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Herbert Zimmermann - One of the best experts on this subject based on the ideXlab platform.
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anhydrous Octyl Glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields
Journal of Chemical Physics, 2017Co-Authors: Rauzah Hashim, Akihiko Sugimura, Hockseng Nguan, Matiur Rahman, Herbert ZimmermannAbstract:A static deuterium nuclear magnetic resonance (2HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of Octyl-b-D-Glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the 2H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery t...
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anhydrous Octyl Glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields
Journal of Chemical Physics, 2017Co-Authors: Rauzah Hashim, Akihiko Sugimura, Hockseng Nguan, Matiur Rahman, Herbert ZimmermannAbstract:A static deuterium nuclear magnetic resonance (2HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of Octyl-b-D-Glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the 2H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery to the lamellar phase again with time. Moreover, these phase transformations are accompanied by a transient current. A similar observation was made in a computational study when an electric field was applied to a water cluster system. Increasing the field strength distorts the water cluster and weakens its hydrogen bonds leading to a structural breakdown beyond a threshold field-strength. Therefore, we suggest the observed field-induced transition is likely due to a structure change of the βOG lamellar assembly caused by the field effect and not due to Joule heating.
Richard W Pastor - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics simulations of Octyl Glucoside micelles dynamic properties
Journal of Physical Chemistry B, 2001Co-Authors: Stephen Bogusz, And Richard M Venable, Richard W PastorAbstract:Dynamic properties of Octyl Glucoside (OG) micelles were explored using molecular dynamics simulations. Systems studied included individual β-OG micelles containing 10, 20, 27, 34, 50, and 75 lipids; two 20 lipid β-OG micelles; a disperse solution of 27 β-OG; and four molecules of glucose. Calculated 13C NMR T1 relaxation times for the tail carbons of micelle aggregation numbers between 34 and 75 agreed well with experiment; these results are consistent with estimates of the micelle size based on translational diffusion. However, T1's for the headgroup carbons, which couple strongly with the solvent, were too large. This was primarily due to the low viscosity of the TIP3P water model, and subsequent scaling of the relaxation times led to agreement with experiment for the carbons in the glucose ring, but not the exocyclic carbon; the likely reason for the latter discrepancy is a torsional potential barrier that is slightly too high. A detailed analysis of the micelle dynamics revealed shape changes on the ...
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molecular dynamics simulations of Octyl Glucoside micelles structural properties
Journal of Physical Chemistry B, 2000Co-Authors: Stephen Bogusz, And Richard M Venable, Richard W PastorAbstract:Molecular dynamics simulations were used to explore the effect of aggregate size on structural properties of Octyl Glucoside (OG) micelles. Systems included micelles of 1, 5, 10, 20, 27, 34, 50, and 75 surfactant molecules in water, as well as an OG bilayer, and neat octane. Micelles consisting of 5 lipids were unstable, while those of 10 or more remained intact (except for rare single lipid escapes) during the 4 ns simulations. Aggregate shape and internal properties (tail length, dihedral angle distributions, and isomerization rates) change little with size. In contrast, surface properties (hydrophobic accessible surface area and headgroup cluster size) vary with size, a consequence of the decreasing surface area-to-volume ratio in larger aggregates. Micelles in the studied size range are nonspherical with rough, uneven surfaces. Their tail lengths are comparable to those in the bilayer and neat octane, indicating that packing into a compact highly curved shape does not significantly distort the tails. ...
Rauzah Hashim - One of the best experts on this subject based on the ideXlab platform.
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anhydrous Octyl Glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields
Journal of Chemical Physics, 2017Co-Authors: Rauzah Hashim, Akihiko Sugimura, Hockseng Nguan, Matiur Rahman, Herbert ZimmermannAbstract:A static deuterium nuclear magnetic resonance (2HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of Octyl-b-D-Glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the 2H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery t...
