nanofibrous membranes are porous, thin and lightweight, and exhibit toughness and strength to some extent. They give little increase in weight and thickness when incorporated into a laminate. More important, they can be used as a functional agent carrier for the laminate. The nanofiber membranes used in this paper were prepared by electrospinning of Nylon-6 (PA6), Epoxy 609 (EPO 1691-410) and thermoplastic polyurethane (TPU), with a thickness ranging from 20 to 150 μm. The non-woven fabrics were attached to one side of a glass/epoxy fabric lamina prior to lamination and each fabric was arranged in between two adjacent plies of the laminate. The nanofibrous membranes were characterized through scanning electron microscopy (SEM) and tensile testing, whereas the mechanical properties of the laminate were understood in terms of three-point bending and short-beam shear tests. Results have shown that the nanofibrous membranes in the ply interfaces with a proper thickness did not affect the mechanical performance of the composite laminates significantly

  13. Separation of gases through gas enrichment membrane composites

    Science.gov (United States)

    Swedo, Raymond J.; Kurek, Paul R.

    1988-01-01

    Thin film composite membranes having as a permselective layer a film of a homopolymer of certain vinyl alkyl ethers are useful in the separation of various gases. Such homopolymers have a molecular weight of greater than 30,000 and the alkyl group of the vinyl alkyl monomer has from 4 to 20 carbon atoms with branching within the alkyl moiety at least at the carbon atom bonded to the ether oxygen or at the next adjacent carbon atom. These membranes show excellent hydrolytic stability, especially in the presence of acidic or basic gaseous components.

  14. Gas separation by composite solvent-swollen membranes

    Science.gov (United States)

    Matson, Stephen L.; Lee, Eric K. L.; Friesen, Dwayne T.; Kelly, Donald J.

    1989-01-01

    There is disclosed a composite immobulized liquid membrane of a solvent-swollen polymer and a microporous organic or inorganic support, the solvent being at least one highly polar solvent containing at least one nitrogen, oxygen, phosphorous or sulfur atom, and having a boiling point of at least 100.degree. C. and a specified solubility parameter. The solvent or solvent mixture is homogeneously distributed through the solvent-swollen polymer from 20% to 95% by weight. The membrane is suitable for acid gas scrubbing and oxygen/nitrogen separation.

  15. Composite hollow fiber membranes for organic solvent-based liquid-liquid extraction

    NARCIS (Netherlands)

    He, T.; Bolhuis-Versteeg, Lydia A.M.; Mulder, M.H.V.; Wessling, Matthias

    2004-01-01

    Instability issues of liquid membranes extraction significantly limit its wide application in industry. We report research on the application of a new composite hollow fiber membrane to stabilizing liquid membrane extraction. These type of composite membranes have either a polysulfone (PSf)

  16. Changes in lipid composition of the brain cellular membranes of an hibernating mammal during its circannual rhythm.

    Science.gov (United States)

    Robert, J; Montaudon, D; Dubourg, L; Rebel, G; Miro, J L; Canguilhem, B

    1982-01-01

    The lipid composition of whole brain hemispheres and subcellular fractions of European Hamsters (Cricetus cricetus) was investigated at four different periods of the year. 1. No difference was observed in winter between hibernating animals and active animals awake for 24 hr. 2. A slight increase of cholesterol/phospholipid molar ratio was observed in winter. 3. A slight increase of the ratio ethanolamine phosphoglycerides/choline phosphoglycerides was observed in summer and autumn. 4. Some changes in sugar moieties proportions of gangliosides were observed, with a tendency of increased polysialylation in winter. 5. An increase of docosahexaenoic acid was observed in summer, while a slight increase of linoleic acid and of the monounsaturated fatty acids was observed in winter. These changes were mainly exhibited in the synaptosomal fraction. All the changes observed were of very small magnitude and might not be sufficient for the maintenance of a fluid state of membranes during hibernation.

  17. Preparation and characterization of the PVDF-based composite membrane for direct methanol fuel cells

    OpenAIRE

    Qian Liu, Laizhou Song, Zhihui Zhang, Xiaowei Liu

    2010-01-01

    The polyvinylidene fluoride-sulfonated polystyrene composite membrane with proton exchange performance, denoted as PVDF-SPS, was prepared using a thermally induced polymerization technique. The thermal stability of the PVDF-SPS composite membrane was investigated using thermogravimetric (TG) analysis. The complex formation of the composite membrane was ascertained by Fourier transform infrared spectroscopy (FTIR). The surface compositions of the PVDF-SPS membrane were analyzed using X-ray pho...

  18. Electrospinning synthesis and characterization of PLA-PEG-MNPs composite fibrous membranes

    Science.gov (United States)

    Kumar, M.; Klimke, S.; Preiss, A.; Unruh, D.; Wengerowsky, D.; Lehmann, R.; Sindelar, R.; Klingelhöfer, G.; Boča, R.; Renz, F.

    2017-11-01

    An electrospinning technique was used to fabricate PLA, PLA-PEG and PLA-PEG-MNPs composite fibrous membranes. The morphology of electrospun composite membranes were characterized by scanning electron microscope. To test the potential availability of MNPs in PLA-PEG composite membranes, TG, Raman, Mössbauer, VSM and ICP-OES analysis were used. The PLA-PEG composite fibrous membranes showed the presence of MNPs, hence offers the possibility for magnetically triggered on-demand drug delivery.

  19. Layer-by-layer cell membrane assembly

    Science.gov (United States)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  20. Polybenzimidazole/Mxene composite membranes for intermediate temperature polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Fei, Mingming; Lin, Ruizhi; Deng, Yuming; Xian, Hongxi; Bian, Renji; Zhang, Xiaole; Cheng, Jigui; Xu, Chenxi; Cai, Dongyu

    2018-01-01

    This report demonstrated the first study on the use of a new 2D nanomaterial (Mxene) for enhancing membrane performance of intermediate temperature (>100 °C) polymer electrolyte membrane fuel cells (ITPEMFCs). In this study, a typical Ti3C2T x -MXene was synthesized and incorporated into polybenzimidazole (PBI)-based membranes by using a solution blending method. The composite membrane with 3 wt% Ti3C2T x -MXene showed the proton conductivity more than 2 times higher than that of pristine PBI membrane at the temperature range of 100 °C-170 °C, and led to substantial increase in maximum power density of fuel cells by ˜30% tested at 150 °C. The addition of Ti3C2T x -MXene also improved the mechanical properties and thermal stability of PBI membranes. At 3 wt% Ti3C2T x -MXene, the elongation at break of phosphoric acid doped PBI remained unaffected at 150 °C, and the tensile strength and Young’s modulus was increased by ˜150% and ˜160%, respectively. This study pointed out promising application of MXene in ITPEMFCs.

  1. Antimicrobial Bacterial Cellulose-Silver Nanoparticles Composite Membranes

    Directory of Open Access Journals (Sweden)

    Hernane S. Barud

    2011-01-01

    Full Text Available Antimicrobial bacterial cellulose-silver nanoparticles composite membranes have been obtained by “in situ” preparation of Ag nanoparticles from hydrolytic decomposition of silver nitrate solution using triethanolamine as reducing and complexing agent. The formation of silver nanoparticles was evidenced by the X-ray diffraction, scanning electron microscopy (SEM, transmission electron microscopy (TEM, and absorption in the UV-Visible (350 nm to 600 nm. Thermal and mechanical properties together with swelling behavior for water were considered. TEA concentration was observed to be important in order to obtain only Ag particles and not a mixture of silver oxides. It was also observed to control particle size and amount of silver contents in bacterial cellulose. The composite membranes exhibited strong antimicrobial activity against Gram-negative and Gram-positive bacteria.

  2. Solid polymer electrolyte composite membrane comprising plasma etched porous support

    Science.gov (United States)

    Liu, Han; LaConti, Anthony B.

    2010-10-05

    A solid polymer electrolyte composite membrane and method of manufacturing the same. According to one embodiment, the composite membrane comprises a rigid, non-electrically-conducting support, the support preferably being a sheet of polyimide having a thickness of about 7.5 to 15 microns. The support has a plurality of cylindrical pores extending perpendicularly between opposing top and bottom surfaces of the support. The pores, which preferably have a diameter of about 0.1 to 5 microns, are made by plasma etching and preferably are arranged in a defined pattern, for example, with fewer pores located in areas of high membrane stress and more pores located in areas of low membrane stress. The pores are filled with a first solid polymer electrolyte, such as a perfluorosulfonic acid (PFSA) polymer. A second solid polymer electrolyte, which may be the same as or different than the first solid polymer electrolyte, may be deposited over the top and/or bottom of the first solid polymer electrolyte.

  3. Evaluation of Ultrafiltration Performance for Phospholipid Separation

    Science.gov (United States)

    Aryanti, N.; Wardhani, D. H.; Maulana, Z. S.; Roberto, D.

    2017-11-01

    Ultrafiltration membrane for degumming of crude palm oil has been applied as an alternative method since the membrane process required less procedure than the conventional degumming. This research focused on the examination of ultrafiltration performance for phospholipid separation from model crude palm oil degumming. Specifically, profile flux and rejection, as well as blocking mechanism, were investigated. Feed consisting of Refined Crude Palm Oil – Isopropanol – Lecithin mixtures were represented as crude palm oil degumming. Lecithin was denoted a phospholipid component, and the concentrations of lecithin in feed were varied to 0.1%, 0.2%, and 0.3%. The concentration of phospholipid was determined as phosphor content. At the concentration of lecithin in feed representing phospholipid concentration of 8,45 mg/kg, 8,45 mg/kg, 24,87 mg/kg and 57,58 mg/kg, respectively. Flux profiles confirmed that there was a flux decline during filtration. In addition, the lecithin concentrations do not significantly effect on further flux decline. Rejection characteristic and phospholipid concentration in the permeate showed that the phospholipid rejections by ultrafiltration were in the range of 23-79,5% representing permeate’s phospholipid concentration of 1,73 - 44,25 mg/kg. Evaluation of fouling mechanism by Hermia’s blocking model confirmed that the standard blocking is the dominant mechanism in the ultrafiltration of lecithin mixture.

  4. Cell signalling and phospholipid metabolism. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Boss, W.F.

    1990-12-31

    These studies explored whether phosphoinositide (PI) has a role in plants analogous to its role in animal cells. Although no parallel activity of PI in signal transduction was found in plant cells, activity of inositol phospholipid kinase was found to be modulated by light and by cell wall degrading enzymes. These studies indicate a major role for inositol phospholipids in plant growth and development as membrane effectors but not as a source of second messengers.

  5. Nutritional Deficiencies and Phospholipid Metabolism

    Directory of Open Access Journals (Sweden)

    Nidia N. Gomez

    2011-04-01

    Full Text Available Phospholipids are important components of the cell membranes of all living species. They contribute to the physicochemical properties of the membrane and thus influence the conformation and function of membrane-bound proteins, such as receptors, ion channels, and transporters and also influence cell function by serving as precursors for prostaglandins and other signaling molecules and modulating gene expression through the transcription activation. The components of the diet are determinant for cell functionality. In this review, the effects of macro and micronutrients deficiency on the quality, quantity and metabolism of different phospholipids and their distribution in cells of different organs is presented. Alterations in the amount of both saturated and polyunsaturated fatty acids, vitamins A, E and folate, and other micronutrients, such as zinc and magnesium, are discussed. In all cases we observe alterations in the pattern of phospholipids, the more affected ones being phosphatidylcholine, phosphatidylethanolamine and sphingomyelin. The deficiency of certain nutrients, such as essential fatty acids, fat-soluble vitamins and some metals may contribute to a variety of diseases that can be irreversible even after replacement with normal amount of the nutrients. Usually, the sequelae are more important when the deficiency is present at an early age.

  6. Curvature of double-membrane organelles generated by changes in membrane size and composition.

    Directory of Open Access Journals (Sweden)

    Roland L Knorr

    Full Text Available Transient double-membrane organelles are key players in cellular processes such as autophagy, reproduction, and viral infection. These organelles are formed by the bending and closure of flat, double-membrane sheets. Proteins are believed to be important in these morphological transitions but the underlying mechanism of curvature generation is poorly understood. Here, we describe a novel mechanism for this curvature generation which depends primarily on three membrane properties: the lateral size of the double-membrane sheets, the molecular composition of their highly curved rims, and a possible asymmetry between the two flat faces of the sheets. This mechanism is evolutionary advantageous since it does not require active processes and is readily available even when resources within the cell are restricted as during starvation, which can induce autophagy and sporulation. We identify pathways for protein-assisted regulation of curvature generation, organelle size, direction of bending, and morphology. Our theory also provides a mechanism for the stabilization of large double-membrane sheet-like structures found in the endoplasmic reticulum and in the Golgi cisternae.

  7. Effect of phospholipid composition and phase on nanodisc films at the solid-liquid interface as studied by neutron reflectivity

    DEFF Research Database (Denmark)

    Wadsäter, Maria Helena; Barker, Robert; Mortensen, Kell

    2013-01-01

    of the cell membrane and can act as a nanometer-sized container for functional single membrane proteins. In this study, we present a general nanodisc-based system, intended for structural and functional studies of membrane proteins. In this method, the nanodiscs are aligned at a solid surface, providing...... the ability to determine the average structure of the film along an axis perpendicular to the interface as measured by neutron reflectivity. The nanodisc film was optimized in terms of nanodisc coverage, reduced film roughness, and stability for time-consuming studies. This was achieved by a systematic...

  8. Fabrication and characterization of magnetic composite membrane pressure sensor

    KAUST Repository

    Khan, Mohammed Asadullah

    2016-04-20

    This paper describes a magnetic field powered pressure sensor, which comprises a coil array and a magnetic composite membrane. The composite membrane is made by embedding a ribbon of the amorphous soft magnetic alloy Vitrovac®, in a 17 mm x 25 mm x 1.5 mm Polydimethylsiloxane (PDMS) layer. PDMS is chosen for its low Young\\'s modulus and the amorphous alloy for its high permeability. The membrane is suspended 1.5 mm above a 17x19 array of microfabricated planar coils. The coils are fabricated by patterning a 620 nm thick gold layer. Each coil occupies an area of 36000 μm2 and consists of 14 turns. The sensor is tested by subjecting it to pressure and simultaneously exciting it by a 24 A/m, 100 kHz magnetic field. A pressure change from 0 kPa to 5.1 kPa, results in a 5400 ppm change in the voltage output.

  9. Organic/inorganic composite membranes based on polybenzimidazole and nano-SiO2

    International Nuclear Information System (INIS)

    Pu Hongting; Liu Lu; Chang Zhihong; Yuan Junjie

    2009-01-01

    Organic/inorganic composite membranes based on polybenzimidazole (PBI) and nano-SiO 2 were prepared in this work. However, the preparation of PBI/SiO 2 composite membrane is not easy since PBI is insoluble in water, while nano-SiO 2 is hydrophilic due to the hydrophilicity of nano-SiO 2 and water-insolubility of PBI. Thus, a solvent-exchange method was employed to prepare the composite membrane. The morphology of the composite membranes was studied by scanning electron microscopy (SEM). It was revealed that inorganic particles were dispersed homogenously in the PBI matrix. The thermal stability of the composite membrane is higher than that of pure PBI, both for doped and undoped membranes. PBI/SiO 2 composite membranes with up to 15 wt% SiO 2 exhibited improved mechanical properties compared with PBI membranes. The proton conductivity of the composite membranes containing phosphoric acid was studied. The nano-SiO 2 in the composite membranes enhanced the ability to trap phosphoric acid, which improved the proton conductivity of the composite membranes. The membrane with 15 wt% of inorganic material is oxidatively stable and has a proton conductivity of 3.9 x 10 -3 S/cm at 180 deg. C.

  10. Alboserpin, a Factor Xa Inhibitor from the Mosquito Vector of Yellow Fever, Binds Heparin and Membrane Phospholipids and Exhibits Antithrombotic Activity

    Czech Academy of Sciences Publication Activity Database

    Calvo, E.; Mizurini, D.M.; Sa-Nunes, A.; Ribeiro, J.M.C.; Andersen, J. F.; Mans, B.J.; Monteiro, R.Q.; Kotsyfakis, Michalis; Francischetti, I.M.B.

    2011-01-01

    Roč. 286, č. 32 (2011), 27998-28010 ISSN 0021-9258 Institutional research plan: CEZ:AV0Z60220518 Keywords : serpin * mosquito * Aedes albopictus * phospholipids * Factor Xa * heparin * binding affinity * coagulation * thrombus * bleeding Subject RIV: GJ - Animal Vermins ; Diseases, Veterinary Medicine Impact factor: 4.773, year: 2011

  11. Development of electrospun composite as substitutive diaphragm membrane

    Science.gov (United States)

    Mohsenzadeh, E.; Khenoussi, N.; Schacher, L.; Adolphe, D.; Hemmerlé, J.; Schneider, A.; Bahlouli, N.; Wagner-Kocher, C.

    2017-10-01

    The diaphragm is the most important muscle for respiration with a bi-domed structure, which is separating thoracic cavity from abdominal cavity. Partial formation of diaphragm, with unknown reason during fetal development caused a birth defect called congenital diaphragmatic hernia (CDH). It allows the abdomen contents to go up into the chest cavity resulting in pulmonary hypoplasia, which is the major cause of the mortality. There are several types of membrane, which can be used as prostheses to close the existing hole. In this project, we study the tensile properties of electrospun PA-6 nanowebs and electrospun PA-6/B composite as substitution membrane by a comparison with the tensile properties of tendon part of pig’s diaphragm.

  12. Electrospun Superhydrophobic Organic/Inorganic Composite Nanofibrous Membranes for Membrane Distillation.

    Science.gov (United States)

    Li, Xiong; Yu, Xufeng; Cheng, Cheng; Deng, Li; Wang, Min; Wang, Xuefen

    2015-10-07

    Electrospun superhydrophobic organic/inorganic composite nanofibrous membranes exhibiting excellent direct contact membrane distillation (DCMD) performance were fabricated by a facile route combining the hydrophobization of silica nanoparticles (SiO2 NPs) and colloid electrospinning of the hydrophobic silica/poly(vinylidene fluoride) (PVDF) matrix. Benefiting from the utilization of SiO2 NPs with three different particle sizes, the electrospun nanofibrous membranes (ENMs) were endowed with three different delicate nanofiber morphologies and fiber diameter distribution, high porosity, and superhydrophobic property, which resulted in excellent waterproofing and breathability. Significantly, structural attributes analyses have indicated the major contributing role of fiber diameter distribution on determining the augment of permeate vapor flux through regulating mean flow pore size (MFP). Meanwhile, the extremely high liquid entry pressure of water (LEPw, 2.40 ± 0.10 bar), robust nanofiber morphology of PVDF immobilized SiO2 NPs, remarkable mechanical properties, thermal stability, and corrosion resistance endowed the as-prepared membranes with prominent desalination capability and stability for long-term MD process. The resultant choreographed PVDF/silica ENMs with optimized MFP presented an outstanding permeate vapor flux of 41.1 kg/(m(2)·h) and stable low permeate conductivity (∼2.45 μs/cm) (3.5 wt % NaCl salt feed; ΔT = 40 °C) over a DCMD test period of 24 h without membrane pores wetting detected. This result was better than those of typical commercial PVDF membranes and PVDF and modified PVDF ENMs reported so far, suggesting them as promising alternatives for MD applications.

  13. Using neurolipidomics to identify phospholipid mediators of synaptic (dys)function in Alzheimer's Disease

    OpenAIRE

    Bennett, Steffany A. L.; Valenzuela, Nicolas; Xu, Hongbin; Franko, Bettina; Fai, Stephen; Figeys, Daniel

    2013-01-01

    Not all of the mysteries of life lie in our genetic code. Some can be found buried in our membranes. These shells of fat, sculpted in the central nervous system into the cellular (and subcellular) boundaries of neurons and glia, are themselves complex systems of information. The diversity of neural phospholipids, coupled with their chameleon-like capacity to transmute into bioactive molecules, provides a vast repertoire of immediate response second messengers. The effects of compositional cha...

  14. Poly(vinyl chloride) polyacrylonitrile composite membranes for the dehydration of acetic acid

    NARCIS (Netherlands)

    Koops, G.H.; Nolten-Oude Hendrikman, J.A.M.; Nolten-Oude Hendrikman, J.A.M.; Mulder, M.H.V.; Smolders, C.A.; Smolders, C.A.

    1993-01-01

    Composite membranes have been prepared consisting of a poly(vinyl chloride) (PVC) top layer on either a dense polyacrylonitrile (PAN) layer (bi-layer membrane) or a porous PAN support layer (normal composite membrane) and studied with respect to the dehydration of acetic acid. Especially, the

  15. Synthesis of a composite inorganic membrane for the separation of nitrogen, tetrafluoromethane and hexafluoropropylene

    Directory of Open Access Journals (Sweden)

    Hertzog Bissett

    2011-09-01

    Full Text Available Composite inorganic membranes were synthesised for gas component separation of N2, CF4 and C3F6. Selectivities lower than Knudsen selectivities were obtained due to membrane defects. A composite ceramic membrane consisting of a ceramic support structure, a MFI intermediate zeolite layer and a Teflon top layer, was developed to improve separation.

  16. Interaction of Cytotoxic and Cytoprotective Bile Acids with Model Membranes: Influence of the Membrane Composition.

    Science.gov (United States)

    Esteves, M; Ferreira, M J; Kozica, A; Fernandes, A C; Gonçalves da Silva, A; Saramago, B

    2015-08-18

    To understand the role of bile acids (BAs) in cell function, many authors have investigated their effect on biomembrane models which are less complex systems, but there are still many open questions. The present study aims to contribute for the deepening of the knowledge of the interaction between BAs and model membranes, in particular, focusing on the effect of BA mixtures. The cytotoxic deoxycholic acid (DCA), the cytoprotective ursodeoxycholic acid (UDCA), and the equimolar mixture (DCA + UDCA) were investigated. Monolayers and liposomes were taken as model membranes with two lipid compositions: an equimolar mixture of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), sphingomyelin (SM), and cholesterol (Chol)) traditionally associated with the formation of lipid rafts and an equimolar POPC/SM binary mixture. The obtained results showed that DCA causes the fluidization of monolayers and bilayers, leading to the eventual rupture of POPC/SM liposomes at high concentration. UDCA may provide a stabilization of POPC/SM membranes but has a negligible effect on the Chol-containing liposomes. In the case of equimolar mixture DCA/UDCA, the interactions depend not only on the lipid composition but also on the design of the experiment. The BA mixture has a greater impact on the monolayers than do pure BAs, suggesting a cooperative DCA-UDCA interaction that enhances the penetration of UDCA in both POPC/SM and POPC/SM/Chol monolayers. For the bilayers, the presence of UDCA in the mixture decreases the disturbing effect of DCA.

  17. Reprint of: Seasonal changes in the composition of storage and membrane lipids in overwintering larvae of the codling moth, Cydia pomonella.

    Science.gov (United States)

    Rozsypal, Jan; Koštál, Vladimír; Berková, Petra; Zahradníčková, Helena; Šimek, Petr

    2015-12-01

    The codling moth (Cydia pomonella) is a major insect pest of apples worldwide. It overwinters as a diapausing fifth instar larva. The overwintering is often a critical part of the insect life-cycle in temperate zone. This study brings detailed analysis of seasonal changes in lipid composition and fluidity in overwintering larvae sampled in the field. Fatty acid composition of triacylglycerol (TG) depots in the fat body and relative proportions of phospholipid (PL) molecular species in biological membranes were analyzed. In addition, temperature of melting (Tm) in TG depots was assessed by using differential scanning calorimetry and the conformational order (fluidity) of PL membranes was analyzed by measuring the anisotropy of fluorescence polarization of diphenylhexatriene probe in membrane vesicles. We observed a significant increase of relative proportion of linoleic acid (C18:2n6) at the expense of palmitic acid (C16:0) in TG depots during the larval transition to diapause accompanied with decreasing melting temperature of total lipids, which might increase the accessibility of depot fats for enzymatic breakdown during overwintering. The fluidity of membranes was maintained very high irrespective of developmental mode or seasonally changing acclimation status of larvae. The seasonal changes in PL composition were relatively small. We discuss these results in light of alternative survival strategies of codling moth larvae (supercooling vs. freezing), variability and low predictability of environmental conditions, and other cold tolerance mechanisms such as extending the supercooling capacity and massive accumulation of cryoprotective metabolites. Copyright © 2015. Published by Elsevier Ltd.

  18. Anhydrous proton conducting composite membranes containing Nafion and triazole modified POSS

    International Nuclear Information System (INIS)

    Lei, M.; Wang, Y.G.; Zhang, F.F.; Huang, C.; Xu, X.; Zhang, R.; Fan, D.Y.

    2014-01-01

    Development of membrane electrolytes having reasonable proton conductivity and mechanical strength under anhydrous conditions is of great importance for proton exchange membrane fuel cells operated at elevated temperature. With the introduction of triazole modified polyhedral oligomeric silsesquioxanes (Tz-POSS) into Nafion membrane, the formed composite electrolytes exhibit improved mechanical properties compared to pristine Nafion membrane due to the well distribution of Tz-POSS inside the membrane. The anhydrous proton conductivity of the formed composite membranes increases initially with the increase in temperature, reaching about 0.02 Scm −1 at 140 °C. With further increase in temperature to about 150 °C, the composite membrane reaches its glass transition point above which the proton conductivity decreases dramatically. The performance of assembled single cell from composite membrane is slightly dependent on humidification conditions at 95 °C, reaching 0.45 V at 600 mAcm −2 using hydrogen and oxygen as reaction gases

  19. Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs)-Based Composite Membranes: A Review.

    Science.gov (United States)

    Ma, Lining; Dong, Xinfa; Chen, Mingliang; Zhu, Li; Wang, Chaoxian; Yang, Fenglin; Dong, Yingchao

    2017-03-18

    Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs)-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization techniques of CNTs, and then reviews the fabrication methods for CNTs-based composite membranes in detail. The applications of CNTs-based composite membranes in water treatment are comprehensively reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metal ions and emerging pollutants as well as membrane separation coupled with assistant techniques. Furthermore, the future direction and perspective for CNTs-based composite membranes are also briefly outlined.

  20. Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs-Based Composite Membranes: A Review

    Directory of Open Access Journals (Sweden)

    Lining Ma

    2017-03-01

    Full Text Available Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization techniques of CNTs, and then reviews the fabrication methods for CNTs-based composite membranes in detail. The applications of CNTs-based composite membranes in water treatment are comprehensively reviewed, including seawater or brine desalination, oil-water separation, removal of heavy metal ions and emerging pollutants as well as membrane separation coupled with assistant techniques. Furthermore, the future direction and perspective for CNTs-based composite membranes are also briefly outlined.

  1. Selectively gas-permeable composite membrane and process for production thereof

    International Nuclear Information System (INIS)

    Okita, K.; Asako, S.

    1984-01-01

    A selectively gas-permeable composite membrane and a process for producing said composite membrane are described. The composite membrane comprises a polymeric material support and a thin membrane deposited on the support, said thin membrane being obtained by glow discharge plasma polymerization of an organosilane compound containing at least one double bond or triple bond. Alternatively, the composite membrane comprises a polymeric material support having an average pore diameter of at least 0.1 micron, a hardened or cross-linked polyorganosiloxane layer on the support, and a thin membrane on the polyorganosiloxane layer, said thin membrane being obtained by plasma polymerization due to glow discharge of an organosilane compound containing at least one double bond or triple bond

  2. Chemical modification of polysulfone: composite anionic exchange membrane with TiO2 nano-particles

    CSIR Research Space (South Africa)

    Nonjola, PT

    2013-04-01

    Full Text Available Synthesis of quaternary polysulfone/Titanium dioxide (QPSf/TiO2) nanocomposite membranes by the recasting procedure as suitable electrolyte in alkaline fuel cells is described. The composite membranes were characterized by ionic conductivity...

  3. Novel Nonporous Fouling-Resistant Enzymatic Composite Membranes for Waste Water Treatment

    National Research Council Canada - National Science Library

    Freeman, Benny D

    2005-01-01

    .... Permeation properties of thin-films made of these gels is also reported. Approximately 20 m2 of chitosan composite membrane were prepared at our industrial partner, Membrane Technology and Research (MTR...

  4. Alteration in membrane fluidity and lipid composition, and modulation of H(+)-ATPase activity in Saccharomyces cerevisiae caused by decanoic acid.

    Science.gov (United States)

    Alexandre, H; Mathieu, B; Charpentier, C

    1996-03-01

    Decanoic acid, a lipophilic agent, inhibited in vitro the plasma membrane H(+)-ATPase of Saccharomyces cerevisiae grown in YPD medium. Conversely, when decanoic acid (35 microM) was present in the growth medium, the measured H(+)-ATPase activity was four times higher than that of control cells. Km, and pH and orthovanadate sensitivity were the same for the two growth conditions, which indicated that H(+)-ATPase activation was not due to conformational changes in the enzyme. The activation process was not entirely reversible which showed that plasma membrane H(+)-ATPase activation is due to several mechanisms. 1,6-diphenyl-1,3,5-hexatriene anisotropy performed on protoplasts from cells grown in YPD revealed that as decanoic acid concentration was increased, anisotropy significantly decreased, i.e. membrance fluidity increased. Cells grown in media containing decanoic acid exhibited greater membrane fluidity compared with control cells. Furthermore, these cells did not show any fluidifying effect when increased concentrations of decanoic acid were added. Chemical analysis of cell membrane lipid composition revealed a modification in the distribution of the phospholipid fatty acids and sterols in cells grown in the presence of 35 microM decanoic acid compared with control cells. Our results support the view that the plasma membrane H(+)-ATPase activation induced by decanoic acid is correlated with an alteration in membrane lipid constituents.

  5. Composite proton exchange membrane based on sulfonated organic nanoparticles

    Science.gov (United States)

    Pitia, Emmanuel Sokiri

    As the world sets its sight into the future, energy remains a great challenge. Proton exchange membrane (PEM) fuel cell is part of the solution to the energy challenge because of its high efficiency and diverse application. The purpose of the PEM is to provide a path for proton transport and to prevent direct mixing of hydrogen and oxygen at the anode and the cathode, respectively. Hence, PEMs must have good proton conductivity, excellent chemical stability, and mechanical durability. The current state-of-the-art PEM is a perfluorosulfonate ionomer, Nafion®. Although Nafion® has many desirable properties, it has high methanol crossover and it is expensive. The objective of this research was to develop a cost effective two-phase, composite PEM wherein a dispersed conductive organic phase preferentially aligned in the transport direction controls proton transport, and a continuous hydrophobic phase provides mechanical durability to the PEM. The hypothesis that was driving this research was that one might expect better dispersion, higher surface to volume ratio and improved proton conductivity of a composite membrane if the dispersed particles were nanometer in size and had high ion exchange capacity (IEC, = [mmol sulfonic acid]/gram of polymer). In view of this, considerable efforts were employed in the synthesis of high IEC organic nanoparticles and fabrication of a composite membrane with controlled microstructure. High IEC, ~ 4.5 meq/g (in acid form, theoretical limit is 5.4 meq/g) nanoparticles were achieved by emulsion copolymerization of a quaternary alkyl ammonium (QAA) neutralized-sulfonated styrene (QAA-SS), styrene, and divinylbenzene (DVB). The effects of varying the counterion of the sulfonated styrene (SS) monomer (alkali metal and QAA cations), SS concentration, and the addition of a crosslinking agent (DVB) on the ability to stabilize the nanoparticles to higher IECs were assessed. The nanoparticles were ion exchanged to acid form. The extent of ion

  6. Trichoderma viride cellulase induces resistance to the antibiotic pore-forming peptide alamethicin associated with changes in the plasma membrane lipid composition of tobacco BY-2 cells

    Directory of Open Access Journals (Sweden)

    Andreasson Erik

    2010-12-01

    Full Text Available Abstract Background Alamethicin is a membrane-active peptide isolated from the beneficial root-colonising fungus Trichoderma viride. This peptide can insert into membranes to form voltage-dependent pores. We have previously shown that alamethicin efficiently permeabilises the plasma membrane, mitochondria and plastids of cultured plant cells. In the present investigation, tobacco cells (Nicotiana tabacum L. cv Bright Yellow-2 were pre-treated with elicitors of defence responses to study whether this would affect permeabilisation. Results Oxygen consumption experiments showed that added cellulase, already upon a limited cell wall digestion, induced a cellular resistance to alamethicin permeabilisation. This effect could not be elicited by xylanase or bacterial elicitors such as flg22 or elf18. The induction of alamethicin resistance was independent of novel protein synthesis. Also, the permeabilisation was unaffected by the membrane-depolarising agent FCCP. As judged by lipid analyses, isolated plasma membranes from cellulase-pretreated tobacco cells contained less negatively charged phospholipids (PS and PI, yet higher ratios of membrane lipid fatty acid to sterol and to protein, as compared to control membranes. Conclusion We suggest that altered membrane lipid composition as induced by cellulase activity may render the cells resistant to alamethicin. This induced resistance could reflect a natural process where the plant cells alter their sensitivity to membrane pore-forming agents secreted by Trichoderma spp. to attack other microorganisms, and thus adding to the beneficial effect that Trichoderma has for plant root growth. Furthermore, our data extends previous reports on artificial membranes on the importance of lipid packing and charge for alamethicin permeabilisation to in vivo conditions.

  7. Gradient composite metal-ceramic foam as supportive component for planar SOFCs and MIEC membranes

    Science.gov (United States)

    Smorygo, Oleg; Mikutski, Vitali; Marukovich, Alexander; Sadykov, Vladislav; Usoltsev, Vladimir; Mezentseva, Natalia; Borodinecs, Anatolijs; Bobrenok, Oleg

    2011-06-01

    A novel approach to the design of planar gradient porous supports for the thin-film SOFCs and MIEC membranes is described. The support's thermal expansion is controlled by the creation of a two-component composite metal-ceramic foam structure. Thin MIEC membranes and SOFCs were prepared on the composite supports by the layerwise deposition of composite functional layers including complex fluorites and perovskites. Lab-scale studies demonstrated promising performance of both MIEC membrane and SOFC.

