The Experts below are selected from a list of 135 Experts worldwide ranked by ideXlab platform

Justas Barauskas - One of the best experts on this subject based on the ideXlab platform.

  • the lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and Glycerol Dioleate by phospholipase a2 and triacylGlycerol lipase
    Chemistry and Physics of Lipids, 2017
    Co-Authors: Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
    Abstract:

    Abstract The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/Glycerol Dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalyses degradation of the phospholipid component, SPC, and porcine pancreatic triacylGlycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO. Evolution of the structure was found to be very different and linked to specificity of the two types of enzymes. PLA2, which hydrolyses the lamellar forming component, SPC, induces a reversed micellar lipid phase, while TGL which hydrolysis the reverse phase forming compound, GDO, induces a lamellar phase.

  • relationship between structure and fluctuations of lipid nonlamellar phases deposited at the solid liquid interface
    Journal of Physical Chemistry B, 2017
    Co-Authors: Tommy Nylander, Maria Wadsater, Justas Barauskas, Olaf Soltwedel, Marina Ganeva, Christopher Hirst, James Holdaway, Marianna Yanez Arteta, Henrich Frielinghaus, Olaf Holderer
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon–aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (HII) and micellar cubic phase (Fd3m) layers at the solid–liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic HII phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HII film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate.

  • Relationship between Structure and Fluctuations of Lipid Nonlamellar Phases Deposited at the Solid–Liquid Interface
    2017
    Co-Authors: Tommy Nylander, Justas Barauskas, Maria Wadsäter, Olaf Soltwedel, Marina Ganeva, Christopher Hirst, James Holdaway, Marianna Yanez Arteta, Henrich Frielinghaus, Olaf Holderer
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon–aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (HII) and micellar cubic phase (Fd3m) layers at the solid–liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic HII phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HII film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate

  • interfacial properties of popc gdo liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces
    Physical Chemistry Chemical Physics, 2016
    Co-Authors: Debby P Chang, Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Aleksandra P Dabkowska, Richard A Campbell, Tommy Nylander
    Abstract:

    Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I2) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules. Their interactions with various interfaces, and the consequences for the particle structure and integrity, are essential considerations in their effectiveness as drug delivery vehicles. Here, we have studied LCNPs formed of equal fractions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and Glycerol Dioleate in the presence of different fractions of the stabilizer Polysorbate 80. We have used a combination of ellipsometry, quartz crystal microbalance with dissipation monitoring and neutron reflectometry to reveal the structure and composition of the adsorbed layer on both anionic silica and cationic (aminopropyltriethoxysilane) silanized surfaces. For both types of surfaces, there is a spread near-surface layer comprising lipid and polymer as well as a sparse coverage of intact particles. The composition of the near-surface layer is very close to that of the particles, in contrast to the lipid bilayer observed with related systems. The interaction is stronger for cationic than anionic surfaces, which is rationalized in terms of the negative zeta potential of the LCNPs. The work shows that the attachment of and spreading from LCNPs is influenced by the properties of the surface, the internal structure, composition and stability of the particles as well as the nature of the stabilizer.

  • structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and Glycerol Dioleate
    Soft Matter, 2015
    Co-Authors: Maria Wadsater, Justas Barauskas, Sarah E Rogers, Fredrik Tiberg, Robert J Thomas, Maximilian W. A. Skoda, Tommy Nylander
    Abstract:

    Well-defined, stable and highly structured I2 (Fdm) liquid crystalline nanoparticles (LCNP) of 50/50 (wt/wt) soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO), can be formed by using a low fraction (5–10 wt%) of the dispersing polymeric surfactant polyoxyethylene (20) sorbitan monooleate (polysorbate 80 or P80). In the present study we used small angle neutron scattering (SANS) and deuterated P80 (d-P80) to determine the location and concentration of P80 within the LCNP and small angle X-ray scattering (SAXS) to reveal the internal structure. SANS data suggests that some d-P80 already penetrates the particle core at 5%. However, the content of d-P80 is still low enough not to significantly change the internal Fdm structure of the LCNP. At higher fractions of P80 a phase separation occurs, in which a SPC and P80 rich phase is formed at the particle surface. The surface layer becomes gradually richer in both solvent and d-P80 when the surfactant concentration is increased from 5 to 15%, while the core of the particle is enriched by GDO, resulting in loss of internal structure and reduced hydration. We have used neutron reflectometry to reveal the location of the stabiliser within the adsorbed layer on an anionic silica and cationic (aminopropyltriethoxysilane (APTES) silanized) surface. d-P80 is enriched closest to the supporting surface and slightly more so for the cationic APTES surface. The results are relevant not only for the capability of LCNPs as drug delivery vehicles but also as means of preparing functional surface coatings.

Tommy Nylander - One of the best experts on this subject based on the ideXlab platform.

  • the lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and Glycerol Dioleate by phospholipase a2 and triacylGlycerol lipase
    Chemistry and Physics of Lipids, 2017
    Co-Authors: Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
    Abstract:

    Abstract The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/Glycerol Dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalyses degradation of the phospholipid component, SPC, and porcine pancreatic triacylGlycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO. Evolution of the structure was found to be very different and linked to specificity of the two types of enzymes. PLA2, which hydrolyses the lamellar forming component, SPC, induces a reversed micellar lipid phase, while TGL which hydrolysis the reverse phase forming compound, GDO, induces a lamellar phase.

  • relationship between structure and fluctuations of lipid nonlamellar phases deposited at the solid liquid interface
    Journal of Physical Chemistry B, 2017
    Co-Authors: Tommy Nylander, Maria Wadsater, Justas Barauskas, Olaf Soltwedel, Marina Ganeva, Christopher Hirst, James Holdaway, Marianna Yanez Arteta, Henrich Frielinghaus, Olaf Holderer
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon–aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (HII) and micellar cubic phase (Fd3m) layers at the solid–liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic HII phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HII film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate.

  • Relationship between Structure and Fluctuations of Lipid Nonlamellar Phases Deposited at the Solid–Liquid Interface
    2017
    Co-Authors: Tommy Nylander, Justas Barauskas, Maria Wadsäter, Olaf Soltwedel, Marina Ganeva, Christopher Hirst, James Holdaway, Marianna Yanez Arteta, Henrich Frielinghaus, Olaf Holderer
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon–aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (HII) and micellar cubic phase (Fd3m) layers at the solid–liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic HII phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HII film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate

  • interfacial properties of popc gdo liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces
    Physical Chemistry Chemical Physics, 2016
    Co-Authors: Debby P Chang, Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Aleksandra P Dabkowska, Richard A Campbell, Tommy Nylander
    Abstract:

    Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I2) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules. Their interactions with various interfaces, and the consequences for the particle structure and integrity, are essential considerations in their effectiveness as drug delivery vehicles. Here, we have studied LCNPs formed of equal fractions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and Glycerol Dioleate in the presence of different fractions of the stabilizer Polysorbate 80. We have used a combination of ellipsometry, quartz crystal microbalance with dissipation monitoring and neutron reflectometry to reveal the structure and composition of the adsorbed layer on both anionic silica and cationic (aminopropyltriethoxysilane) silanized surfaces. For both types of surfaces, there is a spread near-surface layer comprising lipid and polymer as well as a sparse coverage of intact particles. The composition of the near-surface layer is very close to that of the particles, in contrast to the lipid bilayer observed with related systems. The interaction is stronger for cationic than anionic surfaces, which is rationalized in terms of the negative zeta potential of the LCNPs. The work shows that the attachment of and spreading from LCNPs is influenced by the properties of the surface, the internal structure, composition and stability of the particles as well as the nature of the stabilizer.

  • structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and Glycerol Dioleate
    Soft Matter, 2015
    Co-Authors: Maria Wadsater, Justas Barauskas, Sarah E Rogers, Fredrik Tiberg, Robert J Thomas, Maximilian W. A. Skoda, Tommy Nylander
    Abstract:

    Well-defined, stable and highly structured I2 (Fdm) liquid crystalline nanoparticles (LCNP) of 50/50 (wt/wt) soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO), can be formed by using a low fraction (5–10 wt%) of the dispersing polymeric surfactant polyoxyethylene (20) sorbitan monooleate (polysorbate 80 or P80). In the present study we used small angle neutron scattering (SANS) and deuterated P80 (d-P80) to determine the location and concentration of P80 within the LCNP and small angle X-ray scattering (SAXS) to reveal the internal structure. SANS data suggests that some d-P80 already penetrates the particle core at 5%. However, the content of d-P80 is still low enough not to significantly change the internal Fdm structure of the LCNP. At higher fractions of P80 a phase separation occurs, in which a SPC and P80 rich phase is formed at the particle surface. The surface layer becomes gradually richer in both solvent and d-P80 when the surfactant concentration is increased from 5 to 15%, while the core of the particle is enriched by GDO, resulting in loss of internal structure and reduced hydration. We have used neutron reflectometry to reveal the location of the stabiliser within the adsorbed layer on an anionic silica and cationic (aminopropyltriethoxysilane (APTES) silanized) surface. d-P80 is enriched closest to the supporting surface and slightly more so for the cationic APTES surface. The results are relevant not only for the capability of LCNPs as drug delivery vehicles but also as means of preparing functional surface coatings.

Fredrik Tiberg - One of the best experts on this subject based on the ideXlab platform.

  • the lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and Glycerol Dioleate by phospholipase a2 and triacylGlycerol lipase
    Chemistry and Physics of Lipids, 2017
    Co-Authors: Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
    Abstract:

    Abstract The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/Glycerol Dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalyses degradation of the phospholipid component, SPC, and porcine pancreatic triacylGlycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO. Evolution of the structure was found to be very different and linked to specificity of the two types of enzymes. PLA2, which hydrolyses the lamellar forming component, SPC, induces a reversed micellar lipid phase, while TGL which hydrolysis the reverse phase forming compound, GDO, induces a lamellar phase.

  • interfacial properties of popc gdo liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces
    Physical Chemistry Chemical Physics, 2016
    Co-Authors: Debby P Chang, Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Aleksandra P Dabkowska, Richard A Campbell, Tommy Nylander
    Abstract:

    Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I2) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules. Their interactions with various interfaces, and the consequences for the particle structure and integrity, are essential considerations in their effectiveness as drug delivery vehicles. Here, we have studied LCNPs formed of equal fractions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and Glycerol Dioleate in the presence of different fractions of the stabilizer Polysorbate 80. We have used a combination of ellipsometry, quartz crystal microbalance with dissipation monitoring and neutron reflectometry to reveal the structure and composition of the adsorbed layer on both anionic silica and cationic (aminopropyltriethoxysilane) silanized surfaces. For both types of surfaces, there is a spread near-surface layer comprising lipid and polymer as well as a sparse coverage of intact particles. The composition of the near-surface layer is very close to that of the particles, in contrast to the lipid bilayer observed with related systems. The interaction is stronger for cationic than anionic surfaces, which is rationalized in terms of the negative zeta potential of the LCNPs. The work shows that the attachment of and spreading from LCNPs is influenced by the properties of the surface, the internal structure, composition and stability of the particles as well as the nature of the stabilizer.

  • structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and Glycerol Dioleate
    Soft Matter, 2015
    Co-Authors: Maria Wadsater, Justas Barauskas, Sarah E Rogers, Fredrik Tiberg, Robert J Thomas, Maximilian W. A. Skoda, Tommy Nylander
    Abstract:

    Well-defined, stable and highly structured I2 (Fdm) liquid crystalline nanoparticles (LCNP) of 50/50 (wt/wt) soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO), can be formed by using a low fraction (5–10 wt%) of the dispersing polymeric surfactant polyoxyethylene (20) sorbitan monooleate (polysorbate 80 or P80). In the present study we used small angle neutron scattering (SANS) and deuterated P80 (d-P80) to determine the location and concentration of P80 within the LCNP and small angle X-ray scattering (SAXS) to reveal the internal structure. SANS data suggests that some d-P80 already penetrates the particle core at 5%. However, the content of d-P80 is still low enough not to significantly change the internal Fdm structure of the LCNP. At higher fractions of P80 a phase separation occurs, in which a SPC and P80 rich phase is formed at the particle surface. The surface layer becomes gradually richer in both solvent and d-P80 when the surfactant concentration is increased from 5 to 15%, while the core of the particle is enriched by GDO, resulting in loss of internal structure and reduced hydration. We have used neutron reflectometry to reveal the location of the stabiliser within the adsorbed layer on an anionic silica and cationic (aminopropyltriethoxysilane (APTES) silanized) surface. d-P80 is enriched closest to the supporting surface and slightly more so for the cationic APTES surface. The results are relevant not only for the capability of LCNPs as drug delivery vehicles but also as means of preparing functional surface coatings.

  • Formation of Highly Structured Cubic Micellar Lipid Nanoparticles of Soy Phosphatidylcholine and Glycerol Dioleate and Their Degradation by TriacylGlycerol Lipase
    2015
    Co-Authors: Maria Wadsäter, Justas Barauskas, Tommy Nylander, Fredrik Tiberg
    Abstract:

    Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I2) structure show good drug loading ability of peptides and proteins as well as some small molecules. Due to their controllable small size and inner morphology, such nanoparticles are suitable for drug delivery using several different administration routes, including intravenous, intramuscular, and subcutaneous injection. A very interesting system in this regard, is the two component soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO) system, which depending on the ratio of the lipid components form a range of reversed liquid crystalline phases. For a 50/50 (w/w) ratio in excess water, these lipids have been shown to form a reversed cubic micellar (I2) phase of the Fd3m structure. Here, we demonstrate that this SPC/GDO phase, in the presence of small quantities (5–10 wt %) of Polysorbate 80 (P80), can be dispersed into nanoparticles, still with well-defined Fd3m structure. The resulting nanoparticle dispersion has a narrow size distribution and exhibit good long-term stability. In pharmaceutical applications, biodegradation pathways of the drug delivery vehicles and their components are important considerations. In the second part of the study we show how the structure of the particles evolves during exposure to a triacylGlycerol lipase (TGL) under physiological-like temperature and pH. TGL catalyzes the lipolytic degradation of acylglycerides, such as GDO, to monoglycerides, Glycerol, and free fatty acids. During the degradation, the interior phase of the particles is shown to undergo continuous phase transitions from the reversed I2 structure to structures of less negative curvature (2D hexagonal, bicontinuous cubic, and sponge), ultimately resulting in the formation of multilamellar vesicles

  • formation of highly structured cubic micellar lipid nanoparticles of soy phosphatidylcholine and Glycerol Dioleate and their degradation by triacylGlycerol lipase
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Maria Wadsater, Justas Barauskas, Tommy Nylander, Fredrik Tiberg
    Abstract:

    Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I2) structure show good drug loading ability of peptides and proteins as well as some small molecules. Due to their controllable small size and inner morphology, such nanoparticles are suitable for drug delivery using several different administration routes, including intravenous, intramuscular, and subcutaneous injection. A very interesting system in this regard, is the two component soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO) system, which depending on the ratio of the lipid components form a range of reversed liquid crystalline phases. For a 50/50 (w/w) ratio in excess water, these lipids have been shown to form a reversed cubic micellar (I2) phase of the Fd3m structure. Here, we demonstrate that this SPC/GDO phase, in the presence of small quantities (5–10 wt %) of Polysorbate 80 (P80), can be dispersed into nanoparticles, still with well-defined Fd3m structure. The resulting nanoparticle dispersion has a narr...

