The Experts below are selected from a list of 44799 Experts worldwide ranked by ideXlab platform
Bodo Dobner - One of the best experts on this subject based on the ideXlab platform.
-
impact of headgroup asymmetry and protonation state on the Aggregation Behavior of a new type of glycerol diether bolalipid
Langmuir, 2018Co-Authors: Simon Drescher, Annette Meister, Alfred Blume, Christian Otto, Sindy Muller, Vasil M Garamus, Christopher J Garvey, Susanne Grunert, Anke Lischka, Bodo DobnerAbstract:In the present work, we describe the synthesis and the temperature-dependent Aggregation Behavior of a new class of asymmetrical glycerol diether bolalipids. These bolalipids are composed of a membrane-spanning alkyl chain with 32 carbon atoms (C32) in the sn-3 position, a methyl-branched C16 alkyl chain in the sn-2 position, and a zwitterionic phosphocholine headgroup in the sn-1 position of a glycerol moiety. The long C32 alkyl chain is terminated either by a second phosphocholine (PC-Gly(2C16Me)C32-PC) or by a phosphodimethylethanolamine headgroup (PC-Gly(2C16Me)C32-Me2PE). The temperature- and pH-dependent Aggregation Behavior of both lipids was studied using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) experiments. The morphology of the formed aggregates in an aqueous suspension was visualized by transmission electron microscopy (TEM). We show that PC-Gly(2C16Me)C32-PC and PC-Gly...
-
Impact of Headgroup Asymmetry and Protonation State on the Aggregation Behavior of a New Type of Glycerol Diether Bolalipid
2018Co-Authors: Simon Drescher, Annette Meister, Alfred Blume, Christian Otto, Vasil M Garamus, Christopher J Garvey, Anke Lischka, Sindy Müller, Susanne Grünert, Bodo DobnerAbstract:In the present work, we describe the synthesis and the temperature-dependent Aggregation Behavior of a new class of asymmetrical glycerol diether bolalipids. These bolalipids are composed of a membrane-spanning alkyl chain with 32 carbon atoms (C32) in the sn-3 position, a methyl-branched C16 alkyl chain in the sn-2 position, and a zwitterionic phosphocholine headgroup in the sn-1 position of a glycerol moiety. The long C32 alkyl chain is terminated either by a second phosphocholine (PC-Gly(2C16Me)C32-PC) or by a phosphodimethylethanolamine headgroup (PC-Gly(2C16Me)C32-Me2PE). The temperature- and pH-dependent Aggregation Behavior of both lipids was studied using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) experiments. The morphology of the formed aggregates in an aqueous suspension was visualized by transmission electron microscopy (TEM). We show that PC-Gly(2C16Me)C32-PC and PC-Gly(2C16Me)C32-Me2PE at pH 5 self-assemble into large lamellar aggregates and large lipid vesicles. Within these structures, the bolalipid molecules are probably assembled in a monolayer with fully interdigitated chains. The lipid molecules seem to be tilted with respect to the layer normal to ensure a dense packing of the alkyl chains. A temperature increase leads to a transition from a lamellar gel phase to the liquid-crystalline phase at about 28–30 °C for both bolalipids. The lamellar aggregates of PC-Gly(2C16Me)C32-Me2PE started to transform into nanofibers when the pH value of the suspension was increased to above 11. At pH 12, these nanofibers were the dominant aggregates
-
an asymmetrical glycerol diether bolalipid with protonable phosphodimethylethanolamine headgroup the impact of ph on Aggregation Behavior and miscibility with dppc