  8. Phospholipids and protein adaptation of Pseudomonas sp. to the xenoestrogen tributyltin chloride (TBT).

    Science.gov (United States)

    Bernat, Przemysław; Siewiera, Paulina; Soboń, Adrian; Długoński, Jerzy

    2014-09-01

    A tributyltin (TBT)-resistant strain of Pseudomonas sp. isolated from an overworked car filter was tested for its adaptation to TBT. The isolate was checked for organotin degradation ability, as well as membrane lipid and cellular protein composition in the presence of TBT. The phospholipid profiles of bacteria, grown with and without increased amounts of TBT, were characterized using liquid chromatography/electrospray ionization/mass spectrometry. The strain reacted to the biocide by changing the composition of its phospholipids. TBT induced a twofold decline in the amounts of many molecular species of phosphatidylglycerol and an increase in the levels of phosphatidic acid (by 58%) and phosphatidylethanolamine (by 70%). An increase in the degree of saturation of phospholipid fatty acids of TBT exposed Pseudomonas sp. was observed. These changes in the phospholipid composition and concentration reflect the mechanisms which support optimal lipid ordering in the presence of toxic xenobiotic. In the presence of TBT the abundances of 16 proteins, including TonB-dependent receptors, porins and peroxidases were modified, which could indicate a contribution of some enzymes to TBT resistance.

  9. Inositol depletion restores vesicle transport in yeast phospholipid flippase mutants.

    Science.gov (United States)

    Yamagami, Kanako; Yamamoto, Takaharu; Sakai, Shota; Mioka, Tetsuo; Sano, Takamitsu; Igarashi, Yasuyuki; Tanaka, Kazuma

    2015-01-01

    In eukaryotic cells, type 4 P-type ATPases function as phospholipid flippases, which translocate phospholipids from the exoplasmic leaflet to the cytoplasmic leaflet of the lipid bilayer. Flippases function in the formation of transport vesicles, but the mechanism remains unknown. Here, we isolate an arrestin-related trafficking adaptor, ART5, as a multicopy suppressor of the growth and endocytic recycling defects of flippase mutants in budding yeast. Consistent with a previous report that Art5p downregulates the inositol transporter Itr1p by endocytosis, we found that flippase mutations were also suppressed by the disruption of ITR1, as well as by depletion of inositol from the culture medium. Interestingly, inositol depletion suppressed the defects in all five flippase mutants. Inositol depletion also partially restored the formation of secretory vesicles in a flippase mutant. Inositol depletion caused changes in lipid composition, including a decrease in phosphatidylinositol and an increase in phosphatidylserine. A reduction in phosphatidylinositol levels caused by partially depleting the phosphatidylinositol synthase Pis1p also suppressed a flippase mutation. These results suggest that inositol depletion changes the lipid composition of the endosomal/TGN membranes, which results in vesicle formation from these membranes in the absence of flippases.

  10. Biofouling in membrane bioreactors: nexus between polyacrylonitrile surface charge and community composition.

    Science.gov (United States)

    Marbelia, Lisendra; Hernalsteens, Marie-Aline; Ilyas, Shazia; Öztürk, Basak; Szymczyk, Anthony; Springael, Dirk; Vankelecom, Ivo

    2018-02-15

    The influence of membrane surface charge on biofouling community composition during activated sludge filtration in a membrane bioreactor was investigated in this study using polyacrylonitrile-based membranes. Membranes with different surface properties were synthesized by phase inversion followed by a layer-by-layer modification. Various characterization results showed that the membranes differed only in their surface chemical composition and charge, ie two of them were negative, one neutral and one positive. Membrane fouling experiments were performed for 40 days and the biofouling communities were analyzed. PCR-DGGE fingerprinting indicated selective enrichment of bacterial populations from the sludge suspension within the biofilms at any time point. The biofilm community composition seemed to change with time. However, no difference was observed between the biofilm community of differently charged membranes at specific time points. It could be concluded that membrane charges do not play a decisive role in the long-term selection of the key bacterial foulants.

  11. The Drosophila melanogaster phospholipid flippase dATP8B is required for odorant receptor function.

    Directory of Open Access Journals (Sweden)

    Yu-Chi Liu

    2014-03-01

    Full Text Available The olfactory systems of insects are fundamental to all aspects of their behaviour, and insect olfactory receptor neurons (ORNs exhibit exquisite specificity and sensitivity to a wide range of environmental cues. In Drosophila melanogaster, ORN responses are determined by three different receptor families, the odorant (Or, ionotropic-like (IR and gustatory (Gr receptors. However, the precise mechanisms of signalling by these different receptor families are not fully understood. Here we report the unexpected finding that the type 4 P-type ATPase phospholipid transporter dATP8B, the homologue of a protein associated with intrahepatic cholestasis and hearing loss in humans, is crucial for Drosophila olfactory responses. Mutations in dATP8B severely attenuate sensitivity of odorant detection specifically in Or-expressing ORNs, but do not affect responses mediated by IR or Gr receptors. Accordingly, we find dATP8B to be expressed in ORNs and localised to the dendritic membrane of the olfactory neurons where signal transduction occurs. Localisation of Or proteins to the dendrites is unaffected in dATP8B mutants, as is dendrite morphology, suggesting instead that dATP8B is critical for Or signalling. As dATP8B is a member of the phospholipid flippase family of ATPases, which function to determine asymmetry in phospholipid composition between the outer and inner leaflets of plasma membranes, our findings suggest a requirement for phospholipid asymmetry in the signalling of a specific family of chemoreceptor proteins.

  12. The N-terminal segment of pulmonary surfactant lipopeptide SP-C has intrinsic propensity to interact with and perturb phospholipid bilayers

    DEFF Research Database (Denmark)

    Plasencia, Inés; Rivas, Luis; Keough, Kevin M W

    2004-01-01

    spontaneously with bilayers composed of either zwitterionic (phosphatidylcholine) or anionic (phosphatidylglycerol) phospholipids. The peptides show higher affinity for anionic than for zwitterionic membranes. Interaction of the peptides with both zwitterionic and anionic membranes promotes phospholipid vesicle...

  13. Promiscuous and specific phospholipid binding by domains in ZAC, a membrane-associated Arabidopsis protein with an ARF GAP zinc finger and a C2 domain

    DEFF Research Database (Denmark)

    Jensen, R B; Lykke-Andersen, K; Frandsen, G I

    2000-01-01

    Arabidopsis proteins were predicted which share an 80 residue zinc finger domain known from ADP-ribosylation factor GTPase-activating proteins (ARF GAPs). One of these is a 37 kDa protein, designated ZAC, which has a novel domain structure in which the N-terminal ARF GAP domain and a C-terminal C2...... containing the ZAC-C2 domain bind anionic phospholipids non-specifically, with some variance in Ca2+ and salt dependence. Similar assays demonstrated specific affinity of the ZAC N-terminal region (residues 1-174) for phosphatidylinositol 3-monophosphate (PI-3-P). Binding was dependent in part on an intact...

  14. Novel composite membranes based on PBI and dicationic ionic liquids for high temperature polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Hooshyari, Khadijeh; Javanbakht, Mehran; Adibi, Mina

    2016-01-01

    Two types of innovative composite membranes based on polybenzimidazole (PBI) containing dicationic ionic liquid 1,3-di(3-methylimidazolium) propane bis (trifluoromethylsulfonyl) imide (PDC 3 ) and monocationic ionic liquid 1-hexyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide (PMC 6 ) are prepared as electrolyte for high temperature fuel cells applications under anhydrous conditions. The analyses of results display promising characteristics such as high proton conductivity and thermal stability. Moreover the fuel cell performance of PA doped PDC 3 composite membranes is enhanced in comparison with PA doped PMC 6 and PA doped PBI membranes at high temperatures. Dicationic ionic liquid with high number of charge carriers provides well-developed ionic channels which form facile pathways and considerably develop the anhydrous proton conductivity. The highest proton conductivity of 81 mS/cm is achieved for PA doped PDC 3 composite membranes with PBI/IL mole ratio: 4 at 180 °C. A power density of 0.44 W/cm 2 is obtained at 0.5 V and 180 °C for PA doped PDC 3 composite membranes, which proves that these developed composite membranes can be considered as most promising candidates for high temperature fuel cell applications with enhanced proton conductivity.

  15. Coiled coil driven membrane fusion between cyclodextrin vesicles and liposomes

    NARCIS (Netherlands)

    Versluis, Frank; Voskuhl, Jens; Vos, Jan; Friedrich, Heiner; Ravoo, Bart Jan; Bomans, Paul H H; Stuart, Marc C A; Sommerdijk, Nico A J M; Kros, Alexander

    2014-01-01

    Controlled fusion events between natural membranes composed of phospholipids with synthetic unnatural membranes will yield valuable fundamental information on the mechanism of membrane fusion. Here, fusion between vastly different phospholipid liposomes and cyclodextrin amphiphile based vesicles

  16. Polyglutamine expansion in huntingtin alters its interaction with phospholipids.

    Science.gov (United States)

    Kegel, Kimberly B; Sapp, Ellen; Alexander, Jonathan; Valencia, Antonio; Reeves, Patrick; Li, Xueyi; Masso, Nicholas; Sobin, Lindsay; Aronin, Neil; DiFiglia, Marian

    2009-09-01

    Huntingtin has an expanded polyglutamine tract in patients with Huntington's disease. Huntingtin localizes to intracellular and plasma membranes but the function of huntingtin at membranes is unknown. Previously we reported that exogenously expressed huntingtin bound pure phospholipids using protein-lipid overlays. Here we show that endogenous huntingtin from normal (Hdh(7Q/7Q)) mouse brain and mutant huntingtin from Huntington's disease (Hdh(140Q/140Q)) mouse brain bound to large unilamellar vesicles containing phosphoinositol (PI) PI 3,4-bisphosphate, PI 3,5-bisphosphate, and PI 3,4,5-triphosphate [PI(3,4,5)P3]. Huntingtin interactions with multivalent phospholipids were similar to those of dynamin. Mutant huntingtin associated more with phosphatidylethanolamine and PI(3,4,5)P3 than did wild-type huntingtin, and associated with other phospholipids not recognized by wild-type huntingtin. Wild-type and mutant huntingtin also bound to large unilamellar vesicles containing cardiolipin, a phospholipid specific to mitochondrial membranes. Maximal huntingtin-phospholipid association required inclusion of huntingtin amino acids 171-287. Endogenous huntingtin recruited to the plasma membrane in cells that incorporated exogenous PI 3,4-bisphosphate and PI(3,4,5)P3 or were stimulated by platelet-derived growth factor or insulin growth factor 1, which both activate PI 3-kinase. These data suggest that huntingtin interacts with membranes through specific phospholipid associations and that mutant huntingtin may disrupt membrane trafficking and signaling at membranes.

  17. Feruloyl Dioleoyglycerol Antioxidant Capacity in Phospholipid Vesicles

    Science.gov (United States)

    Ferulic acid and its esters are known to be effective antioxidants. Feruloyl dioleoylglycerol was assessed for its ability to serve as an antioxidant in model membrane phospholipid vesicles. The molecule was incorporated into single-lamellar vesicles of 1,2-dioleoyl-sn-glycero-3-phosphocholine at ...

  18. Effect of ration size on fillet fatty acid composition, phospholipid allostasis and mRNA expression patterns of lipid regulatory genes in gilthead sea bream (Sparus aurata).

    Science.gov (United States)

    Benedito-Palos, Laura; Calduch-Giner, Josep A; Ballester-Lozano, Gabriel F; Pérez-Sánchez, Jaume

    2013-04-14

    The effect of ration size on muscle fatty acid (FA) composition and mRNA expression levels of key regulatory enzymes of lipid and lipoprotein metabolism have been addressed in juveniles of gilthead sea bream fed a practical diet over the course of an 11-week trial. The experimental setup included three feeding levels: (i) full ration until visual satiety, (ii) 70 % of satiation and (iii) 70 % of satiation with the last 2 weeks at the maintenance ration. Feed restriction reduced lipid content of whole body by 30 % and that of fillet by 50 %. In this scenario, the FA composition of fillet TAG was not altered by ration size, whereas that of phospholipids was largely modified with a higher retention of arachidonic acid and DHA. The mRNA transcript levels of lysophosphatidylcholine acyltransferases, phosphatidylethanolamine N-methyltransferase and FA desaturase 2 were not regulated by ration size in the present experimental model. In contrast, mRNA levels of stearoyl-CoA desaturases were markedly down-regulated by feed restriction. An opposite trend was found for a muscle-specific lipoprotein lipase, which is exclusive of fish lineage. Several upstream regulatory transcriptions were also assessed, although nutritionally mediated changes in mRNA transcripts were almost reduced to PPARα and β, which might act in a counter-regulatory way on lipolysis and lipogenic pathways. This gene expression pattern contributes to the construction of a panel of biomarkers to direct marine fish production towards muscle lean phenotypes with increased retentions of long-chain PUFA.

  19. Fatty acid composition of plasma phospholipids and risk of prostate cancer in a case-control analysis nested within the European Prospective Investigation into Cancer and Nutrition.

    NARCIS (Netherlands)

    Crowe, F.L.; Allen, N.E.; Appleby, P.N.; Overvad, K.; Aardestrup, I.V.; Johnsen, N.F.; Tjonneland, A.; Linseisen, J.; Kaaks, R.; Boeing, H.; Kroger, J.; Trichopoulou, A.; Zavitsanou, A.; Trichopoulos, D.; Sacerdote, C.; Palli, D.; Tumino, R.; Agnoli, C.; Kiemeney, L.A.L.M.; Bueno-De-Mesquita, H.B.; Chirlaque, M.D.; Ardanaz, E.; Larrañaga, N.; Quiros, J.R.; Sanchez, M.J.; Gonzalez, C.A.; Stattin, P; Hallmans, G.; Bingham, S.; Khaw, K.T.; Rinaldi, S.; Slimani, N.; Jenab, M.; Riboli, E.; Key, T.J.

    2008-01-01

    BACKGROUND: Plausible biological mechanisms underlie possible associations between fatty acids in blood and risk of prostate cancer; epidemiologic evidence for an association, however, is inconsistent. OBJECTIVE: The objectives were to assess the association between plasma phospholipid fatty acids

  20. Alboserpin, a factor Xa inhibitor from the mosquito vector of yellow fever, binds heparin and membrane phospholipids and exhibits antithrombotic activity.

    Science.gov (United States)

    Calvo, Eric; Mizurini, Daniella M; Sá-Nunes, Anderson; Ribeiro, José M C; Andersen, John F; Mans, Ben J; Monteiro, Robson Q; Kotsyfakis, Michail; Francischetti, Ivo M B

    2011-08-12

    The molecular mechanism of factor Xa (FXa) inhibition by Alboserpin, the major salivary gland anticoagulant from the mosquito and yellow fever vector Aedes albopictus, has been characterized. cDNA of Alboserpin predicts a 45-kDa protein that belongs to the serpin family of protease inhibitors. Recombinant Alboserpin displays stoichiometric, competitive, reversible and tight binding to FXa (picomolar range). Binding is highly specific and is not detectable for FX, catalytic site-blocked FXa, thrombin, and 12 other enzymes. Alboserpin displays high affinity binding to heparin (K(D) ~ 20 nM), but no change in FXa inhibition was observed in the presence of the cofactor, implying that bridging mechanisms did not take place. Notably, Alboserpin was also found to interact with phosphatidylcholine and phosphatidylethanolamine but not with phosphatidylserine. Further, annexin V (in the absence of Ca(2+)) or heparin outcompetes Alboserpin for binding to phospholipid vesicles, suggesting a common binding site. Consistent with its activity, Alboserpin blocks prothrombinase activity and increases both prothrombin time and activated partial thromboplastin time in vitro or ex vivo. Furthermore, Alboserpin prevents thrombus formation provoked by ferric chloride injury of the carotid artery and increases bleeding in a dose-dependent manner. Alboserpin emerges as an atypical serpin that targets FXa and displays unique phospholipid specificity. It conceivably uses heparin and phosphatidylcholine/phosphatidylethanolamine as anchors to increase protein localization and effective concentration at sites of injury, cell activation, or inflammation.

  1. Exploring the structure-properties relationships of novel polyamide thin film composite membranes

    DEFF Research Database (Denmark)

    Briceño, Kelly; Javakhishvili, Irakli; Guo, Haofei

    Polysulfone (PSU) is a material widely used in the fabrication of membranes for ultrafiltration and as a support for nanofiltration and reverse osmosis membranes. Interfacial polymerization usually combines amine and acid chloride monomers for the fabrication of thin film composite membranes[1...

  2. Studies on poly (vinyl chloride/silica dioxide composite hollow fiber membrane

    Directory of Open Access Journals (Sweden)

    Mei Shuo

    2016-01-01

    Full Text Available Poly (vinyl chloride/silica dioxide composite hollow fiber membranes were prepared by using the method of immersion-precipitation process. The influences of stretching ratio on the formation of the interfacial microporous of poly (vinyl chloride/silica dioxide composite hollow fiber membranes were specifically investigated by scanning electron microscope, dynamic mechanical analysis, and finite element method. Results show that with the stretching ratio increasing, numerous IFM appear on the surface of membranes. Finite element method actually reflects the dynamic change of microporous structure of poly (vinyl chloride/silica dioxide composite hollow fiber membranes.

  3. Nafion®/H-ZSM-5 composite membranes with superior performance for direct methanol fuel cells

    NARCIS (Netherlands)

    Yildirim, M.H.; Curos, Anna Roca; Motuzas, Julius; Motuzas, J.; Julbe, Anne; Stamatialis, Dimitrios; Wessling, Matthias

    2009-01-01

    Solution cast composite direct methanol fuel cell membranes (DEZ) based on DE2020 Nafion® dispersion and in-house prepared H-ZSM-5 zeolites with different Si/Al ratios were prepared and thoroughly characterized for direct methanol fuel cell (DMFC) applications. All composite membranes have indeed

  4. Electrically conductive bacterial cellulose composite membranes produced by the incorporation of graphite nanoplatelets in pristine bacterial cellulose membranes

    Directory of Open Access Journals (Sweden)

    T. Zhou

    2013-09-01

    Full Text Available Graphite nanoplatelets (GNPs were utilized to improve the electrical conductivity of pristine bacterial cellulose (BC membranes. By physical and chemical methods, flake-shaped GNPs, weaving through the surface layer of web-like cellulose nanofibrils, were indeed fixed or trapped by the adjacent nanofibrils in the BC surface network, for comparison, rod-shaped multi-walled carbon nanotubes (MWCNTs were homogeneously inserted into BC membrane through the pore structures and tunnels within the BC membrane. Strong physical and chemical interaction exists between the BC nanofibrils and the particles of GNP or MWCNT even after 15 h sonication. BC membrane with 8.7 wt% incorporated GNPs reached the maximum electrical conductivity of 4.5 S/cm, while 13.9 wt% MWCNT/BC composite membrane achieved the maximum electrical conductivity of 1.2 S/cm. Compared with one dimensional (1-D MWCNTs, as long as GNPs inserted into BC membranes, the 2-D reinforcement of GNPs was proven to be more effective in improving the electrical conductivity of BC membranes thus not only break the bottleneck of further improvement of the electrical conductivity of BC-based composite membranes but also broaden the applications of BC and GNPs.

  5. Impact of Ionic Liquids on Silver Thermoplastic Composite Membrane Polyurethane for Propane/Propylene Separation

    OpenAIRE

    Wang, Yu; Yong Goh, Tee; Goodrich, Peter; Atilhan, Mert; Khraisheh, Majeda; Rooney, David; Thompson, Jillian; Jacquemin, Johan

    2017-01-01

    This work describes newly synthesized composite polymeric membranes and their utilization in propane/propylene separation in a gas mixture. The nonporous composite polymers were successfully synthesized by using thermoplastic polyurethane (TPU) and several silver salts/silver salts with ionic liquids (ILs). Our studies showed that silver bis(trifluoromethanesulfonyl)imide (Ag[Tf2N]) containing membranes outperformed other silver salt containing membranes in terms of selectivity. In addition, ...

  6. MinD and MinE Interact with Anionic Phospholipids and Regulate Division Plane Formation in Escherichia coli*

    Science.gov (United States)

    Renner, Lars D.; Weibel, Douglas B.

    2012-01-01

    The Min proteins (MinC, MinD, and MinE) form a pole-to-pole oscillator that controls the spatial assembly of the division machinery in Escherichia coli cells. Previous studies identified that interactions of MinD with phospholipids positioned the Min machinery at the membrane. We extend these studies by measuring the affinity, kinetics, and ATPase activity of E. coli MinD, MinE, and MinDE binding to supported lipid bilayers containing varying compositions of anionic phospholipids. Using quartz crystal microbalance measurements, we found that the binding affinity (Kd) for the interaction of recombinant E. coli MinD and MinE with lipid bilayers increased with increasing concentration of the anionic phospholipids phosphatidylglycerol and cardiolipin. The Kd for MinD (1.8 μm) in the presence of ATP was smaller than for MinE (12.1 μm) binding to membranes consisting of 95:5 phosphatidylcholine/cardiolipin. The simultaneous binding of MinD and MinE to membranes revealed that increasing the concentration of anionic phospholipid stimulates the initial rate of adsorption (kon). The ATPase activity of MinD decreased in the presence of anionic phospholipids. These results indicate that anionic lipids, which are concentrated at the poles, increase the retention of MinD and MinE and explain its dwell time at this region of bacterial cells. These studies provide insight into interactions between MinD and MinE and between these proteins and membranes that are relevant to understanding the process of bacterial cell division, in which the interaction of proteins and membranes is essential. PMID:23012351

  7. Dietary fatty acids alter mitochondrial phospholipid fatty acyl ...

    African Journals Online (AJOL)

    Dr. J. T. Ekanem

    type and relative amount of fatty acids that make up the membrane. Naturally, the phospholipid fatty acyl profiles of biological membranes vary dramatically across species2,3. For instance, the phospholpid fatty acid profiles of cellular membranes in yeasts are different from those in flies and those of mouse are different from ...

  8. Fabrication and Water Treatment Application of Carbon Nanotubes (CNTs)-Based Composite Membranes: A Review

    OpenAIRE

    Ma, Lining; Dong, Xinfa; Chen, Mingliang; Zhu, Li; Wang, Chaoxian; Yang, Fenglin; Dong, Yingchao

    2017-01-01

    Membrane separation technology is widely explored for various applications, such as water desalination and wastewater treatment, which can alleviate the global issue of fresh water scarcity. Specifically, carbon nanotubes (CNTs)-based composite membranes are increasingly of interest due to the combined merits of CNTs and membrane separation, offering enhanced membrane properties. This article first briefly discusses fabrication and growth mechanisms, characterization and functionalization tec...

  9. Membrane composition and dynamics: a target of bioactive virgin olive oil constituents.

    Science.gov (United States)

    Lopez, Sergio; Bermudez, Beatriz; Montserrat-de la Paz, Sergio; Jaramillo, Sara; Varela, Lourdes M; Ortega-Gomez, Almudena; Abia, Rocio; Muriana, Francisco J G

    2014-06-01

    The endogenous synthesis of lipids, which requires suitable dietary raw materials, is critical for the formation of membrane bilayers. In eukaryotic cells, phospholipids are the predominant membrane lipids and consist of hydrophobic acyl chains attached to a hydrophilic head group. The relative balance between saturated, monounsaturated, and polyunsaturated acyl chains is required for the organization and normal function of membranes. Virgin olive oil is the richest natural dietary source of the monounsaturated lipid oleic acid and is one of the key components of the healthy Mediterranean diet. Virgin olive oil also contains a unique constellation of many other lipophilic and amphipathic constituents whose health benefits are still being discovered. The focus of this review is the latest evidence regarding the impact of oleic acid and the minor constituents of virgin olive oil on the arrangement and behavior of lipid bilayers. We highlight the relevance of these interactions to the potential use of virgin olive oil in preserving the functional properties of membranes to maintain health and in modulating membrane functions that can be altered in several pathologies. This article is part of a Special Issue entitled: Membrane Structure and Function: Relevance in the Cell's Physiology, Pathology and Therapy. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. CO2 adsorption using TiO2 composite polymeric membranes: A kinetic study.

    Science.gov (United States)

    Hafeez, Sarah; Fan, X; Hussain, Arshad; Martín, C F

    2015-09-01

    CO2 is the main greenhouse gas which causes global climatic changes on larger scale. Many techniques have been utilised to capture CO2. Membrane gas separation is a fast growing CO2 capture technique, particularly gas separation by composite membranes. The separation of CO2 by a membrane is not just a process to physically sieve out of CO2 through the controlled membrane pore size. It mainly depends upon diffusion and solubility of gases, particularly for composite dense membranes. The blended components in composite membranes have a high capability to adsorb CO2. The adsorption kinetics of the gases may directly affect diffusion and solubility. In this study, we have investigated the adsorption behaviour of CO2 in pure and composite membranes to explore the complete understanding of diffusion and solubility of CO2 through membranes. Pure cellulose acetate (CA) and cellulose acetate-titania nanoparticle (CA-TiO2) composite membranes were fabricated and characterised using SEM and FTIR analysis. The results indicated that the blended CA-TiO2 membrane adsorbed more quantity of CO2 gas as compared to pure CA membrane. The high CO2 adsorption capacity may enhance the diffusion and solubility of CO2 in the CA-TiO2 composite membrane, which results in a better CO2 separation. The experimental data was modelled by Pseudo first-order, pseudo second order and intra particle diffusion models. According to correlation factor R(2), the Pseudo second order model was fitted well with experimental data. The intra particle diffusion model revealed that adsorption in dense membranes was not solely consisting of intra particle diffusion. Copyright © 2015. Published by Elsevier B.V.

  11. Changes in the Fatty Acid Composition of Brain and Liver Phospholipids from Rats Fed Fat-Free Diet

    Directory of Open Access Journals (Sweden)

    Ivančica Delaš

    2008-01-01

    Full Text Available This study has been undertaken with the aim of elucidating the effect of a fat-free diet (FFD, which is known to be deficient in essential fatty acids (EFA, on the composition of fatty acids in the brain and liver glycerophospholipids of rats. Changes in the stereochemical distribution of fatty acids linked to the sn-1 or sn-2 position were of special interest. Two groups of animals were fed either the control diet (CD or the FFD for two weeks. From the total lipid extracts of the brain and liver tissues, phosphatidylcholine (PC, phosphatidylethanolamine (PE and phosphatidylinositol+phosphatidylserine (PI+PS fractions were separated by column and thin layer chromatography (TLC. After digestion with phospholipase A2 (PLA2, fatty acids from the sn-1 and sn-2 positions were separately converted into methyl esters and analyzed by gas chromatography. In animals fed FFD, the relative levels of unsaturated fatty acids increased in the sn-1 position of the PI+PS fraction in both liver and brain tissues, as well as in the PE fraction from the brain tissue. In other fractions no statistically significant differences were found. When the levels of particular fatty acids were evaluated, significant decreases in the amounts of palmitic (PA, 16:0, stearic (SA, 18:0, and nervonic (NA, 24:1n-9 acids, and/or significant increases of eicosenoic (ENA, 20:1n-9, arachidonic (AA, 20:4n-6 and docosahexaenoic (DHA, 22:6n-3 acids were detected in some fractions. It can be concluded that in the brain and liver glycerophospholipids of rats fed FFD, the EFAs lacking in the diet were moderately substituted by endogenously synthesized unsaturated fatty acids.

  12. Hierarchical Composite Membranes with Robust Omniphobic Surface Using Layer-By-Layer Assembly Technique

    KAUST Repository

    Woo, Yun Chul

    2018-01-17

    In this study, composite membranes were fabricated via layer-by-layer (LBL) assembly of negatively-charged silica aerogel (SiA) and 1H, 1H, 2H, 2H – Perfluorodecyltriethoxysilane (FTCS) on a polyvinylidene fluoride phase inversion membrane, and interconnecting them with positively-charged poly(diallyldimethylammonium chloride) (PDDA) via electrostatic interaction. The results showed that the PDDA-SiA-FTCS coated membrane had significantly enhanced the membrane structure and properties. New trifluoromethyl and tetrafluoroethylene bonds appeared at the surface of the coated membrane, which led to lower surface free energy of the composite membrane. Additionally, the LBL membrane showed increased surface roughness. The improved structure and property gave the LBL membrane an omniphobic property, as indicated by its good wetting resistance. The membrane performed a stable air gap membrane distillation (AGMD) flux of 11.22 L/m2h with very high salt rejection using reverse osmosis brine from coal seam gas produced water as feed with the addition of up to 0.5 mM SDS solution. This performance was much better compared to those of the neat membrane. The present study suggests that the enhanced membrane properties with good omniphobicity via LBL assembly make the porous membranes suitable for long-term AGMD operation with stable permeation flux when treating challenging saline wastewater containing low surface tension organic contaminants.

  13. High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes.

    Science.gov (United States)

    Chen, Wei; Chen, Shuyu; Liang, Tengfei; Zhang, Qiang; Fan, Zhongli; Yin, Hang; Huang, Kuo-Wei; Zhang, Xixiang; Lai, Zhiping; Sheng, Ping

    2018-03-05

    Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3-20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

  14. High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes

    Science.gov (United States)

    Chen, Wei; Chen, Shuyu; Liang, Tengfei; Zhang, Qiang; Fan, Zhongli; Yin, Hang; Huang, Kuo-Wei; Zhang, Xixiang; Lai, Zhiping; Sheng, Ping

    2018-04-01

    Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3-20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

  15. High-flux water desalination with interfacial salt sieving effect in nanoporous carbon composite membranes

    KAUST Repository

    Chen, Wei

    2018-03-05

    Freshwater flux and energy consumption are two important benchmarks for the membrane desalination process. Here, we show that nanoporous carbon composite membranes, which comprise a layer of porous carbon fibre structures grown on a porous ceramic substrate, can exhibit 100% desalination and a freshwater flux that is 3-20 times higher than existing polymeric membranes. Thermal accounting experiments demonstrated that the carbon composite membrane saved over 80% of the latent heat consumption. Theoretical calculations combined with molecular dynamics simulations revealed the unique microscopic process occurring in the membrane. When the salt solution is stopped at the openings to the nanoscale porous channels and forms a meniscus, the vapour can rapidly transport across the nanoscale gap to condense on the permeate side. This process is driven by the chemical potential gradient and aided by the unique smoothness of the carbon surface. The high thermal conductivity of the carbon composite membrane ensures that most of the latent heat is recovered.

  16. Development of cesium phosphotungstate salt and chitosan composite membrane for direct methanol fuel cells.

    Science.gov (United States)

    Xiao, Yanxin; Xiang, Yan; Xiu, Ruijie; Lu, Shanfu

    2013-10-15

    A novel composite membrane has been developed by doping cesium phosphotungstate salt (CsxH3-xPW12O40 (0≤x≤3), Csx-PTA) into chitosan (CTS/Csx-PTA) for application in direct methanol fuel cells (DMFCs). Uniform distribution of Csx-PTA nanoparticles has been achieved in the chitosan matrix. The proton conductivity of the composite membrane is significantly affected by the Csx-PTA content in the composite membrane as well as the Cs substitution in PTA. The highest proton conductivity for the CTS/Csx-PTA membranes was obtained with x=2 and Cs2-PTA content of 5 wt%. The value is 6×10(-3) S cm(-1) and 1.75×10(-2) S cm(-1) at 298 K and 353 K, respectively. The methanol permeability of CTS/Cs2-PTA membrane is about 5.6×10(-7), 90% lower than that of Nafion-212 membrane. The highest selectivity factor (φ) was obtained on CTS/Cs2-PTA-5 wt% composite membrane, 1.1×10(4)/Scm(-3)s. The present study indicates the promising potential of CTS/Csx-PTA composite membrane as alternative proton exchange membranes in direct methanol fuel cells. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Study on the Durability of Recast Nafion/Montmorillonite Composite Membranes in Low Humidification Conditions

    Directory of Open Access Journals (Sweden)

    A. Pozio

    2011-01-01

    Full Text Available Nafion composite membranes were formed from a recasting procedure previously reported by the authors. Montmorillonite (MMT was used as a filler in the recasting procedure, and dimethylformamide (DMF was used as the casting solvent. Fuel cell tests performed with the recast membrane showed that at low relative humidity (R.H. the conductivity of the MMT-containing membranes is 10% higher than that of the MMT-free samples. In order to investigate the durability of such composite perfluorosulfonate membranes, long-term fuel cell experiments have been carried out. Results evidenced a strong effect of low RH on the lifetime of commercial polymer membranes, but the addition of a small silicate amount to the polymeric membrane reduced strongly the membrane degradation.

  18. Thin-film composite crosslinked polythiosemicarbazide membranes for organic solvent nanofiltration (OSN)

    KAUST Repository

    Aburabie, Jamaliah

    2015-01-01

    In this work we report a new class of solvent stable thin-film composite (TFC) membrane fabricated on crosslinked polythiosemicarbazide (PTSC) as substrate that exhibits superior stability compared with other solvent stable polymeric membranes reported up to now. Integrally skinned asymmetric PTSC membranes were prepared by the phase inversion process and crosslinked with an aromatic bifunctional crosslinker to improve the solvent stability. TFC membranes were obtained via interfacial polymerization using trimesoyl chloride (TMC) and diaminopiperazine (DAP) monomers. The membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and contact angle measurement.The membranes exhibited high fluxes toward solvents like tetrahydrofuran (THF), dimethylformamide (DMF) and dimethylsulfoxide (DMSO) ranging around 20L/m2 h at 5bar with a molecular weight cut off (MWCO) of around 1000g/mol. The PTSC-based thin-film composite membranes are very stable toward polar aprotic solvents and they have potential applications in the petrochemical and pharmaceutical industry.

