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Sökning: WFRF:(Barauskas Justas)

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1.
  • Badell, Maria Valldeperas, et al. (författare)
  • Lipid Sponge-Phase Nanoparticles as Carriers for Enzymes
  • 2018
  • Ingår i: Biophysical Journal. - : Cell Press. - 0006-3495 .- 1542-0086. ; 114:3, suppl 1, s. 15A-15A
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
    • Immobilization of enzymes into different support materials has been widely studied as means to control their activity and stability. Here we will consider lipid liquid crystalline phases as enzyme carriers, as they have been demonstrated to have a high potential in a range of applications such as drug delivery, protein encapsulation or crystallization thanks to the wide range of self-assembly structures they can form, which have cavities of nano-scale dimensions. Furthermore, such structures have also been observed in a range of living organisms. Although, reverse cubic or hexagonal lipid aqueous phase can be used to entrap smaller biomolecules, it is still challenging to encapsulate bioactive macromolecules, such as proteins. Here, we will present a novel lipid system able to form highly swollen sponge phases (L3), with aqueous pores up to 13 nm of diameter. We will show that this structure is preserved even in excess aqueous solution, where they form sponge-like nanoparticles (L3 NPs) in which two enzymes of different sizes, Aspartic protease and beta-galactosidase (34 KDa and 460 KDa, respectively), could be included. To reveal the nature of the interaction between the enzymes and the lipid matrix, we studied the adsorption of both proteins on the lipid layers formed by the L3 NPs. The results will be discussed in terms of the ability of these nanoparticles to encapsulate and release of the proteins in the lipid matrix.
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2.
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3.
  • Barauskas, Justas, et al. (författare)
  • Bioadhesive Lipid Compositions : Self-Assembly Structures, Functionality, and Medical Applications
  • 2014
  • Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 11:3, s. 895-903
  • Tidskriftsartikel (refereegranskat)abstract
    • Lipid-based liquid crystalline compositions of phospholipids and diglycerides have unique bioadhesive properties with several medical applications, as exemplified by a lipid-based medical device indicated for management and relief of intraoral pain. The present paper describes the relation between self-assembly properties of phosphatidyl choline (PC) and glycerol dioleate (GDO) mixtures in the presence of aqueous fluids and functional attributes of the system, including: film formation and bioadhesion, intraoral coverage, acceptance by patients, and potential as a drug delivery system. The phase behavior of PC/GDO was characterized using synchrotron small-angle X-ray scattering. Functional properties, including the presence of study formulations at intraoral surfaces, ease of attachment, taste, and degree of and intraoral pain, were assessed in a crossover clinical pilot study in head and neck cancer patients. An optimum in functional properties was indicated for formulations with a PC/GDO weight ratio of about 35/65, where the lipids form a reversed cubic liquid crystalline micellar phase structure (Fd3m space group) over the relevant temperature range (25-40 degrees C).
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4.
  • Barauskas, Justas, et al. (författare)
  • Cubic phase nanoparticles (Cubosome): Principles for controlling size, structure, and stability
  • 2005
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 21:6, s. 2569-2577
  • Tidskriftsartikel (refereegranskat)abstract
    • Methods and compositions for producing lipid-based cubic phase nanoparticles were first discovered in the 1990s. Since then a number of studies have been presented, but little is known about how to control key properties such as particle size, morphology, and stability of cubic phase dispersions. In the present work we give examples of how these properties can be tuned by composition and processing conditions. Importantly we show that stable particle dispersions with consistent size and structure can be produced by a simple processing scheme comprising a homogenization and heat treatment step.
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5.
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6.
  • Barauskas, Justas, et al. (författare)
  • Phase behavior of the phytantriol/water system
  • 2003
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 19:23, s. 9562-9565
  • Tidskriftsartikel (refereegranskat)abstract
    • Phytantriol, 3,7,11,15-tetramethyl-1,2,3-hexadecanetriol, is frequiently used as a cosmetic ingredient; however, very little is known about its physical and chemical properti s. Here, we present the phase behavior of phytantriol in water, as determined by X-ray diffraction. At room temperature, the phase sequence upon increasing the water concentration is reversed micellar, lamellar, cubic phase Q(230), and cubic phase Q(224). At 44 degreesC, the cubic liquid crystals are transformed into a reversed hexagonal phase. The temperature-composition phase diagram of phytantriol/water mixtures is, thus, qualitatively similar to that of aqueous glycerol monooleate. The chemical stability of phytantriol makes it an interesting alternative to glycerol monooleate in exploiting various scientific and technical applications of, in particular, the cubic liquid crystalline phases.
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7.
  • Barauskas, Justas, et al. (författare)
  • Self-assembled lipid superstructures: Beyond vesicles and liposomes
  • 2005
  • Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:8, s. 1615-1619
  • Tidskriftsartikel (refereegranskat)abstract
    • A unique set of nanoparlicle dispersions of self-assembled lipid mesophases with distinctive reversed cubic, hexagonal, and sponge phase structures has been prepared by use of original lipid combinations and a simple, generally applicable and scalable method. All key properties, particle size distributions, shape, phase structure, and stability, are controlled predictably and reproducibly. The results suggest the cross-disciplinary use of nonlamellar particle structures in science and technology as, for instance, biomimetics, in vivo drug delivery vehicles for diagnostic and therapeutic agents, protein crystallization matrices, and soft nanoporous materials.
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8.