Maria Wadsater - One of the best experts on this subject based on the ideXlab platform.

  • the lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and Glycerol Dioleate by phospholipase a2 and triacylGlycerol lipase
    Chemistry and Physics of Lipids, 2017
    Co-Authors: Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Tommy Nylander
    Abstract:

    Abstract The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/Glycerol Dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A2 (PLA2) that catalyses degradation of the phospholipid component, SPC, and porcine pancreatic triacylGlycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO. Evolution of the structure was found to be very different and linked to specificity of the two types of enzymes. PLA2, which hydrolyses the lamellar forming component, SPC, induces a reversed micellar lipid phase, while TGL which hydrolysis the reverse phase forming compound, GDO, induces a lamellar phase.

  • relationship between structure and fluctuations of lipid nonlamellar phases deposited at the solid liquid interface
    Journal of Physical Chemistry B, 2017
    Co-Authors: Tommy Nylander, Maria Wadsater, Justas Barauskas, Olaf Soltwedel, Marina Ganeva, Christopher Hirst, James Holdaway, Marianna Yanez Arteta, Henrich Frielinghaus, Olaf Holderer
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon–aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (HII) and micellar cubic phase (Fd3m) layers at the solid–liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic HII phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HII film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate.

  • interfacial properties of popc gdo liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces
    Physical Chemistry Chemical Physics, 2016
    Co-Authors: Debby P Chang, Maria Wadsater, Justas Barauskas, Fredrik Tiberg, Aleksandra P Dabkowska, Richard A Campbell, Tommy Nylander
    Abstract:

    Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I2) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules. Their interactions with various interfaces, and the consequences for the particle structure and integrity, are essential considerations in their effectiveness as drug delivery vehicles. Here, we have studied LCNPs formed of equal fractions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and Glycerol Dioleate in the presence of different fractions of the stabilizer Polysorbate 80. We have used a combination of ellipsometry, quartz crystal microbalance with dissipation monitoring and neutron reflectometry to reveal the structure and composition of the adsorbed layer on both anionic silica and cationic (aminopropyltriethoxysilane) silanized surfaces. For both types of surfaces, there is a spread near-surface layer comprising lipid and polymer as well as a sparse coverage of intact particles. The composition of the near-surface layer is very close to that of the particles, in contrast to the lipid bilayer observed with related systems. The interaction is stronger for cationic than anionic surfaces, which is rationalized in terms of the negative zeta potential of the LCNPs. The work shows that the attachment of and spreading from LCNPs is influenced by the properties of the surface, the internal structure, composition and stability of the particles as well as the nature of the stabilizer.

  • structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and Glycerol Dioleate
    Soft Matter, 2015
    Co-Authors: Maria Wadsater, Justas Barauskas, Sarah E Rogers, Fredrik Tiberg, Robert J Thomas, Maximilian W. A. Skoda, Tommy Nylander
    Abstract:

    Well-defined, stable and highly structured I2 (Fdm) liquid crystalline nanoparticles (LCNP) of 50/50 (wt/wt) soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO), can be formed by using a low fraction (5–10 wt%) of the dispersing polymeric surfactant polyoxyethylene (20) sorbitan monooleate (polysorbate 80 or P80). In the present study we used small angle neutron scattering (SANS) and deuterated P80 (d-P80) to determine the location and concentration of P80 within the LCNP and small angle X-ray scattering (SAXS) to reveal the internal structure. SANS data suggests that some d-P80 already penetrates the particle core at 5%. However, the content of d-P80 is still low enough not to significantly change the internal Fdm structure of the LCNP. At higher fractions of P80 a phase separation occurs, in which a SPC and P80 rich phase is formed at the particle surface. The surface layer becomes gradually richer in both solvent and d-P80 when the surfactant concentration is increased from 5 to 15%, while the core of the particle is enriched by GDO, resulting in loss of internal structure and reduced hydration. We have used neutron reflectometry to reveal the location of the stabiliser within the adsorbed layer on an anionic silica and cationic (aminopropyltriethoxysilane (APTES) silanized) surface. d-P80 is enriched closest to the supporting surface and slightly more so for the cationic APTES surface. The results are relevant not only for the capability of LCNPs as drug delivery vehicles but also as means of preparing functional surface coatings.