  19. Composite Nafion 117-TMSP membrane for Fe-Cr redox flow battery applications

    Science.gov (United States)

    Haryadi, Gunawan, Y. B.; Mursid, S. P.; Harjogi, D.

    2016-04-01

    The modification of Nafion 117 - TMSP (trimethoxysylilprophanthiol) composite membrane has been conducted by in-situ sol-gel method followed by characterization of structural and properties of material using spectroscopic techniques. The performance of composite membrane has then been examined in the single stack module of Fe-Cr Redox Flow Battery. It was found that the introduction of silica from TMSP through sol-gel process within the Nafion 117 membrane produced composite membrane that has slightly higher proton conductivity values as compared to the pristine of Nafion 117 membrane observed by electrochemical impedance spectroscopy. The degree of swelling of water in the composite membrane demonstrated greatly reduced than a pristine Nafion 117 signifying low water cross over. The SEM-EDX measurements indicated that there was no phase separation occurred suggesting that silica nanoparticles are distributed homogeneously within the composite membrane. The composite membrane used as separator in the system of Fe-Cr Redox Flow Battery revealed no cross mixing (crossover) occurred between anolyte and catholyte in the system as observed from the total voltage measurements that closed to the theoretical value. The battery efficiency generally increased as the volume of the electrolytes enlarged.

  20. Biochar composite membrane for high performance pollutant management: Fabrication, structural characteristics and synergistic mechanisms.

    Science.gov (United States)

    Ghaffar, Abdul; Zhu, Xiaoying; Chen, Baoliang

    2018-02-01

    Biochar, a natural sourced carbon-rich material, has been used commonly in particle shape for carbon sequestration, soil fertility and environmental remediation. Here, we report a facile approach to fabricate freestanding biochar composite membranes for the first time. Wood biochars pyrolyzed at 300 °C and 700 °C were blended with polyvinylidene fluoride (PVdF) in three percentages (10%, 30% and 50%) to construct membranes through thermal phase inversion process. The resultant biochar composite membranes possess high mechanical strength and porous structure with uniform distribution of biochar particles throughout the membrane surface and cross-section. The membrane pure water flux was increased with B300 content (4825-5411 ± 21 L m -2 h -1 ) and B700 content (5823-6895 ± 72 L m -2 h -1 ). The membranes with B300 were more hydrophilic with higher surface free energy (58.84-60.31 mJ m -2 ) in comparison to B700 (56.32-51.91 mJ m -2 ). The biochar composite membranes indicated promising adsorption capacities (47-187 mg g -1 ) to Rhodamine B (RhB) dye. The biochar membranes also exhibited high retention (74-93%) for E. coli bacterial suspensions through filtration. After simple physical cleaning, both the adsorption and sieving capabilities of the biochar composite membranes could be effectively recovered. Synergistic mechanisms of biochar/PVdF in the composite membrane are proposed to elucidate the high performance of the membrane in pollutant management. The multifunctional biochar composite membrane not only effectively prevent the problems caused by directly using biochar particle as sorbent but also can be produced in large scale, indicating great potential for practical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Genetic interactions between a phospholipase A2 and the Rim101 pathway components in S. cerevisiae reveal a role for this pathway in response to changes in membrane composition and shape.

    Science.gov (United States)

    Mattiazzi, M; Jambhekar, A; Kaferle, P; Derisi, J L; Krizaj, I; Petrovic, U

    2010-06-01

    Modulating composition and shape of biological membranes is an emerging mode of regulation of cellular processes. We investigated the global effects that such perturbations have on a model eukaryotic cell. Phospholipases A(2) (PLA(2)s), enzymes that cleave one fatty acid molecule from membrane phospholipids, exert their biological activities through affecting both membrane composition and shape. We have conducted a genome-wide analysis of cellular effects of a PLA(2) in the yeast Saccharomyces cerevisiae as a model system. We demonstrate functional genetic and biochemical interactions between PLA(2) activity and the Rim101 signaling pathway in S. cerevisiae. Our results suggest that the composition and/or the shape of the endosomal membrane affect the Rim101 pathway. We describe a genetically and functionally related network, consisting of components of the Rim101 pathway and the prefoldin, retromer and SWR1 complexes, and predict its functional relation to PLA(2) activity in a model eukaryotic cell. This study provides a list of the players involved in the global response to changes in membrane composition and shape in a model eukaryotic cell, and further studies are needed to understand the precise molecular mechanisms connecting them.

  2. CO2-Philic Thin Film Composite Membranes: Synthesis and Characterization of PAN-r-PEGMA Copolymer

    KAUST Repository

    Karunakaran, Madhavan

    2017-07-06

    In this work, we report the successful fabrication of CO2-philic polymer composite membranes using a polyacrylonitrile-r-poly(ethylene glycol) methyl ether methacrylate (PAN-r-PEGMA) copolymer. The series of PAN-r-PEGMA copolymers with various amounts of PEG content was synthesized by free radical polymerization in presence of AIBN initiator and the obtained copolymers were used for the fabrication of composite membranes. The synthesized copolymers show high molecular weights in the range of 44-56 kDa. We were able to fabricate thin film composite (TFC) membranes by dip coating procedure using PAN-r-PEGMA copolymers and the porous PAN support membrane. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were applied to analyze the surface morphology of the composite membranes. The microscopy analysis reveals the formation of the defect free skin selective layer of PAN-r-PEGMA copolymer over the porous PAN support membrane. Selective layer thickness of the composite membranes was in the range of 1.32-1.42 mu m. The resulting composite membrane has CO2 a permeance of 1.37 x 10(-1) m(3)/m(2).h.bar and an ideal CO2/N-2, selectivity of 65. The TFC membranes showed increasing ideal gas pair selectivities in the order CO2/N-2 > CO2/CH4 > CO2/H-2. In addition, the fabricated composite membranes were tested for long-term single gas permeation measurement and these membranes have remarkable stability, proving that they are good candidates for CO2 separation.

  3. CO2-Philic Thin Film Composite Membranes: Synthesis and Characterization of PAN-r-PEGMA Copolymer

    Directory of Open Access Journals (Sweden)

    Madhavan Karunakaran

    2017-07-01

    Full Text Available In this work, we report the successful fabrication of CO2-philic polymer composite membranes using a polyacrylonitrile-r-poly(ethylene glycol methyl ether methacrylate (PAN-r-PEGMA copolymer. The series of PAN-r-PEGMA copolymers with various amounts of PEG content was synthesized by free radical polymerization in presence of AIBN initiator and the obtained copolymers were used for the fabrication of composite membranes. The synthesized copolymers show high molecular weights in the range of 44–56 kDa. We were able to fabricate thin film composite (TFC membranes by dip coating procedure using PAN-r-PEGMA copolymers and the porous PAN support membrane. Scanning electron microscopy (SEM and atomic force microscopy (AFM were applied to analyze the surface morphology of the composite membranes. The microscopy analysis reveals the formation of the defect free skin selective layer of PAN-r-PEGMA copolymer over the porous PAN support membrane. Selective layer thickness of the composite membranes was in the range of 1.32–1.42 μm. The resulting composite membrane has CO2 a permeance of 1.37 × 10−1 m3/m2·h·bar and an ideal CO2/N2, selectivity of 65. The TFC membranes showed increasing ideal gas pair selectivities in the order CO2/N2 > CO2/CH4 > CO2/H2. In addition, the fabricated composite membranes were tested for long-term single gas permeation measurement and these membranes have remarkable stability, proving that they are good candidates for CO2 separation.

  4. Extending David Horrobin's membrane phospholipid theory of schizophrenia: overactivity of cytosolic phospholipase A(2) in the brain is caused by overdrive of coupled serotonergic 5HT(2A/2C) receptors in response to stress.

    Science.gov (United States)

    Eggers, Arnold E

    2012-12-01

    David Horrobin's membrane phospholipid theory of schizophrenia has held up well over time because his therapeutic prediction that dietary supplementation with eicosapentaenoic acid (EPA) would have a therapeutic effect has been partially verified and undergoes continued testing. In the final version of his theory, he hypothesized that there was hyperactivity of phosphoslipase A(2) (PLA(2)) or a related enzyme but did not explain how the hyperactivity came about. It is known that serotonergic 5HT(2A/2C) receptors are coupled to PLA(2), which hydrolyzes both arachidonic acid (AA) and EPA from diacylglycerides at the sn-2 position. In this paper, Horrobin's theory is combined with a previously published theory of chronic stress in which it was hypothesized that a disinhibited dorsal raphe nucleus, the principal nucleus of the serotonergic system, can organize the neuropathology of diseases such as migraine, hypertension, and the metabolic syndrome. The new or combined theory is that schizophrenia is a disease of chronic stress in which a disinhibited DRN causes widespread serotonergic overdrive in the cerebral cortex. This in turn causes overdrive of cPLA(2) and both central and peripheral depletion of AA and EPA. Because EPA is present in smaller amounts, it falls below threshold for maintaining an intracellular balance between AA-derived and EPA-derived second messenger cascades, which leads to abnormal patterns of neuronal firing. There are two causes of neuronal dysfunction: the disinhibited DRN and EPA depletion. Schizophrenia is statistically associated with metabolic syndrome, hypertension, and migraine because they form a cluster of diseases with similar pathophysiology. The theory provides an explanation for both the central and peripheral phospholipid abnormalities in schizophrenia. It also explains the role of stress in schizophrenia, elevated serum PLA(2) activity in schizophrenia, the relationship between untreated schizophrenia and metabolic syndrome

  5. Performance of a 1 kW Class Nafion-PTFE Composite Membrane Fuel Cell Stack

    Directory of Open Access Journals (Sweden)

    Pattabiraman Krishnamurthy

    2012-01-01

    Full Text Available Composite membranes have been prepared by impregnation of Nafion into the expanded polytetrafluoroethylene (EPTFE matrix. Nafion loading in the composite membranes was kept constant at 2 mg/cm2. The lower amount of electrolyte per unit area in the composite membranes offers cost advantages compared to conventional membrane of 50 μm thickness with an electrolyte loading of ~9 mg/cm2. Composite membranes (30 μm thickness were found to have higher thermal stability and mechanical strength compared to the conventional membranes (50 μm thickness. The performance of the membrane electrode assembly made with these composite membranes was comparable to that of the conventional membranes. Single cells fabricated from these MEAs were tested for their performance and durability before scaling them up for large area. The performance of a 20-cell stack of active area 330 cm2 fabricated using these membranes is reported.

  6. Novel structure design of composite proton exchange membranes with continuous and through-membrane proton-conducting channels

    Science.gov (United States)

    Wang, Hang; Tang, Chenxiao; Zhuang, Xupin; Cheng, Bowen; Wang, Wei; Kang, Weimin; Li, Hongjun

    2017-10-01

    The primary goal of this study is to develop a high-performanced proton exchange membrane with the characteristics of through-membrane and continuous solution blown nanofibers as proton-conducting channels. The curled sulfonated phenolphthalein poly (ether sulfone) and poly (vinylidene fluoride) nanofibers were separately fabricated through the solution blowing process which is a new nanofiber fabricating method with high productivity, then they were fabricated into a sandwich-structured mat. Then this sandwich-structured mat was hot-pressed to form the designed structure using different melting temperatures of the two polymers by melting and making poly (vinylidene fluoride) flow into the phenolphthalein poly (ether sulfone) nanofiber mat. The characteristics of the composite membrane, such as morphology and performance of the membrane, were investigated. The characterization results proved the successful preparation of the membrane structure. Performance results showed that the novel structured membrane with through-membrane nanofibers significantly improved water swelling and methanol permeability, though its conductivity is lower than that of Nafion, the cell performance showed comparable results. Therefore, the novel structure design can be considered as a promising method for preparing of proton exchange membranes.

  7. Phospholipids of marine origin: the orange roughy (Hoplostethus atlanticus)

    CSIR Research Space (South Africa)

    De Koning, AJ

    2005-09-01

    Full Text Available and 0.1% free cholesterol. The fatty acid compositions of the phospholipids and the non-phosphorylated lipids were different, the phospholipids having a high level of docosahexaenoic acid (C22:6 n-3) of 40.4%, whereas the non-phosphorylated lipids had a...

  8. Fabrication of an Anti-Biofouling Plasma-Filtration Membrane by an Electrospinning Process Using Photo-Cross-linkable Zwitterionic Phospholipid Polymers.

    Science.gov (United States)

    Seo, Jiae; Seo, Ji-Hun

    2017-06-14

    The goal of this study is to fabricate a stable plasma filtration membrane with antibiofouling properties via an electrospinning process. To this end, a random-type copolymer consisting of zwitterionic phosphorylcholine (PC) groups and ultraviolet (UV)-cross-linkable phenyl azide groups was synthesized. The zwitterionic PC group provides antibiofouling properties, and the phenyl azide group enables the stable maintenance of the fibrous nanostructure of hydrophilic zwitterion polymers in aqueous medium via a simple UV curing process. To demonstrate the antibiofouling nature of the PC group, a polymer without antibiofouling PC groups was also prepared for comparison. The successful synthesis of the random-type copolymers containing phenyl azide groups was proven by 1 H nuclear magnetic resonance and Fourier transform infrared spectroscopy, and the fibrous structure of the prepared membranes was observed by field emission scanning electron microscopy. The antibiofouling properties were analyzed by fluorescein isothiocyanate-labeled bovine serum albumin adsorption and platelet adhesion tests. The experimental results show that membranes containing zwitterionic PC groups exhibited obvious decreases in platelet adhesion and protein adsorption. Platelet-rich plasma solution was filtered using the prepared membranes to test their filtration properties. The sequential filtration process removed 80% and almost 98% of the platelets. This finding confirmed that the membrane retained its blood-inert biomaterial surface in a complex medium that included blood plasma and platelets.

  9. Removal of Zn (II) and Ga (III) from waste waters using activated composite membranes

    International Nuclear Information System (INIS)

    Melita, L.; Meghea, A.; Munoz Tapia, M.; Gives, J. de

    2001-01-01

    The present study refers to the preparation of activated composite membrane (ACM) containing Aliquat 336 as a carrier, and testing their properties towards the selective transport of Ga and Zn cations. A new type of liquid membrane was prepared, named Activated Composite Membrane (ACM). The stability of these membrane increases, referring to other common membranes used before. These membranes have also good characteristics to separate metals. We cast membranes in two steps, first we used non-woven fabric (Hollytex 3329, France) as a support to manufacture reinforced polysulfone (PS) membrane which was obtained by the phase inversion technique, and second, a thin top layer of polyamide containing Aliquat 336 of two different concentrations (0.5 and 1 M) was obtained by interfacial polymerisation. The membrane thus prepared is composed of polyamide and polysulfone layers containing carrier. The surface texture of the membrane under study was examined by scanning electron microscopy (SEM) using a JSM-6300 scanning electron microscope. The chemical elemental analysis of freshly prepared membranes was performed, by X-ray diffraction measuring the energy distribution of the X-ray signal generated by a focused electron beam. A correlation between the carrier content in the membrane and the concentration of metal separated was obtained from the results of the membrane analysis by using the inductively coupled plasma (ICP) technique. The competition between gallium and zinc in the membrane surface is presented by the retaining membrane capacity. This type of membrane is relatively new for metal removal (Ga and Zn) from waste waters and the best cation retention was obtained for Zn. (authors)

  10. Hydrophilic nanofibers as new supports for thin film composite membranes for engineered osmosis.

    Science.gov (United States)

    Bui, Nhu-Ngoc; McCutcheon, Jeffrey R

    2013-02-05

    Engineered osmosis (e.g., forward osmosis, pressure-retarded osmosis, direct osmosis) has emerged as a new platform for applications to water production, sustainable energy, and resource recovery. The lack of an adequately designed membrane has been the major challenge that hinders engineered osmosis (EO) development. In this study, nanotechnology has been integrated with membrane science to build a next generation membrane for engineered osmosis. Specifically, hydrophilic nanofiber, fabricated from different blends of polyacrylonitrile and cellulose acetate via electrospinning, was found to be an effective support for EO thin film composite membranes due to its intrinsically wetted open pore structure with superior interconnectivity. The resulting composite membrane exhibits excellent permselectivity while also showing a reduced resistance to mass transfer that commonly impacts EO processes due to its thin, highly porous nanofiber support layer. Our best membrane exhibited a two to three times enhanced water flux and 90% reduction in salt passage when compared to a standard commercial FO membrane. Furthermore, our membrane exhibited one of the lowest structural parameters reported in the open literature. These results indicate that hydrophilic nanofiber supported thin film composite membranes have the potential to be a next generation membrane for engineered osmosis.

  11. Electrochemical characterization and transport phenomena of polystyrene based barium–magnesium phosphate composite membrane

    Directory of Open Access Journals (Sweden)

    Mohammad Mujahid Ali Khan

    2016-09-01

    Full Text Available The polystyrene based barium–magnesium (BMP composite membrane was prepared by sol–gel method. The physico-chemical characterization of the BMP composite membrane was established by XRD, FTIR and simultaneous SEM studies. The membrane was found to be crystalline in nature with uniform arrangement of particles indicating no sign of visible cracks. Membrane potential is a measurable and important parameter to characterize the charge property of the membrane. Membrane potentials have been measured across the polystyrene based barium–magnesium (BMP composite membrane separating various 1:1 electrolytes at different concentrations and followed the order KCl < NaCl < LiCl. The membrane was found to be cation-selective. Membrane potentials have been used to calculate transport number, mobility ratio, distribution coefficient, charge effectiveness, and also the fixed charge density which is a central parameter governing the membrane phenomena by utilizing Teorell, Meyer, and Sievers method. The order of surface charge density for uni-univalent electrolytes solution was found to be LiCl < NaCl < KCl.

  12. Intake of a Western diet containing cod instead of pork alters fatty acid composition in tissue phospholipids and attenuates obesity and hepatic lipid accumulation in mice

    Czech Academy of Sciences Publication Activity Database

    Liisberg, U.; Fauske, K. R.; Kuda, Ondřej; Fjare, E.; Myrmel, L. S.; Norberg, N.; Froyland, L.; Graff, I. E.; Liaset, B.; Kristiansen, K.; Kopecký, Jan; Madsen, L.

    2016-01-01

    Roč. 33, Jul (2016), s. 119-127 ISSN 0955-2863 Institutional support: RVO:67985823 Keywords : diet * dietary lipids * endocannabinoids * fish oil * phospholipids * liver * obesity Subject RIV: FB - Endocrinology, Diabetology, Metabolism, Nutrition Impact factor: 4.518, year: 2016

  13. Characteristics of polyimide-based composite membranes fabricated by low-temperature plasma polymerization

    International Nuclear Information System (INIS)

    Dung Thi Tran; Mori, Shinsuke; Suzuki, Masaaki

    2008-01-01

    Composite membranes were prepared by the deposition of plasma-polymerized allylamine films onto a porous polyimide substrate. The relationship between the plasma conditions and the membrane characteristics was described in terms of monomer flow rate, plasma discharge power, plasma polymerization time, and so on. Scanning electron microscope (SEM) images indicate that the thickness of the plasma polymer layer increased and the membrane skin pore size decreased gradually with the increasing of plasma polymerization time. Fourier transform infrared (FTIR) spectra demonstrate the appearance of amine groups in the plasma deposited polymer and the contact angle measurements indicate that the hydrophilicity of the membrane surfaces increased significantly after plasma polymerization. The composite membranes can reject salt from sodium chloride feed solution, and membrane separation performance depends strongly on the plasma conditions applied during the preparation of the plasma deposited polymer films

  14. Polysulphone composite membranes modified with two types of ...

    Indian Academy of Sciences (India)

    The presence of carbon fibrous additives in the PSU matrix improved its hydrophilicity. Porosity and topography of the PSU membranes were also changed upon incorporation of carbon additives. The mechanical properties of the PSU membranes were improved after SCF addition. All physicochemical properties of the ...

  15. Polysulfone - CNT composite membrane with enhanced water permeability

    Science.gov (United States)

    Hirani, Bhakti; Kar, Soumitra; Aswal, V. K.; Bindal, R. C.; Goyal, P. S.

    2018-04-01

    Polymeric membranes are routinely used for water purification. The performance of these conventional membranes can be improved by incorporating nanomaterials, such as metal oxide nanoparticle and carbon nanotubes (CNTs). This manuscript reports the synthesis and characterization of polysulfone (Psf) based nanocomposite membranes where multi wall carbon nanotubes (MWCNTs) and oleic acid coated Fe3O4 nanoparticles have been impregnated onto the polymeric host matrix. The performance of the membranes was evaluated by water permeability and solute rejection measurements. It was observed that the permeability of Psf membrane increases three times at 0.1% loading of MWCNT without compromise in selectivity. It was further observed that the increase in permeability is not affected upon addition of Fe3O4 nanoparticles into the membrane. In order to get a better insight into the membrane microstructure, small angle neutron scattering (SANS) studies were carried out. There is a good correlation between the water permeability and the pore sizes of the membranes as measured using SANS.

  16. Preparation and properties of a composite charged membrane

    NARCIS (Netherlands)

    Noordegraaf, D.A.; Smolders, C.A.; de Boer, R.; Romijn, D.J.

    1982-01-01

    In order to develop a low pressure desalination membrane with fixed ionic charges, we made use of the normally unwanted crosslinking tendency in preparing the polyelectrolyte poly(styrenesulfonate) by sulfonation of polystyrene. After dipcoating a poly(sulfone) or poly(phenylene oxide) UF membrane

  17. Enterococcus faecalis and pathogenic streptococci inactivate daptomycin by releasing phospholipids.

    Science.gov (United States)

    Ledger, Elizabeth V K; Pader, Vera; Edwards, Andrew M

    2017-10-01

    Daptomycin is a lipopeptide antibiotic with activity against Gram-positive bacteria. We showed previously that Staphylococcus aureus can survive daptomycin exposure by releasing membrane phospholipids that inactivate the antibiotic. To determine whether other pathogens possess this defence mechanism, phospholipid release and daptomycin activity were measured after incubation of Staphylococcus epidermidis, group A or B streptococci, Streptococcus gordonii or Enterococcus faecalis with the antibiotic. All bacteria released phospholipids in response to daptomycin, which resulted in at least partial inactivation of the antibiotic. However, E. faecalis showed the highest levels of lipid release and daptomycin inactivation. As shown previously for S. aureus, phospholipid release by E. faecalis was inhibited by the lipid biosynthesis inhibitor platensimycin. In conclusion, several pathogenic Gram-positive bacteria, including E. faecalis, inactivate daptomycin by releasing phospholipids, which may contribute to the failure of daptomycin to resolve infections caused by these pathogens.

  18. MALDI imaging MS of phospholipids in the mouse lung.

    Science.gov (United States)

    Berry, Karin A Zemski; Li, Bilan; Reynolds, Susan D; Barkley, Robert M; Gijón, Miguel A; Hankin, Joseph A; Henson, Peter M; Murphy, Robert C

    2011-08-01

    Lipid mediators are important in lung biochemistry and are derived from the enzymatic oxidation of arachidonic and docosahexaenoic acids, which are PUFAs that are present in phospholipids in cell membranes. In this study, MALDI imaging MS was used to determine the localization of arachidonate- and docosahexaenoate-containing phospholipids in mouse lung. These PUFA-containing phospholipids were determined to be uniquely abundant at the lining of small and large airways, which were unequivocally identified by immunohistochemistry. In addition, it was found that the blood vessels present in the lung were characterized by sphingomyelin molecular species, and lung surfactant phospholipids appeared evenly distributed throughout the lung parenchyma, indicating alveolar localization. This technique revealed unexpected high concentrations of arachidonate- and docosahexaenoate-containing phospholipids lining the airways in pulmonary tissue, which could serve as precursors of lipid mediators affecting airways biology.

  19. Thin film composite membranes of glossy polymers for gas separation : preparation and characterization

    NARCIS (Netherlands)

    Ebert, Katrin

    1995-01-01

    The application of polymeric composite membranes can be very interesting in the field of gas separation. The two main parameters which determine the applicability of membranes are the selectivity and the permeability. Good selectivities can be achieved by developing proper materials, high permeation

  20. Sulfonated poly(ether ether ketone) based composite membranes for nanofiltration of acidic and alkaline media

    NARCIS (Netherlands)

    Dalwani, M.R.; Bargeman, Gerrald; Hosseiny, Seyed Schwan; Schwan Hosseiny, Seyed; Boerrigter, M.E.; Wessling, Matthias; Benes, Nieck Edwin

    2011-01-01

    Several thin film composite nanofiltration membranes have been prepared by spin coating a sulfonated poly(ether ether ketone) solution on a polyethersulfone support, followed by thermal treatment. The most optimal developed nanofiltration membrane shows a clean water permeance of ∼4.5 L m−2 h−1

  1. CO2-selective PEO–PBT (PolyActive™)/graphene oxide composite membranes

    KAUST Repository

    Karunakaran, Madhavan

    2015-07-31

    CO2-selective graphene oxide (GO) nano-composite membranes were prepared for the first time by embedding GO into a commercially available poly(ethylene oxide)–poly(butylene terephthalate) (PEO–PBT) copolymer (PolyActive™). The as-prepared GO membrane shows high CO2 permeability (143 Barrer) and CO2/N2 selectivity (α = 73).

  2. Exceptionally strong and robust millimeter-scale graphene–alumina composite membranes

    International Nuclear Information System (INIS)

    Berdova, Maria; Franssila, Sami; Perros, Alexander Pyymaki; Kim, Wonjae; Riikonen, Juha; Li, Changfeng; Lipsanen, Harri; Ylitalo, Tuomo; Kassamakov, Ivan; Hæggström, Edward; Heino, Jouni

    2014-01-01

    Graphene has attracted attention as a potential strengthening material and functional component in suspended membranes as utilized in micro and nanosystems. Development of a practical and scalable fabrication process is a necessary step to allow the exceptional material properties of graphene to be fully exploited in composite structures. Using standard and scalable microfabrication processes, we fabricated free-standing chemical vapor deposition monolayer graphene-reinforced Al 2 O 3 composite membranes, 0.5 mm in diameter, that are strong and robust. Bulge tests revealed that the graphene reinforcement increased the membrane fracture strength by a factor of at least three and maximum sustainable strain from 0.28% to at least 0.69%. We show that the graphene-reinforced membranes are even tolerant to significant cracking without loss of membrane integrity. The graphene composite membranes’ freestanding area of ∼200 000 μm 2 is almost a thousand times larger than suspended graphene membranes reported elsewhere. The presented graphene composite membranes may be seen as representing an interesting new class of durable composite materials warranting further study and having potential for broad applicability in a variety of fields. (paper)

  3. TiO2/bi A-SPAES(Ds 1.0) composite membranes for proton exchange membrane in direct methanol fuel cell (DMFC).

    Science.gov (United States)

    Zhang, Ni; Zhong, Chuanqing; Xie, Bing; Liu, Huiling; Wang, Xingzu

    2014-09-01

    A series of TiO2/bi A-SPAES(Ds 1.0) composite membranes with various contents of nano-sized TiO2 particles were prepared through sol-gel method. Scanning electron microscopy (SEM) images indicated the TiO2 particles were well dispersed within polymer matrix. These membranes were used for proton exchange membrane (PEM) for performance evaluation in direct methanol fuel cell (DMFC). These composite membranes showed good thermal stability and mechanical strength. It was found that the water uptake of these membranes enhanced with the TiO2 amount increasing in these composite membranes. Meanwhile, the introduction of TiO2 particles increased the proton conductivity and reduced the methanol permeability. The proton conductivities of these composite membranes with 8% TiO2 particles (0.120 S/cm and 0.128 S/cm) were higher than those of Nafion 117 membrane (0.114 S/cm and 0.117 S/cm) at 80 degrees C and 100 degrees C. Specially, the methanol diffusion coefficient (1.2 x 10(-7) cm2/s) of the composite membrane with 8% TiO2 content was much lower than that of Nafion 117 membrane (2.1 x 10(-6) cm2/s). As a result, the TiO2/bi A-SPAES composite membrane was considered as a promising material for PEM in DMFC.

  4. 1,2-Dielaidoylphosphocholine/1,2-dimyristoylphosphoglycerol supported phospholipid bilayer formation in calcium and calcium-free buffer

    International Nuclear Information System (INIS)

    Evans, Kervin O.

    2012-01-01

    Phospholipid membranes are useful in the field of biocatalysis because a supported phospholipid membrane can create a biomimetic platform where biocatalytic processes can readily occur. In this work, supported bilayer formation from sonicated phospholipid vesicles containing 1,2-dielaidoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] was studied using a quartz crystal microbalance with dissipation monitoring and an atomic force microscope. The molar percentages of DEPC and DMPG were varied to determine the effect of overall lipid composition on supported bilayer formation. This work also explored the effect that calcium ion concentration had on supported bilayer formation. Results show that vesicles with up to 50 mol% dimyristoylphosphoglycerol can form a supported bilayer without the presence of calcium ions; however, supported bilayer formation in calcium buffer was inhibited as the anionic (negatively charged) lipid concentration increased. Data suggest that supported phospholipid bilayer formation in the absence of Ca 2+ from vesicles containing negatively charged lipids is specific to phosphatidylglycerol. - Highlights: ► SPB formation of DEPC vesicles containing 0 to 50 mol% DMPG monitored using QCM-D. ► Ca 2+ inhibited SPB formation of DEPC vesicles containing 30 to 50 mol% DMPG. ► Vesicles containing DMPG at 0 to 50 mol% formed SPB in buffer free of Ca 2+ .

  5. 1,2-Dielaidoylphosphocholine/1,2-dimyristoylphosphoglycerol supported phospholipid bilayer formation in calcium and calcium-free buffer

    Energy Technology Data Exchange (ETDEWEB)

    Evans, Kervin O., E-mail: Kervin.Evans@ars.usda.gov

    2012-01-31

    Phospholipid membranes are useful in the field of biocatalysis because a supported phospholipid membrane can create a biomimetic platform where biocatalytic processes can readily occur. In this work, supported bilayer formation from sonicated phospholipid vesicles containing 1,2-dielaidoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-[phospho-rac-(1-glycerol)] was studied using a quartz crystal microbalance with dissipation monitoring and an atomic force microscope. The molar percentages of DEPC and DMPG were varied to determine the effect of overall lipid composition on supported bilayer formation. This work also explored the effect that calcium ion concentration had on supported bilayer formation. Results show that vesicles with up to 50 mol% dimyristoylphosphoglycerol can form a supported bilayer without the presence of calcium ions; however, supported bilayer formation in calcium buffer was inhibited as the anionic (negatively charged) lipid concentration increased. Data suggest that supported phospholipid bilayer formation in the absence of Ca{sup 2+} from vesicles containing negatively charged lipids is specific to phosphatidylglycerol. - Highlights: Black-Right-Pointing-Pointer SPB formation of DEPC vesicles containing 0 to 50 mol% DMPG monitored using QCM-D. Black-Right-Pointing-Pointer Ca{sup 2+} inhibited SPB formation of DEPC vesicles containing 30 to 50 mol% DMPG. Black-Right-Pointing-Pointer Vesicles containing DMPG at 0 to 50 mol% formed SPB in buffer free of Ca{sup 2+}.

  6. Liposome Model Systems to Study the Endosomal Escape of Cell-Penetrating Peptides: Transport across Phospholipid Membranes Induced by a Proton Gradient

    Directory of Open Access Journals (Sweden)

    Fatemeh Madani

    2011-01-01

    Full Text Available Detergent-mediated reconstitution of bacteriorhodopsin (BR into large unilamellar vesicles (LUVs was investigated, and the effects were carefully characterized for every step of the procedure. LUVs were prepared by the extrusion method, and their size and stability were examined by dynamic light scattering. BR was incorporated into the LUVs using the detergent-mediated reconstitution method and octyl glucoside (OG as detergent. The result of measuring pH outside the LUVs suggested that in the presence of light, BR pumps protons from the outside to the inside of the LUVs, creating acidic pH inside the vesicles. LUVs with 20% negatively charged headgroups were used to model endosomes with BR incorporated into the membrane. The fluorescein-labeled cell-penetrating peptide penetratin was entrapped inside these BR-containing LUVs. The light-induced proton pumping activity of BR has allowed us to observe the translocation of fluorescein-labeled penetratin across the vesicle membrane.

  7. Synthesis and membrane behavior of a new class of unnatural phospholipid analogs useful as phospholipase A2 degradable liposomal drug carriers

    DEFF Research Database (Denmark)

    Andresen, Thomas Lars; Jørgensen, Kent

    2005-01-01

    A new and unnatural type of lipid analogs with the phosphocholine and phosphoglycerol head groups linked to the C-2 position of the glycerol moiety have been synthesized and the thermodynamic lipid membrane behavior has been investigated using differential scanning calorimetry. From the heat capa...... results also suggest new approaches to rationally design liposomal drug carries that can undergo a triggered activation in diseased tissue by overexpressed PLA2....