  • Barauskas, Justas, et al. (författare)
  • ''Sponge" nanoparticle dispersions in aqueous mixtures of diglycerol monooleate, glycerol dioleate, and polysorbate 80
  • 2006
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:14, s. 6328-6334
  • Tidskriftsartikel (refereegranskat)abstract
    • Lipid nanoparticles of nonlamellar lyotropic phases have a wide solubilizing and encapsulating spectrum for a range of substances thanks to their nanostructured interior featuring both lipophilic and hydrophilic domains. As a consequence, these systems have emerged as promising drug delivery systems in various pharmaceutical and diagnostic applications. Here we present the phase behavior and dispersion properties of a novel three-component lipid system composed of diglycerol monooleate (DGMO), glycerol dioleate (GDO), and polysorbate 80 (P80) which shows several advantageous features relating to drug delivery applications including: spontaneous dispersion formation with a narrow size distribution and tunable particle phase-structure. The obtained phase diagram shows the presence of lamellar (L-alpha), hexagonal (H-2), and reverse bicontinuous cubic (V-2) liquid crystalline phases and an inverse micellar (L-2) solution. A particularly interesting observation is the presence of a phase region where two liquid phases coexist, most likely the L-2 and L-3 ("sponge phase"). These two phase structures appear also to coexist in the submicron particles formed in the dilute water region, where the L-3 element appears to stabilize nanoparticles with inner L-2 structure. Increasing the fraction of the dispersing P80 component results in the growth of the more water rich L-3 "surface phase" at the expense of the size of the inner L-2 core.
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9.
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10.
  • Barauskas, Justas, et al. (författare)
  • Synthesis and aqueous phase behavior of 1-glyceryl monooleyl ether
  • 2005
  • Ingår i: Colloids and Surfaces B: Biointerfaces. - : Elsevier BV. - 1873-4367 .- 0927-7765. ; 41:1, s. 49-53
  • Tidskriftsartikel (refereegranskat)abstract
    • Synthesis of 1-glyceryl monooleyl ether (GME) has been accomplished yielding material of high purity (99.6%). The aqueous phase behavior of synthesized lipid has been investigated by using polarized microscopy and small angle X-ray diffraction. As a result, a partial temperature-composition phase diagram has been constructed. GME forms a reversed micellar solution and reversed hexagonal liquid crystalline phase at low and high hydration, respectively. The hexagonal phase coexists with excess water and is stable up to about 63 degreesC. These findings make GME an interesting alternative to glycerol monoesters in various fields of applications. (C) 2004 Elsevier B.V. All rights reserved.
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11.
  • Barauskas, Justas, et al. (författare)
  • Thermomyces lanuginosus lipase-catalyzed hydrolysis of the lipid cubic liquid crystalline nanoparticles
  • 2016
  • Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 137, s. 50-59
  • Tidskriftsartikel (refereegranskat)abstract
    • In this study well-ordered glycerol monooleate (GMO)-based cubic liquid crystalline nanoparticles (LCNPs) have been used as substrates for Thermomyces lanuginosus lipase in order to establish the relation between the catalytic activity, measured by pH-stat titration, and the change in morphology and nano-structure determined by cryogenic transmission electron microscopy and synchrotron small angle X-ray diffraction. The initial lipase catalyzed LCNP hydrolysis rate is approximately 25% higher for large 350 nm nanoparticles compared to the small 190 nm particles, which is attributed to the increased number of structural defects on the particle surface. At pH 8.0 and 8.4 bicontinuous Im3m cubic LCNPs transform into "sponge"-like assemblies and disordered multilamellar onion-like structures upon exposure to lipase. At pH 6.5 and 7.5 lipolysis induced phase transitions of the inner core of the particles, following the sequence Im3m cubic -> reversed hexagonal -> reversed micellar Fd3m cubic -> reversed micelles. These transitions to the liquid crystalline phases with higher negative curvature of the lipid/water interface were found to trigger protonation of the oleic acid produced during lipase catalyzed reaction. The increase curvature of the reversed discrete micellar cubic phase was suggested to cause an increase in the oleic acid pK(a) to a larger value observed by pH-stat titration. (C) 2015 Elsevier B.V. All rights reserved.
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12.
  • Barauskas, Justas, et al. (författare)
  • Towards redox active liquid crystalline phases of lipids: a monoolein/water system with entrapped derivatives of ferrocene
  • 2003
  • Ingår i: Chemistry and Physics of Lipids. - 0009-3084. ; 123:1, s. 87-97
  • Tidskriftsartikel (refereegranskat)abstract
    • The phase and electrochemical behavior of the aqueous mixtures of monoolein (MO) and synthetic ferrocene (Fc) derivatives containing long alkyl chains -(Z)-octadec-9-enoylferrocene (1), (Z)-octadecen-9-ylferrocene (2), and ferrocenylmethyl (Z)-octadec-9-enoate (3)-were studied. At low hydration, the reversed micelles (L-2 phase) and cubic Q(230) phase of MO can accommodate relatively high amounts ( > 6 wt.%) of the Fc-derivative 2, whereas at high hydration, the pseudoternary cubic phase Q(224) is destabilized even at about 2 wt.% of this Fc. Increasing the Fc-derivative content induces L-alpha L-2 and L-alpha --> reversed bicontinuous cubic phase (Q(II)) H-II transitions depending upon hydration. A rough study of the MO system containing compounds I and 3 indicates very similar phase behavior to that of the MO/2/H2O system. Compound 2 apparently has no effect on the lipid monolayer thickness in the pseudoternary L-alpha, H-II and Q(II) liquid crystalline phases of MO. Within a 3D-structure of the Q224 phase, derivatives 1-3 exhibit electrochemical activity on the gold electrode. The one-electron redox conversion processes are electro-chemically quasi-reversible and controlled by diffusion. The values of apparent diffusion coefficient (D-app) and heterogeneous electron-transfer rate constant (k(s)) of Fcs are significantly lo er in the cubic,phase matrix when compared to the acetonitrile solution. By contrast, the MO H-II phase with entrapped Fc-derivatives does not exhibit electrochemical activity on the electrode surface. It is suggested that the diffusional anisotropy and/or localized aggregation of compounds 1-3 within a 2D-structure of the H-II phase account(s) for the latter observation. (C) 2003 Elsevier Science Ireland Ltd. All rights reserved.