Polymers, 2017Co-Authors: Thomas Markowski, Annette Meister, Alfred Blume, Bodo Dobner, Sindy Muller, Simon DrescherAbstract:Investigations regarding the self-assembly of (bola)phospholipids in aqueous media are crucial to understand the complex relationship between chemical structure of lipids and the shape and size of their aggregates in water. Here, we introduce a new asymmetrical glycerol diether bolaphospholipid, the compound Me₂PE-Gly(2C16)C32-OH. This bolalipid contains a long (C32) ω-hydroxy alkyl chain bond to glycerol in the sn-3 position, a C16 alkyl chain at the sn-2 position, and a protonable phosphodimethylethanolamine (Me₂PE) headgroup at the sn-1 position of the glycerol. The Aggregation Behavior of this bolalipid was studied as a function of temperature and pH using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. We show that this bolalipid aggregates into condensed lamellar sheets in acidic milieu and in large sheet-like aggregates at neutral pH-value. By contrast, at a pH-value of 10, where the Me₂PE headgroup is only partially protonated, small lipid disks with diameter 50⁻100 nm were additionally found. Moreover, the miscibility of this asymmetrical bolalipid with the bilayer-forming phosphatidylcholine DPPC was investigated by means of DSC and TEM. The incorporation of bolalipids into phospholipid membranes could result in stabilized liposomes applicable for drug delivery purposes. We show that mixtures of DPPC and Me₂PE-Gly(2C16)C32-OH form large lamellar aggregates at pH of 5, 7, and 10. However, closed lipid vesicles (liposomes) with an increased thermal stability were not found.
-
highly asymmetrical glycerol diether bolalipids synthesis and temperature dependent Aggregation Behavior
Langmuir, 2015Co-Authors: Thomas Markowski, Simon Drescher, Gunter Forster, Bobdan Lechner, Annette Meister, Alfred Blume, Bodo DobnerAbstract:In the present work, we describe the synthesis and temperature-dependent Aggregation Behavior of two examples of a new class of highly asymmetrical glycerol diether bolaphospholipids. The bolalipids contain a long alkyl chain (C32) bound to glycerol in the sn-3 position, carrying a hydroxyl group at the ω position. The C16 alkyl chain in the sn-2 position either possesses a racemic methyl branch at the 10 position of the short alkyl chain (lipid II) or does not (lipid I). The sn-1 position of the glycerol is linked to a zwitterionic phosphocholine moiety. The temperature-dependent Aggregation Behavior of both bolalipids was studied using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and X-ray scattering. Aggregate structures were visualized by transmission electron microscopy (TEM). We show that both bolalipids self-assemble into large lamellar sheetlike aggregates. Closed lipid vesicles or other aggregate structures such as tubes or nanofibers, as usually found ...
Andres S Martinez - One of the best experts on this subject based on the ideXlab platform.
-
drone Aggregation Behavior in the social wasp vespula germanica hymenoptera vespidae effect of kinship and density
Scientific Reports, 2020Co-Authors: Maite Masciocchi, Barbara Angeletti, Juan C Corley, Andres S MartinezAbstract:Inbreeding can have negative consequences on population viability because of the reduced fitness of the progeny. In general, most species have developed mechanisms to minimize inbreeding such as dispersal and kin avoidance Behavior. In the eusocial Hymenoptera, related individuals typically share a common nest and have relatively short mating periods, this could lead to inbreeding, and because of their single-locus complementary sex determination system, it may generate diploid males that could result in infertile triploid progeny representing a cost for the colony. Vespula germanica, is an eusocial wasp that has invaded many parts of the world, despite likely facing a reduced genetic pool during the arrival phases. We ask whether male wasp display specific Aggregation Behavior that favors genetic diversity, key to reduce inbreeding. Through a set of laboratory experiments, we investigated the effects of drone nestmateship and density on the Aggregation Behavior of V. germanica drones. We show that drones avoid aggregating with their nestmates at all densities while non-nestmates are avoided only at high densities. This suggests that lek genetic diversity and density could be regulated through drone Behavior and in the long run minimize inbreeding favoring invasion success.
Juan C Corley - One of the best experts on this subject based on the ideXlab platform.