  8. Progesterone modulation of transmembrane helix-helix interactions between the α-subunit of Na/K-ATPase and phospholipid N-methyltransferase in the oocyte plasma membrane

    Directory of Open Access Journals (Sweden)

    Askari Amir

    2010-05-01

    Full Text Available Abstract Background Progesterone binding to the surface of the amphibian oocyte initiates the meiotic divisions. Our previous studies with Rana pipiens oocytes indicate that progesterone binds to a plasma membrane site within the external loop between the M1 and M2 helices of the α-subunit of Na/K-ATPase, triggering a cascade of lipid second messengers and the release of the block at meiotic prophase. We have characterized this site, using a low affinity ouabain binding isoform of the α1-subunit. Results Preparations of isolated plasma membranes from Rana oocytes demonstrate that physiological levels of progesterone (or the non-metabolizable progestin R5020 successively activate phosphatidylethanolamine-N-methyltransferase (PE-NMT and sphingomyelin synthase within seconds. Inhibition of PE-NMT blocks the progesterone induction of meiosis in intact oocytes, whereas its initial product, phosphatidylmonomethylethanolamine (PME, can itself initiate meiosis in the presence of the inhibitor. Published X-ray crystallographic data on Na/K-ATPase, computer-generated 3D projections, heptad repeat analysis and hydrophobic cluster analysis of the transmembrane helices predict that hydrophobic residues L, V, V, I, F and Y of helix M2 of the α1-subunit interact with F, L, G, L, L and F, respectively, of helix M3 of PE-NMT. Conclusion We propose that progesterone binding to the first external loop of the α1-subunit facilitates specific helix-helix interactions between integral membrane proteins to up-regulate PE-NMT, and, that successive interactions between two or more integral plasma membrane proteins induce the signaling cascades which result in completion of the meiotic divisions.

  9. Comparison of biofouling mechanisms between cellulose triacetate (CTA) and thin-film composite (TFC) polyamide forward osmosis membranes in osmotic membrane bioreactors.

    Science.gov (United States)

    Wang, Xinhua; Zhao, Yanxiao; Yuan, Bo; Wang, Zhiwei; Li, Xiufen; Ren, Yueping

    2016-02-01

    There are two types of popular forward osmosis (FO) membrane materials applied for researches on FO process, cellulose triacetate (CTA) and thin film composite (TFC) polyamide. However, performance and fouling mechanisms of commercial TFC FO membrane in osmotic membrane bioreactors (OMBRs) are still unknown. In current study, its biofouling behaviors in OMBRs were investigated and further compared to the CTA FO membrane. The results indicated that β-D-glucopyranose polysaccharides and microorganisms accounted for approximately 77% of total biovolume on the CTA FO membrane while β-D-glucopyranose polysaccharides (biovolume ratio of 81.1%) were the only dominant biofoulants on the TFC FO membrane. The analyses on the biofouling structure implied that a tighter biofouling layer with a larger biovolume was formed on the CTA FO membrane. The differences in biofouling behaviors including biofoulants composition and biofouling structure between CTA and TFC FO membranes were attributed to different membrane surface properties. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. PALLADIUM/COPPER ALLOY COMPOSITE MEMBRANES FOR HIGH TEMPERATURE HYDROGEN SEPARATION

    Energy Technology Data Exchange (ETDEWEB)

    J. Douglas Way

    2004-08-31

    This report summarizes progress made during the first year of research funding from DOE Grant No. DE-FG26-03NT41792 at the Colorado School of Mines. The period of performance was September 1, 2003 through August of 2004. Composite membranes, consisting of a thin Pd alloy film supported on a porous substrate have been investigated as a means of reducing the membrane cost and improving H{sub 2} flux. An electroless plating technique was utilized to deposit subsequent layers of palladium and copper over zirconia and alumina-based microfilters. The composite membranes thus made were annealed and tested at temperatures ranging from 250 to 500 C, under very high feed pressures (up to 450 psig) using pure gases and gaseous mixtures containing H{sub 2}, CO, CO{sub 2}, H{sub 2}O and H{sub 2}S, with the purpose of determining the effects these variables had on the H{sub 2} permeation rate, selectivity and percent recovery. The inhibition caused by CO/CO{sub 2} gases on a 7 {micro}m thick Pd-Cu composite membrane was less than 17% over a wide range of compositions at 350 C. H{sub 2}S caused a strong inhibition of the H{sub 2} flux of the same Pd-Cu composite membrane, which is accentuated at levels of 100 ppm or higher. The membrane was exposed to 50 ppm three times without permanent damage. At higher H{sub 2}S levels, above 100 ppm the membrane suffered some physical degradation and its performances was severely affected. The use of sweep gases improved the hydrogen flux and recovery of a Pd-Cu composite membrane. Recently, we have been able to dramatically reduce the thickness of these Pd alloy membranes to approximately one micron. This is significant because at this thickness, it is the cost of the porous support that controls the materials cost of a composite Pd alloy membrane, not the palladium inventory. Very recent results show that the productivity of our membranes is very high, essentially meeting the DOE pure hydrogen flux target value set by the DOE Hydrogen

  11. Highly Hydrophilic Thin-Film Composite Forward Osmosis Membranes Functionalized with Surface-Tailored Nanoparticles

    KAUST Repository

    Tiraferri, Alberto

    2012-09-26

    Thin-film composite polyamide membranes are state-of-the-art materials for membrane-based water purification and desalination processes, which require both high rejection of contaminants and high water permeabilities. However, these membranes are prone to fouling when processing natural waters and wastewaters, because of the inherent surface physicochemical properties of polyamides. The present work demonstrates the fabrication of forward osmosis polyamide membranes with optimized surface properties via facile and scalable functionalization with fine-tuned nanoparticles. Silica nanoparticles are coated with superhydrophilic ligands possessing functional groups that impart stability to the nanoparticles and bind irreversibly to the native carboxyl moieties on the membrane selective layer. The tightly tethered layer of nanoparticles tailors the surface chemistry of the novel composite membrane without altering the morphology or water/solute permeabilities of the membrane selective layer. Surface characterization and interfacial energy analysis confirm that highly hydrophilic and wettable membrane surfaces are successfully attained. Lower intermolecular adhesion forces are measured between the new membrane materials and model organic foulants, indicating the presence of a bound hydration layer at the polyamide membrane surface that creates a barrier for foulant adhesion. © 2012 American Chemical Society.

  12. Inositol phospholipids regulate the guanine-nucleotide-exchange factor Tiam1 by facilitating its binding to the plasma membrane and regulating GDP/GTP exchange on Rac1.

    Science.gov (United States)

    Fleming, Ian N; Batty, Ian H; Prescott, Alan R; Gray, Alex; Kular, Gursant S; Stewart, Hazel; Downes, C Peter

    2004-09-15

    Binding of the Rac1-specific guanine-nucleotide-exchange factor, Tiam1, to the plasma membrane requires the N-terminal pleckstrin homology domain. In the present study, we show that membrane-association is mediated by binding of PtdIns(4,5)P(2) to the pleckstrin homology domain. Moreover, in 1321N1 astrocytoma cells, translocation of Tiam1 to the cytosol, following receptor-mediated stimulation of PtdIns(4,5)P(2) breakdown, correlates with decreased Rac1-GTP levels, indicating that membrane-association is required for GDP/GTP exchange on Rac1. In addition, we show that platelet-derived growth factor activates Rac1 in vivo by increasing PtdIns(3,4,5)P(3) concentrations, rather than the closely related lipid, PtdIns(3,4)P(2). Finally, the data demonstrate that PtdIns(4,5)P(2) and PtdIns(3,4,5)P(3) bind to the same pleckstrin homology domain in Tiam1 and that soluble inositol phosphates appear to compete with lipids for this binding. Together, these novel observations provide strong evidence that distinct phosphoinositides regulate different functions of this enzyme, indicating that local concentrations of signalling lipids and the levels of cytosolic inositol phosphates will play crucial roles in determining its activity in vivo.

  13. Membrane fatty acid composition and radiation response of Bp8 sarcoma ascites tumour cells

    International Nuclear Information System (INIS)

    Harms-Ringdahl, M.

    1987-01-01

    Radiation responses of Bp8 sarcoma ascites tumour cells with differences in membrane fatty acid composition was studied. The cells were grown i.p. in NMRI mice and their membrane composition was changed in response to different dietary regimes provided to the hosts. Cell survival, varied insignificantly between the four dietary groups, while repair capacity differed significantly. Increased repair capacity was observed for ascites cells grown in animals on diets enriched in sunflower seed oil and coconut oil, compared with cells from mice fed the hydrogenated lard diet or from cells from the control animals. The membrane fatty acid composition of the cells from the two dietary groups with increased levels of repair capacity differed extensively, and in general there was no correlation between radiation response and the membrane fatty acid composition of the four groups. For coconut oil and control groups with marked differences in membrane fatty acid composition, the effects of irradiation on ascites tumour growth rate and cell cycle distribution were followed in vivo. For none of the parameters was an effect on membrane fatty acid composition on radiation response observed. (author)

  14. Functionalized carbon nanotube via distillation precipitation polymerization and its application in nafion-based composite membranes.

    Science.gov (United States)

    He, Guangwei; Zhao, Jing; Hu, Shen; Li, Lingqiao; Li, Zongyu; Li, Yifan; Li, Zhen; Wu, Hong; Yang, Xinlin; Jiang, Zhongyi

    2014-09-10

    The objective of this study is to develop a novel approach to in situ functionalizing multiwalled carbon nanotubes (MWCNTs) and exploring their application in Nafion-based composite membranes for efficient proton conduction. Covalent grafting of acrylate-modified MWCNTs with poly(methacrylic acid-co-ethylene glycol dimethacrylate), poly(vinylphosphonic acid-co-ethylene glycol dimethacrylate), and sulfonated poly(styrene-co-divinylbenzene) was achieved via surface-initiated distillation precipitation polymerization. The formation of core-shell structure was verified by TEM images, and polymer layers with thickness around 30 nm were uniformly covered on the MWCNTs. The graft yield reached up to 93.3 wt % after 80 min of polymerization. The functionalized CNTs (FCNTs) were incorporated into the Nafion matrix to prepare composite membranes. The influence of various functional groups (-COOH, -PO3H2, and -SO3H) in FCNTs on proton transport of the composite membranes was studied. The incorporation of FCNTs afforded the composite membranes significantly enhanced proton conductivities under reduced relative humidity. The composite membrane containing 5 wt % phosphorylated MWCNTs (PCNTs) showed the highest proton conductivity, which was attributed to the construction of lower-energy-barrier proton transport pathways by PCNTs, and excellent water-retention and proton-conduction properties of the cross-linked polymer in PCNTs. Moreover, the composite membranes exhibited an enhanced mechanical stability.

  15. Physically Gelled Room-Temperature Ionic Liquid-Based Composite Membranes for CO2/N-2 Separation: Effect of Composition and Thickness on Membrane Properties and Performance

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, PT; Voss, BA; Wiesenauer, EF; Gin, DL; Nobe, RD

    2013-07-03

    An aspartame-based, low molecular-weight organic gelator (LMOG) was used to form melt-infused and composite membranes with two different imidazolium-based room-temperature ionic liquids (RTILs) for CO2 separation from N-2. Previous work demonstrated that LMOGs can gel RTILs at low, loading levels, and this aspartame-based LMOG was selected because it has been reported to gel a large number of RTILs. The imidazolium-based RTILs were used because of their inherent good properties for CO2/light gas separations. Analysis of the resulting bulk RTIL/LMOG physical gels showed that these materials have high sol-gel transition temperatures (ca. 135 degrees C) suitable for flue gas applications. Gas permeabilities and burst pressure measurements of thick, melt infused membranes revealed a trade-off between high CO2 permeabilities and good mechanical stability as a function of the LMOG loading. Defect-free, composite membranes of the gelled RTILs were successfully fabricated by choosing an appropriate porous membrane support (hydrophobic PTFE) using a suitable coating technique (roller coating). The thicknesses of the applied composite gel layers ranged from 10.3 to 20.7 mu m, which represents an order of magnitude decrease in active layer thickness, compared to the original melt-infused gel RTIL membranes.

  16. Development of composite metallic membranes for hydrogen purification

    International Nuclear Information System (INIS)

    Gaillard, F.

    2003-12-01

    Fuel cells are able to convert chemical energy into electric power. There are different types of cells; the best for automotive applications are Proton Exchange Membrane Fuel Cells. But, these systems need hydrogen of high purity. However, fuel reforming generates a mixture of gases, from which hydrogen has to be extracted before supplying the electrochemical cell. The best way for the purification of hydrogen is the membrane separation technology. Palladium is selectively permeable to hydrogen and this is the reason why this metal is largely used for the membrane development. This work deals with the development of hydrogen-selective membranes by deposition of a thin film of palladium onto a porous mechanical support. For this, we have used the electroless plating technique: a palladium salt and a reducing agent are mixed and the deposition takes place onto the catalytic surface of the substrate. After bibliographic investigations, experimental studies have been performed first with a dense metallic substrate in order to better understand the different parameters controlling the deposition. First of all, potentiometric measurements have been carried out to follow the electrochemical reactions in the bath. Then, kinetic measurements of the coating thickness have been recorded to understand the effect of the bath conditions on the yield and the adhesion of the film. Finally, the electroless plating method has been applied to deposit palladium membranes onto porous stainless steel substrates. After optimisation, the resulting membranes were tested for their hydrogen permeation properties. (author)

  17. Magic angle spinning 31P NMR spectroscopy reveals two essentially identical ionization states for the cardiolipin phosphates in phospholipid liposomes.

    Science.gov (United States)

    Kooijman, E E; Swim, L A; Graber, Z T; Tyurina, Y Y; Bayır, H; Kagan, V E

    2017-01-01

    Specific membrane lipid composition is crucial for optimized structural and functional organization of biological membranes. Cardiolipin is a unique phospholipid and important component of the inner mitochondrial membrane. It is involved in energy metabolism, inner mitochondrial membrane transport, regulation of multiple metabolic reactions and apoptotic cell death. The physico-chemical properties of cardiolipin have been studied extensively but despite all these efforts there is still lingering controversy regarding the ionization of the two phosphate groups of cardiolipin. Results obtained in the 1990s and early 2000s suggested that cardiolipin has two disparate pKa values where one of the protons was proposed to be stabilized by an intramolecular hydrogen bond. This has led to extensive speculations on the roles of these two putative ionization states of cardiolipin in mitochondria. More recently the notion of two pKa values has been challenged and rejected by several groups. These studies relied on external measurements of proton adsorption or electrophoretic mobility of membranes but did not take into account the low pH phase behavior and chemical stability of cardiolipin. Here we used 31 P NMR to show that in the physiologically relevant membrane phospholipid environment, cardiolipin carries two negative charges at physiological pH. We additionally demonstrate the pH dependent phase behavior and chemical stability of cardiolipin containing membranes. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Biosynthesis of ether-phospholipids including plasmalogens, peroxisomes and human disease: new insights into an old problem

    NARCIS (Netherlands)

    Wanders, Ronald J. A.; Brites, Pedro

    2010-01-01

    Ether-phospholipids represent an important subclass of phospholipids in animal cell membranes characterized by the presence of an ether bond at the sn-I position and the enrichment of PUFAs at the sn-2 position. Of the different ether-phospholipids, plasmalogens are the most abundant form and their

  19. Interaction of neurotransmitters with a phospholipid bilayer

    DEFF Research Database (Denmark)

    Peters, Günther H.J.; Werge, Mikkel; Elf-Lind, Maria Northved

    2014-01-01

    (GOL) with a dipalmitoylphosphatidylcholine (DPPC) bilayer. In agreement with previously published experimental data, we found the lowest membrane affinity for the charged molecules and a moderate affinity for zwitterionic and polar molecules. The affinity can be ranked as follows: ACH–GLU ... phospholipids. Even at that position, these solutes were noticeably hydrated and carried ∼30–80% of the bulk water along. The mobility of hydration water...

  20. Morphological and Physical Analysis of Natural Phospholipids-Based Biomembranes

    OpenAIRE

    Jacquot, Adrien; Francius, Grégory; Razafitianamaharavo, Angelina; Dehghani, Fariba; Tamayol, Ali; Linder, Michel; Arab-Tehrany, Elmira

    2014-01-01

    International audience; Background: Liposomes are currently an important part of biological, pharmaceutical, medical and nutritional research, as they are considered to be among the most effective carriers for the introduction of various types of bioactive agents into target cells.Scope of Review: In this work, we study the lipid organization and mechanical properties of biomembranes made of marine and plant phospholipids. Membranes based on phospholipids extracted from rapeseed and salmon ar...

  1. Membrane fouling mechanism transition in relation to feed water composition

    KAUST Repository

    Myat, Darli Theint

    2014-12-01

    The impact of secondary effluent wastewater from the Eastern Treatment Plant (ETP), Melbourne, Australia, before and after ion exchange (IX) treatment and polyaluminium chlorohydrate (PACl) coagulation, on hydrophobic polypropylene (PP) and hydrophilic polyvinylidene fluoride (PVDF) membrane fouling was studied. Laboratory fouling tests were operated over 3-5 days with regular, intermittent backwash. During the filtration with PP membranes, organic rejection data indicated that humic adsorption on hydrophobic PP membrane occurred during the first 24h of filtration and contributed to fouling for both raw wastewater and pre-treated wastewaters. However, after the first 24h of filtration the contribution of humic substances to fouling diminished and biopolymers that contribute to cake layer development became more prominent in their contribution to the fouling rate. For PVDF membranes, the per cent removal of humic substances from both raw wastewater and pre-treated wastewaters was very small as indicated by no change in UV254 from the feed to the permeate over the filtration period, even during the early stages of filtration. This suggested that the hydrophobic PP membrane adsorbed humic substances while the hydrophilic PVDF membrane did not. The highest mass of biopolymer removal by each PVDF membrane was from ETP water followed by PACl and IX treated water respectively. This was possibly due to differences in the backwashing efficiency linked to the filter cake contributed by biopolymers. Hydraulic backwashing was more effective during the later stages of filtration for the ETP water compared to IX and PACl treated waters, indicating that the filter cake contributed by ETP biopolymers was more extensively removed by hydraulic backwashing. It was proposed that humic substances may act to stabilise biopolymers in solution and that removing humics substances by coagulation or IX results in greater adhesive forces between the biopolymers and membrane/filter cake

  2. Electrospun Nafion®/Polyphenylsulfone Composite Membranes for Regenerative Hydrogen Bromine Fuel Cells.

    Science.gov (United States)

    Park, Jun Woo; Wycisk, Ryszard; Pintauro, Peter N; Yarlagadda, Venkata; Van Nguyen, Trung

    2016-02-29

    The regenerative H₂/Br₂-HBr fuel cell, utilizing an oxidant solution of Br₂ in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA) ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion ® PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU), for mechanical reinforcement, and swelling control. After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion ® 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H₂-Br₂ fuel cell power output with a 65 μm thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 μm Nafion ® 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H₂/Br₂-HBr systems.

  3. Electrospun Nafion®/Polyphenylsulfone Composite Membranes for Regenerative Hydrogen Bromine Fuel Cells

    Science.gov (United States)

    Park, Jun Woo; Wycisk, Ryszard; Pintauro, Peter N.; Yarlagadda, Venkata; Van Nguyen, Trung

    2016-01-01

    The regenerative H2/Br2-HBr fuel cell, utilizing an oxidant solution of Br2 in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA) ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion® PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU), for mechanical reinforcement, and swelling control. After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion® 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H2-Br2 fuel cell power output with a 65 μm thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 μm Nafion® 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H2/Br2-HBr systems. PMID:28773268

  4. Electrospun Nafion®/Polyphenylsulfone Composite Membranes for Regenerative Hydrogen Bromine Fuel Cells

    Directory of Open Access Journals (Sweden)

    Jun Woo Park

    2016-02-01

    Full Text Available The regenerative H2/Br2-HBr fuel cell, utilizing an oxidant solution of Br2 in aqueous HBr, shows a number of benefits for grid-scale electricity storage. The membrane-electrode assembly, a key component of a fuel cell, contains a proton-conducting membrane, typically based on the perfluorosulfonic acid (PFSA ionomer. Unfortunately, the high cost of PFSA membranes and their relatively high bromine crossover are serious drawbacks. Nanofiber composite membranes can overcome these limitations. In this work, composite membranes were prepared from electrospun dual-fiber mats containing Nafion® PFSA ionomer for facile proton transport and an uncharged polymer, polyphenylsulfone (PPSU, for mechanical reinforcement, and swelling control. After electrospinning, Nafion/PPSU mats were converted into composite membranes by softening the PPSU fibers, through exposure to chloroform vapor, thus filling the voids between ionomer nanofibers. It was demonstrated that the relative membrane selectivity, referenced to Nafion® 115, increased with increasing PPSU content, e.g., a selectivity of 11 at 25 vol% of Nafion fibers. H2-Br2 fuel cell power output with a 65 μm thick membrane containing 55 vol% Nafion fibers was somewhat better than that of a 150 μm Nafion® 115 reference, but its cost advantage due to a four-fold decrease in PFSA content and a lower bromine species crossover make it an attractive candidate for use in H2/Br2-HBr systems.

  5. Annexin-Phospholipid Interactions. Functional Implications

    Directory of Open Access Journals (Sweden)

    Javier Turnay

    2013-01-01

    Full Text Available Annexins constitute an evolutionary conserved multigene protein superfamily characterized by their ability to interact with biological membranes in a calcium dependent manner. They are expressed by all living organisms with the exception of certain unicellular organisms. The vertebrate annexin core is composed of four (eight in annexin A6 homologous domains of around 70 amino acids, with the overall shape of a slightly bent ring surrounding a central hydrophilic pore. Calcium- and phospholipid-binding sites are located on the convex side while the N-terminus links domains I and IV on the concave side. The N-terminus region shows great variability in length and amino acid sequence and it greatly influences protein stability and specific functions of annexins. These proteins interact mainly with acidic phospholipids, such as phosphatidylserine, but differences are found regarding their affinity for lipids and calcium requirements for the interaction. Annexins are involved in a wide range of intra- and extracellular biological processes in vitro, most of them directly related with the conserved ability to bind to phospholipid bilayers: membrane trafficking, membrane-cytoskeleton anchorage, ion channel activity and regulation, as well as antiinflammatory and anticoagulant activities. However, the in vivo physiological functions of annexins are just beginning to be established.

  6. Molecular phospholipid films on solid supports

    DEFF Research Database (Denmark)

    Czolkos, Ilja; Jesorka, Aldo; Orwar, Owe

    2011-01-01

    and aided the development of membrane-based applications in, for example, biosensing, self-assembled reaction kinetics and catalysis. Assembly and preparation of lipid films on supporting surfaces is a challenging engineering task with the goal of fabricating mechanically, chemically and thermodynamically...... stable lipid membranes. In this review, the current state of the art of molecularly thin lipid layer fabrication is presented with an emphasis on support materials, film formation mechanisms, characterisation methods, and applications.......Phospholipid membranes are versatile structures for mimicking biological surfaces. Bilayer and monolayer membranes can be formed on solid supports, leading to enhanced stability and accessibility of the biomimetic molecular film. This has facilitated functional studies of membrane proteins...

  7. Facile fabrication and characterization of poly(tetrafluoroethylene)@polypyrrole/nano-silver composite membranes with conducting and antibacterial property

    Science.gov (United States)

    Shi, Zhiquan; Zhou, Hui; Qing, Xutang; Dai, Tingyang; Lu, Yun

    2012-06-01

    Porous poly(tetrafluoroethylene) (PTFE) membranes play an important role in air purification and separation engineering. To achieve the bi-functionality of conducting and antibacterial property, two kinds of poly(tetrafluoroethylene)@ polypyrrole/nano-silver composite membranes have been prepared. One involves hydrophobic polypyrrole/nano-silver composite with hollow capsule nanostructures immobilized on the surface of the PTFE membranes. The other is a type of composite membranes with polypyrrole/nano-silver composite wholly packed on the fibrils of the expand PTFE membrane to form core/shell coaxial cable structures. The structure and morphology of the two kinds of composite membranes have been characterized by FTIR, UV-vis, XRD, TGA and SEM measurements. Possible formation mechanisms of the hollow capsules and the core/shell nanocable structures have been discussed in detail. The antibacterial effects of composite membranes are also briefly investigated.

  8. Electrospun hydrophilic fumed silica/polyacrylonitrile nanofiber-based composite electrolyte membranes

    International Nuclear Information System (INIS)

    Jung, Hong-Ryun; Ju, Dong-Hyuk; Lee, Wan-Jin; Zhang, Xiangwu; Kotek, Richard

    2009-01-01

    Hydrophilic fumed silica (SiO 2 )/polyacrylonitrile (PAN) composite electrolyte membranes were prepared by electrospinning composite solutions of SiO 2 and PAN in N,N-dimethylformamide (DMF). Among electrospinning solutions with various SiO 2 contents, the 12 wt% SiO 2 in PAN solution has highest zeta potential (-40.82 mV), and exhibits the best dispersibility of SiO 2 particles. The resultant 12 wt% SiO 2 /PAN nanofiber membrane has the smallest average fiber diameter, highest porosity, and largest specific surface area. In addition, this membrane has a three-dimensional network structure, which is fully interconnected with combined mesopores and macropores because of a good SiO 2 dispersion. Composite electrolyte membranes were prepared by soaking these porous nanofiber membranes in 1 M lithium hexafluorophosphate (LiPF 6 ) in ethylene carbonate (EC)/dimethyl carbonate (DMC) (1:1 vol%). It is found that 12 wt% SiO 2 /PAN electrolyte membrane has the highest conductivity (1.1 x 10 -2 S cm -1 ) due to the large liquid electrolyte uptake (about 490%). In addition, the electrochemical performance of composite electrolyte membranes is also improved after the introduction of SiO 2 . For initial cycle, 12 wt% SiO 2 /PAN composite electrolyte membrane delivers the discharge capacity of 139 mAh g -1 as 98% of theoretical value, and still retains a high value of 127 mAh g -1 as 89% at 150th cycle, which is significantly higher that of pure PAN nanofiber-based electrolyte membranes.

  9. Nafion/sulfated {beta}-cyclodextrin composite membranes for direct methanol fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Jae-Deok; Kwak, Seung-Yeop [Department of Materials Science and Engineering, Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul 151-744 (Korea)

    2008-10-15

    Proton-conducting composite membranes based on H{sup +}-form sulfated {beta}-cyclodextrin (sb-CD) in a Nafion matrix are prepared via the solution-casting method and their methanol permeabilities, proton conductivities, proton diffusion coefficients and cell performances are measured. The methanol permeabilities of the composite membranes increase very slightly with increases in their sb-CD content. As a result of adding sb-CD with its many sulfonic acid groups into the Nafion matrix, the proton conductivities of the composite membranes increase with increases in their sb-CD content. The methanol permeability and proton conductivity results are used to show that the best selectivity of the membranes is that of the NC5 membrane ('NCx' denotes a Nafion/sb-CD composite membrane containing x wt.% sb-CD). The proton diffusion coefficients are measured with {sup 1}H pulsed field gradient nuclear magnetic resonance (PFG-NMR) and found to increase with increase in the sb-CD content in the order NC5 > NC3 > NC1 > NC0. Thus the presence of sb-CD in the Nafion membranes increases the proton diffusion coefficients as well as the proton conductivities, ionic cluster size, water uptakes and the ion-exchange capacities (IECs). A maximum power density of 58 mW cm{sup -2} is obtained for the NC5 membrane. The combination of these effects should lead to an improvement in the performance of direct methanol fuel cells prepared with Nafion/sb-CD composite membranes. (author)

  10. Glomerular basement membrane composition and the filtration barrier.

    Science.gov (United States)

    Miner, Jeffrey H

    2011-09-01

    The glomerular basement membrane (GBM) is an especially thick basement membrane that contributes importantly to the kidney's filtration barrier. The GBM derives from the fusion of separate podocyte and endothelial cell basement membranes during glomerulogenesis and consists primarily of laminin-521 (α5β2γ1), collagen α3α4α5(IV), nidogens-1 and -2, and agrin. Of these nine proteins, mutations in the genes encoding four of them (LAMB2, COL4A3, COL4A4, and COL4A5) cause glomerular disease in humans as well as in mice. Furthermore, mutation of a fifth (Lama5) gene in podocytes in mice causes proteinuria, nephrotic syndrome, and progression to renal failure. These results highlight the importance of the GBM for establishing and maintaining a properly functioning glomerular filtration barrier.

  11. Water vapor permeation and dehumidification performance of poly(vinyl alcohol)/lithium chloride composite membranes

    KAUST Repository

    Bui, Duc Thuan

    2015-10-09

    Thin and robust composite membranes comprising stainless steel scaffold, fine and porous TiO2 and polyvinyl alcohol/lithium chloride were fabricated and studied for air dehumidification application. Higher hydrophilicity, sorption and permeation were observed for membranes with increased lithium chloride content up to 50%. The permeation and sorption properties of the membranes were investigated under different temperatures. The results provided a deeper insight into the membrane water vapor permeation process. It was specifically noted that lithium chloride significantly reduces water diffusion energy barrier, resulting in the change of permeation energy from positive to negative values. Higher water vapor permeance was observed for the membrane with higher LiCl content at lower temperature. The isothermal air dehumidification tests show that the membrane is suitable for dehumidifying air in high humid condition. Additionally, results also indicate a trade-off between the humidity ratio drop with the water vapor removal rate when varying air flowrate.

  12. Rheological properties of poly(vinyl alcohol) (PVA) derived composite membranes for fuel cells

    International Nuclear Information System (INIS)

    Remiš, T

    2017-01-01

    Rheological properties of new anhydrous proton conducting membrane based on PVA, tetraethyl orthosilicate (TEOS),sulfosuccinic acid (SSA), titanium dioxide (TiO 2 )was examined at various stoichiometric ratios. SSA was used as sulfonating agents to form a crosslinked structure and as proton source, whereas TEO Sand TiO 2 were utilized to improve the thermal and mechanical properties of the membrane. In order to verify that all the substances were immobilized into the matrix, the membranes were analysed by means of FT-IR. The rheological, mechanical and thermal properties of the membranes were investigated using rheometer ARES G2 and thermogravimetic analyser (TGA).The analysis of mixed PVA solutions exhibited a unique behaviour of viscosity with increased crosslink density. The dynamic storage modulus G´ of dried composite membranes shows better mechanical resistance and increased tolerance to pressure applied during membrane electrode assembly (MEA). (paper)

  13. Rheological properties of poly(vinyl alcohol) (PVA) derived composite membranes for fuel cells

    Science.gov (United States)

    Remiš, T.

    2017-01-01

    Rheological properties of new anhydrous proton conducting membrane based on PVA, tetraethyl orthosilicate (TEOS),sulfosuccinic acid (SSA), titanium dioxide (TiO2)was examined at various stoichiometric ratios. SSA was used as sulfonating agents to form a crosslinked structure and as proton source, whereas TEO Sand TiO2were utilized to improve the thermal and mechanical properties of the membrane. In order to verify that all the substances were immobilized into the matrix, the membranes were analysed by means of FT-IR. The rheological, mechanical and thermal properties of the membranes were investigated using rheometer ARES G2 and thermogravimetic analyser (TGA).The analysis of mixed PVA solutions exhibited a unique behaviour of viscosity with increased crosslink density. The dynamic storage modulus G´ of dried composite membranes shows better mechanical resistance and increased tolerance to pressure applied during membrane electrode assembly (MEA).

  14. Preparation and characterization of polystyrene based Nickel molybdate composite membrane electrical–electrochemical properties

    Directory of Open Access Journals (Sweden)

    Urfi Ishrat

    2016-09-01

    Full Text Available The functional properties of the polystyrene based Nickel Molybdate composite membrane prepared by applying 70 MPa pressure are described. The fabricated membrane was characterized by using Fourier Transform Infrared, X-ray diffraction, particle size analyzer and Scanning electron microscopy technique and has been investigated for its functional, diffusive, electrochemical and electrical properties. The impedance data of membrane having capacitive and resistive components are plotted, which show the sequence of semicircles representing an electrical phenomenon due to grain material, grain boundary and interfacial phenomenon. The diffusion of electrolytes was determined by the TMS method revealing dependence of membrane potential on the charge on the membrane matrix, charge and size of permeating ions. The membrane determined the activity of cations with good accuracy in the higher concentration range and shows a great selectivity for K+. Other electrochemical properties like transport number have been discussed its selectivity.

  15. Graphene oxide doped ionic liquid ultrathin composite membranes for efficient CO2 capture

    KAUST Repository

    Karunakaran, Madhavan

    2016-11-28

    Advanced membrane systems with high flux and sufficient selectivity are required for industrial gas separation processes. In order to achieve high flux and high selectivity, the membrane material should be as thin as possible and it should have selective sieving channels and long term stability. This could be achieved by designing a three component material consisting of a blend of an ionic liquid and graphene oxide covered by a highly permeable low selective polymeric coating. By using a simple dip coating technique, we prepared high flux and CO selective ultrathin graphene oxide (GO)/ionic liquid membranes on a porous ultrafiltration support. The ultrathin composite membranes derived from GO/ionic liquid complex displays remarkable combinations of permeability (CO flux: 37 GPU) and selectivity (CO/N selectivity: 130) that surpass the upper bound of ionic liquid membranes for CO/N separation. Moreover, the membranes were stable when tested for 120 hours.

  16. Structure, composition, and strength of nitrifying membrane-aerated biofilms

    DEFF Research Database (Denmark)

    Pellicer i Nàcher, Carles; Smets, Barth F.

    2014-01-01

    Membrane-aerated biofilm reactors (MABRs) are a novel technology based on the growth of biofilms on oxygen-permeable membranes. Hereby, MABRs combine all the advantages of biofilm growth with a more flexible and efficient control of the oxygen load. In the present work, flow cell operation...... had a higher content of proteins and a lower level of carbohydrates. Staining analyses revealed that the EPS in the stronger biofilm regions had hydrophilic nature and distributed around dense microbial aggregates, whereas it was homogeneously distributed in the weaker strata. Overall, the obtained...