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anhydrous Octyl Glucoside phase transition from lamellar to isotropic induced by electric and magnetic fields
Journal of Chemical Physics, 2017Co-Authors: Rauzah Hashim, Akihiko Sugimura, Hockseng Nguan, Matiur Rahman, Herbert ZimmermannAbstract:A static deuterium nuclear magnetic resonance (2HNMR) technique (magnetic field, B = 7.05 T) was employed to monitor the thermotropic lamellar phase of the anhydrous 1:1 mixture sample of Octyl-b-D-Glucoside (βOG) and that of partially deuterium labelled at the alpha position on the chain, i.e.,βOG-d2 In the absence of an electric field, the 2H NMR spectrum of the mixture gives a typical quadrupolar doublet representing the aligned lamellar phase. Upon heating to beyond the clearing temperature at 112 °C, this splitting converts to a single line expected for an isotropic phase. Simultaneous application of magnetic and electric fields (E = 0.4 MV/m) at 85 °C in the lamellar phase, whose direction was set to be parallel or perpendicular to the magnetic field, resulted in the change of the doublet into a single line and this recovers to the initial doublet with time for both experimental geometries. This implies E- and B-field-induced phase transitions from the lamellar to an isotropic phase and a recovery to the lamellar phase again with time. Moreover, these phase transformations are accompanied by a transient current. A similar observation was made in a computational study when an electric field was applied to a water cluster system. Increasing the field strength distorts the water cluster and weakens its hydrogen bonds leading to a structural breakdown beyond a threshold field-strength. Therefore, we suggest the observed field-induced transition is likely due to a structure change of the βOG lamellar assembly caused by the field effect and not due to Joule heating.
J L Parra - One of the best experts on this subject based on the ideXlab platform.
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liposomes as protective agents of stratum corneum against Octyl Glucoside a study based on high resolution low temperature scanning electron microscopy
Micron, 2001Co-Authors: O Lopez, M Cocera, Paul Walther, Ernst Wehrli, L Coderch, J L Parra, A De La MazaAbstract:Abstract The ability of phosphatidylcholine (PC) liposomes to protect pig stratum corneum (SC) against the action of the nonionic surfactant Octyl Glucoside (OG) was investigated “in vitro” using double-layer coating for high-resolution, low-temperature scanning electron microscopy. This technique has been useful in preventing drying artifacts in the study of biological materials. The treatment of SC with OG led to a perturbation mainly in the corneocytes. However, the incubation of the tissue with liposomes prior to the OG treatment resulted in a progressive decrease in these perturbations and, consequently, in the progressive protection of the SC against the action of the surfactant.
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protective effect caused by the exopolymer excreted by pseudoalteromonas antarctica nf3 on liposomes against the action of Octyl Glucoside
International Journal of Pharmaceutics, 2000Co-Authors: M Cocera, O Lopez, J L Parra, M E Mercade, J Guinea, A De La MazaAbstract:The capacity of the glycoprotein (GP) excreted by Pseudoalteromonas antarctica NF3, to protect phosphatidylcholine (PC) liposomes against the action of Octyl Glucoside (OG) was studied in detail. Increasing amounts of GP assembled with liposomes resulted for the same interaction step in a linear increase in the effective surfactant to PC molar ratios (Re) and in a linear fall in the surfactant partitioning between bilayer and the aqueous phase (partition coefficients K). Thus, the higher the proportion of GP assembled with liposomes the lower the surfactant ability to alter the permeability of vesicles and the lower its affinity with these bilayer structures. In addition, increasing GP proportions resulted in a progressive increase of the free surfactant concentration (SW) needed to produce the same alterations in liposomes. The fact that SW was always lower than the surfactant critical micelle concentration indicates that the interaction was mainly ruled by the action of surfactant monomers, regardless of the amount of assembled GP.
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Octyl Glucoside as a tool to induce structural modifications in the stratum corneum
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2000Co-Authors: O Lopez, M Cocera, Paul Walther, L Coderch, A De La Maza, J L ParraAbstract:Abstract The combined action of the Octyl Glucoside (OG) surfactant at concentrations 10 and 20 mM and ultrasonic stimulation was used to induce structural modifications in the pig stratum corneum (SC). The composition of the disaggregated material and the microstructure of the residual tissue after treatment were studied. This combined treatment mainly removed proteins and small amounts of lipids. The disaggregated components formed complexes via hydrophobic interactions and covalent bonds. The presence in the disaggregated fraction of glutamic acid residues covalently linked to ceramides indicated that the OG affected the corneocyte envelopes. The loss of SC cohesion was associated with the disaggregation of the protein tissue components. This fact underlines the important role played by the corneocyte envelopes in the tissue cohesion. Transmission electron microscopy (TEM) showed that the lamellar lipid structure was only slightly affected by the treatment, despite the strong disruption of the protein domains. TEM image analysis also confirmed that the interlamellar spaces of treated SC were similar to those of the native tissue. High resolution low-temperature scanning electron microscopy corroborated these observations. However, this technique detected alterations of the lipid areas attributed to the interaction of the proteins liberated from the corneocytes and the lipids. These results suggest a tissue disaggregation process in layers, which occurred by disruption of SC into corneocytes, disaggregation of the corneocyte envelopes and preservation of the intercellular lamellae structure.