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13.
  • Brennan, Jennifer L., et al. (författare)
  • Enzymatic Activity of Lipase-Nanoparticle Conjugates and the Digestion of Lipid Liquid Crystalline Assemblies
  • 2010
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 26:16, s. 13590-13599
  • Tidskriftsartikel (refereegranskat)abstract
    • Variants of lipase were attached to gold nanoparticles (NPs) and their enzymatic activity was studied. The two bioengineered lipase variants have been prepared with biotin groups attached to different residues on the protein outer surface. The biotinylation was evidenced by denaturing polyacrylamide gel electrophoresis and quantified by the ([2-(4'-hydroxyazobenzene)]benzoic acid spectrophotometric test. NPs of 14 +/- 1 nm diameter coated with thiolated-polyethylene glycol ligands containing controlled proportions of biotin moieties have been prepared and characterized by transmission electron microscopy, UV-vis spectroscopy, small angle neutron scattering, and elemental analysis. These biotin-functionalized NPs were conjugated to lipase using streptavidin as a linker molecule. Enzyme activity assays on the lipase-nanoparticle conjugates show that the lipase loading and activity of the NPs can be controlled by varying the percentage of biotin groups in the particle protecting coat. The lipase-NP conjugates prepared using one variant display higher activity than those prepared using the other variant, demonstrating orientation-dependent enzyme activity. Cryogenic transmission electron microscopy was used to visualize the enzymatic activity of lipase-NP on well-defined lipid substrates. It was found that lipase-coated NPs are able to digest the substrates in a different manner in comparison to the free lipase.
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14.
  • Cárdenas, Marité, et al. (författare)
  • Thiol-Specific and Non-Specific Interactions Between DNA and Gold Nanoparticles
  • 2006
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22, s. 3294-3299
  • Tidskriftsartikel (refereegranskat)abstract
    • The contribution of nonspecific interactions to the overall interactions of thiol-ssDNA and dsDNA macromolecules with gold nanoparticles was investigated. A systematic investigation utilizing dynamic light scattering and cryogenic transmission electron microscopy has been performed to directly measure and visualize the changes in particle size and appearance during functionalization of gold nanoparticles with thiol-ssDNA and nonthiolated dsDNA. The results show that both thiol-ssDNA and dsDNA do stabilize gold nanoparticle dispersions, but possible nonspecific interactions between the hydrophobic DNA bases and the gold surface promote interparticle interactions and cause aggregation within rather a short period of time. We also discuss the adsorption mechanisms of dsDNA and thiol-ssDNA to gold particles.
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15.
  • Chang, Debby, et al. (författare)
  • Adsorption of lipid liquid crystalline nanoparticles : effects of particle composition, internal structure, and phase behavior
  • 2012
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 28:29, s. 10688-10696
  • Tidskriftsartikel (refereegranskat)abstract
    • Controlling the interfacial behavior and properties of lipid liquid crystalline nanoparticles (LCNPs) at surfaces is essential for their application for preparing functional surface coatings as well as understanding some aspects of their properties as drug delivery vehicles. Here we have studied a LCNP system formed by mixing soy phosphatidylcholine (SPC), forming liquid crystalline lamellar structures in excess water, and glycerol dioleate (GDO), forming reversed structures, dispersed into nanoparticle with the surfactant polysorbate 80 (P80) as stabilizer. LCNP particle properties were controlled by using different ratios of the lipid building blocks as well as different concentrations of the surfactant P80. The LCNP size, internal structure, morphology, and charge were characterized by dynamic light scattering (DLS), synchrotron small-ange X-ray scattering (SAXS), cryo-transmission electron microscopy (cryo-TEM), and zeta potential measurements, respectively. With increasing SPC to GDO ratio in the interval from 35:65 to 60:40, the bulk lipid phase structure goes from reversed cubic micellar phase with Fd3m space group to reversed hexagonal phase. Adding P80 results in a successive shift toward more disorganized lamellar type of structures. This is also seen from cryo-TEM images for the LCNPs, where higher P80 ratios results in more extended lamellar layers surrounding the inner, more dense, lipid-rich particle core with nonlamellar structure. When put in contact with a solid silica surface, the LCNPs adsorb to form multilayer structures with a surface excess and thickness values that increase strongly with the content of P80 and decreases with increasing SPC:GDO ratio. This is reflected in both the adsorption rate and steady-state values, indicating that the driving force for adsorption is largely governed by attractive interactions between poly(ethylene oxide) (PEO) units of the P80 stabilizer and the silica surface. On cationic surface, i.e., silica modified with 3-aminopropltriethoxysilane (APTES), the slightly negatively charged LCNPs give rise to a very significant adsorption, which is relatively independent of LCNP composition. Finally, the dynamic thickness measurements indicate that direct adsorption of intact particles occurred on the cationic surface, while a slow buildup of the layer thickness with time is seen for the weakly interacting systems.
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16.