  17. Mixed Matrix Composite Membranes Containing POSS Molecules for Carbon Dioxide Removal Application

    KAUST Repository

    Rini, Eki Listya

    2011-05-10

    CO2 removal by membrane processes is considerably potential for several applications such as natural gas and synthesis gas purification, enhanced oil recovery application, and carbon dioxide capture in combat against global warming. Dense polymeric membranes are commonly utilized for these type of gas separation applications. Nevertheless, the intrinsic properties of dense polymeric membranes, which commonly characterize by the low gas permeability versus high gas selectivity trade–off or vice versa, is less desirable. In order to meet the increased demand of CO2 removal, a strategy to improve the gas separation performance of a polymeric membrane is investigated in this study. With this regard, mixed matrix membranes in which inorganic non porous fillers are incorporated into a polymeric matrix were prepared to achieve the aforementioned objective. The mixed matrix membranes were prepared from Pebax® block copolymers and PEG POSS® molecules. These hybrid membranes were formed as both dense and multilayer composite membranes. The dense transparent membranes with well–dispersed fillers could be obtained by variation of the solvent mixture. The DSC analyses showed that incorporation of PEG POSS® into Pebax® matrix altered the thermal properties of the matrix. The multilayer composite membranes were then prepared from a PTMSP gutter layer deposited on a PAN porous support and an adjacent hybrid Pebax®/PEG POSS® as the top layer. These hybrid multilayer composite membranes exhibited an enhanced CO2 selectiv4 ity by a factor of two relative to the pure Pebax®. In these hybrid systems, the CO2 separation was presumably enhanced by the high ether oxides content from PEG POSS® that has high affinities for CO2. For particular composition of Pebax® and PEG POSS® concentrations, the PTMSP gutter layer harnessed the CO2 selectivity without losing the CO2 permeation rate. At the same time, these membrane, however, suffered severe adhesion between the gutter layer

  18. Polysulphone composite membranes modified with two types of ...

    Indian Academy of Sciences (India)

    This study presents a detailed evaluation of the impact of carbon fibrous materials on the physicochemical properties of polysulphone (PSU) membranes and their preliminary osteoblast-like cells response in vitro. Multiwalled carbon nanotubes (MWCNTs) and short carbon fibres (SCFs) were incorporated into PSU and ...

  19. Fullerene and dendrimer based nano-composite gas separation membranes

    NARCIS (Netherlands)

    Sterescu, D.M.

    2007-01-01

    This thesis describes the development of new materials for membrane based gas separation processes. Long-term stable, loosely packed (high free volume) amorphous polymer films were prepared by introduction of super-molecular pendant groups, which possess hardsphere properties to avoid dense

  20. Chitosan/bioactive glass nanoparticle composite membranes for periodontal regeneration

    NARCIS (Netherlands)

    Mota, J.; Yu, N.; Caridade, S.G.; Luz, G.M.; Gomes, M.E.R.; Reis, R.L.; Jansen, J.A.; Walboomers, X.F.; Mano, J.F.

    2012-01-01

    Barrier membranes are used in periodontal applications with the aim of supporting periodontal regeneration by physically blocking migration of epithelial cells. The present work proposes a combination of chitosan (CHT) with bioactive glass nanoparticles (BG-NPs) in order to produce a novel guided

  1. Sulfonated carbon black-based composite membranes for fuel cell ...

    Indian Academy of Sciences (India)

    C/min under nitrogen atmosphere. All data were collected from a second heating cycle and glass tran- sition temperatures (Tg) were calculated as a midpoint of thermogram. 2.5d FTIR studies: FTIR spectra were recorded for mem- branes using Perkin Elmer Pyris 1 FTIR spectrophoto- meter. Membrane and carbon black ...

  2. Preparation of Nanofibrous Silver/Poly(vinylidene fluoride) Composite Membrane with Enhanced Infrared Extinction and Controllable Wetting Property.

    Science.gov (United States)

    Ren, Da-Ming; Huang, Hua-Kun; Yu, Yun; Li, Zeng-Tian; Jiang, Li-Wang; Chen, Shui-Mei; Lam, Kwok-Ho; Lin, Bo; Shi, Bo; He, Fu-An; Wu, Hui-Jun

    2018-05-01

    Nanofibrous silver (Ag)/poly(vinylidene fluoride) (PVDF) composite membranes were obtained from a two-step preparation method. In the first step, the electrospun silver nitrate (AgNO3)/PVDF membranes were prepared and the influence of the AgNO3 content on the electrospinning process was studied. According to scanning electron microscopy (SEM) results, when the electrospinning solution contained AgNO3 in the range between 3 to 7 wt.%, the nanofiber morphologies can be obtained. In the second step, the electrospun AgNO3/PVDF membranes were reduced by sodium borohydride to form the nanofibrous Ag/PVDF composite membranes. The resultant composite membranes were characterized by SEM, X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), differential scanning calorimetry, X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared. The XRD, XPS, and EDS characterizations proved the existence of Ag in the nanofibrous Ag/PVDF composite membranes. The crystallinity degree of PVDF for composite membranes declined with the increase in Ag content. More importantly, the nanofibrous Ag/PVDF composite membranes had obviously higher Rosseland extinction coefficients and lower thermal radiative conductivities in comparison with electrospun PVDF membrane, which demonstrates that such composite membranes with high porosity, low density, and good water vapor permeability are promising thermal insulating materials to block the heat transfer resulting from thermal radiation. In addition, three different methods for surface modification have been used to successfully improve the hydrophobicity of nanofibrous Ag/PVDF composite membranes.

  3. Methylmercury Increases and Eicosapentaenoic Acid Decreases the Relative Amounts of Arachidonic Acid-Containing Phospholipids in Mouse Brain.

    Science.gov (United States)

    Zeng, Ying-Xu; Du, Zhen-Yu; Mjøs, Svein Are; Grung, Bjørn; Midtbø, Lisa K

    2016-01-01

    The membrane phospholipid composition in mammalian brain can be modified either by nutrients such as dietary fatty acids, or by certain toxic substances such as methylmercury (MeHg), leading to various biological and toxic effects. The present study evaluated the effects of eicosapentaenoic acid (EPA) and MeHg on the composition of the two most abundant membrane phospholipid classes, i.e., phosphatidylcholines (PtdCho) and phosphatidylethanolamines (PtdEtn), in mouse brain by using a two-level factorial design. The intact membrane PtdCho and PtdEtn species were analyzed by liquid chromatography-mass spectrometry. The effects of EPA and MeHg on the PtdCho and PtdEtn composition were evaluated by principal component analysis and ANOVA. The results showed that EPA and MeHg had different effects on the composition of membrane PtdCho and PtdEtn species in brain, where EPA showed strongest impact. EPA led to large reductions in the levels of arachidonic acid (ARA)-containing PtdCho and PtdEtn species in brain, while MeHg tended to elevate the levels of ARA-containing PtdCho and PtdEtn species. EPA also significantly increased the levels of PtdCho and PtdEtn species with n-3 fatty acids. Our results indicate that EPA may to some degree counteract the alterations of the PtdCho and PtdEtn pattern induced by MeHg, and thus alleviate the MeHg neurotoxicity in mouse brain through the inhibition of ARA-derived pro-inflammatory factors. These results may assist in the understanding of the interaction between MeHg, EPA and phospholipids, as well as the risk and benefits of a fish diet.

  4. Determination of the separate lipid and protein profile structures derived from the total membrane profile structure or isolated sarcoplasmic reticulum via x-ray and neutron diffraction

    International Nuclear Information System (INIS)

    Herbette, L.; Blasie, J.K.

    1984-01-01

    Sarcoplasmic reticulum (SR) membranes were prepared to contain biosynthetically deuterated SR phospholipids utilizing specific and general phospholipid exchange proteins (PLEP). Functional measurements and freeze fracture on SR dispersions and x-ray diffraction of hydrated oriented membrane multilayers revealed that the exchanged SR membranes were very similar to unexchanged SR membranes. Low resolution (28-A) neutron diffraction studies utilizing SR membranes exchanged with either protonated or perdeuterated SR phospholipids allowed direct determination of the lipid profile within the isolated SR membrane at two different unit cell repeat distances. These lipid profile structures were found to be highly asymmetric regarding the conformation of the fatty acid chain extents and compositional distribution of phospholipid molecules in the inner vs. outer monolayer of the SR membrane bilayer. The relatively high resolution (11-A) electron-density profile from x-ray diffraction was decomposed by utilizing the asymmetry in the number of phospholipid molecules residing in the inner vs. outer monolayer of the SR lipid bilayer as obtained from the neutron diffraction study. To our knowledge, this represents the first direct determination of a lipid bilayer profile structure within an isolated membrane system

  5. In vitro evaluation of hydroxyapatite-chitosan-gelatin composite membrane in guided tissue regeneration.

    Science.gov (United States)

    Hunter, Kimberly T; Ma, Teng

    2013-04-01

    Resorbable biomaterials have been investigated as barrier membranes to compartmentalize the periodontal defects while selectively guiding osteoprogenitor cell proliferation and bone tissue expansion. Hydroxyapatite (H), chitosan (C), and gelatin (G) have chemical similarity to the structural components of natural bone and their composites have been tested as bone scaffolds. Human mesenchymal stem or stromal cells (hMSCs) are inducible osteoprogenitors and are responsible for bone tissue repair and regeneration. In this study, the dynamic interactions of hMSC with composite hydroxyapatite-chitosan-gelatin (HCG) membranes were investigated. The association of HCG formed a biodegradable membrane with ~60 wt % water and an initial stiffness of ~20 kPa. Preconditioning in serum-containing media resulted in the formation nanopores in the HCG membranes and the increase of extracellular matrix (ECM) protein adsorption. Expression of integrin α(2)β(1) and α(5)β(1) coincided with ECM enrichment, suggesting the enhanced cell-ECM interactions. The elevated expression of bone marker proteins and genes in the HCG membranes suggests the progression of hMSC osteogenic differentiation in the absence of chemical induction. The results showed that the HCG membranes possess sufficient mechanical and structural properties to function as a barrier membrane, and that the adsorbed ECM proteins effectively functionalized the HCG membranes and promoted hMSC osteogenic differentiation. Copyright © 2012 Wiley Periodicals, Inc.

  6. Novel polyvinyl alcohol-bioglass 45S5 based composite nanofibrous membranes as bone scaffolds

    International Nuclear Information System (INIS)

    Shankhwar, Nisha; Kumar, Manishekhar; Mandal, Biman B.; Srinivasan, A.

    2016-01-01

    Composite nanofibrous membranes based on sol-gel derived 45SiO 2 24.5CaO 24.5 Na 2 O 6 P 2 O 5 (bioglass, BG) and 43SiO 2 24.5CaO 24.5 Na 2 O 6 P 2 O 5 2Fe 2 O 3 (magnetic bioglass, MBG) blended with polyvinyl alcohol (PVA) have been electrospun. These low cost membranes were mostly amorphous in structure with minor crystalline (sodium calcium phosphate) precipitates. All membranes were biodegradable. Among these, the composites exhibited higher tensile strength, better proliferation of human osteosarcoma MG63 cells and higher alkaline phosphatase enzyme activity than the bare PVA membrane, indicating their potential in bone tissue engineering. The magnetic PVA-MBG scaffold was also found to be a promising candidate for magnetic hyperthermia application. - Highlights: • Electrospun low-cost PVA-45S5 bioglass (BG) nanofibrous membranes • PVA-BG membranes containing 2 wt.% Fe 2 O 3 exhibit spontaneous magnetization. • BG fillers strongly enhanced mechanical strength and bioresponse of membranes. • Membranes show promise for bone scaffold and hyperthermia applications.

  7. Surface and charge transport characterization of polyaniline-cellulose acetate composite membranes.

    Science.gov (United States)

    Qaiser, Asif A; Hyland, Margaret M; Patterson, Darrell A

    2011-02-24

    This study elucidates the charge transport processes of polyaniline (PANI) composite membranes and correlates them to the PANI deposition site and the extent of PANI surface layering on the base microporous membranes. PANI was deposited either as a surface layer or inside the pores of cellulose acetate microporous membranes using various in situ chemical polymerization techniques. The extent of PANI layering at the surface of the base membrane and its oxidation and doping states were characterized using Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). PANI deposition on the membranes showed a strong dependence on the polymerization technique and polymerization time within a single technique. In XPS, the deconvolution of C 1s and N 1s core-level spectra of the composite membranes was used to quantify the extent of PANI layering at the surface along with its oxidation and doping states. PANI incompletely covered the surface of the base microporous membranes for all the employed techniques. However, the extent of the layering increased with the polymerization time in a particular technique. The charge transport through the bulk membrane and charge transfer at the membrane/electrode interface were studied by electrochemical impedance spectroscopy (EIS). The data were analyzed using the equivalent circuit modeling technique. The modeling parameters revealed that PANI deposition at the surface enhanced the interfacial charge transfer but the process depended on the extent of the surface coverage of the membrane. In addition, the charge transport in the bulk membrane depended on the PANI intercalation level, which varied depending on the polymerization technique employed. In addition, the EIS of electrolyte-soaked membranes was also conducted to evaluate the effects of PANI deposition site on charge transport in the presence of an electrolyte. PANI layering at the pore walls of the base membrane from diaphragmatic polymerization

  8. Vitamin B1 thiazole derivative reduces transmembrane current through ionic channels formed by toxins from black widow spider venom and sea anemone in planar phospholipid membranes.

    Science.gov (United States)

    Shatursky, Oleg Ya; Volkova, Tatyana M; Romanenko, Olexander V; Himmelreich, Nina H; Grishin, Eugene V

    2007-02-01

    The vitamin B1 (thiamine) structural analogue 3-decyloxycarbonylmethyl-4-methyl-5-(beta-hydroxyethyl) thiazole chloride (DMHT) (0.1 mM) reversibly reduced transmembrane currents in CaCl2 and KCl solutions via ionic channels produced by latrotoxins (alpha-latrotoxin (alpha-LT) and alpha-latroinsectotoxin (alpha-LIT)) from black widow spider venom and sea anemone toxin (RTX) in the bilayer lipid membranes (BLMs). Introduction of DMHT from the cis-side of BLM bathed in 10 mM CaCl2 inhibited transmembrane current by 31.6+/-3% and by 61.8+/-3% from the trans-side of BLM for alpha-LT channels. Application of DMHT in the solution of 10 mM CaCl2 to the cis-side of BLM decreased the current through the alpha-LIT and RTX channels by 52+/-4% and 50+/-5%, respectively. Addition of Cd2+ (1 mM) to the cis- or trans-side of the membrane after the DMHT-induced depression of Ca2+-current across the alpha-LT channels caused its further decrease by 85+/-5% that coincides favorably with the intensity of Cd2+ blocking in control experiments without DMHT. These data suggest that DMHT inhibiting is not specific for latrotoxin channels only and DMHT may exert its action on alpha-LT channels without considerable influence on the ionogenic groups of Ca2+-selective site inside the channel cavity. The binding kinetics of DMHT with the alpha-LT channel shows no cooperativity and allows to expect that the DMHT binding site of the toxin is formed by one ionogenic group as the slopes of inhibition rate determined in log-log coordinates are 1.25 on the trans-side and 0.68 on the cis-side. Similar pK of binding (5.4 on the trans-side and 5.7 on the cis-side) also suggest that DMHT may interact with the same high affinity site of alpha-LT channel on either side of the BLM. The comparative analysis of effective radii measured for alpha-LT, alpha-LIT and RTX channels on the cis-side (0.9 nm, 0.53 nm and 0.55 nm, correspondingly) and for alpha-LT channel on the trans-side (0.28+/-0.18 nm) with the

  9. Using neurolipidomics to identify phospholipid mediators of synaptic (dysfunction in Alzheimer’s Disease

    Directory of Open Access Journals (Sweden)

    Steffany A L Bennett

    2013-07-01

    Full Text Available Not all of the mysteries of life lie in our genetic code. Some can be found buried in our membranes. These shells of fat, sculpted in the central nervous system into the cellular (and subcellular boundaries of neurons and glia, are themselves complex systems of information. The diversity of neural phospholipids, coupled with their chameleon-like capacity to transmute into bioactive molecules, provides a vast repertoire of immediate response second messengers. The effects of compositional changes on synaptic function have only begun to be appreciated. Here, we mined 29 different neurolipidomic datasets for changes in neuronal membrane phospholipid metabolism in Alzheimer’s Disease. Three overarching metabolic disturbances were detected. We found that an increase in the hydrolysis of platelet activating factor precursors and ethanolamine-containing plasmalogens, coupled with a failure to regenerate relatively rare alkyl-acyl and alkenyl-acyl structural phospholipids, correlated with disease severity. Accumulation of specific bioactive metabolites (i.e., PC(O-16:0/2:0 and PE(P-16:0/0:0 was associated with aggravating tau pathology, enhancing vesicular release, and signaling neuronal loss. Finally, depletion of PI(16:0/20:4, PI(16:0/22:6, and PI(18:0/22:6 was implicated in accelerating Aβ42 biogenesis. Our analysis further suggested that converging disruptions in platelet activating factor, plasmalogen, phosphoinositol and phosphoethanolamine, and docosahexaenoic acid metabolism may contribute mechanistically to catastrophic vesicular depletion, impaired receptor trafficking, and morphological dendritic deformation. Together, this analysis supports an emerging hypothesis that aberrant phospholipid metabolism may be one of multiple critical determinants required for Alzheimer disease conversion.

  10. Preparation and characteristics of acrylic acid/styrene composite plasma polymerized membranes

    Science.gov (United States)

    Jiang, Zhongqing; Jiang, Zhong-jie; Shi, Yicai; Meng, Yuedong

    2010-08-01

    Plasma polymerization has gained increasing interest for the deposition of functional plasma-polymerized membranes suitable for a wide range of applications on account of its advantageous features. In this work, acrylic acid/styrene composite plasma polymerized membranes were synthesized by plasma polymerization of a mixture of acrylic acid and styrene monomers in a low-frequency after-glow capacitively coupled plasma (CCP) discharge process. The structure and composition of the plasma polymerized membranes were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The results showed that the partial pressure ratio between acrylic acid (AA) and styrene (St), applied discharge power and the energy of the extracted particles have considerable effects on the structure and the content of functional groups of the deposited membranes.

  11. The membrane interaction of amphiphilic model peptides affects phosphatidylserine headgroup and acyl chain order and dynamics. Application of the phospholipid headgroup electrometer concept to phosphatidylserine

    International Nuclear Information System (INIS)

    de Kroon, A.I.P.M.; Killian, J.A.; de Gier, J.; de Kruijff, B.

    1991-01-01

    Deuterium nuclear magnetic resonance ( 2 H NMR) was used to study the interaction of amphiphilic model peptides with model membranes consisting of 1,2-dioleoyl-sn-glycero-3-phospho-L-serine deuterated either at the β-position of the serine moiety ([2- 2 H]DOPS) or at the 11-position of the acyl chains ([11,11- 2 H 2 ]DOPS). The peptides are derived from the sequences H-Ala-Met-Leu-Trp-Ala-OH and H-Arg-Met-Leu-Trp-Ala-OH and contain a positive charge of +1 or +2 at the amino terminus or one positive charge at each end of the molecule. Upon titration of dispersions of DOPS with the peptides, the divalent peptides show a similar extent of binding to the DOPS bilyers, which is larger than that of the single charged peptide. Under these conditions the values of the quadrupolar splitting of both [2- 2 H]DOPS and [11,11- 2 H 2 ]DOPS are decreased, indicating that the peptides reduce the order of both the DOPS headgroup and the acyl chains. The extent of the decrease depends on the amount of peptide bound and on the position of the charged moieties in the peptide molecule. Titrations of DOPS with poly(L-lysine) 100 , which were included for reasons of comparison, reveal increased Δv q values. When the peptide-lipid titrations are carried out without applying a freeze-thaw procedure to achieve full equilibration, two-component 2 H NMR spectra occur. The apparently limited accessibility of the lipid to the peptides under these circumstances is discussed in relation to the ability of the peptides to exhibit transbilayer movement. 2 H spin-lattice relaxation time T1 measurements demonstrate a decrease of the rates of motion of both headgroup and acyl chains of DOPS in the presence of the peptides

  12. The GacS/A-RsmA Signal Transduction Pathway Controls the Synthesis of Alkylresorcinol Lipids that Replace Membrane Phospholipids during Encystment of Azotobacter vinelandii SW136.

    Directory of Open Access Journals (Sweden)

    Yanet Romero

    Full Text Available Azotobacter vinelandii is a soil bacterium that undergoes a differentiation process that forms cysts resistant to desiccation. During encystment, a family of alkylresorcinols lipids (ARs are synthesized and become part of the membrane and are also components of the outer layer covering the cyst, where they play a structural role. The synthesis of ARs in A. vinelandii has been shown to occur by the activity of enzymes encoded in the arsABCD operon. The expression of this operon is activated by ArpR, a LysR-type transcriptional regulator whose transcription occurs during encystment and is dependent on the alternative sigma factor RpoS. In this study, we show that the two component response regulator GacA, the small RNA RsmZ1 and the translational repressor protein RsmA, implicated in the control of the synthesis of other cysts components (i.e., alginate and poly-ß-hydroxybutyrate, are also controlling alkylresorcinol synthesis. This control affects the expression of arsABCD and is exerted through the regulation of arpR expression. We show that RsmA negatively regulates arpR expression by binding its mRNA, repressing its translation. GacA in turn, positively regulates arpR expression through the activation of transcription of RsmZ1, that binds RsmA, counteracting its repressor activity. This regulatory cascade is independent of RpoS. We also show evidence suggesting that GacA exerts an additional regulation on arsABCD expression through an ArpR independent route.

  13. Ultrathin Sicopion Composite Cation-Exchange Membranes: Characteristics and Electrodialytic Performance following a Conditioning Procedure

    Directory of Open Access Journals (Sweden)

    Erik Ayala-Bribiesca

    2012-01-01

    Full Text Available The aim of this work was to investigate the properties of Sicopion membranes: an ultrathin (≈20 μm composite cation-exchange membrane (CEM made from sulphonated poly(ether-ether-ketone (SPEEK containing different levels of sulphonic-functionalized silica particles (SFSPs. Sicopion membranes were conditioned according to the French Normalization Association procedure, consisting in a series of acid and alkaline washes, and their electrodialytic characteristics were compared to an existent commercial food-grade membrane (CMX-SB. Electrical conductivity of Sicopion membranes was higher than that of CMX-SB membranes (9.92 versus 6.98 mS/cm, as well as their water content (34.0 versus 27.6%. As the SFSP level was reduced, the ion-exchange capacity (IEC of Sicopion membranes increased. Concerning their electrodialytic performances, Sicopion membranes presented a lower demineralization rate than CMX-SB membranes (35.9 versus 45.5%, due to an OH− leakage through the pores created by dislodging the SFSP particles during the conditioning procedure.

  14. Polyamide Thin-Film Composite Membranes for Potential Raw Biogas Purification: Experiments and Modelling.

    Czech Academy of Sciences Publication Activity Database

    Šimčík, Miroslav; Růžička, Marek; Kárászová, Magda; Sedláková, Zuzana; Vejražka, Jiří; Veselý, M.; Čapek, P.; Friess, K.; Izák, Pavel

    2016-01-01

    Roč. 167, JUL 14 (2016), s. 163-173 ISSN 1383-5866 R&D Projects: GA ČR GA14-12695S; GA TA ČR TE01020080; GA MŠk(CZ) LD13018; GA MŠk LH14006 Institutional support: RVO:67985858 Keywords : thin film composite membrane * biogas membrane separation * transport model ing Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.359, year: 2016

  15. Polyamide Thin-Film Composite Membranes for Potential Raw Biogas Purification: Experiments and Modelling.

    Czech Academy of Sciences Publication Activity Database

    Šimčík, Miroslav; Růžička, Marek; Kárászová, Magda; Sedláková, Zuzana; Vejražka, Jiří; Veselý, M.; Čapek, P.; Friess, K.; Izák, Pavel

    2016-01-01

    Roč. 167, JUL 14 (2016), s. 163-173 ISSN 1383-5866 R&D Projects: GA ČR GA14-12695S; GA TA ČR TE01020080; GA MŠk(CZ) LD13018; GA MŠk LH14006 Institutional support: RVO:67985858 Keywords : thin film composite membrane * biogas membrane separation * transport modeling Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 3.359, year: 2016

  16. Silicon/Porous Silicon Composite Membrane for High Sensitivity Pressure Sensor

    Science.gov (United States)

    2009-07-21

    for integrating with other processes on silicon wafer. The fabrication of silicone rubber membranes for making microvalves has been reported [5...alcohol (IPA) is used along with HF to increase the wettability of the silicon surface and to remove the bubbles formed during the reaction. Aluminium ...Report for AOARD funded Project No. AOARD-074061 Title: Silicon /Porous Silicon composite membrane for high sensitivity pressure sensor PI

  17. A novel CO2- and SO2-tolerant dual phase composite membrane for oxygen separation

    DEFF Research Database (Denmark)

    Cheng, Shiyang; Søgaard, Martin; Han, Li

    2015-01-01

    A novel dual phase composite oxygen membrane (Al0.02Ga0.02Zn0.96O1.02 – Gd0.1Ce0.9O1.95-δ) was successfully prepared and tested. The membrane shows chemical stability against CO2 and SO2, and a stable oxygen permeation over 300 hours in CO2 was demonstrated. ZnO is cheap and non...

  18. Composite Pd and Pd Alloy Porous Stainless Steel Membranes for Hydrogen Production and Process Intensification

    Energy Technology Data Exchange (ETDEWEB)

    Yi Hua Ma; Nikolaos Kazantzis; Ivan Mardilovich; Federico Guazzone; Alexander Augustine; Reyyan Koc

    2011-11-06

    The synthesis of composite Pd membranes has been modified by the addition of a Al(OH){sub 3} graded layer and sequential annealing at high temperatures to obtain membranes with high permeance and outstanding selectivity stability for over 4000 hours at 450°C. Most of the membranes achieved in this work showed H{sub 2} flux well above 2010 DOE targets and in some case, also above 2015 DOE targets. Similar composite membranes were tested in water gas shift reaction atmospheres and showed to be stable with high CO conversion and high hydrogen recovery for over 1000 hours. The H{sub 2} permeance of composite Pd-Au membranes was studied as well as its resistance in H{sub 2}S containing atmospheres. H{sub 2}S poisoning of Pd-based membranes was reduced by the addition of Au and the loss undergone by membranes was found to be almost totally recoverable with 10-30 wt%Au. PSA technique was studied to test the possibility of H{sub 2}S and COS removal from feed stream with limited success since the removal of H{sub 2}S also led to the removal of a large fraction of the CO{sub 2}. The economics of a WGS bundle reactor, using the information of the membranes fabricated under this project and integrated into an IGCC plant were studied based on a 2D reactor modeling. The calculations showed that without a government incentive to impose a CO{sub 2} tax, application of WGS membrane reactors in IGCC would be not as economically attractive as regular pulverized coal plants.

  19. Crosslinked cellulose thin film composite nanofiltration membranes with zero salt rejection

    KAUST Repository

    Puspasari, Tiara

    2015-05-14

    We report a new synthetic route of fabricating regenerated cellulose nanofiltration membranes. The membranes are composite membranes with a thin selective layer of cellulose, which was prepared by regeneration of trimethylsilyl cellulose (a hydrophobic cellulose derivative) film followed by crosslinking. Filtration experiments using mixtures of sugar and sodium chloride showed that solutes above 300 Da were highly rejected whereas practically no rejection was observed for NaCl. This is a big advantage for a complete desalination as the existing commercial nanofiltration membranes typically exhibit NaCl rejection in the range of 30–60%. Membranes with zero NaCl rejection are required for recovery and purification applications in food, chemical and pharmaceutical industry.

  20. REMOVAL OF CU (II AND FE (II IONS THROUGH THIN FILM COMPOSITE (TFC WITH HYBRID MEMBRANE

    Directory of Open Access Journals (Sweden)

    NURUL AIDA SULAIMAN

    2016-07-01

    Full Text Available In recent years, there has been rising concern about environmental issues and specifically about the presence of heavy metal in water. Therefore, the removal of heavy metal ions from wastewater is very important with respect to the ecological health and public health. This paper presents the possibility of removing metal ions by using a hybrid membrane through thin film composite (TFC membrane which represents an integrated polymer complexation method. The hybrid membrane was formulated from blended poly(vinyl alcohol (PVA and chitosan which was cross linked with various concentration of tetraethyl orthosilicate (TEOS such as 1%, 3% w/w and 5%w/w through using sol-gel technique under acidic condition. The hybrid membrane was coated on polysulfone membrane as the porous support. The separation process was conducted on the different heavy metal solutions containing Cu (II and Fe (II ions at various concentrations (50,100,150,200,250 ppm.The properties of the thin film composite (TFC membranes were characterized by using Fourier Transform Infrared (FTIR spectroscopy and hermogravimetric Analysis (TGA. The influence of TEOS concentration and Cu (II and Fe (II ion concentration was investigated with the aim to identify on the removal percentage efficiency of Cu (II and Fe (II ions. Result showed that the fabricated thin film composites with higher concentrations of TEOS were able to remove higher percentage Cu (II and Fe (II from the feed solution.

  1. Preparation and characterization of composite membrane via layer by layer assembly for desalination

    Energy Technology Data Exchange (ETDEWEB)

    Wasim, Maria, E-mail: maria-be24@hotmail.co.uk; Sabir, Aneela; Shafiq, Muhammad; Islam, Atif; Jamil, Tahir

    2017-02-28

    Highlights: • Cellulose acetate based polymer composite membranes were formed via layer by layer assembly for nanofiltration. • Modified membranes shown improved MgSO{sub 4} salt rejection property up to 98.9%. • Surface roughness and antibacterial property of fabricated membrane were successfully studied. - Abstract: Cellulose acetate (CA) incorporated with sepiolite and Polyvinylpyrrolidone (PVP) multilayer composite on Polysulfone (PSf) substrate have been prepared by layer by layer (LbL) assembly method. Fourier TransformInfrared Spectroscopy (FTIR) results verified the hydrogen bonding among the components of composite membrane. Atomic force microscopy (AFM), scanning electron microscope (SEM) was carried out for the determination and elucidation of roughness and morphology of the fabricated membranes on PSf substrate. The AFM and SEM results showed the increased surface roughness with the porous and spongy structure. The performance results verified that the successful incorporation of sepiolite in membranes showed maximum MgSO{sub 4} rejection (98.9%) and flux of 38.7 L/m{sup 2} h. Whereas, in case of NaCl the rejection is 98.3% and flux is 34.9L/m{sup 2} h. The modification was evidenced to be effective in increasing the surface hydrophilicity that led to increase in surface roughness. The chlorine resistivity is improved by dropping the active sites for chlorine attack and protecting the underlying PSf substrate.

  2. A new concept in polymeric thin-film composite nanofiltration membranes with antibacterial properties.

    Science.gov (United States)

    Mollahosseini, Arash; Rahimpour, Ahmad

    2013-01-01

    A new, thin film, biofouling resistant, nanofiltration (NF) membrane was fabricated with two key characteristics, viz. a low rate of silver (Ag) release and long-lasting antibacterial properties. In the new approach, nanoparticles were embedded completely in a polymeric thin-film layer. A comparison was made between the new thin-film composite (TFC), NF membrane and thin-film nanocomposite (TFN), and antibacterial NF membranes. Both types of NF membrane were fabricated by interfacial polymerization on a polysulphone sublayer using m-phenylenediamine and trimesoyl chloride as an amine monomer and an acid chloride monomer, respectively. Energy dispersive X-ray (EDX) microanalysis demonstrated the presence of Ag nanoparticles. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to study the cross-sectional and surface morphological properties of the NF membranes. Permeability and salt rejection were tested using a dead-end filtration cell. Ag leaching from the membranes was measured using inductively coupled mass spectrometry (ICP-MS). Morphological studies showed that the TFC NF membranes had better thin-film formation (a more compact structure and a smoother surface) than TFN NF membranes. Performance experiments on TFC NF membranes revealed that permeability was good, without sacrificing salt rejection. The antibacterial properties of the fabricated membranes were tested using the disk diffusion method and viable plate counts. The antibiofouling properties of the membranes were examined by measuring the quantity of bacterial cells released from the biofilm formed (as a function of the amount of biofilm present). A more sensitive surface was observed compared to that of a typical antibacterial NF membrane. The Ag leaching rates were low, which will likely result in long-lasting antibacterial and biofouling resistant properties.

  3. Synthesis of hyperbranched copolyimides and their application as selective layers in composite membranes

    Czech Academy of Sciences Publication Activity Database

    Peter, Jakub; Kosmala, Barbara; Bleha, Miroslav

    2009-01-01

    Roč. 245, 1-3 (2009), s. 516-526 ISSN 0011-9164. [Engineering with Membranes 2008; Membrane Processes: Development, Monitoring and Modelling – From the Nano to the Macro Scale – EWM 2008. Vale do Lobo, Algarve, 25.05.2008-28.05.2008] R&D Projects: GA MPO 2A-1TP1/116 Institutional research plan: CEZ:AV0Z40500505 Keywords : hyperbranched polyimide * composite membrane * gas separation * soluble polyimide Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.034, year: 2009

  4. Preparation and properties of novel magnetic composite nanostructures: Arrays of nanowires in porous membranes

    International Nuclear Information System (INIS)

    Vazquez, M.; Hernandez-Velez, M.; Asenjo, A.; Navas, D.; Pirota, K.; Prida, V.; Sanchez, O.; Baldonedo, J.L.

    2006-01-01

    In the present work, we introduce our latest achievements in the development of novel highly ordered composite magnetic nanostructures employing anodized nanoporous membranes as precursor templates where long-range hexagonal symmetry is induced by self-assembling during anodization process. Subsequent processing as electroplating, sputtering or pressing are employed to prepare arrays of metallic, semiconductor or polymeric nanowires embedded in oxide or metallic membranes. Particular attention is paid to recent results on controlling the magnetic anisotropy in arrays of metallic nanowires, particularly Co, and nanohole arrays in Ni membranes

  5. Surface modification of thin film composite reverse osmosis membrane by glycerol assisted oxidation with sodium hypochlorite

    Science.gov (United States)

    Raval, Hiren D.; Samnani, Mohit D.; Gauswami, Maulik V.