  • formation of highly structured cubic micellar lipid nanoparticles of soy phosphatidylcholine and Glycerol Dioleate and their degradation by triacylGlycerol lipase
    ACS Applied Materials & Interfaces, 2014
    Co-Authors: Maria Wadsater, Justas Barauskas, Tommy Nylander, Fredrik Tiberg
    Abstract:

    Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I2) structure show good drug loading ability of peptides and proteins as well as some small molecules. Due to their controllable small size and inner morphology, such nanoparticles are suitable for drug delivery using several different administration routes, including intravenous, intramuscular, and subcutaneous injection. A very interesting system in this regard, is the two component soy phosphatidylcholine (SPC)/Glycerol Dioleate (GDO) system, which depending on the ratio of the lipid components form a range of reversed liquid crystalline phases. For a 50/50 (w/w) ratio in excess water, these lipids have been shown to form a reversed cubic micellar (I2) phase of the Fd3m structure. Here, we demonstrate that this SPC/GDO phase, in the presence of small quantities (5–10 wt %) of Polysorbate 80 (P80), can be dispersed into nanoparticles, still with well-defined Fd3m structure. The resulting nanoparticle dispersion has a narr...

Barauskas Justas - One of the best experts on this subject based on the ideXlab platform.

  • The lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and Glycerol Dioleate by phospholipase A and triacylGlycerol lipase.
    'Elsevier BV', 2018
    Co-Authors: Wadsäter Maria, Barauskas Justas, Tiberg Fredrik, Nylander Tommy
    Abstract:

    The effects of different lipolytic enzymes on the structure of lipid liquid crystalline nano-particles (LCNP) have been investigated by cryogenic transmission electron microscopy (cryo-TEM) and synchrotron small angle X-ray diffraction (SAXD). Here we used highly structured cubic micellar (Fd3m) nanoparticles of 50/50 (wt%/wt%) soy phosphatidyl choline (SPC)/Glycerol Dioleate (GDO) as substrate. Two types of lipolytic enzymes were used, phospholipase A (PLA) that catalyses degradation of the phospholipid component, SPC, and porcine pancreatic triacylGlycerol lipase (TGL) that facilitate the hydrolysis of the diglyceride, GDO. Evolution of the structure was found to be very different and linked to specificity of the two types of enzymes. PLA, which hydrolyses the lamellar forming component, SPC, induces a reversed micellar lipid phase, while TGL which hydrolysis the reverse phase forming compound, GDO, induces a lamellar phase

  • Relationship between Structure and Fluctuations of Lipid Nonlamellar Phases Deposited at the Solid-Liquid Interface
    'American Chemical Society (ACS)', 2017
    Co-Authors: Nylander Tommy, Barauskas Justas, Wadsäter Maria, Soltwedel Olaf, Ganeya Marina, Hirst Christopher, Holdaway James, Arteta, Marianna Yanez, Frielinghaus Henrich, Holderer Olaf
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron, reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (Hr) and micellar cubic phase (Fd3m) layers at: the solid liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic,H-II phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HE film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate

  • Relationship Between Structure and Fluctuations of Lipid Non-Lamellar Phases Deposited at the Solid/liquid Interface
    'American Chemical Society (ACS)', 2017
    Co-Authors: Nylander Tommy, Barauskas Justas, Wadsäter Maria, Soltwedel Olaf, Hirst Christopher, Frielinghaus Henrich, Ganeva Marina, Holdaway, James A., Yanez Arteta Marianna, Holderer Olaf
    Abstract:

    The structure and dynamics of nanostructure films formed by mixtures of soy phosphatidylcholine and Glycerol Dioleate at the silicon–aqueous interface were studied by grazing incidence neutron spin echo spectroscopy (GINSES), specular and off-specular neutron reflectometry, and small-angle X-ray diffraction. Reverse hexagonal (HII) and micellar cubic phase (Fd3m) layers at the solid–liquid interface have been identified with neutron reflectometry measurements. A preferred orientation of the liquid crystalline (LC) domains was observed only for the anisotropic HII phase. The size of the LC domains was found to be about 1 micrometer as estimated from the width of the diffraction peaks. GINSES revealed that the cubic phase forms rather rigid films. In comparison, the HII film was more flexible, appearing as a modified undulation spectrum of the cylinders due to the interaction with the substrate

  • Characterization and stability study of cranberry flavonoids in lipid liquid crystalline systems
    'Royal College of Obstetricians & Gynaecologists (RCOG)', 2017
    Co-Authors: Linkeviciute Ausra, Naujalis Evaldas, Budiene Jurga, Katelnikovas Arturas, Barauskas Justas
    Abstract:

    The main objective of the present study was to investigate mixtures of soy phosphatidylcholine (SPC) and Glycerol Dioleate (GDO) as encapsulation matrices for cranberry flavonoids. The effects of flavonoids loading into non-aqueous formulations, non-lamellar liquid crystalline phases, and their colloidal dispersions were studied by using synchrotron small angle X-ray diffraction, dynamic light scattering. Flavonoids incorporation is discussed with respect to the lipid aggregation behavior, self-assembled nanostructure, and chemical stability by using antioxidant activity assay. The obtained results show that SPC/GDO-based formulations can incorporate relatively high amounts of flavonoids and serve as liquid crystalline delivery vehicles in the form of bulk phases or colloidal dispersions. Practical applications: Our results show that SPC/GDO-based formulations can incorporate relatively high amounts of cranberry flavonoids. The effect flavonoid extracts on the nanostructure of bulk SPC/GDO LC phases are lipid weight ratio-dependent. Flavonoids loaded into SPC/GDO-based formulations and LC phases retain their antioxidant properties. The self-assembled lipid liquid crystalline systems protect bioactive compounds from degradation. These facts are important for the community working in the field of self-assembly of lipid structures, food chemistry, and delivery vehicles of nutraceuticals

  • Interfacial properties of POPC/GDO liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces
    'Royal Society of Chemistry (RSC)', 2016
    Co-Authors: Chang, Debby P., Barauskas Justas, Tiberg Fredrik, Wadsäter Maria, Dabkowska, Aleksandra P., Campbell, Richard A., Nylander Tommy
    Abstract:

    Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I2) phase have high potential in drug delivery applications due to their ability to encapsulate both hydrophobic and hydrophilic drug molecules. Their interactions with various interfaces, and the consequences for the particle structure and integrity, are essential considerations in their effectiveness as drug delivery vehicles. Here, we have studied LCNPs formed of equal fractions of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and Glycerol Dioleate in the presence of different fractions of the stabilizer Polysorbate 80. We have used a combination of ellipsometry, quartz crystal microbalance with dissipation monitoring and neutron reflectometry to reveal the structure and composition of the adsorbed layer on both anionic silica and cationic (aminopropyltriethoxysilane) silanized surfaces. For both types of surfaces, there is a spread near-surface layer comprising lipid and polymer as well as a sparse coverage of intact particles. The composition of the near-surface layer is very close to that of the particles, in contrast to the lipid bilayer observed with related systems. The interaction is stronger for cationic than anionic surfaces, which is rationalized in terms of the negative zeta potential of the LCNPs. The work shows that the attachment of and spreading from LCNPs is influenced by the properties of the surface, the internal structure, composition and stability of the particles as well as the nature of the stabilizer