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use of wide and small angle x ray diffraction to study the modifications in the stratum corneum induced by Octyl Glucoside
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2000Co-Authors: O Lopez, M Cocera, L Coderch, A De La Maza, L Campos, J L ParraAbstract:Abstract The combined action of the Octyl Glucoside (OG) surfactant at concentrations 10 and 20 mM and ultrasonic stimulation was used to induce structural modifications in the pig stratum corneum (SC). The composition of the disaggregated material and the microstructure of the residual tissue after treatment were studied. This combined treatment mainly removed proteins and small amount of lipids. The disaggregated components formed complexes via hydrophobic interactions and covalent bonds. The presence in the disaggregated fraction of glutamic acid residues covalently linked to ceramides indicated that the OG affected the corneocyte envelopes. The correlation between the loss of the tissue cohesion and the disaggregation of the protein components underlines the important role played by the corneocyte envelopes in this cohesion. Wide and small angle X-ray diffraction showed that although the treatment produced a small loss of order in the SC structure arrangement (tissue disaggregation) the lamellar structure of the intercellular lipids remained almost unaffected. This fact sharply contrasts with the fragility of the corneocyte envelopes and the structural proteins against OG. A tissue disaggregation process in layers is proposed, which occurred by disruption of SC into corneocytes, disaggregation of the corneocyte envelopes and preservation of the intercellular lamellar structure.
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ability of the exopolymer excreted by pseudoalteromonas antarctica nf3 to coat liposomes and to protect these structures against Octyl Glucoside
Journal of Biomaterials Science-polymer Edition, 1999Co-Authors: A De La Maza, O Lopez, J L Parra, L Codech, M Sabes, J GuineaAbstract:The ability of an exopolymer of glycoproteic character (GP) excreted by a new gram-negative specie Pseudoalteromonas antarctica NF3, to coat phosphatidylcholine (PC) liposomes and to protect these bilayers against the action of the nonionic surfactant Octyl Glucoside (OG) has been investigated. TEM micrographs of freeze-fractured liposome/GP aggregates reveal that the addition of GP to liposomes led to the formation of a covering structure (polymer adsorbed onto the bilayers) that tightly coated PC bilayers. The complete coating was already achieved when the proportion of GP assembled with liposomes was approximately 10% (wt% vs total PC). Higher GP amounts resulted in a growth of this coating structure which exhibited at the highest GP proportion in the system (31 % of assembled GP) a multilayered structure. An increasing resistance of PC liposomes to be affected by OG both at sublytic and lytic levels occurred as the proportion of GP in the system rose; this protective effect being more effective when t...
A De La Maza - One of the best experts on this subject based on the ideXlab platform.
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liposomes as protective agents of stratum corneum against Octyl Glucoside a study based on high resolution low temperature scanning electron microscopy
Micron, 2001Co-Authors: O Lopez, M Cocera, Paul Walther, Ernst Wehrli, L Coderch, J L Parra, A De La MazaAbstract:Abstract The ability of phosphatidylcholine (PC) liposomes to protect pig stratum corneum (SC) against the action of the nonionic surfactant Octyl Glucoside (OG) was investigated “in vitro” using double-layer coating for high-resolution, low-temperature scanning electron microscopy. This technique has been useful in preventing drying artifacts in the study of biological materials. The treatment of SC with OG led to a perturbation mainly in the corneocytes. However, the incubation of the tissue with liposomes prior to the OG treatment resulted in a progressive decrease in these perturbations and, consequently, in the progressive protection of the SC against the action of the surfactant.
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protective effect caused by the exopolymer excreted by pseudoalteromonas antarctica nf3 on liposomes against the action of Octyl Glucoside
International Journal of Pharmaceutics, 2000Co-Authors: M Cocera, O Lopez, J L Parra, M E Mercade, J Guinea, A De La MazaAbstract:The capacity of the glycoprotein (GP) excreted by Pseudoalteromonas antarctica NF3, to protect phosphatidylcholine (PC) liposomes against the action of Octyl Glucoside (OG) was studied in detail. Increasing amounts of GP assembled with liposomes resulted for the same interaction step in a linear increase in the effective surfactant to PC molar ratios (Re) and in a linear fall in the surfactant partitioning between bilayer and the aqueous phase (partition coefficients K). Thus, the higher the proportion of GP assembled with liposomes the lower the surfactant ability to alter the permeability of vesicles and the lower its affinity with these bilayer structures. In addition, increasing GP proportions resulted in a progressive increase of the free surfactant concentration (SW) needed to produce the same alterations in liposomes. The fact that SW was always lower than the surfactant critical micelle concentration indicates that the interaction was mainly ruled by the action of surfactant monomers, regardless of the amount of assembled GP.