-
drone Aggregation Behavior in the social wasp vespula germanica hymenoptera vespidae effect of kinship and density
Scientific Reports, 2020Co-Authors: Maite Masciocchi, Barbara Angeletti, Juan C Corley, Andres S MartinezAbstract:Inbreeding can have negative consequences on population viability because of the reduced fitness of the progeny. In general, most species have developed mechanisms to minimize inbreeding such as dispersal and kin avoidance Behavior. In the eusocial Hymenoptera, related individuals typically share a common nest and have relatively short mating periods, this could lead to inbreeding, and because of their single-locus complementary sex determination system, it may generate diploid males that could result in infertile triploid progeny representing a cost for the colony. Vespula germanica, is an eusocial wasp that has invaded many parts of the world, despite likely facing a reduced genetic pool during the arrival phases. We ask whether male wasp display specific Aggregation Behavior that favors genetic diversity, key to reduce inbreeding. Through a set of laboratory experiments, we investigated the effects of drone nestmateship and density on the Aggregation Behavior of V. germanica drones. We show that drones avoid aggregating with their nestmates at all densities while non-nestmates are avoided only at high densities. This suggests that lek genetic diversity and density could be regulated through drone Behavior and in the long run minimize inbreeding favoring invasion success.
Simon Drescher - One of the best experts on this subject based on the ideXlab platform.
-
impact of headgroup asymmetry and protonation state on the Aggregation Behavior of a new type of glycerol diether bolalipid
Langmuir, 2018Co-Authors: Simon Drescher, Annette Meister, Alfred Blume, Christian Otto, Sindy Muller, Vasil M Garamus, Christopher J Garvey, Susanne Grunert, Anke Lischka, Bodo DobnerAbstract:In the present work, we describe the synthesis and the temperature-dependent Aggregation Behavior of a new class of asymmetrical glycerol diether bolalipids. These bolalipids are composed of a membrane-spanning alkyl chain with 32 carbon atoms (C32) in the sn-3 position, a methyl-branched C16 alkyl chain in the sn-2 position, and a zwitterionic phosphocholine headgroup in the sn-1 position of a glycerol moiety. The long C32 alkyl chain is terminated either by a second phosphocholine (PC-Gly(2C16Me)C32-PC) or by a phosphodimethylethanolamine headgroup (PC-Gly(2C16Me)C32-Me2PE). The temperature- and pH-dependent Aggregation Behavior of both lipids was studied using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) experiments. The morphology of the formed aggregates in an aqueous suspension was visualized by transmission electron microscopy (TEM). We show that PC-Gly(2C16Me)C32-PC and PC-Gly...
-
Impact of Headgroup Asymmetry and Protonation State on the Aggregation Behavior of a New Type of Glycerol Diether Bolalipid
2018Co-Authors: Simon Drescher, Annette Meister, Alfred Blume, Christian Otto, Vasil M Garamus, Christopher J Garvey, Anke Lischka, Sindy Müller, Susanne Grünert, Bodo DobnerAbstract:In the present work, we describe the synthesis and the temperature-dependent Aggregation Behavior of a new class of asymmetrical glycerol diether bolalipids. These bolalipids are composed of a membrane-spanning alkyl chain with 32 carbon atoms (C32) in the sn-3 position, a methyl-branched C16 alkyl chain in the sn-2 position, and a zwitterionic phosphocholine headgroup in the sn-1 position of a glycerol moiety. The long C32 alkyl chain is terminated either by a second phosphocholine (PC-Gly(2C16Me)C32-PC) or by a phosphodimethylethanolamine headgroup (PC-Gly(2C16Me)C32-Me2PE). The temperature- and pH-dependent Aggregation Behavior of both lipids was studied using differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, small-angle X-ray scattering (SAXS), and small-angle neutron scattering (SANS) experiments. The