  • Chang, Debby, et al. (författare)
  • Adsorption of lipid liquid crystalline nanoparticles on cationic, hydrophilic, and hydrophobic surfaces
  • 2012
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 4:5, s. 2643-2651
  • Tidskriftsartikel (refereegranskat)abstract
    • Investigation of nonlamellar nanoparticles formed by dispersion of self-assembled lipid liquid crystalline phases is stimulated by their many potential applications in science and technology; resulting from their unique solubilizing, encapsulating, and space-dividing nature. Understanding the interfacial behavior of lipid liquid crystalline nanoparticles (LCNPs) at surfaces can facilitate the exploitation of such systems for a number of potentially interesting uses, including preparation of functional surface coatings and uses as carriers of biologically active substances. We have studied the adsorption of LCNP, based on phosphatidylcholine/glycerol dioleate and Polysorbate 80 as stabilizers, at different model surfaces by use of in situ ellipsometry. The technique allows time-resolved monitoring of the layer thickness and the amount adsorbed, thereby providing insights into the restructuring of the lipid nanoparticle upon adsorption. The effects of solvent condition, electrolyte concentration, particle size, and surface chemistry on adsorbed layer properties were investigated. Furthermore, the internal structures of the particles were investigated by cryo-transmission electron microscopy and small angle X-ray diffraction on the corresponding liquid crystalline phases in excess water. LCNPs are shown to form well-defined layers at the solid–liquid interface with a structure and coverage that are determined by the interplay between the self-assembly properties of the lipids and lipid surface interactions, respectively. At the hydrophobic surface, hydrophobic interaction results in a structural transition from the original LCNP morphology to a monolayer structure at the interface. In contrast, at cationic and hydrophilic surfaces, relaxation is a relatively slow process, resulting in much thicker adsorbed layers, with thickness and adsorption behavior that to a greater extent reflect the original bulk LCNP properties.
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17.
  • Chang, Debby, et al. (författare)
  • Non-lamellar lipid liquid crystalline structures at interfaces
  • 2015
  • Ingår i: Advances in Colloid and Interface Science. - : Elsevier. - 0001-8686 .- 1873-3727. ; 222, s. 135-147
  • Forskningsöversikt (refereegranskat)abstract
    • The self-assembly of lipids leads to the formation of a rich variety of nano-structures, not only restricted to lipid bilayers, but also encompassing non-lamellar liquid crystalline structures, such as cubic, hexagonal, and sponge phases. These non-lamellar phases have been increasingly recognized as important for living systems, both in terms of providing compartmentalization and as regulators of biological activity. Consequently, they are of great interest for their potential as delivery systems in pharmaceutical, food and cosmetic applications. The compartmentalizing nature of these phases features mono- or bicontinuous networks of both hydrophilic and hydrophobic domains. To utilize these non-lamellar liquid crystalline structures in biomedical devices for analyses and drug delivery, it is crucial to understand how they interact with and respond to different types of interfaces. Such non-lamellar interfacial layers can be used to entrap functional biomolecules that respond to lipid curvature as well as the confinement. It is also important to understand the structural changes of deposited lipid in relation to the corresponding bulk dispersions. They can be controlled by changing the lipid composition or by introducing components that can alter the curvature or by deposition on nano-structured surface, e.g. vertical nano-wire arrays. Progress in the area of liquid crystalline lipid based nanoparticles opens up new possibilities for the preparation of well-defined surface films with well-defined nano-structures. This review will focus on recent progress in the formation of non-lamellar dispersions and their interfacial properties at the solid/liquid and biologically relevant interfaces.
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18.
  • Chang, Debby P., et al. (författare)
  • Interfacial properties of POPC/GDO liquid crystalline nanoparticles deposited on anionic and cationic silica surfaces
  • 2016
  • Ingår i: Physical Chemistry, Chemical Physics - PCCP. - : Royal Society of Chemistry. - 1463-9076 .- 1463-9084. ; 18:38, s. 26630-26642
  • Tidskriftsartikel (refereegranskat)abstract
    • Reversed lipid liquid crystalline nanoparticles (LCNPs) of the cubic micellar (I-2) 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.
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19.
  • Dabkowska, Aleksandra P., et al. (författare)
  • Non-lamellar lipid assembly at interfaces : controlling layer structure by responsive nanogel particles
  • 2017
  • Ingår i: Interface Focus. - : ROYAL SOC. - 2042-8898 .- 2042-8901. ; 7:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Biological membranes do not only occur as planar bilayer structures, but depending on the lipid composition, can also curve into intriguing three-dimensional structures. In order to fully understand the biological implications as well as to reveal the full potential for applications, e.g. for drug delivery and other biomedical devices, of such structures, well-defined model systems are required. Here, we discuss the formation of lipid non-lamellar liquid crystalline (LC) surface layers spin-coated from the constituting lipids followed by hydration of the lipid layer. We demonstrate that hybrid lipid polymer films can be formed with different properties compared with the neat lipid LC layers. The nanostructure and morphologies of the lipid films formed reflect those in the bulk. Most notably, mixed lipid layers, which are composed of glycerol monooleate and diglycerol monooleate with poly(N-isopropylacrylamide) nanogels, can form films of reverse cubic phases that are capable of responding to temperature stimulus. Owing to the presence of the nanogel particles, changing the temperature not only regulates the hydration of the cubic phase lipid films, but also the lateral organization of the lipid domains within the lipid self-assembled film. This opens up the possibility for new nanostructured materials based on lipid-polymer responsive layers.
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20.