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Octyl Glucoside as a tool to induce structural modifications in the stratum corneum
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2000Co-Authors: O Lopez, M Cocera, Paul Walther, L Coderch, A De La Maza, J L ParraAbstract:Abstract The combined action of the Octyl Glucoside (OG) surfactant at concentrations 10 and 20 mM and ultrasonic stimulation was used to induce structural modifications in the pig stratum corneum (SC). The composition of the disaggregated material and the microstructure of the residual tissue after treatment were studied. This combined treatment mainly removed proteins and small amounts of lipids. The disaggregated components formed complexes via hydrophobic interactions and covalent bonds. The presence in the disaggregated fraction of glutamic acid residues covalently linked to ceramides indicated that the OG affected the corneocyte envelopes. The loss of SC cohesion was associated with the disaggregation of the protein tissue components. This fact underlines the important role played by the corneocyte envelopes in the tissue cohesion. Transmission electron microscopy (TEM) showed that the lamellar lipid structure was only slightly affected by the treatment, despite the strong disruption of the protein domains. TEM image analysis also confirmed that the interlamellar spaces of treated SC were similar to those of the native tissue. High resolution low-temperature scanning electron microscopy corroborated these observations. However, this technique detected alterations of the lipid areas attributed to the interaction of the proteins liberated from the corneocytes and the lipids. These results suggest a tissue disaggregation process in layers, which occurred by disruption of SC into corneocytes, disaggregation of the corneocyte envelopes and preservation of the intercellular lamellae structure.
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use of wide and small angle x ray diffraction to study the modifications in the stratum corneum induced by Octyl Glucoside
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2000Co-Authors: O Lopez, M Cocera, L Coderch, A De La Maza, L Campos, J L ParraAbstract:Abstract The combined action of the Octyl Glucoside (OG) surfactant at concentrations 10 and 20 mM and ultrasonic stimulation was used to induce structural modifications in the pig stratum corneum (SC). The composition of the disaggregated material and the microstructure of the residual tissue after treatment were studied. This combined treatment mainly removed proteins and small amount of lipids. The disaggregated components formed complexes via hydrophobic interactions and covalent bonds. The presence in the disaggregated fraction of glutamic acid residues covalently linked to ceramides indicated that the OG affected the corneocyte envelopes. The correlation between the loss of the tissue cohesion and the disaggregation of the protein components underlines the important role played by the corneocyte envelopes in this cohesion. Wide and small angle X-ray diffraction showed that although the treatment produced a small loss of order in the SC structure arrangement (tissue disaggregation) the lamellar structure of the intercellular lipids remained almost unaffected. This fact sharply contrasts with the fragility of the corneocyte envelopes and the structural proteins against OG. A tissue disaggregation process in layers is proposed, which occurred by disruption of SC into corneocytes, disaggregation of the corneocyte envelopes and preservation of the intercellular lamellar structure.
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ability of the exopolymer excreted by pseudoalteromonas antarctica nf3 to coat liposomes and to protect these structures against Octyl Glucoside
Journal of Biomaterials Science-polymer Edition, 1999Co-Authors: A De La Maza, O Lopez, J L Parra, L Codech, M Sabes, J GuineaAbstract:The ability of an exopolymer of glycoproteic character (GP) excreted by a new gram-negative specie Pseudoalteromonas antarctica NF3, to coat phosphatidylcholine (PC) liposomes and to protect these bilayers against the action of the nonionic surfactant Octyl Glucoside (OG) has been investigated. TEM micrographs of freeze-fractured liposome/GP aggregates reveal that the addition of GP to liposomes led to the formation of a covering structure (polymer adsorbed onto the bilayers) that tightly coated PC bilayers. The complete coating was already achieved when the proportion of GP assembled with liposomes was approximately 10% (wt% vs total PC). Higher GP amounts resulted in a growth of this coating structure which exhibited at the highest GP proportion in the system (31 % of assembled GP) a multilayered structure. An increasing resistance of PC liposomes to be affected by OG both at sublytic and lytic levels occurred as the proportion of GP in the system rose; this protective effect being more effective when t...