morphology of the formed aggregates in an aqueous suspension was visualized by transmission electron microscopy (TEM). We show that PC-Gly(2C16Me)C32-PC and PC-Gly(2C16Me)C32-Me2PE at pH 5 self-assemble into large lamellar aggregates and large lipid vesicles. Within these structures, the bolalipid molecules are probably assembled in a monolayer with fully interdigitated chains. The lipid molecules seem to be tilted with respect to the layer normal to ensure a dense packing of the alkyl chains. A temperature increase leads to a transition from a lamellar gel phase to the liquid-crystalline phase at about 28–30 °C for both bolalipids. The lamellar aggregates of PC-Gly(2C16Me)C32-Me2PE started to transform into nanofibers when the pH value of the suspension was increased to above 11. At pH 12, these nanofibers were the dominant aggregates
-
an asymmetrical glycerol diether bolalipid with protonable phosphodimethylethanolamine headgroup the impact of ph on Aggregation Behavior and miscibility with dppc
Polymers, 2017Co-Authors: Thomas Markowski, Annette Meister, Alfred Blume, Bodo Dobner, Sindy Muller, Simon DrescherAbstract:Investigations regarding the self-assembly of (bola)phospholipids in aqueous media are crucial to understand the complex relationship between chemical structure of lipids and the shape and size of their aggregates in water. Here, we introduce a new asymmetrical glycerol diether bolaphospholipid, the compound Me₂PE-Gly(2C16)C32-OH. This bolalipid contains a long (C32) ω-hydroxy alkyl chain bond to glycerol in the sn-3 position, a C16 alkyl chain at the sn-2 position, and a protonable phosphodimethylethanolamine (Me₂PE) headgroup at the sn-1 position of the glycerol. The Aggregation Behavior of this bolalipid was studied as a function of temperature and pH using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy. We show that this bolalipid aggregates into condensed lamellar sheets in acidic milieu and in large sheet-like aggregates at neutral pH-value. By contrast, at a pH-value of 10, where the Me₂PE headgroup is only partially protonated, small lipid disks with diameter 50⁻100 nm were additionally found. Moreover, the miscibility of this asymmetrical bolalipid with the bilayer-forming phosphatidylcholine DPPC was investigated by means of DSC and TEM. The incorporation of bolalipids into phospholipid membranes could result in stabilized liposomes applicable for drug delivery purposes. We show that mixtures of DPPC and Me₂PE-Gly(2C16)C32-OH form large lamellar aggregates at pH of 5, 7, and 10. However, closed lipid vesicles (liposomes) with an increased thermal stability were not found.
-
highly asymmetrical glycerol diether bolalipids synthesis and temperature dependent Aggregation Behavior
Langmuir, 2015Co-Authors: Thomas Markowski, Simon Drescher, Gunter Forster, Bobdan Lechner, Annette Meister, Alfred Blume, Bodo DobnerAbstract:In the present work, we describe the synthesis and temperature-dependent Aggregation Behavior of two examples of a new class of highly asymmetrical glycerol diether bolaphospholipids. The bolalipids contain a long alkyl chain (C32) bound to glycerol in the sn-3 position, carrying a hydroxyl group at the ω position. The C16 alkyl chain in the sn-2 position either possesses a racemic methyl branch at the 10 position of the short alkyl chain (lipid II) or does not (lipid I). The sn-1 position of the glycerol is linked to a zwitterionic phosphocholine moiety. The temperature-dependent Aggregation Behavior of both bolalipids was studied using differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, and X-ray scattering. Aggregate structures were visualized by transmission electron microscopy (TEM). We show that both bolalipids self-assemble into large lamellar sheetlike aggregates. Closed lipid vesicles or other aggregate structures such as tubes or nanofibers, as usually found ...
Liqiang Zheng - One of the best experts on this subject based on the ideXlab platform.