    2018-01-01

    Need for improvement in water flux of thin film composite (TFC) RO membrane has been appreciated by researchers world over and surface modification approach is found promising to achieve higher water flux and solute rejection. Thin film composite RO membrane was exposed to 2000 mg/l sodium hypochlorite solution with varying concentrations of glycerol ranging from 1 to 10%. It was found that there was a drop in concentration of sodium hypochlorite after the addition of glycerol because of a new compound resulted from the oxidation of glycerol with sodium hypochlorite. The water flux of the membrane treated with 1% glycerol with 2000 mg/l sodium hypochlorite for 1 h was about 22% more and salt rejection was 1.36% greater than that of only sodium hypochlorite treated membrane for the same concentration and time. There was an increase in salt rejection of membrane with increase in concentration of glycerol from 1% to 5%, however, increasing glycerol concentration further up to 10%, the salt rejection declined. The water flux was found declining from 1% glycerol solution to 10% glycerol solution. The membrane samples were characterized to understand the change in chemical structure and morphology of the membrane.

  6. LCA of Egg Phospholipids

    OpenAIRE

    Berggren, Anders

    2013-01-01

    Egg phospholipids are a group of fats or lipids in the egg yolk, commonly used as emulsifiers in the chemical industry to facilitate the dissolving of substances. The pharmaceutical company Fresenius-Kabi manufactures this product and seeks a better understanding of the product’s major environmental impacts in order to comply with the ISO 14001 requirements, communicate its environmental performance and choose raw materials that result in lower environmental impacts. The aim of this study is ...

  7. Structure and mechanism of ATP-dependent phospholipid transporters

    DEFF Research Database (Denmark)

    Lopez Marques, Rosa Laura; Poulsen, Lisbeth Rosager; Bailly, Aurélien

    2015-01-01

    Background ATP-binding cassette (ABC) transporters and P4-ATPases are two large and seemingly unrelated families of primary active pumps involved in moving phospholipids from one leaflet of a biological membrane to the other. Scope of review This review aims to identify common mechanistic features...... in the way phospholipid flipping is carried out by two evolutionarily unrelated families of transporters. Major conclusions Both protein families hydrolyze ATP, although they employ different mechanisms to use it, and have a comparable size with twelve transmembrane segments in the functional unit. Further......, despite differences in overall architecture, both appear to operate by an alternating access mechanism and during transport they might allow access of phospholipids to the internal part of the transmembrane domain. The latter feature is obvious for ABC transporters, but phospholipids and other hydrophobic...

  8. Formation and Regulation of Mitochondrial Membranes

    Directory of Open Access Journals (Sweden)

    Laila Cigana Schenkel

    2014-01-01

    Full Text Available Mitochondrial membrane phospholipids are essential for the mitochondrial architecture, the activity of respiratory proteins, and the transport of proteins into the mitochondria. The accumulation of phospholipids within mitochondria depends on a coordinate synthesis, degradation, and trafficking of phospholipids between the endoplasmic reticulum (ER and mitochondria as well as intramitochondrial lipid trafficking. Several studies highlight the contribution of dietary fatty acids to the remodeling of phospholipids and mitochondrial membrane homeostasis. Understanding the role of phospholipids in the mitochondrial membrane and their metabolism will shed light on the molecular mechanisms involved in the regulation of mitochondrial function and in the mitochondrial-related diseases.

  9. Preparation of mixed matrix PES-based nanofiltration membrane filled with PANI-co-MWCNT composite nanoparticles

    International Nuclear Information System (INIS)

    Bagheripour, Ehsan; Moghadassi, Abdolreza; Hosseini, Sayed Mohsen

    2016-01-01

    Mixed matrix polyethersulfone/PANI-co-MWCNTs composite nanoparticle nanofiltration membrane was prepared by casting solution technique. Polyvinylpyrrolidone was also used as membrane pore former in membrane fabrication. The effect of polyaniline-co-multi walled carbon nanotubes composite nanoparticle concentration in the casting solution on membrane structure and performance was investigated. Scanning optical microscopy and scanning electron microscopy, FTIR analysis, porosity, mean pore size, contact angle, water content, NaCl/Na2SO4 rejection, water flux, tensile strength measurements and 3D surface image were also carried out in membrane characterization. SOM images showed nanoparticle agglomeration at high additive loading ratio. SEM images showed the membrane sub-layer porosity and thickness were changed by use of nanoparticles in membrane matrix. The membrane water content, porosity and pore size were increased by increase of nanoparticle concentration, except for 1%wt. Use of PANI-co- MWCNT nanoparticles in the membrane matrix caused a decrease of membrane contact angle from 63.43 to 46.76o. Salt rejection and water flux were improved initially by increase of nanoparticle concentration up to 0.1%wt and then decreased by more additive concentration. In addition, the membranes tensile strength was reduced by increase of PANI-co-MWCNTs composite nanoparticle concentration. 3D surface images showed a smoother surface for mixed matrix membrane filled with 0.1wt% PANI-co-MWCNTs. Modified membrane containing 0.1wt% composite nanoparticles showed better performance compared to others.

  10. Preparation of mixed matrix PES-based nanofiltration membrane filled with PANI-co-MWCNT composite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Bagheripour, Ehsan; Moghadassi, Abdolreza; Hosseini, Sayed Mohsen [Faculty of Engineering, Arak University, Arak (Iran, Islamic Republic of)

    2016-04-15

    Mixed matrix polyethersulfone/PANI-co-MWCNTs composite nanoparticle nanofiltration membrane was prepared by casting solution technique. Polyvinylpyrrolidone was also used as membrane pore former in membrane fabrication. The effect of polyaniline-co-multi walled carbon nanotubes composite nanoparticle concentration in the casting solution on membrane structure and performance was investigated. Scanning optical microscopy and scanning electron microscopy, FTIR analysis, porosity, mean pore size, contact angle, water content, NaCl/Na2SO4 rejection, water flux, tensile strength measurements and 3D surface image were also carried out in membrane characterization. SOM images showed nanoparticle agglomeration at high additive loading ratio. SEM images showed the membrane sub-layer porosity and thickness were changed by use of nanoparticles in membrane matrix. The membrane water content, porosity and pore size were increased by increase of nanoparticle concentration, except for 1%wt. Use of PANI-co- MWCNT nanoparticles in the membrane matrix caused a decrease of membrane contact angle from 63.43 to 46.76o. Salt rejection and water flux were improved initially by increase of nanoparticle concentration up to 0.1%wt and then decreased by more additive concentration. In addition, the membranes tensile strength was reduced by increase of PANI-co-MWCNTs composite nanoparticle concentration. 3D surface images showed a smoother surface for mixed matrix membrane filled with 0.1wt% PANI-co-MWCNTs. Modified membrane containing 0.1wt% composite nanoparticles showed better performance compared to others.

  11. Enhanced Critical Size Defect Repair in Rabbit Mandible by Electrospun Gelatin/β-TCP Composite Nanofibrous Membranes

    Directory of Open Access Journals (Sweden)

    Mingming Xu

    2015-01-01

    Full Text Available The design and fabrication of biodegradable barrier membranes with satisfactory structure and composition remain a considerable challenge for periodontal tissue regeneration. We have developed a biomimetic nanofibrous membrane made from a composite of gelatin and β-tricalcium phosphate (β-TCP. We previously confirmed the in vitro biological performance of the membrane material, but the efficacy of the membranes in promoting bone repair in situ has not yet been examined. Gelatin/β-TCP composite nanofibers were fabricated by incorporation of 20 wt.% β-TCP nanoparticles into electrospun gelatin nanofibers. Electron microscopy showed that the composite membranes presented a nonwoven structure with an interconnected porous network and had a rough surface due to the β-TCP nanoparticles, which were distributed widely and uniformly throughout the gelatin-fiber matrix. The repair efficacy of rabbit mandible defects implanted with bone substitute (Bio-Oss and covered with the gelatin/β-TCP composite nanofibrous membrane was evaluated in comparison with pure gelatin nanofibrous membrane. Gross observation, histological examination, and immunohistochemical analysis showed that new bone formation and defect closure were significantly enhanced by the composite membranes compared to the pure gelatin ones. From these results, we conclude that nanofibrous gelatin/β-TCP composite membranes could serve as effective barrier membranes for guided tissue regeneration.

  12. Composite mixed ion-electron conducting (MIEC) membranes for hydrogen generation and separation

    Science.gov (United States)

    Wang, Haibing

    Decomposition of steam under a chemical driving force at moderate temperatures (˜900°C) offers a convenient and economical way to generate hydrogen. A significant amount of hydrogen can be generated and separated by splitting steam and removing oxygen using a mixed ion-electron conducting (MIEC) membrane. In this work, Gd0.2Ce0.8O1.9-deltaGd 0.08Sr0.88Ti0.95Al0.05O3+/-delta MIEC membranes have been explored in which, Gd0.2Ce 0.8O1.9-delta (GDC) functions as a predominantly oxygen ionic conductor, and Gd0.08Sr0.88Ti0.95Al 0.05O3+/-delta (GSTA) functions as a predominantly n-type electronic conductor under the process conditions. During the hydrogen generation process, oxygen transports from the feed side to the permeate side through coupled diffusion of oxygen ions and electrons under an oxygen partial pressure gradient across membranes. This process results in a H2-rich product on the feed side and depleted fuel gases on the permeate side. In this work, membrane architectures comprising self-supported thick membranes and thin membranes supported on porous supports of the same composition have been studied. The effect of membrane thickness on hydrogen generation has been studied by measuring the area-specific hydrogen generation rates at different experimental conditions. Experimental results have shown that the hydrogen generation process for the thick membranes was controlled by the oxygen bulk diffusion through membranes, while the hydrogen generation process for the dense thin membranes was controlled by both the surface exchange reactions and oxygen bulk diffusion process. The area-specific hydrogen generation rates of the supported dense thin membranes were significantly enhanced by applying a porous catalytic layer onto the surface of the membrane. Experimental results showed that the area-specific hydrogen generation rates were higher when the surface catalytic layer was exposed to the feed side rather than the permeate side. A mathematical model for

  13. Surface Functionalization of Thin-Film Composite Membranes with Copper Nanoparticles for Antimicrobial Surface Properties

    KAUST Repository

    Ben-Sasson, Moshe

    2014-01-07

    Biofouling is a major operational challenge in reverse osmosis (RO) desalination, motivating a search for improved biofouling control strategies. Copper, long known for its antibacterial activity and relatively low cost, is an attractive potential biocidal agent. In this paper, we present a method for loading copper nanoparticles (Cu-NPs) on the surface of a thin-film composite (TFC) polyamide RO membrane. Cu-NPs were synthesized using polyethyleneimine (PEI) as a capping agent, resulting in particles with an average radius of 34 nm and a copper content between 39 and 49 wt.%. The positive charge of the Cu-NPs imparted by the PEI allowed a simple electrostatic functionalization of the negatively charged RO membrane. We confirmed functionalization and irreversible binding of the Cu-NPs to the membrane surface with SEM and XPS after exposing the membrane to bath sonication. We also demonstrated that Cu-NP functionalization can be repeated after the Cu-NPs dissolve from the membrane surface. The Cu-NP functionalization had minimal impact on the intrinsic membrane transport parameters. Surface hydrophilicity and surface roughness were also maintained, and the membrane surface charge became positive after functionalization. The functionalized membrane exhibited significant antibacterial activity, leading to an 80-95% reduction in the number of attached live bacteria for three different model bacterial strains. Challenges associated with this functionalization method and its implementation in RO desalination are discussed. © 2013 American Chemical Society.

  14. Palladium/Copper Alloy Composite Membranes for High Temperature Hydrogen Separation

    Energy Technology Data Exchange (ETDEWEB)

    J. Douglas Way; Paul M. Thoen

    2006-08-31

    This report summarizes progress made during the a three year University Coal Research grant (DEFG26-03NT41792) at the Colorado School of Mines. The period of performance was September 1, 2003 through August of 2006. We made excellent progress toward our goal of contributing to the development of high productivity, sulfur tolerant composite metal membranes for hydrogen production and membrane reactors. Composite Pd and Pd alloy metal membranes with thin metal films (1-7 {micro}m) were prepared on porous stainless steel and ceramic supports that meet or exceed the DOE 2010 and 2015 pure hydrogen flux targets at differential pressure of only 20 psi. For example, a 2 {micro}m pure Pd membrane on a Pall AccuSep{reg_sign} substrate achieved an ideal H{sub 2}/N{sub 2} separation factor of over 6000, with a pure hydrogen flux of 210 SCFH/ft{sup 2} at only 20 psig feed pressure. Similar performance was achieved with a Pd{sub 80}Au{sub 20} composite membrane on a similar stainless steel substrate. Extrapolating the pure hydrogen flux of this PdAu membrane to the DOE Fossil Energy target conditions of 150 psia feed pressure and 50 psia permeate pressure gives a value of 508 SCFH/ft{sup 2}, exceeding the 2015 target. At these thicknesses, it is the support cost that will dominate the cost of a large scale module. In a direct comparison of FCC phase PdCu and PdAu alloys on identical supports, we showed that a Pd{sub 85}Au{sub 15} (mass %) alloy membrane is not inhibited by CO, CO{sub 2}, or steam present in a water-gas shift feed mixture at 400 C, has better resistance to sulfur than a Pd{sub 94}Cu{sub 6} membrane, and has over twice the hydrogen permeance.

  15. Free Vibrations of a Nonlinearly Deformable Isotropic on the Average Composite Rectangular Membrane

    Science.gov (United States)

    Tarasyuk, I. A.; Kravchuk, A. S.; Mikhasev, G. I.

    2018-03-01

    A refined vibration equation of a rectangular membrane is derived in this paper. It allows determining the natural frequencies as functions of the mechanical characteristics of an asymmetrically stretched membrane. The dynamic equation is generalized to the case of a nonlinearly deformable isotropic on the average composite material. An approximate analytical solution of the problem is found employing a new homogenization technique. This method is based on estimation of the effective deformation characteristics of the composite material. The range of its effective characteristics is obtained from the rule of mixtures for the stresses and strains found assuming Voigt and Reuss hypotheses. The nonlinear behavior of the material is modeled using the bilinear Prandtl diagrams as constitutive equations for components of the composite. The effective elastic moduli, hardening modulus, yield stress, and the natural frequencies as functions of elastoplastic characteristics of the composite are obtained analytically in a closed form.

  16. Cholesterol interactions with fluid-phase phospholipids: effect on the lateral organization of the bilayer.

    Science.gov (United States)

    Halling, Katrin K; Ramstedt, Bodil; Nyström, Joel H; Slotte, J Peter; Nyholm, Thomas K M

    2008-10-01

    The lateral organization of lipids and proteins in cell membranes is recognized as an important factor in several cellular processes. Cholesterol is thought to function as a modulator of the lateral segregation of lipids into cholesterol-poor and cholesterol-rich domains. We investigated how the affinity of cholesterol for different phospholipids, as seen in cholesterol partitioning between methyl-beta-cyclodextrin and large unilamellar vesicles, was reflected in the lateral organization of lipids in complex bilayers. We especially wanted to determine how the low-T(m) lipid affected the lateral structure. Partition experiments showed that cholesterol had a higher affinity for N-oleoyl-sphingomyelin (OSM) than for palmitoyl-oleoyl-phosphatidylcholine (POPC) bilayers, but the highest preference was for N-palmitoyl-sphingomyelin (PSM)-containing bilayers. Partial phase diagrams of POPC/PSM/cholesterol and OSM/PSM/cholesterol bilayers at 23 degrees C and 37 degrees C were used to gain insight into the lateral organization of lipids in bilayers. Analysis of phase diagrams revealed that the phospholipid composition of cholesterol-poor and cholesterol-rich domains reflected the affinity that cholesterol exhibited toward bilayers composed of different lipids. Therefore, the determined affinity of cholesterol for different phospholipid bilayers was useful in predicting the cholesterol-induced lateral segregation of lipids in complex bilayers.

  17. Amine Enrichment of Thin-Film Composite Membranes via Low Pressure Plasma Polymerization for Antimicrobial Adhesion.

    Science.gov (United States)

    Reis, Rackel; Dumée, Ludovic F; He, Li; She, Fenghua; Orbell, John D; Winther-Jensen, Bjorn; Duke, Mikel C

    2015-07-15

    Thin-film composite membranes, primarily based on poly(amide) (PA) semipermeable materials, are nowadays the dominant technology used in pressure driven water desalination systems. Despite offering superior water permeation and salt selectivity, their surface properties, such as their charge and roughness, cannot be extensively tuned due to the intrinsic fabrication process of the membranes by interfacial polymerization. The alteration of these properties would lead to a better control of the materials surface zeta potential, which is critical to finely tune selectivity and enhance the membrane materials stability when exposed to complex industrial waste streams. Low pressure plasma was employed to introduce amine functionalities onto the PA surface of commercially available thin-film composite (TFC) membranes. Morphological changes after plasma polymerization were analyzed by SEM and AFM, and average surface roughness decreased by 29%. Amine enrichment provided isoelectric point changes from pH 3.7 to 5.2 for 5 to 15 min of plasma polymerization time. Synchrotron FTIR mappings of the amine-modified surface indicated the addition of a discrete 60 nm film to the PA layer. Furthermore, metal affinity was confirmed by the enhanced binding of silver to the modified surface, supported by an increased antimicrobial functionality with demonstrable elimination of E. coli growth. Essential salt rejection was shown minimally compromised for faster polymerization processes. Plasma polymerization is therefore a viable route to producing functional amine enriched thin-film composite PA membrane surfaces.

  18. High-performance sulfosuccinic acid cross-linked PVA composite pervaporation membrane for desalination.

    Science.gov (United States)

    Zhang, Rui; Liang, Bin; Qu, Ting; Cao, Bing; Li, Pei

    2017-10-25

    Pervaperation (PV), as a novel technology, has shown great promise in fresh water production from salty water. However, the low water flux of the present membranes hinders their practical applications. Here, a new type of PV composite membrane, consisting of a selective skin layer fabricated from poly(vinyl alcohol) (PVA) cross-linked by sulfosuccinic acid and a porous support layer using a commercial polyacrylonitrile (PAN) ultrafiltration membrane, was developed for applications in desalination. The separation performance of S-PVA/PAN composite PV membranes with different S-PVA layer thicknesses was tested in detail. The best result showed a water flux of 27.9 kg m -2  h -1 with a salt rejection of 99.8%, which was obtained at a vacuum of 100 Pa and temperature of 70°C when separating a 35,000 ppm NaCl solution. The S-PVA/PAN composite membranes could also be used for the desalination of high-concentration (100,000 ppm) NaCl solutions with a water flux of 11.2 kg m -2  h -1 with a salt rejection of 99.8%. Moreover, a stable desalination performance was obtained for a 120 h operation time. This study shows the possibility of using PV in desalination applications for seawater, brackish water and reverse osmosis concentrate treatment.

  19. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification.

    Science.gov (United States)

    Reis, Rackel; Dumée, Ludovic F; Tardy, Blaise L; Dagastine, Raymond; Orbell, John D; Schutz, Jürg A; Duke, Mikel C

    2016-07-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

  20. EFFECT OF BENTONITE AS FILLER IN COMPOSITE MEMBRANE PERFORMANCE POLYVINYLIDENE FLUORIDE (PVDF-POLYMETHYLMETHACRYLATE (PMMA

    Directory of Open Access Journals (Sweden)

    Erda Marniza

    2018-02-01

    Full Text Available Abstract. The effect of bentonite as filler on the performance of the composite membrane of PVDF-PMMA has been performed. This study was conducted to determine the performance PVDF-PMMA composite membranes and membrane applications PVDF-PMMA-Bentonite on oily wastes. Bentonite is obtained from North Aceh while PVDF membrane-PMMA by phase inversion method. This study uses an oily waste water model was made by mixing surfactant tween 80 with concentration of 2% with palm oil and gas oil. Membrane PVDF-PMMA-Bentonite is analyzing using cell ultrafiltration (flux test, FTIR and SEM-EDX. The results showed that the value of flux with the addition of bentonite is greater than without bentonite. Good flux values contained in the PVDF-PMMA-Bentonite (1:1:2 amounted to 32.143 L/m2.h.bar with permeability of 21.428 L/m2.h. FTIR characterization analysis results show that bentonite can add to pore at wave number 1520 cm -1 and 1660 cm-1 SEM and EDX results showed regular shape and uniform pore. Keywords: Membrane, bentonite, filler, FTIR, SEM-EDX, Oily wastewater

  1. High Dehumidification Performance of Amorphous Cellulose Composite Membranes prepared from Trimethylsilyl Cellulose

    KAUST Repository

    Puspasari, Tiara

    2018-04-11

    Cellulose is widely regarded as an environmentally friendly, natural and low cost material which can significantly contribute the sustainable economic growth. In this study, cellulose composite membranes were prepared via regeneration of trimethylsilyl cellulose (TMSC), an easily synthesized cellulose derivative. The amorphous hydrophilic feature of the regenerated cellulose enabled fast permeation of water vapour. The pore-free cellulose layer thickness was adjustable by the initial TMSC concentration and acted as an efficient gas barrier. As a result, a 5,000 GPU water vapour transmission rate (WVTR) at the highest ideal selectivity of 1.1 x 106 was achieved by the membranes spin coated from a 7% (w/w) TMSC solution. The membranes maintained a 4,000 GPU WVTR with selectivity of 1.1 x 104 in the mixed-gas experiments, surpassing the performances of the previously reported composite membranes. This study provides a simple way to not only produce high performance membranes but also to advance cellulose as a low-cost and sustainable membrane material for dehumidification applications.

  2. Ethanol production and maximum cell growth are highly correlated with membrane lipid composition during fermentation as determined by lipidomic analysis of 22 Saccharomyces cerevisiae strains.

    Science.gov (United States)

    Henderson, Clark M; Lozada-Contreras, Michelle; Jiranek, Vladimir; Longo, Marjorie L; Block, David E

    2013-01-01

    Optimizing ethanol yield during fermentation is important for efficient production of fuel alcohol, as well as wine and other alcoholic beverages. However, increasing ethanol concentrations during fermentation can create problems that result in arrested or sluggish sugar-to-ethanol conversion. The fundamental cellular basis for these problem fermentations, however, is not well understood. Small-scale fermentations were performed in a synthetic grape must using 22 industrial Saccharomyces cerevisiae strains (primarily wine strains) with various degrees of ethanol tolerance to assess the correlation between lipid composition and fermentation kinetic parameters. Lipids were extracted at several fermentation time points representing different growth phases of the yeast to quantitatively analyze phospholipids and ergosterol utilizing atmospheric pressure ionization-mass spectrometry methods. Lipid profiling of individual fermentations indicated that yeast lipid class profiles do not shift dramatically in composition over the course of fermentation. Multivariate statistical analysis of the data was performed using partial least-squares linear regression modeling to correlate lipid composition data with fermentation kinetic data. The results indicate a strong correlation (R(2) = 0.91) between the overall lipid composition and the final ethanol concentration (wt/wt), an indicator of strain ethanol tolerance. One potential component of ethanol tolerance, the maximum yeast cell concentration, was also found to be a strong function of lipid composition (R(2) = 0.97). Specifically, strains unable to complete fermentation were associated with high phosphatidylinositol levels early in fermentation. Yeast strains that achieved the highest cell densities and ethanol concentrations were positively correlated with phosphatidylcholine species similar to those known to decrease the perturbing effects of ethanol in model membrane systems.

  3. Membrane stress tensor in the presence of lipid density and composition inhomogeneities.

    Science.gov (United States)

    Bitbol, A-F; Peliti, L; Fournier, J-B

    2011-05-01

    We derive the expression of the stress tensor for one- and two-component lipid membranes with density and composition inhomogeneities. We first express the membrane stress tensor as a function of the free-energy density by means of the principle of virtual work. We then apply this general result to a monolayer model which is shown to be a local version of the area-difference elasticity (ADE) model. The resulting stress tensor expression generalizes the one associated with the Helfrich model, and can be specialized to obtain the one associated with the ADE model. Our stress tensor directly gives the force exchanged through a boundary in a monolayer with density and composition inhomogeneities. Besides, it yields the force density, which is also directly obtained in covariant formalism. We apply our results to study the forces induced in a membrane by a local perturbation.

  4. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    International Nuclear Information System (INIS)

    Bradshaw, J.P.; Gilchrist, P.J.; Duff, K.C.; Saxena, A.M.

    1994-01-01

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein

  5. Neutron diffraction studies of amphipathic helices in phospholipid bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bradshaw, J.P.; Gilchrist, P.J. [Univ. of Edinburgh (United Kingdom); Duff, K.C. [Univ. of Edinburgh Medical School (United Kingdom); Saxena, A.M. [Brookhaven National Laboratory, Upton, NY (United States)

    1994-12-31

    The structural feature which is thought to facilitate the interaction of many peptides with phospholipid bilayers is the ability to fold into an amphipathic helix. In most cases the exact location and orientation of this helix with respect to the membrane is not known, and may vary with factors such as pH and phospholipid content of the bilayer. The growing interest in this area is stimulated by indications that similar interactions can contribute to the binding of certain hormones to their cell-surface receptors. We have been using the techniques of neutron diffraction from stacked phospholipid bilayers in an attempt to investigate this phenomenon with a number of membrane-active peptides. Here we report some of our findings with three of these: the bee venom melittin; the hormone calcitonin; and a synthetic peptide representing the ion channel fragment of influenza A M2 protein.

  6. PAN composite membrane with different solvent affinities controlled by surface modification methods

    Czech Academy of Sciences Publication Activity Database

    Dragan, E. S.; Mihai, M.; Schauer, Jan; Ghimici, L.

    2005-01-01

    Roč. 43, č. 18 (2005), s. 4161-4171 ISSN 0887-624X R&D Projects: GA ČR(CZ) GA203/05/0080 Institutional research plan: CEZ:AV0Z40500505 Keywords : composite membrane * functionalization of polymers * polyelectrolytes Subject RIV: CD - Macromolecular Chemistry Impact factor: 3.027, year: 2005

  7. Multi-response data treatment of dynamic and steady state permeation measurement on composite membrane

    Czech Academy of Sciences Publication Activity Database

    Fíla, V.; Bernauer, B.; Hrabánek, Pavel

    2006-01-01

    Roč. 200, 1-3 (2006), s. 120-121 ISSN 0011-9164 R&D Projects: GA AV ČR(CZ) 1QS401250509 Institutional research plan: CEZ:AV0Z40400503 Keywords : composite membrane * physical chemistry * Wicke-Kalenbach permeation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.917, year: 2006

  8. Development of robust fluorinated TiO2/PVDF composite hollow fiber membrane for CO2 capture in gas-liquid membrane contactor

    Science.gov (United States)

    Lin, Yuqing; Xu, Yilin; Loh, Chun Heng; Wang, Rong

    2018-04-01

    Gas-liquid membrane contactor (GLMC) is a promising method to attain high efficiency for CO2 capture from flue gas, biogas and natural gas. However, membranes used in GLMC are prone to pore wetting due to insufficient hydrophobicity and low chemical resistance, resulting in significant increase in mass transfer resistance. To mitigate this issue, inorganic-organic fluorinated titania/polyvinylidene fluoride (fTiO2/PVDF) composite hollow fiber (HF) membranes was prepared via facile in-situ vapor induced hydrolyzation method, followed by hydrophobic modification. The proposed composite membranes were expected to couple the superb chemical stability of inorganic and high permeability/low cost of organic materials. The continuous fTiO2 layer deposited on top of PVDF substrate was found to possess a tighter microstructure and better hydrophobicity, which effectively prevented the membrane from wetting and lead to a high CO2 absorption flux (12.7 × 10-3 mol m-2 s-1). In a stability test with 21-day operation of GLMC using 1M monoethanolamine (MEA) as the absorbent, the fTiO2/PVDF membrane remained to be intact with a CO2 absorption flux decline of ∼16%, while the pristine PVDF membrane suffered from a flux decline of ∼80% due to membrane damage. Overall, this work provides an insight into the preparation of high-quality inorganic/organic composite HF membranes for CO2 capture in GLMC application.

  9. Cross-linked PAN-based thin-film composite membranes for non-aqueous nanofiltration

    KAUST Repository

    Pérez-Manríquez, Liliana

    2015-01-01

    A new approach on the development of cross-linked PAN based thin film composite (TFC) membranes for non-aqueous application is presented in this work. Polypropylene backed neat PAN membranes fabricated by phase inversion process were cross-linked with hydrazine to get excellent solvent stability toward dimethylformamide (DMF). By interfacial polymerization a selective polyamide active layer was coated over the cross-linked PAN using N,N′-diamino piperazine (DAP) and trimesoyl chloride (TMC) as monomers. Permeation and molecular weight cut off (MWCO) experiments using various dyes were done to evaluate the performance of the membranes. Membranes developed by such method show excellent solvent stability toward DMF with a permeance of 1.7 L/m2 h bar and a molecular weight cut-off of less than 600 Da.

  10. High temperature proton exchange membranes based on polybenzimidazole and clay composites for fuel cells

    DEFF Research Database (Denmark)

    Plackett, David; Siu, Ana; Li, Qingfeng

    2011-01-01

    dispersion of modified laponite clay was achieved in polybenzimidazole (PBI) solutions which, when cast and allowed to dry, resulted in homogeneous and transparent composite membranes containing up to 20 wt% clay in the polymer. The clay was organically modified using a series of ammonium...... and pyridinium salts with varying polarity and hydrogen-bonding capacity. Clay modification by ion-exchange reactions involving replacement of interlayer inorganic cations was confirmed using X-ray photoelectron and infrared spectroscopy techniques. The cast PBI membranes were characterized by their water uptake......-doped pristine PBI membranes. In accordance with the hydrogen permeability measurements, fuel cell tests exhibited high open circuit voltages (i.e., 1.02 V) at room temperature as well as high I–V performance compared with normal PBI membranes....

  11. Channel Protein-Containing Liposomes as Delivery Vehicles for the Controlled Release of Drugs-Optimization of the Lipid Composition

    NARCIS (Netherlands)

    Šmisterová, J.; Deemter, M. van; Schaaf, G. van der; Meijberg, W.; Robillard, G.

    2005-01-01

    In the design of liposomal drug formulations containing a controllable channel protein (MscL), the lipid composition is dictated in part by this membrane protein. This work addresses the question whether therapeutically optimal lipid compositions (phospholipid with high Tm/cholesterol/PEG) are

  12. Hydrophilic treatment poly(tetrafluoroethylene) reinforced sulfonated poly(ether ether ketone) composite membrane for proton exchange membrane fuel cell application

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Cheng; Zhang, Yu.; Xiao, Shaohua [Proton Exchange Membrane Fuel Cell Key Materials and Technology Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China); Graduate University of Chinese Academy of Sciences, Beijing 100039 (China); Zhang, Huamin [Proton Exchange Membrane Fuel Cell Key Materials and Technology Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian 116023 (China)

    2009-12-01

    A reinforced composite membrane based on SPEEK (sulfonated poly ether ether ketone) and porous PTFE substrate (polytetrafluoroethylene) is fabricated and investigated for proton exchange membrane fuel cell application. In order to improve the combination between SPEEK polymer and PTFE matrix, PTFE substrate is hydrophilically pretreated by naphthalene sodium solution. The experimental results indicate that SPEEK can impregnate into treated PTFE substrate (abbreviated as trPTFE) more easily. The variation of PTFE surface property before and after treatment is characterized by water contact angle experiment and ATR-FTIR technique. The impregnated status of SPEEK polymer in PTFE matrix is also characterized by ATR-FTIR. According to the appearance photo of two composite membranes, it is showed that SPEEK/trPTFE composite membrane has more uniform and homogeneous morphology. Moreover, the mechanical property of SPEEK/trPTFE composite membrane also has an advantage over pristine SPEEK membrane. Due to the reinforced effect of trPTFE substrate, thinner composite membrane can be applied in single cell evolution and achieves better performance as a result. (author)

  13. Relating performance of thin-film composite forward osmosis membranes to support layer formation and structure

    KAUST Repository

    Tiraferri, Alberto

    2011-02-01

    Osmotically driven membrane processes have the potential to treat impaired water sources, desalinate sea/brackish waters, and sustainably produce energy. The development of a membrane tailored for these processes is essential to advance the technology to the point that it is commercially viable. Here, a systematic investigation of the influence of thin-film composite membrane support layer structure on forward osmosis performance is conducted. The membranes consist of a selective polyamide active layer formed by interfacial polymerization on top of a polysulfone support layer fabricated by phase separation. By systematically varying the conditions used during the casting of the polysulfone layer, an array of support layers with differing structures was produced. The role that solvent quality, dope polymer concentration, fabric layer wetting, and casting blade gate height play in the support layer structure formation was investigated. Using a 1M NaCl draw solution and a deionized water feed, water fluxes ranging from 4 to 25Lm-2h-1 with consistently high salt rejection (>95.5%) were produced. The relationship between membrane structure and performance was analyzed. This study confirms the hypothesis that the optimal forward osmosis membrane consists of a mixed-structure support layer, where a thin sponge-like layer sits on top of highly porous macrovoids. Both the active layer transport properties and the support layer structural characteristics need to be optimized in order to fabricate a high performance forward osmosis membrane. © 2010 Elsevier B.V.