  • Dabkowska, A. P., et al. (författare)
  • Temperature responsive lipid liquid crystal layers with embedded nanogels
  • 2017
  • Ingår i: Chemical Communications. - : Royal Society of Chemistry. - 1359-7345 .- 1364-548X. ; 53:8, s. 1417-1420
  • Tidskriftsartikel (refereegranskat)abstract
    • Polymer nanogels are embedded within layers consisting of a nonlamellar liquid crystalline lipid phase to act as thermoresponsive controllers of layer compactness and hydration. As the nanogels change from the swollen to the collapsed state via a temperature trigger, they enable on-demand release of water from the mixed polymer-lipid layer while the lipid matrix remains intact. Combining stimuli-responsive polymers with responsive lipid-based mesophase systems opens up new routes in biomedical applications such as functional biomaterials, bioanalysis and drug delivery.
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21.
  • Engstedt, Jenni, et al. (författare)
  • Phase behavior of soybean phosphatidylcholine and glycerol dioleate in hydrated and dehydrated states studied by small-angle X-ray scattering
  • 2023
  • Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 19:43, s. 8305-8317
  • Tidskriftsartikel (refereegranskat)abstract
    • Soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) form liquid crystal nanostructures in aqueous environments, and their mixtures can effectively encapsulate active pharmaceutical ingredients (API). When used in a subcutaneous environment, the liquid crystalline matrix gradually hydrates and degrades in the tissue whilst slowly releasing the API. Hydration dependent SPC/GDO phase behavior is complex, non-trivial, and still not fully understood. A deeper understanding of this system is important for controlling its function in drug delivery applications. The phase behavior of the mixture of SPC/GDO/water was studied as a function of hydration and lipid ratio. Small-angle X-ray scattering (SAXS) was used to identify space groups in liquid crystalline phases and to get detailed structural information on the isotropic reverse micellar phase. The reported pseudo ternary phase diagram includes eight different phases and numerous multiphase regions in a thermodynamically consistent way. For mixtures with SPC as the predominant component, the system presents a reverse hexagonal, lamellar and R3m phase. For mixtures with lower SPC concentrations, reverse cubic (Fd3m and Pm3n) as well as intermediate and isotropic micellar phases were identified. By modeling the SAXS data using a core–shell approach, the properties of the isotropic micellar phase were studied in detail as a function of concentration. Moreover, SAXS analysis of other phases revealed new structural features in relation to lipid–water interactions. The new improved ternary phase diagram offers valuable insight into the complex phase behavior of the SPC/GDO system. The detailed structural information is important for understanding what APIs can be incorporated in the liquid crystal structure.
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22.
  • Engstedt, Jenni, et al. (författare)
  • Swelling kinetics of mixtures of soybean phosphatidylcholine and glycerol dioleate
  • 2024
  • Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 239
  • Tidskriftsartikel (refereegranskat)abstract
    • Lipid-based drug delivery systems offer the potential to enhance bioavailability, reduce dosing frequency, and improve patient adherence. In aqueous environment, initially dry lipid depots take up water and form liquid crystalline phases. Variation of lipid composition, depot size and hydration-induced phase transitions will plausibly affect the diffusion in and out of the depot. Lipid depots of soybean phosphatidylcholine (SPC) and glycerol dioleate (GDO) mixtures were hydrated for varying time durations in a phosphate-buffered saline (PBS) buffer and then analyzed with Karl Fischer titration, magnetic resonance imaging (MRI) and gravimetrically. Mathematical modeling of the swelling process using diffusion equations, was used to estimate the parameters of diffusion. Both composition of lipid mixture and depot size affect swelling kinetics… The diffusion parameters obtained in Karl Fischer titration and MRI (with temporal and spatial resolution respectively) are in good agreement. Remarkably, the MRI results show a gradient of water content within the depot even after the end of diffusion process. Apparently contradicting the first Fick's law in its classical form, these results find an explanation using the generalized Fick's law that considers the gradient of chemical potential rather than concentration as the driving force of diffusion.
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23.
  • Gilbert, Jennifer, et al. (författare)
  • Immobilisation of β-galactosidase within a lipid sponge phase: structure, stability and kinetics characterisation
  • 2019
  • Ingår i: Nanoscale. - 2040-3372. ; 11:44, s. 21291-21301
  • Tidskriftsartikel (refereegranskat)abstract
    • In the formulation of an active enzyme enclosed in a matrix for controlled delivery, it is a challenge to achieve a high protein load and to ensure high activity of the protein. For the first time to our knowledge, we report the use of a highly swollen lipid sponge (L3) phase for encapsulation of the large active enzyme, β-galactosidase (β-gal, 238 kDa). This enzyme has large relevance for applications in, e.g. the production of lactose free milk products. The formulation consisted of diglycerol monooleate (DGMO), and a mixture of mono-, di- and triglycerides (Capmul GMO-50) stabilised by polysorbate 80 (P80). The advantage of this type of matrix is that it can be produced on a large scale with a fairly simple and mild process as the system is in practice self-dispersing, yet it has a well-defined internal nano-structure. Minor effects on the sponge phase structure due to the inclusion of the enzyme were observed using small angle X-ray scattering (SAXS). The effect of encapsulation on the enzymatic activity and kinetic characteristics of β-galactosidase activity was also investigated and can be related to the enzyme stability and confinement within the lipid matrix. The encapsulated β-galactosidase maintained its activity for a significantly longer time when compared to the free solution at the same temperature. Differences in the particle size and charge of sponge-like nanoparticles (L3-NPs) with and without the enzyme were analysed by dynamic light scattering (DLS) and zeta-potential measurements. Moreover, all the initial β-galactosidase was encapsulated within L3-NPs as revealed by size exclusion chromatography.
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24.