-
Aggregation Behavior of surface active imidazolium ionic liquids in ethylammonium nitrate effect of alkyl chain length cations and counterions
Journal of Physical Chemistry B, 2012Co-Authors: Liqiang ZhengAbstract:The Aggregation Behavior of surface active imidazolium ionic liquids (ILs) with different alkyl chain length, cations, and counterions, namely, 1-alkyl-3-methylimidazolium bromide ([Cnmim]Br (n = 8, 10, 12)), 1-dodecyl-2,3-dimethylimidazolium bromide ([C12bmim]Br), 1-(2,4,6-trimethylphenyl)-3-dodecylimidazolium bromide ([C12pim]Br), and 1-dodecyl-3-methylimidazolium tetrafluoroborate ([C12mim][BF4]) in a protic room temperature IL, ethylammonium nitrate (EAN), was investigated through surface tension measurements and 1H NMR spectroscopy. Surface tension results show that surface properties and micellization Behavior of surface active ILs in EAN are significantly affected by the structure of the cations, the basicity of counterions, and the hydrophobicity of alkyl chains. A detailed analysis of chemical shifts of various protons of surface active ILs and EAN was employed to investigate the micelle formation mechanism. Hydrogen bonding interaction is found to occur between the protons at C-2 on the imidazol...
-
Aggregation Behavior of long chain n aryl imidazolium bromide in aqueous solution
Langmuir, 2011Co-Authors: Lijuan Shi, Han Yan, Yanan Gao, Liqiang ZhengAbstract:The Aggregation Behavior of three long-chain N-aryl imidazolium ionic liquids (ILs), 1-(2,4,6-trimethylphenyl)-3-alkylimidazolium bromide [C(n)pim]Br (n = 10, 12, and 14), in aqueous solutions was systematically explored by surface tension, electrical conductivity, and (1)H NMR. A lower critical micelle concentration (cmc) for the N-aryl imidazolium ILs is observed compared with that for 1,3-dialkylimidazolium ILs [C(n)mim]Br, indicating that the incorporation of the 2,4,6-trimethylphenyl group into a headgroup favors micellization. The enhanced π-π interactions among the adjacent 2,4,6-trimethylphenyl groups weaken the steric hindrance of headgroups and thus lead to a dense arrangement of [C(n)pim]Br molecules at the air-water interface. An analysis of the (1)H NMR spectra revealed that the introduced 2,4,6-trimethylphenyl group may slightly bend into the hydrophobic regions upon micellization. The micelle formation process for [C(n)pim]Br (n = 10, 12, and 14) was found to be enthalpy-driven in the investigated temperature range, which is attributed to the strong electrostatic self-repulsion of the headgroups and the counterions as well as the π-π interactions among headgroups. Strong, stable fluorescence properties are presented by the new N-aryl imidazolium ILs, indicating their potential application in the field of photochemistry.
-
self Aggregation Behavior of fluorescent carbazole tailed imidazolium ionic liquids in aqueous solutions
Journal of Physical Chemistry B, 2010Co-Authors: Bin Dong, Liqiang Zheng, Yanan Gao, Tohru InoueAbstract:Three amphiphilic imidazolium ionic liquids (ILs), 1-[n-(N-carbazole)alkyl]-3-methylimidazolium bromide [carbazoleC(n)mim]Br (n = 6, 10, and 12), that incorporate a fluorescent carbazole moiety at the terminal of the hydrocarbon chain, were designed and synthesized. Their surface activity, Aggregation Behavior, and thermodynamics of micelle formation in aqueous solutions were systematically investigated by surface tension, electrical conductivity, and (1)H NMR spectroscopy. The incorporation of bulky carbazole groups led to the loose arrangement of [carbazoleC(n)mim]Br molecules at the air-water interface. Both the enhanced hydrophobicity and the pi-pi interaction due to the incorporation of carbazole groups contributed to the lower critical micelle concentration (cmc) and higher micellar Aggregation number, reflecting a strong capability of the designed carbazole-tailed imidazolium ILs for the formation of micelle. The analysis of (1)H NMR spectra revealed that the carbazole moieties may overlap with the middle methylenes of the alkyl chains. The amphiphilic carbazole-tailed imidazolium ILs demonstrated strong and stable fluorescence properties, indicating their potential application in the combined field of surface chemistry and photochemistry.