  14. Preparation of Novel Thin-Film Composite Nanofiltration Membranes for Separation of Amoxicillin

    Directory of Open Access Journals (Sweden)

    A. Akbari

    2014-04-01

    Full Text Available Several novel composite membranes were prepared to separate and recycle amoxicillin from pharmaceutical wastewater via nanofiltration process. The synthesis of these membranes included three stages: 1- preparation of polysulfone ultrafiltration membranes as a support via phase separation process, 2- modification of its surface by interfacial polymerization as a selective layer (polyamide, and 3- self-assembly of TiO2 nanoparticles on the selective layer as an anti-fouling agent. The rejection of all nanofiltration membranes was more than 99% and only its flux was changed proportional to different conditions. In the presence and absence of TiO2 nanoparticles, the pure water flux of polyamide thin-film membrane also obtained 44.4 and 38.4 L/h.m2 at 4 bar pressure, respectively. These were equal to 34 L/h.m2 for amoxicillin solutions. The results showed that TiO2 nanoparticles increased hydrophilicity of polyamide selective layer and therefore, nanoparticles decreased the fouling level. SEM images illustrated the excellent establishment of polyamide layer and distribution of TiO2 nanoparticles on the selective layer. The properties of membrane surface were taken into consideration by using AFM, indicating the increment of surface roughness with interfacial polymerization and TiO2 nanoparticles self-assembly. The pore size of membranes was in the nanoscale (2.653 and 2.604 nm without and with TiO2 nanoparticles self-assembly, respectively

  15. Development of polyelectrolyte multilayer thin film composite membrane for water desalination application

    KAUST Repository

    Fadhillah, F.

    2013-06-01

    Thin film composite membranes were fabricated via spin assisted layer by layer (SA-LbL) assembly by depositing alternate layers of poly(allyl amine hydrochloride) (PAH) and poly(acrylic acid) (PAA) on a polysulfone (PSF) ultrafiltration membrane as support. The suitability of these membranes for potential water purification applications was explored by testing the stability of the deposited thin films and their permeation characteristic using cross-flow permeation cell. Permeation test conducted at a pressure of 40bar, temperature of 25°C, pH of 6 and feed water concentration of 2000ppm NaCl demonstrated that the PAH/PAA multilayer film deposited on polysulfone support remained stable and intact under long-term test conditions. The 120 bilayers of PAH/PAA membrane tested at the above condition showed flux of 15L/m2.h and salt rejection of 65%. The membrane performance evaluation also revealed that SA-LbL PAH/PAA membrane follows the characteristics of the solution diffusion membrane. © 2013 Elsevier B.V.

  16. Enzymatic cleaning of biofouled thin-film composite reverse osmosis (RO) membrane operated in a biofilm membrane reactor.

    Science.gov (United States)

    Khan, Mohiuddin; Danielsen, Steffen; Johansen, Katja; Lorenz, Lindsey; Nelson, Sara; Camper, Anne

    2014-02-01

    Application of environmentally friendly enzymes to remove thin-film composite (TFC) reverse osmosis (RO) membrane biofoulants without changing the physico-chemical properties of the RO surface is a challenging and new concept. Eight enzymes from Novozyme A/S were tested using a commercially available biofouling-resistant TFC polyamide RO membrane (BW30, FilmTech Corporation, Dow Chemical Co.) without filtration in a rotating disk reactor system operated for 58 days. At the end of the operation, the accumulated biofoulants on the TFC RO surfaces were treated with the three best enzymes, Subtilisin protease and lipase; dextranase; and polygalacturonase (PG) based enzymes, at neutral pH (~7) and doses of 50, 100, and 150 ppm. Contact times were 18 and 36 h. Live/dead staining, epifluorescence microscopy measurements, and 5 μm thick cryo-sections of enzyme and physically treated biofouled membranes revealed that Subtilisin protease- and lipase-based enzymes at 100 ppm and 18 h contact time were optimal for removing most of the cells and proteins from the RO surface. Culturable cells inside the biofilm declined by more than five logs even at the lower dose (50 ppm) and shorter incubation period (18 h). Subtilisin protease- and lipase-based enzyme cleaning at 100 ppm and for 18 h contact time restored the hydrophobicity of the TFC RO surface to its virgin condition while physical cleaning alone resulted in a 50° increase in hydrophobicity. Moreover, at this optimum working condition, the Subtilisin protease- and lipase-based enzyme treatment of biofouled RO surface also restored the surface roughness measured with atomic force microscopy and the mass percentage of the chemical compositions on the TFC surface estimated with X-ray photoelectron spectroscopy to its virgin condition. This novel study will encourage the further development and application of enzymes to remove biofoulants on the RO surface without changing its surface properties.

  17. Carbon dioxide selective mixed matrix composite membrane containing ZIF-7 nano-fillers

    KAUST Repository

    Li, Tao

    2013-01-01

    Mixed matrix materials made from selective inorganic fillers and polymers are very attractive for the manufacturing of gas separation membranes. But only few of these materials could be manufactured into high-performance asymmetric or composite membranes. We report here the first mixed matrix composite membrane made of commercially available poly (amide-b-ethylene oxide) (Pebax®1657, Arkema) mixed with the nano-sized zeolitic imidazole framework ZIF-7. This hybrid material has been successfully deposited as a thin layer (less than 1μm) on a porous polyacrylonitrile (PAN) support. An intermediate gutter layer of PTMSP was applied to serve as a flat and smooth surface for coating to avoid polymer penetration into the porous support. Key features of this work are the preparation and use of ultra-small ZIF-7 nano-particles (around 30-35nm) and the membrane processability of Pebax®1657. SEM pictures show that excellent adhesion and almost ideal morphology between the two phases has been obtained simply by mixing the as-synthesized ZIF-7 suspension into the Pebax®1657 dope, and no voids or clusters can be observed. The performance of the composite membrane is characterized by single gas permeation measurement of CO2, N2 and CH4. Both, permeability (PCO2 up to 145barrer) and gas selectivity (CO2/N2 up to 97 and CO2/CH4 up to 30) can be increased at low ZIF- loading. The CO2/CH4 selectivity can be further increased to 44 with the filler loading of 34wt%, but the permeability is reduced compared to the pure Pebax®1657 membrane. Polymer chain rigidification at high filler loading is supposed to be a reason for the reduced permeability. The composite membranes prepared in this work show better performance in terms of permeance and selectivity when compared with asymmetric mixed matrix membranes described in the recent literature. Overall, the ZIF 7/Pebax mixed matrix membranes show a high performance for CO2 separation from methane and other gas streams. They are easy to

  18. Growth of apatite on chitosan-multiwall carbon nanotube composite membranes

    International Nuclear Information System (INIS)

    Yang Jun; Yao Zhiwen; Tang Changyu; Darvell, B.W.; Zhang Hualin; Pan Lingzhan; Liu Jingsong; Chen Zhiqing

    2009-01-01

    Bioactive membranes for guided tissue regeneration would be of value for periodontal therapy. Chitosan-multiwall carbon nanotube (CS-MWNT) composites were treated to deposit nanoscopic apatite for MWNT proportions of 0-4 mass%. Fourier-transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction were used for characterization. Apatite was formed on the CS-MWNT composites at low MWNT concentrations, but the dispersion of the MWNT affects the crystallite size and the Ca/P molar ratio of the composite. The smallest crystallite size was 9 nm at 1 mass% MWNT.

  19. Preparation and characterization of hydroxyapatite/gelatin composite membranes for immunoisolation

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Jyh-Ping, E-mail: jpchen@mail.cgu.edu.tw [Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen Hwa 1st Rd., Kwei-San, Taoyuan 333, Taiwan (China); Chang, Feng-Nian [Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen Hwa 1st Rd., Kwei-San, Taoyuan 333, Taiwan (China)

    2012-12-01

    Highlights: Black-Right-Pointing-Pointer Cross-linking gelatin in the presence of hydroxyapatite forms composite membranes. Black-Right-Pointing-Pointer The membrane was used for immunoisolation and encapsulation of cells. Black-Right-Pointing-Pointer Encapsulated islet cells secrete insulin in response to glucose concentrations. Black-Right-Pointing-Pointer The membrane is a good candidate for bioartificial pancreas development. - Abstract: Composite membranes are fabricated from hydroxyapatite (HAP) and gelatin for immunoisolation of cells. The films were fabricated by crosslinking 5 wt%, 10 wt%, and 20 wt% gelatin with 1 wt% glutaraldehyde (GA) in the presence of HAP. Fourier transform infrared spectroscopy analysis confirms imide bond formation between GA and gelatin, while the crystal structure of HAP powder remains unchanged from X-ray diffraction analysis. The degree of crosslinking depends on crosslinking time and gelatin concentration. For 5% and 10% gelatin, the degree of crosslinking levels off at 90% within 48 h. From scanning electron microscopy micrographs, the microstructure of the composite membrane depends on the amount of gelatin used in the crosslinking reaction. The mechanical strength of the composite membrane could be enhanced by increasing the gelatin concentration. BET analysis indicates that pore size of the micropores on the surface HAP/gelatin agglomerates decreases with increasing gelatin concentration. However, the macropore, through which diffusion of molecules occurs, is larger at higher gelatin concentrations. The permeability coefficients of different molecules through a HAP/gelatin composite membrane increase with increasing gelatin concentration and is inversely correlated with the molecular weight of the molecule. For immunoisolation of cells, the diffusion of large molecules stimulated by the immune system can be rejected by a chamber constructed from the HAP/gelatin membrane. Insulinoma cells were encapsulated in alginate

  20. A graphite-coated carbon fiber epoxy composite bipolar plate for polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Yu, Ha Na; Lim, Jun Woo; Suh, Jung Do; Lee, Dai Gil

    A PEMFC (polymer electrolyte membrane fuel cell or proton exchange membrane fuel cell) stack is composed of GDLs (gas diffusion layers), MEAs (membrane electrode assemblies), and bipolar plates. One of the important functions of bipolar plates is to collect and conduct the current from cell to cell, which requires low electrical bulk and interfacial resistances. For a carbon fiber epoxy composite bipolar plate, the interfacial resistance is usually much larger than the bulk resistance due to the resin-rich layer on the composite surface. In this study, a thin graphite layer is coated on the carbon/epoxy composite bipolar plate to decrease the interfacial contact resistance between the bipolar plate and the GDL. The total electrical resistance in the through-thickness direction of the bipolar plate is measured with respect to the thickness of the graphite coating layer, and the ratio of the bulk resistance to the interfacial contact resistance is estimated using the measured data. From the experiment, it is found that the graphite coating on the carbon/epoxy composite bipolar plate has 10% and 4% of the total electrical and interfacial contact resistances of the conventional carbon/epoxy composite bipolar plate, respectively, when the graphite coating thickness is 50 μm.

  1. Synthesis of mesh-shaped calcia partially stabilized zirconia using eggshell membrane template as filler composite

    Directory of Open Access Journals (Sweden)

    Gema Gempita

    2017-08-01

    Full Text Available This experiment was conducted experimentally to synthesize Calcia Partially Stabilized Zirconia (Ca-PSZ by sol-gel method using eggshell membrane template as a composite filler. The eggshell membrane was used to produce a mesh shaped structure, which hopefully can improve the mechanical properties of the composite. Ca-PSZ filler was synthesized from ZrOCl2 precursor and Ca(NO32 stabilizer with a 24 hours immersion time. Ca-PSZ of synthesis then mixed with the resin matrix to test its composite hardness. The EDS characterization results suggested that the sample contained elements of zirconia, calcium, and oxygen. Whereas, the XRD characterization identified that crystal structures that formed in the sample were nano scale tetragonal. Characterization of SEM showed Ca-PSZ with mesh structured. The average composite hardness value was 15.79 VHN. The composites with Ca-PSZ-synthesized filler could be prepared and its hardness value was higher than the composite with Ca-PSZ filler in spherical particles, but the hardness was still below the composite on the market.

  2. Novel composite Zr/PBI-O-PhT membranes for HT-PEFC applications

    Directory of Open Access Journals (Sweden)

    Mikhail S. Kondratenko

    2013-08-01

    Full Text Available Novel composite membranes for high temperature polymer-electrolyte fuel cells (HT-PEFC based on a poly[oxy-3,3-bis(4′-benzimidazol-2″-ylphenylphtalide-5″(6″-diyl] (PBI-O-PhT polymer with small amounts of added Zr were prepared. It was shown in a model reaction between zirconium acetylacetonate (Zr(acac4 and benzimidazole (BI that Zr-atoms are capable to form chemical bonds with BI. Thus, Zr may be used as a crosslinking agent for PBI membranes. The obtained Zr/PBI-O-PhT composite membranes were examined by means of SAXS, thermomechanical analysis (TMA, and were tested in operating fuel cells by means of stationary voltammetry and impedance spectroscopy. The new membranes showed excellent stability in a 2000-hour fuel cell (FC durability test. The modification of the PBI-O-PhT films with Zr facilitated an increase of the phosphoric acid (PA uptake by the membranes, which resulted in an up to 2.5 times increased proton conductivity. The existence of an optimal amount of Zr content in the modified PBI-O-PhT film was shown. Larger amounts of Zr lead to a lower PA doping level and a reduced conductivity due to an excessively high degree of crosslinking.

  3. In vitro aging of mineralized collagen-based composite as guided tissue regeneration membrane

    International Nuclear Information System (INIS)

    Pan, S.X.; Li, Y.; Feng, H.L.; Bai, W.; Gu, Y.Y.

    2006-01-01

    The technique of guided tissue regeneration (GTR) has been developed for the regeneration of periodontal tissues, bone around natural teeth and dental implants. The aim of this study is to investigate the biodegradability and mechanic behavior of a novel mineralized nano-hydroxyapatite/collagen/poly (lactic acid) (nHAC/PLA) composite as GTR membrane in vitro. The elastic modulus and maximum tensile strength of GTR film samples with different nHAC/PLA ratio were measured to get an optimal nHAC/PLA ratio. Thermogravimetric analysis was conducted to evaluate the change of the inorganic component in the samples during the process of in vitro aging. Morphology of samples was checked by using scanning electron microscopy. On the basis of the above results, it can be concluded that the GTR membranes maintained integrity and the original appearance throughout the 1-month in vitro aging. There is an active dissolution and deposition process of crystals which is propitious to the bone formation on the surface of the composite membrane. The optimal nHAC/PLA ratio of the novel membrane is 0.4:1. For a longer period of bone repair, PLA with higher molecular weight should be chosen as the scaffold for the GTR membrane

  4. Triple-layered PLGA/nanoapatite/lauric acid graded composite membrane for periodontal guided bone regeneration.

    Science.gov (United States)

    Jamuna-Thevi, Kalitheertha; Saarani, Nur Najiha; Abdul Kadir, Mohamed Rafiq; Hermawan, Hendra

    2014-10-01

    This paper discusses the successful fabrication of a novel triple-layered poly(lactic-co-glycolic acid) (PLGA)-based composite membrane using only a single step that combines the techniques of solvent casting and thermally induced phase separation/solvent leaching. The resulting graded membrane consists of a small pore size layer-1 containing 10 wt% non-stoichiometric nanoapatite (NAp)+1-3 wt% lauric acid (LA) for fibroblastic cell and bacterial inhibition, an intermediate layer-2 with 20-50 wt% NAp+1 wt% LA, and a large pore size layer-3 containing 30-100 wt% NAp without LA to allow bone cell growth. The synergic effects of 10-30 wt% NAp and 1 wt% LA in the membrane demonstrated higher tensile strength (0.61 MPa) and a more elastic behavior (16.1% elongation at break) in 3 wt% LA added membrane compared with the pure PLGA (0.49 MPa, 9.1%). The addition of LA resulted in a remarkable plasticizing effect on PLGA at 3 wt% due to weak intermolecular interactions in PLGA. The pure and composite PLGA membranes had good cell viability toward human skin fibroblast, regardless of LA and NAp contents. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Novel composite Zr/PBI-O-PhT membranes for HT-PEFC applications.

    Science.gov (United States)

    Kondratenko, Mikhail S; Ponomarev, Igor I; Gallyamov, Marat O; Razorenov, Dmitry Yu; Volkova, Yulia A; Kharitonova, Elena P; Khokhlov, Alexei R

    2013-01-01

    Novel composite membranes for high temperature polymer-electrolyte fuel cells (HT-PEFC) based on a poly[oxy-3,3-bis(4'-benzimidazol-2″-ylphenyl)phtalide-5″(6″)-diyl] (PBI-O-PhT) polymer with small amounts of added Zr were prepared. It was shown in a model reaction between zirconium acetylacetonate (Zr(acac)4) and benzimidazole (BI) that Zr-atoms are capable to form chemical bonds with BI. Thus, Zr may be used as a crosslinking agent for PBI membranes. The obtained Zr/PBI-O-PhT composite membranes were examined by means of SAXS, thermomechanical analysis (TMA), and were tested in operating fuel cells by means of stationary voltammetry and impedance spectroscopy. The new membranes showed excellent stability in a 2000-hour fuel cell (FC) durability test. The modification of the PBI-O-PhT films with Zr facilitated an increase of the phosphoric acid (PA) uptake by the membranes, which resulted in an up to 2.5 times increased proton conductivity. The existence of an optimal amount of Zr content in the modified PBI-O-PhT film was shown. Larger amounts of Zr lead to a lower PA doping level and a reduced conductivity due to an excessively high degree of crosslinking.

  6. Phospholipid-Dependence of Plant UDP-Glucose Sterol β-d-Glucosyl Transferase 1

    Science.gov (United States)

    Ury, Alain; Benveniste, Pierre; Bouvier-Navé, Pierrette

    1989-01-01

    The phospholipid dependence of the UDP-glucose sterol glucosyl transferase (UDPG-SGTase) from maize coleoptiles was previously demonstrated using the partially purified and highly delipidated enzyme, in the presence of the detergent Triton X-100 (P Ullmann, P Bouvier-Navé, P Benveniste [1987] Plant Physiol 85: 51-55). We now report the reconstitution of the enzyme activity into unilamellar lipid vesicles. This was achieved by adding phospholipids, sterols and β-octylglucoside to the solubilized enzyme and passing the mixture through Sephadex G-50. The treatment led to almost complete removal of the detergents. The incorporation of UDPG-SGTase in the lipid vesicles was demonstrated by (a) coelution of the enzyme activity with the labeled lipid vesicles (average diameter: 260Å) on a Sephacryl S-1000 column and (b) flotation experiments on metrizamide density gradients. Release of dithiobis-(2-nitro-benzoic acid) (DTNB) from DTNB-preloaded vesicles was very slow, indicating good membrane integrity of the vesicles. Treatment of the intact vesicles with the nonpermeant reagent p-chloro-mercuribenzene sulfonate led to more than 95% inactivation of the total enzyme activity, i.e. the activity measured in the presence of Triton X-100 at permeabilizing concentration. This suggests an outward orientation for the active site of the enzyme. Finally, the enzyme was incorporated into vesicles of various phospholipid compositions and the kinetic parameters of the reactions were determined. Our results clearly show that the reconstituted UDPG-SGTase activity is stimulated to a large extent by negatively charged phospholipids. PMID:16667070

  7. Regional distribution of phospholipids in porcine vitreous humor.

    Science.gov (United States)

    Schnepf, Abigail; Yappert, Marta Cecilia; Borchman, Douglas

    2017-07-01

    This project explores the regional phospholipid distribution in porcine vitreous humor, retina, and lens. Matrix-assisted laser desorption mass spectrometry has been used previously to image lipids, proteins, and other metabolites in retinas and lenses. However, the regional composition of phospholipids in vitreous humors is not known. To address this issue, we have applied this mass spectral method to explore the regional phospholipid distribution in porcine vitreous humor both ex-situ and in-vitro. To establish the possible source(s) of phospholipids in the vitreous humor, compositional studies of the lens and retina were also pursued. Due to the overall low levels of phospholipids in vitreous humor, it was necessary to optimize the experimental approaches for ex-situ and in-vitro studies. The sensitivity observed in the spectra of methanol extracts from the lens and retina was higher than that for methanol:chloroform extracts, but the compositional trends were the same. A fourfold improvement in sensitivity was observed in the analysis of vitreous humor extracts obtained with the Bligh and Dyer protocol relative to the other two extraction methods. For ex-situ studies, the 'stamp method' with para-nitroaniline as the matrix was chosen. Throughout the vitreous humor, phosphatidylcholines were the most abundant phospholipids. In-vitro results showed higher relative levels of phospholipids compared to the 'stamp' method. However, more details in the regional phospholipid distribution were provided by the ex-situ approach. Both in-vitro and ex-situ results indicated higher levels of phospholipids in the posterior vitreous region, followed by the anterior and central regions. The posterior region contained more unsaturated species whereas more saturated phospholipids were detected in the anterior region. The observed trends suggest that the phospholipids detected in the posterior vitreous humor migrate from the retina and associated vasculature while those present in

  8. Cs2.5H0.5PWO40/SiO2 as addition self-humidifying composite membrane for proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Wang, L.; Yi, B.L.; Zhang, H.M.; Xing, D.M.

    2007-01-01

    In this paper, we first reported a novel self-humidifying composite membrane for the proton exchange membrane fuel cell (PEMFC). Cs 2.5 H 0.5 PWO 40 /SiO 2 catalyst particles were dispersed uniformly into the Nafion (registered) resin, and then Cs 2.5 H 0.5 PWO 40 -SiO 2 /Nafion composite membrane was prepared using solution-cast method. Compared with the H 3 PWO 40 (PTA) , the Cs 2.5 H 0.5 PWO 40 /SiO 2 was steady due to the substitute of H + with Cs + and the interaction between the Cs 2.5 H 0.5 PWO 40 and SiO 2 . And compared with the performance of the fuel cell with commercial Nafion (registered) NRE-212 membrane, the cell performance with the self-humidifying composite membrane was obviously improved under both humidified and dry conditions at 60 and 80 o C. The best performance under dry condition was obtained at 60 o C. The self-humidifying composite membrane could minimize membrane conductivity loss under dry conditions due to the presence of catalyst and hydrophilic Cs 2.5 H 0.5 PWO 40 /SiO 2 particles

  9. Influence of membrane fatty acid composition and fluidity on airborne survival of Escherichia coli.

    Science.gov (United States)

    Ng, Tsz Wai; Chan, Wing Lam; Lai, Ka Man

    2018-04-01

    Finding ways to predict and control the survival of bacterial aerosols can contribute to the development of ways to alleviate a number of crucial microbiological problems. Significant damage in the membrane integrity of Escherichia coli during aerosolization and airborne suspension has been revealed which has prompted the question of how the membrane fatty acid composition and fluidity influence the survival of airborne bacteria. Two approaches of using isogenic mutants and different growth temperatures were selected to manipulate the membrane fatty acid composition of E. coli before challenging the bacteria with different relative humidity (RH) levels in an aerosol chamber. Among the mutants (fabR - , cfa. fadA - ), fabR - had the lowest membrane fluidity index (FI) and generally showed a higher survival than the parental strain. Surprisingly, its resistance to airborne stress was so strong that its viability was fully maintained even after airborne suspension at 40% RH, a harsh RH level to bacterial survival. Moreover, E. coli cultured at 20 °C with a higher FI than that at 30 and 37 °C generally had a lower survival after aerosolization and airborne suspension. Unlike FI, individual fatty acid and cyclopropane fatty acid composition did not relate to the bacterial survival. Lipid peroxidation of the membrane was undetected in all the bacteria. Membrane fluidity plays a stronger role in determining the bacteria survival during airborne suspension than during aerosolization. Certain relationships between FI and bacteria survival were identified, which could help predict the transmission of bacteria under different conditions.

  10. Preparation and characterization of hydroxyapatite/gelatin composite membranes for immunoisolation

    Science.gov (United States)

    Chen, Jyh-Ping; Chang, Feng-Nian

    2012-12-01

    Composite membranes are fabricated from hydroxyapatite (HAP) and gelatin for immunoisolation of cells. The films were fabricated by crosslinking 5 wt%, 10 wt%, and 20 wt% gelatin with 1 wt% glutaraldehyde (GA) in the presence of HAP. Fourier transform infrared spectroscopy analysis confirms imide bond formation between GA and gelatin, while the crystal structure of HAP powder remains unchanged from X-ray diffraction analysis. The degree of crosslinking depends on crosslinking time and gelatin concentration. For 5% and 10% gelatin, the degree of crosslinking levels off at 90% within 48 h. From scanning electron microscopy micrographs, the microstructure of the composite membrane depends on the amount of gelatin used in the crosslinking reaction. The mechanical strength of the composite membrane could be enhanced by increasing the gelatin concentration. BET analysis indicates that pore size of the micropores on the surface HAP/gelatin agglomerates decreases with increasing gelatin concentration. However, the macropore, through which diffusion of molecules occurs, is larger at higher gelatin concentrations. The permeability coefficients of different molecules through a HAP/gelatin composite membrane increase with increasing gelatin concentration and is inversely correlated with the molecular weight of the molecule. For immunoisolation of cells, the diffusion of large molecules stimulated by the immune system can be rejected by a chamber constructed from the HAP/gelatin membrane. Insulinoma cells were encapsulated in alginate-poly-L-lysine-alginate microcapsules and enclosed in a HAP/gelatin chamber. The chamber did not impair the viability and function of insulinoma cells and cells can secrete insulin in response to glucose concentration change. The chamber is therefore useful for the physiologically controlled secretion of insulin in response to the blood glucose level. Intraperitoneal transplantation of the chamber into streptozotocin-induced diabetic SD rats could

  11. Steel reinforced composite silicone membranes and its integration to microfluidic oxygenators for high performance gas exchange.

    Science.gov (United States)

    Matharoo, Harpreet; Dabaghi, Mohammadhossein; Rochow, Niels; Fusch, Gerhard; Saraei, Neda; Tauhiduzzaman, Mohammed; Veldhuis, Stephen; Brash, John; Fusch, Christoph; Selvaganapathy, P Ravi

    2018-01-01

    Respiratory distress syndrome (RDS) is one of the main causes of fatality in newborn infants, particularly in neonates with low birth-weight. Commercial extracorporeal oxygenators have been used for low-birth-weight neonates in neonatal intensive care units. However, these oxygenators require high blood volumes to prime. In the last decade, microfluidics oxygenators using enriched oxygen have been developed for this purpose. Some of these oxygenators use thin polydimethylsiloxane (PDMS) membranes to facilitate gas exchange between the blood flowing in the microchannels and the ambient air outside. However, PDMS is elastic and the thin membranes exhibit significant deformation and delamination under pressure which alters the architecture of the devices causing poor oxygenation or device failure. Therefore, an alternate membrane with high stability, low deformation under pressure, and high gas exchange was desired. In this paper, we present a novel composite membrane consisting of an ultra-thin stainless-steel mesh embedded in PDMS, designed specifically for a microfluidic single oxygenator unit (SOU). In comparison to homogeneous PDMS membranes, this composite membrane demonstrated high stability, low deformation under pressure, and high gas exchange. In addition, a new design for oxygenator with sloping profile and tapered inlet configuration has been introduced to achieve the same gas exchange at lower pressure drops. SOUs were tested by bovine blood to evaluate gas exchange properties. Among all tested SOUs, the flat design SOU with composite membrane has the highest oxygen exchange of 40.32 ml/min m 2 . The superior performance of the new device with composite membrane was demonstrated by constructing a lung assist device (LAD) with a low priming volume of 10 ml. The LAD was achieved by the oxygen uptake of 0.48-0.90 ml/min and the CO 2 release of 1.05-2.27 ml/min at blood flow rates ranging between 8 and 48 ml/min. This LAD was shown to increase the

  12. Human TMEM30a promotes uptake of antitumor and bioactive choline phospholipids into mammalian cells.

    Science.gov (United States)

    Chen, Rui; Brady, Erin; McIntyre, Thomas M

    2011-03-01

    Antitumor alkylphospholipids initiate apoptosis in transformed HL-60 and Jurkat cells while sparing their progenitors. 1-O-Alkyl-2-carboxymethyl-sn-glycero-3-phosphocholine (Edelfosine) like other short-chained phospholipids--inflammatory platelet-activating factor (PAF) and apoptotic oxidatively truncated phospholipids--are proposed to have intracellular sites of action, yet a conduit for these choline phospholipids into mammalian cells is undefined. Edelfosine is also accumulated by Saccharomyces cerevisiae in a process requiring the membrane protein Lem3p, and the human genome contains a Lem3p homolog TMEM30a. We show that import of choline phospholipids into S. cerevisiae ΔLem3 is partially reconstituted by human TMEM30a and by Lem3p-TMEM30a chimeras, showing the proteins are orthologous. TMEM30a-GFP chimeras expressed in mammalian cells localized in plasma membranes, as well as internal organelles, and ectopic TMEM30a expression promoted uptake of exogenous choline and ethanolamine phospholipids. Short hairpin RNA knockdown of TMEM30a reduced fluorescent choline phospholipid and [(3)H]PAF import. This knockdown also reduced mitochondrial depolarization from exogenous Edelfosine or the mitotoxic oxidatively truncated phospholipid azelaoyl phosphatidylcholine, and the knockdown reduced apoptosis in response to these two phospholipids. These results show that extracellular choline phospholipids with short sn-2 residues can have intracellular roles and sites of metabolism because they are transport substrates for a TMEM30a phospholipid import system. Variation in this mechanism could limit sensitivity to short chain choline phospholipids such as Edelfosine, PAF, and proapoptotic phospholipids.

  13. Thin-film Nanofibrous Composite Membranes Containing Cellulose or Chitin Barrier Layers Fabricated by Ionic Liquids

    Energy Technology Data Exchange (ETDEWEB)

    H Ma; B Hsiao; B Chu

    2011-12-31

    The barrier layer of high-flux ultrafiltration (UF) thin-film nanofibrous composite (TFNC) membranes for purification of wastewater (e.g., bilge water) have been prepared by using cellulose, chitin, and a cellulose-chitin blend, regenerated from an ionic liquid. The structures and properties of regenerated cellulose, chitin, and a cellulose-chitin blend were analyzed with thermogravimetric analysis (TGA) and wide-angle X-ray diffraction (WAXD). The surface morphology, pore size and pore size distribution of TFNC membranes were determined by SEM images and molecular weight cut-off (MWCO) methods. An oil/water emulsion, a model of bilge water, was used as the feed solution, and the permeation flux and rejection ratio of the membranes were investigated. TFNC membranes based on the cellulose-chitin blend exhibited 10 times higher permeation flux when compared with a commercial UF membrane (PAN10, Sepro) with a similar rejection ratio after filtration over a time period of up to 100 h, implying the practical feasibility of such membranes for UF applications.

  14. Polysulfone thin film composite nanofiltration membranes for removal of textile dyes wastewater

    Science.gov (United States)

    Sutedja, Andrew; Aileen Josephine, Claresta; Mangindaan, Dave

    2017-12-01

    This research was conducted to produce nanofiltration (NF) membranes, which have good performance in terms of removal of textile dye (Reactive Red 120, RR120) from simulated wastewater as one of several eco-engineering developments for sustainable water resource management. Phase inversion technique was utilized to fabricate the membrane with polysulfone (PSF) support, dissolved in N-methyl-2 pyrollidone (NMP) solvent, and diethylene glycol (DEG) as non-solvent additive. The fabricated membrane then modified with the additional of dopamine coating and further modified by interfacial polymerization (IP) to form a thin film composite (TFC)-NF membrane with PSF substrate. TFC was formed from interaction between amine monomer (2 %-weight of m-phenylenediamine (MPD) in deionized water) and acyl chloride (0.2 %-weight of trimesoyl chloride (TMC) in hexane). From this study, the fabricated PSF-TFC membrane could remove dyestuff from RR120 wastewater by 88% rejection at 120 psi. The result of this study is promising to be applied in Indonesia where researches on removal of dyes from textile wastewater by using membranes are still quite rare. Therefore, this paper may open new avenues for development of eco-engineering development in Indonesia.

  15. Enhanced Performance of Thin Film Composite Forward Osmosis Membrane by Chemical Post-Treatment

    Science.gov (United States)

    Liu, Zheng; Chen, Jiangrong; Cao, Zhen; Wang, Jian; Guo, Chungang

    2018-01-01

    Forward osmosis is an attractive technique in water purification and desalination fields. Enhancement of the forward osmosis membrane performance is essential to the application of this technique. In this study, an optimized chemical post-treatment approach which was used to improve RO membrane performance was employed for enhancing water flux of thin film composite forward osmosis membrane. Home-made polysulfide-based forward osmosis membrane was prepared and nitric acid, sulfuric acid, ethanol, 2-propanol were employed as post-treatment solutions. After a short-term treatment, all the membrane samples manifested water flux enhancement compared with their untreated counterparts. Over 50% increase of water flux had been obtained by ethanol solution treatment. The swelling, changes of hydrophobicity and solvency in both active layer and substrate were verified as the major causes for the enhancement of the water flux. It is noted that the treatment time and solution concentration should be controlled to get both appropriate water flux and reverse salt flux. The results obtained in this study will be useful for further FO membrane development and application.

  16. Superhydrophilic Thin-Film Composite Forward Osmosis Membranes for Organic Fouling Control: Fouling Behavior and Antifouling Mechanisms

    KAUST Repository

    Tiraferri, Alberto

    2012-10-16

    This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes. © 2012 American Chemical Society.

  17. Superhydrophilic thin-film composite forward osmosis membranes for organic fouling control: fouling behavior and antifouling mechanisms.

    Science.gov (United States)

    Tiraferri, Alberto; Kang, Yan; Giannelis, Emmanuel P; Elimelech, Menachem

    2012-10-16

    This study investigates the fouling behavior and fouling resistance of superhydrophilic thin-film composite forward osmosis membranes functionalized with surface-tailored nanoparticles. Fouling experiments in both forward osmosis and reverse osmosis modes are performed with three model organic foulants: alginate, bovine serum albumin, and Suwannee river natural organic matter. A solution comprising monovalent and divalent salts is employed to simulate the solution chemistry of typical wastewater effluents. Reduced fouling is consistently observed for the superhydrophilic membranes compared to control thin-film composite polyamide membranes, in both reverse and forward osmosis modes. The fouling resistance and cleaning efficiency of the functionalized membranes is particularly outstanding in forward osmosis mode where the driving force for water flux is an osmotic pressure difference. To understand the mechanism of fouling, the intermolecular interactions between the foulants and the membrane surface are analyzed by direct force measurement using atomic force microscopy. Lower adhesion forces are observed for the superhydrophilic membranes compared to the control thin-film composite polyamide membranes. The magnitude and distribution of adhesion forces for the different membrane surfaces suggest that the antifouling properties of the superhydrophilic membranes originate from the barrier provided by the tightly bound hydration layer at their surface, as well as from the neutralization of the native carboxyl groups of thin-film composite polyamide membranes.