  • Hussain, Irshad, et al. (författare)
  • Controlled Step Growth of Molecularly Linked Gold Nanoparticles: From Metallic Monomers to Dimers to Polymeric Nanoparticle Chains.
  • 2009
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 25:4, s. 1934-1939
  • Tidskriftsartikel (refereegranskat)abstract
    • The solution-phase assembly of 15 nm gold particles into relatively linear chains of fairly controllable length of up to 1 mum is achieved by molecularly linking nanoparticles with alkanedithiols. This step-growth process can be controlled to prepare dimers, oligomers, and polymer-like gold nanoparticle chains by varying the ratio of alkanedithiols to nanoparticles. These size-controlled, relatively linear aggregates remain suspended in ethanol solution without precipitation for several weeks to months depending on the chain length. The resulting soluble nanoparticle assemblies were characterized by a variety of techniques including cryogenic transmission electron microscopy. The surface plasmon coupling of regularly spaced gold nanoparticles in these chains could be of interest in the fabrication of optical waveguide and nanoelectronic systems.
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25.
  • Hussain, Irshad, et al. (författare)
  • Emulsions-directed assembly of gold nanoparticles to molecularly-linked and size-controlled spherical aggregates
  • 2010
  • Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 350:1, s. 368-372
  • Tidskriftsartikel (refereegranskat)abstract
    • Aggregation of gold nanoparticles into soluble spherical assemblies using bi-functional ligands i.e., dithiols has recently been demonstrated but with limited control over the size of such assemblies. Herein, we report a new approach to further control the size of water dispersible spherical assemblies by confining gold nanoparticles in tiny oil droplets in water (oil-in-water emulsions) followed by their cross-linking with alkanedithiols. By controlling the size of the oil droplets and the concentration of nanoparticles, the size of spherical aggregates can be controlled from 20 to 400 nm. Cryo-TEM micrographs confirm the formation of covalently-linked soluble spherical nanoparticle assemblies within the oil emulsions in water. Such size-controlled nanoparticle assemblies may have several potential applications including those in gas sensors, controlled delivery, and optical coatings. (C) 2010 Elsevier Inc. All rights reserved.
  •  
26.
  • Johnsson, Markus, et al. (författare)
  • Aqueous phase behavior and dispersed nanoparticles of diglycerol monooleate/glycerol dioleate mixtures
  • 2005
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 21:11, s. 5159-5165
  • Tidskriftsartikel (refereegranskat)abstract
    • The first part of this study concerns the aqueous phase behavior of mixtures of diglycerol monooleate (DGMO) and glycerol dioleate (GDO) examined by X-ray diffraction (XRD). The ternary phase diagram displays a multitude of liquid crystalline phases (polymorphism). With increasing GDO content the following phase sequence was observed: lamellar (L-alpha); two reversed bicontinuous cubic phases (Q(230) and Q(224)); reversed hexagonal (Fiji); the reversed micellar (L-2) phase. The second part deals with the preparation and characterization of aqueous dispersions of the reversed hexagonal phase in the presence of the nonionic triblock copolymer Pluronic F127. Submicrometer-sized monocrystalline H-II phase particles were obtained, as evidenced by cryo-transmission electron microscopy (cryo-TEM), laser diffraction, and XRD, by use of a simple and reproducible preparation method including a heat-treatment step. Moreover, the particle size distributions of the H-II phase nanoparticle dispersions were narrow as determined by laser diffraction measurements. Using XRD, we show that the polymeric stabilizer is depleted from the core of the hexagonal particles and preferentially located at the surface. It is concluded that the preferential distribution of stabilizing agents at particle surfaces is a prerequisite for the formation of structurally well-defined and kinetically stable H-II phase particles (Hexosome).
  •  
27.
  • Johnsson, Markus, et al. (författare)
  • Cubic phases and cubic phase dispersions in a phospholipid-based system
  • 2005
  • Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 127:4, s. 1076-1077
  • Tidskriftsartikel (refereegranskat)abstract
    • A cubic liquid crystalline phase forming system based on the phospholipid dioleoylphosphatidylethanolamine (DOPE) which is fortified with small amounts of PEGylated (poly(ethylene) glycol) glycerol monooleate (PEG(660)-GMO) is characterized. The cubic phase formed by the DOPE/PEG(660)-GMO/water system coexists with water in the dilute part of the phase diagram and can be fragmented into colloidal size particles with retained cubic phase structure.
  •  
28.
  • Johnsson, Markus, et al. (författare)
  • Physicochemical and drug delivery aspects of lipid-based liquid crystalline nanoparticles: A case study of intravenously administered propofol
  • 2006
  • Ingår i: Journal of Nanoscience and Nanotechnology. - : American Scientific Publishers. - 1533-4880. ; 6:9-10, s. 3017-3024
  • Tidskriftsartikel (refereegranskat)abstract
    • Liquid crystalline nanoparticles (LCNP) formed through lipid self-assembly have a range of attractive properties as in vivo drug delivery carriers. In particular they offer: a wide solubilization spectrum, and consequently high drug payloads; effective encapsulation; stabilization and protection of sensitive drug substances. Here we present basic physicochemical features of non-lamellar LCNP systems with a focus on intravenous drug applications. This is exemplified by the formulation properties and in vivo behavior using the drug substance propofol; a well-known anesthetic agent currently used in clinical practice in the form of a stable emulsion. In order to appraise the drug delivery features of the LCNP system the current study was carried out with a marketed propofol emulsion product as reference. In this comparison the propofol-LCNP formulation shows several useful features including: higher drug-loading capacity, lower fat-load, excellent stability, modified pharmacokinetics, and an indication of increased effect duration.