  18. In vitro bioactivity assessment of composite membrane containing antimicrobial lauric acid for guided bone regeneration in dental application

    Science.gov (United States)

    Suleiman, Muhammad Jabir; Kalitheertha, Jamuna Thevi; Sabri, Siti Noorzidah

    2015-07-01

    The manuscript reflect research work in fabrication of a triple layered composite membrane and to perform an in vitro bioactivity evaluation on composite membrane containing antimicrobial lauric acid. Poly(lactic-co-glycolic acid) (PLGA) matrix was incorporated with various amounts of nanoapatite (NAp) and lauric acid (LA) to form a triple-layered composite membrane. This membrane was prepared using a single step fabrication technique comprising of solvent casting, thermally induced phase separation and solvent leaching processes. Apatite mineralization was detected on the composite membranes within 30 days of exposure to simulated body fluid (SBF) and showed increased apatite formation at 30-60wt% of NAp content in the PLGA matrix on layer 3 (L3), that has the highest amount of NAp compared with layer 1 (L1) and layer 2 (L2) of the membrane. However, apatite mineralization was not detected on pure PLGA membrane. In addition, incorporation of LA on L1 and L2 has no influence on apatite mineral formation as none detected on these surfaces. The presence of NAp determines the formation of apatite crystals on the composite membrane. These membranes with triple layered design and bioactive properties showed potential use for guided bone regeneration purposes in dental application.

  19. Structural and dielectric properties of cobaltacarborane composite polybenzimidazole membranes as solid polymer electrolytes at high temperature.

    Science.gov (United States)

    Fuentes, Isabel; Andrio, Andreu; García-Bernabé, Abel; Escorihuela, Jorge; Viñas, Clara; Teixidor, Francesc; Compañ, Vicente

    2018-03-29

    The conductivity of a series of composite membranes, based on polybenzimidazole (PBI) containing the metallacarborane salt M[Co(C2B9H11)2], M[COSANE] and tetraphenylborate, M[B(C6H5)4], M[TPB] both anions having the same number of atoms and the same negative charge, has been investigated. Different cations (M = H+, Li+ and Na+) have been studied and the composite membranes have been characterized by water uptake, swelling ratios, ATR FT-IR, thermogravimetric analysis and electrochemical impedance spectroscopy to explore the dielectric response and ion dynamics in composite membranes. Our results show that conductivity increases with increasing temperature and it is higher for H+ than for Li+ and Na+ for all temperatures under study. The mobility of Li+ is greater in [COSANE]- than in [TPB]- composite PBI@membranes while for Na+ it is the opposite. The temperature dependence of the conductivity of the composite was followed by a typical Arrhenius behaviour with two different regions: (1) between 20 and 100 °C, and (2) between 100 and 150 °C. Using the analysis of electrode polarization (EP) based on the Thrukhan theory we have calculated the ionic diffusion coefficients and the density of carriers. From the double logarithmic plot of the imaginary part of the conductivity (σ'') versus frequency in the entire range of temperatures studied we have determined for each sample at each temperature, the frequency values of the onset (fON) and full development of electrode polarization (fMAX), respectively, which permit us to calculate static permittivity.

  20. New type of chitosan/2-hydroxypropyl-β-cyclodextrin composite membrane for gallic acid encapsulation and controlled release.

    Science.gov (United States)

    Paun, Gabriela; Neagu, Elena; Tache, Andreia; Radu, G L

    2014-01-01

    A new type of chitosan/2-hydroxypropyl-β-cyclodextrin composite membrane have been developed for the encapsulation and controlled release of gallic acid. The morphology of the composite membrane was investigated by infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM), whereas swelling gallic acid and release properties were investigated by UV-visible spectroscopy. The release behavior with pH changes was also explored. The composite membrane based on chitosan/2-hydroxypropyl-β-cyclodextrin with gallic acid included showed improved antioxidant capacities compared to plain chitosan membrane. The information obtained in this study will facilitate the design and preparation of composite membrane based on chitosan and could open a wide range of applications, particularly its use as an antioxidant in food, food packaging, biomedical (biodegradable soft porous scaffolds for enhance the surrounding tissue regeneration), pharmaceutical and cosmetics industries.

  1. Development of a PVAl/chitosan composite membrane compatible with the dermo-epidermic system

    International Nuclear Information System (INIS)

    Almeida, Tiago Luiz de

    2009-03-01

    surface, thus obtaining a composite membrane compatible with the dermo-epidermic system. (author)

  2. Preliminary biocompatible evaluation of nano-hydroxyapatite/polyamide 66 composite porous membrane

    Directory of Open Access Journals (Sweden)

    Yili Qu

    2010-06-01

    Full Text Available Yili Qu1,3, Ping Wang1,3, Yi Man1, Yubao Li2, Yi Zuo2, Jidong Li21State Key Laboratory of Oral Diseases, Sichuan University, Chengdu 610064, China; 2Research Center for Nano-Biomaterials, Analytical and Testing Center, Sichuan University, Chengdu 610064, China; 3These authors contributed equally to this workAbstract: Nano-hydroxyapatite/polyamide 66 (nHA/PA66 composite with good bioactivity and osteoconductivity was employed to develop a novel porous membrane with asymmetric structure for guided bone regeneration (GBR. In order to test material cytotoxicity and to investigate surface-dependent responses of bone-forming cells, the morphology, proliferation, and cell cycle of bone marrow stromal cells (BMSCs of rats cultured on the prepared membrane were determined. The polygonal and fusiform shape of BMSCs was observed by scanning electronic microscopy (SEM. The proliferation of BMSCs cultured on nHA/PA66 membrane tested by the MTT method (MTT: [3-{4,5-dimethylthiazol-2yl}-2,5-diphenyl-2H-tetrazoliumbromide] was higher than that of negative control groups for 1 and 4 days’ incubation and had no significant difference for 7 and 11 days’ culture. The results of cell cycle also suggested that the membrane has no negative influence on cell division. The nHA/PA66 membranes were then implanted into subcutaneous sites of nine Sprague Dawley rats. The wounds and implant sites were free from suppuration and necrosis in all periods. All nHA/PA66 membranes were surrounded by a fibrous capsule with decreasing thickness 1 to 8 weeks postoperatively. In conclusion, the results of the in vitro and in vivo studies reveal that nHA/PA66 membrane has excellent biocompatibility and indicate its use in guided tissue regeneration (GTR or GBR.Keywords: hydroxyapatite/polyamide, barrier membrane, biocompatibility, guided bone regeneration

  3. A microassay for the determination of soluble and membrane-bound glutamate decarboxylase activity--influences of cations, lipid composition, and pyridoxal 5'-phosphate on the glutamate decarboxylase binding to liposomes

    International Nuclear Information System (INIS)

    Hagel, C.; Fleissner, A.; Seifert, R.

    1989-01-01

    A radiochemical microassay for soluble and membrane-bound glutamate decarboxylase (GAD) is described. Up to 180 samples can be determined per day with a variation coefficient of 2%. The method detects newly synthesized gamma-amino-n-butyric acid in the picomole range and can easily be applied to other enzymes whose substrate and product differ by charge. In an aqueous homogenate of brain (1 + 10; w/v) about 15% of the total GAD activity are spun down by centrifugation (1 h, 100,000g) increasing to 35% of the total GAD activity in solutions with 8 mM calcium chloride or 100 mM potassium acetate. There is similar dependence on the cation concentration when GAD binds to phospholipid vesicles (liposomes) as well as dependence on lipid concentration and lipid composition. The coenzyme pyridoxal 5'-phosphate has no influence on GAD binding to liposomes

  4. Silica based composite membranes for methanol fuel cells operating at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, A.; Guzman, C.; Peza-Ledesma, C.; Godinez, Luis A.; Nava, R.; Duron-Torres, S.M.; Ledesma-Garcia, J.; Arriaga, L.G.

    2011-01-15

    Direct methanol fuel cells (DMFCs) are seen as an alternative energy source for several applications, particularly portable power sources. Nafion membranes constitute a well known proton exchange system for DMFC systems due to their convenient electrochemical, mechanical and thermal stability and high proton conductivity properties. But there are problems currently associated with the direct methanol fuel cell technology. Intensive efforts to decrease the methanol crossover are focused mainly on the development of new polymer electrolyte membranes. In this study, Nafion polymer was modified by means of the incorporation of inorganic oxides with different structural properties (SBA-15 and SiO2), both prepared by sol-gel method in order to increase the proton conductivity at high temperature of fuel cell and to contribute decrementing the methanol crossover effect. Composite membranes based in inorganic fillers showed a significant decrease in the concentration of methanol permeation.

  5. Synthesis and performance of antifouling and self-cleaning polyethersulfone/graphene oxide composite membrane functionalized with photoactive semiconductor catalyst.

    Science.gov (United States)

    Dizge, Nadir; Gonuldas, Hakan; Ozay, Yasin; Ates, Hasan; Ocakoglu, Kasim; Harputlu, Ersan; Yildirimcan, Saadet; Unyayar, Ali

    2017-02-01

    This study was performed to synthesize membranes of polyethersulfone (PES) blended with graphene oxide (GO) and PES blended with GO functionalized with photoactive semiconductor catalyst (TiO 2 and ZnO). The antifouling and self-cleaning properties of composite membranes were also investigated. The GO was prepared from natural graphite powder by oxidation method at low temperature. TiO 2 and ZnO nanopowders were synthesized by anhydrous sol-gel method. The surface of TiO 2 and ZnO nanopowders was modified by a surfactant (myristic acid) to obtain a homogeneously dispersed mixture in a solvent, and then GO was functionalized by loading with these metal oxide nanopowders. The PES membranes blended with GO and functionalized GO into the casting solution were prepared via phase inversion method and tested for their antifouling as well as self-cleaning properties. The composite membranes were synthesized as 14%wt. of PES polymer with three different concentrations (0.5, 1.0, and 2.0%wt.) of GO, GO-TiO 2 , and GO-ZnO. The functionalization of membranes improved hydrophilicity property of membranes as compared to neat PES membrane. However, the lowest flux was obtained by functionalized membranes with GO-TiO 2 . The results showed that functionalized membranes demonstrated better self-cleaning property than neat PES membrane. Moreover, the flux recovery rate of functionalized membranes over five cycles was higher than that of neat membrane.

  6. Synthesis of a composite inorganic membrane for the separation of nitrogen, tetrafluoromethane and hexafluoropropylene

    Directory of Open Access Journals (Sweden)

    Hertzog Bissett

    2013-09-01

    Full Text Available The advanced use of inorganic membranes, such as zeolites, in large-scale industrial processes is hindered by the inability to manufacture continuous and defect-free membranes. We therefore aimed to construct such a defect-free membrane. Various zeolites were synthesised on the inner surface of ?-alumina support tubes by a hydrothermal process. Gas permeation properties were investigated at 298 K for single component systems of N2, CF4 and C3F6. Ideal selectivities lower than Knudsen selectivities were obtained as a result of defects from intercrystalline slits and crack formation during synthesis and template removal. A composite ceramic membrane consisting of a ceramic support structure, a mordenite framework inverted intermediate zeolite layer and a Teflon AF 2400 top layer was developed to improve separation. The Teflon layer sealed possible defects present in the separation layer forcing the gas molecules to follow the path through the zeolite pores. Ideal selectivities of 88 and 71 were obtained for N2/CF4 and N2/C3F6 respectively. Adsorption experiments performed on materials present in the membrane structure suggested that although adsorption of C3F6 onto Teflon AF 2400 compared to CF4 results in a considerable contribution to permeation for the composite ceramic membrane, the sealing effect of the zeolite layer by the Teflon layer is the reason for the large N2/CF4 and N2/C3F6 selectivities obtained. The Teflon layer effectively sealed intercrystalline areas in-between zeolite crystals, which resulted in high ideal selectivies for N2/CF4 and N2/C3F6.

  7. Effect of sweet grass (Hierochloe odorata) on the physico-chemical properties of liver cell membranes from rats intoxicated with ethanol.

    Science.gov (United States)

    Dobrzyńska, Izabela; Szachowicz-Petelska, Barbara; Skrzydlewska, Elżbieta; Figaszewski, Zbigniew

    2013-03-01

    Changes in the composition and physicochemical properties of liver cell membranes due to ethanol intoxication are due mainly to reactive oxygen species (ROS). The destructive action of free radicals can be neutralized by administration of antioxidants. The purpose of this study was to investigate the efficacy of sweet grass on the physicochemical and biochemical properties of the rat liver membrane altered by chronic ethanol intoxication. Qualitative and quantitative composition of phospholipids and proteins in the membrane were determined by HPLC. Ethanol increased phospholipid levels and altered the level of integral proteins as determined by decreased phenylalanine, cysteine and lysine. Ethanol significantly enhanced changes in the surface charge density of the liver cell membranes as determined by electrophoresis. Administration of sweet grass to rats intoxicated with ethanol significantly protects lipids and proteins against oxidative modifications. Therefore, sweet grass protects against some of the deleterious membrane changes associated with ethanol exposure. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Uncoupling proteins 2 and 3 alter mitochondrial membrane ...

    African Journals Online (AJOL)

    Saccharomyces cerevisiae). Total phospholipids were extracted and their fatty acyl composition was analysed. Expression of hUCP2 and hUCP3 significantly altered the mitochondrial phospholipid fatty acyl composition. Palmitoleoyl groups (16:1(n-7)) ...

  9. Nafion/ZrSPP composite membrane for high temperature operation of PEMFCs

    International Nuclear Information System (INIS)

    Kim, Young-Taek; Song, Min-Kyu; Kim, Ki-Hyun; Park, Seung-Bae; Min, Sung-Kyu; Rhee, Hee-Woo

    2004-01-01

    Nafion/zirconium sulphophenyl phosphate (ZrSPP) composite membranes were prepared to maintain proton conductivity at elevated temperatures. ZrSPP was precipitated by the reaction of Zr 4+ ion and m-sulphophenyl phosphonic (SPP) acid with a stoichiometric ratio P/Zr = 2. The synthesis of ZrSPP was confirmed by phosphonate (P-O) stretching band, assigned at 900-1300 cm -1 in FTIR spectra. The sharp diffraction pattern at 2θ = 5 deg. indicated crystalline α-layered structure of ZrSPP. The proton conductivity of Nafion/ZrSPP (12.5 wt.%) composite membrane reached ca. 0.07 S/cm at 140 deg. C without extra humidification

  10. Effect of reaction conditions on film morphology of polyaniline composite membranes for gas separation

    KAUST Repository

    Blinova, Natalia V.

    2012-04-21

    Composite membranes combining polyaniline as an active layer with a polypropylene support have been prepared using an in situ deposition technique. The protonated polyaniline layer with a thickness in the range of 90-200 nm was prepared using precipitation, dispersion, or emulsion polymerization of aniline with simultaneous deposition on top of the porous polypropylene support, which was immersed in the reaction mixture. Variables such as temperature, concentration of reagents, presence of steric stabilizers, surfactants, and heteropolyacid were found to control both the formation and the quality of the polyaniline layers. Both morphology and thickness of the layers were characterized using scanning electron microscopy. Selective separation of carbon dioxide from its mixture with methane is used to illustrate potential application of these composite membranes. © 2012 Wiley Periodicals, Inc.

  11. Spectroscopic study on the in vitro degradation of a biodegradable composite periodontal membrane

    Science.gov (United States)

    Taddei, P.; Simoni, R.; Fini, G.

    2001-05-01

    The hydrolithic in vitro degradation of a commercial biodegradable hydroxyapatite (HA)-polymer (poly(ɛ-caprolactone)-poly(oxyethylene)-poly(ɛ-caprolactone) block copolymer, PCL-POE-PCL) composite membrane was investigated by Raman and IR spectroscopies in three aqueous media at 37°C; 0.01 M NaOH solution, saline phosphate buffer (SPB) at pH 7.4 and simulated body fluid (SBF) buffered at pH 7.5. The vibrational results showed that the polymeric component undergoes preferential degradation of POE blocks while HA is removed by the degradation media faster than the polymer. Vibrational spectroscopy appeared to be a valid non-destructive method for investigating the degradation mechanism of the composite membrane.

  12. Glass microporous fiber/nanoporous polytetrafluoroethene composite membranes for high efficient phosphoric acid fuel cell

    International Nuclear Information System (INIS)

    Lu, Chia-Lien; Lee, Wei-Jia; Tseng, Fan-Gang; Chang, Cheng-Ping

    2014-01-01

    This paper reports a high efficient phosphoric acid fuel cell by employing a micro/nano composite proton exchange membrane incorporating glass microfiber (GMF) sealed by polytetrafluoroethylene (PTFE) nano-porous film. This multilayer membrane not only possesses both thermal and chemical stability at phosphoric acid fuel cell working temperature at 150∼220°C but also is cost effective. As a result, the inclusion of the high porosity and proton conductivity from glass microfiber and the prevention of phosphoric acid leakage from PTEF nano film can be achieved at the same time.The composite membrane maximum proton conductivity achieves 0.71 S/cm at 150 °C from AC impedance analysis, much higher than common phosphoric acid porous membranes For single cell test, The GMF fuel cell provides a 63.6mW/cm2 power density at 200mA/cm2 current density while GMF plus methanol treated PTFE (GMF+mPTFE) provides 59.2mW/cm2 power density at 160mA/cm2 current density for hydrogen and oxygen supply at 150 °C. When we change the electrodes that are more suited for phosphoric acid fuel cell, the GMF+mPTFE single cell gets higher performance which achieve 296mW/cm2 power density at 900mA/cm2 current density for hydrogen and oxygen supply at 150 °C

  13. Deoxygenation Affects Composition of Membrane-Bound Proteins in Human Erythrocytes

    Directory of Open Access Journals (Sweden)

    Oksana G. Luneva

    2016-06-01

    Full Text Available Background/Aims: ATP release from erythrocyte plays a key role in hypoxia-induced elevation of blood flow in systematic circulation. We have previously shown that hemolysis contributes to erythrocyte ATP release triggered by several stimuli, including hypoxia, but the molecular mechanisms of hypoxia-increased membrane fragility remain unknown. Methods: In this study, we compared the action of hypoxia on hemolysis, ATP release and the composition of membrane-bound proteins in human erythrocytes. Results: Twenty minutes incubation of human erythrocytes in the oxygen-free environment increased the content of extracellular hemoglobin by ∼1.5 fold. Paired measurements of hemoglobin and ATP content in the same samples, showed a positive correlation between hemolysis and ATP release. Comparative analysis of SDS-PAGE electrophoresis of erythrocyte ghosts obtained under control and deoxygenated conditions revealed a ∼2-fold elevation of the content of membrane-bound protein with Mr of ∼60 kDa. Conclusion: Deoxygenation of human erythrocytes affects composition of membrane-bound proteins. Additional experiments should be performed to identify the molecular origin of 60 kDa protein and its role in the attenuation of erythrocyte integrity and ATP release in hypoxic conditions.

  14. Effects of aging and dietary n-3 fatty acids on rat brain phospholipids: focus on plasmalogens.

    Science.gov (United States)

    André, A; Juanéda, P; Sébédio, J L; Chardigny, J M

    2005-08-01

    The aging brain undergoes modifications in the lipid composition of cell membranes and especially in plasmalogens. These phospholipids represent between one-half and two-thirds of the ethanolamine phospholipids in the brain. They are known to facilitate membrane fusion and act as endogenous antioxidants. During normal aging and in some pathological conditions, plasmalogen and DHA levels fall. In this context, we aimed to evaluate the influence of n-3 FA intake on plasmalogens in the brain during aging. Littermates from two generations of n-3-deficient rats were fed an n-3-deficient diet or an equilibrated diet containing either alpha-linolenic acid alone (alpha-LNA) or with two doses of DHA (0.3 or 0.6% w/w). After weaning, 9 mon of diet, or 21 mon of diet, plasmalogen levels were assessed, and the sn-2 substitutions of plasmenylethanolamines were analyzed in the cortex, striatum, and hippocampus. Our results showed that plasmalogen contents were not influenced by the diet. Plasmalogen levels were significantly decreased in aged rats compared with adults, whereas DHA levels increased in the hippocampus and remained stable in the cortex and striatum. DHA levels were significantly and similarly increased in total phospholipids and especially in plasmenylethanolamines after 9 mon of diet containing alpha-LNA alone or combined with DHA. This study showed that each structure sustained specific age-induced modifications. Dietary n-3 FA may not oppose the physiological decrease in brain plasmalogen levels during aging. Moreover, alpha-LNA appears to be equally as potent as preformed DHA at replacing DHA in the brain of our rat model.

  15. Mordenite/Nafion and analcime/Nafion composite membranes prepared by spray method for improved direct methanol fuel cell performance

    Science.gov (United States)

    Prapainainar, Paweena; Du, Zehui; Kongkachuichay, Paisan; Holmes, Stuart M.; Prapainainar, Chaiwat

    2017-11-01

    The aim of this work was to improve proton exchange membranes (PEMs) used in direct methanol fuel cells (DMFCs). A membrane with a high proton conductivity and low methanol permeability was required. Zeolite filler in Nafion (NF matrix) composite membranes were prepared using two types of zeolite, mordenite (MOR) and analcime (ANA). Spray method was used to prepare the composite membranes, and properties of the membranes were investigated: mechanical properties, solubility, water and methanol uptake, ion-exchange capacity (IEC), proton conductivity, methanol permeability, and DMFC performance. It was found that MOR filler showed higher performance than ANA. The MOR/Nafion composite membrane gave better properties than ANA/Nafion composite membrane, including a higher proton conductivity and a methanol permeability that was 2-3 times lower. The highest DMFC performance (10.75 mW cm-2) was obtained at 70 °C and with 2 M methanol, with a value 1.5 times higher than that of ANA/Nafion composite membrane and two times higher than that of commercial Nafion 117 (NF 117).

  16. Sonication-induced Ostwald ripening of ZIF-8 nanoparticles and formation of ZIF-8/polymer composite membranes

    KAUST Repository

    Thompson, Joshua A.

    2012-08-01

    The effect of typical membrane processing conditions on the structure, interfacial morphology, and gas separation performance of MOF/polymer nanocomposite membranes is investigated. In particular, the ZIF-8/Matrimid® nanocomposite membrane system is examined, and it is shown that ultrasonication - a commonly employed particle dispersion method - induces significant changes in the shape, size distribution, and structure of ZIF-8 particles suspended in an organic solvent during membrane processing. Dynamic light scattering and electron microscopy reveal that ZIF-8 nanoparticles undergo substantial Ostwald ripening when subjected to high intensity ultrasonication as often required in the formation of MOF/polymer nanocomposite membranes. Other characterization techniques reveal that the ripened particles exhibit lower pore volumes and lower surface areas compared to the as-made material. ZIF-8/Matrimid® composite membranes fabricated using two sonication methods show significant differences in microstructure. Permeation measurements show significant enhancement in permeability of CO 2 and increased CO 2/CH 4 selectivity in membranes fabricated with high-intensity sonication. In contrast, composite membranes prepared with low-intensity sonication are found to be defective. A careful evaluation of MOF membrane processing conditions, as well as knowledge of the properties of the MOF material after these membrane processing steps, are necessary to develop reliable processing-structure-property relations for MOF-containing membranes. © 2012 Elsevier Inc. All rights reserved.

  17. Possible mechanism of adhesion in a mica supported phospholipid bilayer

    International Nuclear Information System (INIS)

    Pertsin, Alexander; Grunze, Michael

    2014-01-01

    Phospholipid bilayers supported on hydrophilic solids like silica and mica play a substantial role in fundamental studies and technological applications of phospholipid membranes. In both cases the molecular mechanism of adhesion between the bilayer and the support is of primary interest. Since the possibilities of experimental methods in this specific area are rather limited, the methods of computer simulation acquire great importance. In this paper we use the grand canonical Monte Carlo technique and an atomistic force field to simulate the behavior of a mica supported phospholipid bilayer in pure water as a function of the distance between the bilayer and the support. The simulation reveals a possible adhesion mechanism, where the adhesion is due to individual lipid molecules that protrude from the bilayer and form widely spaced links with the support. Simultaneously, the bilayer remains separated from the bilayer by a thin water interlayer which maintains the bilayer fluidity

  18. Role of Membrane Lipid Fatty Acids in Sperm Cryopreservation

    Directory of Open Access Journals (Sweden)

    Rajes Mandal

    2014-01-01

    Full Text Available Lipid is an important constituent of cell membrane. Membrane lipid composition of spermatozoa has been correlated to different function. Many researchers have related membrane lipid with survival success after cryopreservation or cold shock. Sperm maturation and acrosome reactions are natural phenomenon, but cryopreservation or cold shock is not. Therefore, sperm cells are not programmed for such change and undergo stress. So the change in membrane lipid composition due to cold shock or cryopreservation may be looked upon as response of spermatozoa to a certain stressed condition. A significant body of research worked on the relationship between membrane lipid and fatty acid composition and ability of cell to tolerate adverse change in temperature. However, as the approach of different research groups was different, it is very difficult to compare the changes. Studies have been done with different species, ejaculated/seminal or epididymal sperm. Lipid analyses have been done with whole cell membrane isolated by different methods. Fatty acids estimated were from whole cell, plasma membrane, head membrane, or phospholipids. The cryopreservation condition, media composition, and diluents/cryoprotectants were also different. At this onset a comprehensive review is needed to cover changes of sperm membrane lipid composition of different species under different cryopreservation conditions.

  19. Fe0.4Ta0.5P2O7-based composite membrane for high-temperature, low-humidity proton exchange membrane fuel cells

    International Nuclear Information System (INIS)

    Heo, Pilwon; Shen, Yanbai; Kojima, Keijiro; Pak, Chanho; Choi, Kyoung Hwan; Hibino, Takashi

    2014-01-01

    Highlights: • Fe 0.4 Ta 0.5 P 2 O 7 based composite membranes were prepared with a satisfactory mechanical strength. • It showed high proton conductivity of 0.01 S cm −1 at 150 °C in an unhumidified condition. • The membrane (t > 50 μm) has a gas-impermeability and low area-specific resistance (ASR). • The ASR is 0.17 Ω cm 2 at high temperature of 150 °C and low humidity of 6.6%RH. - Abstract: An inorganic–organic composite membrane composed of Fe 0.4 Ta 0.5 P 2 O 7 (FTPO) and sulfonated polystyrene-b-poly(ethylene/butylene)-b-polystyrene (sSEBS) is prepared and characterized. To gain satisfaction of both the proton conductivity and mechanical strength in composite membranes, the optimal content of sSEBS was determined to be 30 wt%, which resulted in high proton conductivities of approximately 0.01 S cm −1 between 50 and 150 °C even under an unhumidified condition, a tensile strength of 4.1 MPa, and an elongation at break of 613%. A homogeneous distribution of the FTPO particles in the matrix was achieved at the composite membrane thickness greater than 50 μm, providing gas-impermeability and low area-specific resistance (ASR) of the membrane (0.17 Ω cm 2 at 150 °C and H 2 O vapor concentration of 30.8 vol%). Fuel cell tests using the composite membrane provided peak power densities of 265 and 303 mW cm −2 at 150 °C under an unhumidified condition and at a H 2 O vapor concentration of 30.8 vol%, respectively

  20. Bench Scale Thin Film Composite Hollow Fiber Membranes for Post-Combustion Carbon Dioxide Capture

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Paul [General Electric Global Research, Niskayuna, NY (United States); Bhandari, Dhaval [General Electric Global Research, Niskayuna, NY (United States); Narang, Kristi [General Electric Global Research, Niskayuna, NY (United States); McCloskey, Pat [General Electric Global Research, Niskayuna, NY (United States); Singh, Surinder [General Electric Global Research, Niskayuna, NY (United States); Ananthasayanam, Balajee [General Electric Global Research, Niskayuna, NY (United States); Howson, Paul [General Electric Global Research, Niskayuna, NY (United States); Lee, Julia [General Electric Global Research, Niskayuna, NY (United States); Wroczynski, Ron [General Electric Global Research, Niskayuna, NY (United States); Stewart, Frederick [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Christopher [Idaho National Lab. (INL), Idaho Falls, ID (United States); Klaehn, John [Idaho National Lab. (INL), Idaho Falls, ID (United States); McNally, Joshua [Idaho National Lab. (INL), Idaho Falls, ID (United States); Rownaghi, Ali [Georgia Inst. of Technology, Atlanta, GA (United States); Lu, Liu [Georgia Inst. of Technology, Atlanta, GA (United States); Koros, William [Georgia Inst. of Technology, Atlanta, GA (United States); Goizueta, Roberto [Georgia Inst. of Technology, Atlanta, GA (United States); Sethi, Vijay [Western Research Inst., Laramie, WY (United States)

    2015-04-01

    GE Global Research, Idaho National Laboratory (INL), Georgia Institute of Technology (Georgia Tech), and Western Research Institute (WRI) proposed to develop high performance thin film polymer composite hollow fiber membranes and advanced processes for economical post-combustion carbon dioxide (CO2) capture from pulverized coal flue gas at temperatures typical of existing flue gas cleanup processes. The project sought to develop and then optimize new gas separations membrane systems at the bench scale, including tuning the properties of a novel polyphosphazene polymer in a coating solution and fabricating highly engineered porous hollow fiber supports. The project also sought to define the processes needed to coat the fiber support to manufacture composite hollow fiber membranes with high performance, ultra-thin separation layers. Physical, chemical, and mechanical stability of the materials (individual and composite) towards coal flue gas components was considered via exposure and performance tests. Preliminary design, technoeconomic, and economic feasibility analyses were conducted to evaluate the overall performance and impact of the process on the cost of electricity (COE) for a coal-fired plant including capture technologies. At the onset of the project, Membranes based on coupling a novel selective material polyphosphazene with an engineered hollow fiber support was found to have the potential to capture greater than 90% of the CO2 in flue gas with less than 35% increase in COE, which would achieve the DOE-targeted performance criteria. While lab-scale results for the polyphosphazene materials were very promising, and the material was incorporated into hollow-fiber modules, difficulties were encountered relating to the performance of these membrane systems over time. Performance, as measured by both flux of and selectivity for CO2 over other flue gas constituents was found to deteriorate over time, suggesting a system that was

  1. Fish oil increases mitochondrial phospholipid unsaturation, upregulating reactive oxygen species and apoptosis in rat colonocytes

    Science.gov (United States)

    Hong, Mee Young; Chapkin, Robert S.; Barhoumi, Rola; Burghardt, Robert C.; Turner, Nancy D.; Henderson, Cara E.; Sanders, Lisa M.; Fan, Yang-Yi; Davidson, Laurie A.; Murphy, Mary E.; hide

    2002-01-01

    We have shown that a combination of fish oil (high in n-3 fatty acids) with the butyrate-producing fiber pectin, upregulates apoptosis in colon cells exposed to the carcinogen azoxymethane, protecting against colon tumor development. We now hypothesize that n-3 fatty acids prime the colonocytes such that butyrate can initiate apoptosis. To test this, 30 Sprague-Dawley rats were provided with diets differing in the fatty acid composition (corn oil, fish oil or a purified fatty acid ethyl ester diet). Intact colon crypts were exposed ex vivo to butyrate, and analyzed for reactive oxygen species (ROS), mitochondrial membrane potential (MMP), translocation of cytochrome C to the cytosol, and caspase-3 activity (early events in apoptosis). The fatty acid composition of the three major mitochondrial phospholipids was also determined, and an unsaturation index calculated. The unsaturation index in cardiolipin was correlated with ROS levels (R = 0.99; P = 0.02). When colon crypts from fish oil and FAEE-fed rats were exposed to butyrate, MMP decreased (P = 0.041); and translocation of cytochrome C to the cytosol (P = 0.037) and caspase-3 activation increased (P = 0.032). The data suggest that fish oil may prime the colonocytes for butyrate-induced apoptosis by enhancing the unsaturation of mitochondrial phospholipids, especially cardiolipin, resulting in an increase in ROS and initiating apoptotic cascade.

  2. Collagen-chitosan-glycerol bio-composite as artificial tympanic membrane for ruptured inner ear organ

    Science.gov (United States)

    Widiyanti, Prihartini; Setya Angtika, Rara; Githanadi, Brillyana; Hanif Kharisma, Ditya; Asyraf, Tarikh Omar; Wardani, Adita

    2017-05-01

    WHO data in 2012 shows that 5.3% of world population highly suffers from hearing loss and deafness. One of the deafness causes is rupture of tympanic membrane. Tympanic membrane damage which occurs often is perforated tympanic membrane, and it is also commonly known in medical term as tympanic membrane perforation. The causes, for instance, are high frequency of using earphones, traumatic accidents, noise, bacteria, viruses, and infectious microorganism. Tympanoplasty becomes the only treatment that can be widely accepted despite of deficiencies in postoperative complications. Therefore, this research aims to create artificial tympanic membrane made of natural materials such as type I collagen composited with chitosan and made of addition of glycerol to improve its mechanical strength and biodegradability. The method included the process of dissolving acetic acid in distilled water and mixation with chitosan. The solution is next added with glycerol and stirred to be homogeneous. After that, it was minted in petri dish and aerated before characterized. The sample characterization included tensile strength of which tensile test results showed that the value of the elasticity modulus tended to decrease with an increase in collagen concentration. The elasticity modulus values in a row for the variations of 7: 3, 8: 2, and 9: 1 were 35.10 MPa, 54,52MPa, and 47,45MPa respectively. The morphological test with 1000x, 2500x, and 5000x magnification showed their interaction in the formation of pores. Cytotoxicity results, moreover, showed that those samples were non-toxic and safe for the body due to the percentage of living cells. The sound absorption coefficient was between 1000 Hz - 2000 H