  •  
29.
  • Knaapila, Matti, et al. (författare)
  • A new small-angle X-ray scattering set-up on the crystallography beamline I711 at MAX-lab.
  • 2009
  • Ingår i: Journal of Synchrotron Radiation. - 1600-5775. ; 16:Pt 4, s. 498-504
  • Tidskriftsartikel (refereegranskat)abstract
    • A small-angle X-ray scattering (SAXS) set-up has recently been developed at beamline I711 at the MAX II storage ring in Lund (Sweden). An overview of the required modifications is presented here together with a number of application examples. The accessible q range in a SAXS experiment is 0.009-0.3 A(-1) for the standard set-up but depends on the sample-to-detector distance, detector offset, beamstop size and wavelength. The SAXS camera has been designed to have a low background and has three collinear slit sets for collimating the incident beam. The standard beam size is about 0.37 mm x 0.37 mm (full width at half-maximum) at the sample position, with a flux of 4 x 10(10) photons s(-1) and lambda = 1.1 A. The vacuum is of the order of 0.05 mbar in the unbroken beam path from the first slits until the exit window in front of the detector. A large sample chamber with a number of lead-throughs allows different sample environments to be mounted. This station is used for measurements on weakly scattering proteins in solutions and also for colloids, polymers and other nanoscale structures. A special application supported by the beamline is the effort to establish a micro-fluidic sample environment for structural analysis of samples that are only available in limited quantities. Overall, this work demonstrates how a cost-effective SAXS station can be constructed on a multipurpose beamline.
  •  
30.
  • Kocherbitov, Vitaly, et al. (författare)
  • Hydration of Lysozyme Studied by Raman Spectroscopy
  • 2013
  • Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 117:17, s. 4981-4992
  • Tidskriftsartikel (refereegranskat)abstract
    • Hydration plays a fundamental role in maintaining the three-dimensional structure and function of proteins. In this study, Raman spectroscopy was used to probe the hydration induced structural changes at various sites of lysozyme under isothermal conditions in the range of water contents from 0 to 44 wt %. Raman hydration curves were constructed from detailed analysis of marker bands. Transition inflection points (wm) and onsets determined from the hydration curves have shown that structural changes start at 7–10 and end at about 35 wt % water. The onset of structural changes coincides with the onset of the broad glass transition earlier observed in this system. The increase of α-helix content starts at very low concentrations of water with wm = 12 wt %. Monitoring the development of importance for enzymatic action hydrophobic clusters has revealed wm = 15 wt % and completion of the process at 25 wt %. The parameters of 621 cm–1 (Phe) and 1448 cm–1 (CH2 bending) modes were found to be sensitive to hydration, suggesting changes in organization of water molecules near the protein surface. The native structure of lysozyme was achieved at 35 wt % water where its content is high enough for filling the space between lysozyme molecules.
  •  
31.
  • Linkeviciute, Ausra, et al. (författare)
  • Characterization and stability study of cranberry flavonoids in lipid liquid crystalline systems
  • 2017
  • Ingår i: European Journal of Lipid Science and Technology. - : John Wiley & Sons. - 1438-7697 .- 1438-9312. ; 119:8
  • Tidskriftsartikel (refereegranskat)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.
  •  
32.
  • Linkeviciute, Ausra, et al. (författare)
  • Preparation and characterization of quercetin-loaded lipid liquid crystalline systems
  • 2015
  • Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 128, s. 296-303
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of the present study was to investigate mixtures of soy phosphatidylcholine (SPC) and glycerol dioleate (GDO) as encapsulation matrices for antioxidant quercetin. The effects of quercetin 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, cryogenic electron microscopy and high performance liquid chromatography. Quercetin incorporation is discussed in the context of lipid aggregation behavior, self-assembled nanostructure and chemical stability. The obtained results show that SPC/GDO-based formulations can incorporate relatively high amounts of quercetin and serve as liquid crystalline delivery vehicles in the form of bulk phases or colloidal dispersions.
  •  
33.
  • Misiunas, Audrius, et al. (författare)
  • Horse heart cytochrome c entrapped into the hydrated liquid-crystalline phases of phytantriol: X-ray diffraction and Raman spectroscopic characterization
  • 2012
  • Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 1095-7103 .- 0021-9797. ; 378, s. 232-240
  • Tidskriftsartikel (refereegranskat)abstract
    • Small angle X-ray diffraction (SAXD), resonance Raman (RR) spectroscopy with 413 nm excitation, and non-resonance Raman technique with 785 nm excitation were used to probe the influence of entrapped cytochrome c (Cyt c) on the structure of hydrated phytantriol (Phyt) liquid-crystalline phases as well as conformational changes of heme group and secondary structure of the protein. SAXD measurements indicated that incorporation of Cyt c affects both nanostructure dimensions and type of liquid-crystalline phases of hydrated Phyt. The unit cell dimensions decrease with increasing Cyt c concentration for all phases. In addition, protein perturbs the nanostructure of Q(230) and Q(224) liquid-crystalline phases of hydrated Phyt to such an extent that they transform into the Q(229) phase with the Im3m space group. RR data revealed that entrapment of oxidized Cyt c into the Q(230) phase at 1 wt.% content results in near complete reduction of central iron ion of the heme group, while its low-spin state and six-ligand coordination configuration are preserved. Based on the analysis of heme out-of-plane folding vibration near 568 cm(-1) (gamma(21)) and nu(48) mode at 633 cm(-1), it was demonstrated that the protein matrix tension on the heme group is relaxed upon incorporation of protein into Q(230) phase. Non-resonant Raman bands of difference spectra showed the preservation of alpha-helix secondary structure of Cyt c in the liquid-crystalline phase at relatively high (5 wt.%) content. The Cyt c induced spectroscopic changes of Phyt bands were found to be similar as decrease in temperature. (C) 2012 Elsevier Inc. All rights reserved.
  •  
34.
  •  
35.
  • Nylander, Tommy, et al. (författare)
  • Relationship between Structure and Fluctuations of Lipid Nonlamellar Phases Deposited at the Solid-Liquid Interface
  • 2017
  • Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 121:13, s. 2705-2711
  • Tidskriftsartikel (refereegranskat)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.
  •  
36.
  • Popescu, Georgeta, et al. (författare)
  • Liquid crystalline phases and their dispersions in aqueous mixtures of glycerol monooleate and glyceryl monooleyl ether
  • 2007
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 23:2, s. 496-503
  • Tidskriftsartikel (refereegranskat)abstract
    • The aqueous phase behavior of mixtures of 1-glycerol monooleate (GMO) and its ether analogue, 1-glyceryl monooleyl ether (GME) has been investigated by a combination of polarized microscopy, X-ray diffraction, and NMR techniques. Three phase diagrams of the ternary GMO/GME/water system have been constructed at 25, 40, and 55 degrees C. The results demonstrate that the increasing amount of GME favors the formation of the reversed phases, evidenced by the transformation of the lamellar and bicontinuous cubic liquid crystalline phases of the binary GMO/water system into reversed micellar or reversed hexagonal phases. For a particular liquid crystalline phase, increasing the GME content has no effect on the structural characteristics and hydration properties, thus suggesting ideal mixing with GMO. Investigations of dispersed nanoparticle samples using shear and a polymeric stabilizer, Pluronic F127, show the possibility of forming two different kinds of bicontinuous cubic phase nanoparticles by simply changing the GMO/GME ratio. Also NMR self-diffusion measurements confirm that the block copolymer, Pluronic F127, used to facilitate dispersion formation, is associated with nanoparticles and provides steric stabilization.
  •  
37.
  • Talaikis, Martynas, et al. (författare)
  • On the molecular interactions in lipid bilayer-water assemblies of different curvatures
  • 2019
  • Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 123:12, s. 2662-2672
  • Tidskriftsartikel (refereegranskat)abstract
    • This work concerns the importance of intermolecular interactions present in aqueous lipid assembly systems depending on the type of aggregates they form. We have studied aqueous mixtures of diglycerol monooleate, Capmul glycerol monoleate (GMO-50) and polyoxyethylene (20) sorbitan monooleate (Polysorbate 80, P80) using small-angle X-ray scattering (SAXS) measurements to reveal the structure of liquid crystalline phases. On the basis of the SAXS data, a phase diagram was constructed. We discuss the effect of curvature changes of the lipid-aqueous interface obtained by changing the water content and the temperature. The results are related to the intermolecular interactions, as revealed by Raman spectroscopy, with a focus on the bilayer type of system of different curvature and bilayer flexibility, namely, the lamellar phase, bicontinuous cubic phase, and sponge phase. All phases show large similarities in their chain conformation and head group interactions as revealed by the Raman spectra, arising from the fact that all three structures are formed by lipid bilayers. However, subtle differences in the molecular organization of the sponge phase were revealed by employing Raman difference spectroscopy and by analysis of key spectroscopic indicators, which show a less dense hydrocarbon chain packing compared to the inverse bicontinuous cubic or lamellar phase.
  •  
38.
  • Talaikyte, Z, et al. (författare)
  • Interactions of cyclic AMP and its dibutyryl analogue with a lipid layer in the aqueous mixtures of monoolein preparation and dioleoyl phosphatidylcholine as probed by X-ray diffraction and Raman spectroscopy
  • 2004
  • Ingår i: Journal of Biological Physics. - 0092-0606. ; 30:1, s. 83-96
  • Tidskriftsartikel (refereegranskat)abstract
    • Interactions of adenosine 3':5'-cyclic monophosphate (cAMP) and N-6,2'-O-dibutyryl-adenosine 3':5'-cyclic monophosphate (dbcAMP) with a lipid layer composed of monoolein-based preparation and dioleoyl phosphatidylcholine ( DOPC) were investigated by small-angle X-ray diffraction (SAXD) and Raman spectroscopy. The reversed hexagonal (H-II) MO/DOPC/H2O phase of 65:15:20 wt.% composition was selected as a reference system. SAXD revealed that entrapment (at the expense of water) of 3 wt.% cAMP into the reference system did not change the polymorphic form and structural parameters of the phase. The same content of dbcAMP induced the transition from the HII phase to the reversed bicontinuous cubic phase of space group Ia3d. This transition is explained by the increase of lipid head-group area due to the penetration of the acylated adenine group of dbcAMP into the polar/apolar region of lipid layer. The conclusion is supported by Raman spectroscopy, showing the disruption/weakening of hydrogen bonding in the MO/DOPC-based matrix at the N1- and N3-sites of the dbcAMP adenine ring. As distinct from dbcAMP, cAMP remains mostly in the water channels of the HII phase, although the phosphate residue of nucleotide interacts with the quaternary ammonium group of DOPC. Both nucleotides increase the population of gauche isomers in the DOPC choline group.
  •  
39.
  • Tiberg, Fredrik, et al. (författare)
  • Phase Behavior, Functions, and Medical Applications of Soy Phosphatidylcholine and Diglyceride Lipid Compositions
  • 2012
  • Ingår i: Chemistry Letters. - : The Chemical Society of Japan. - 0366-7022 .- 1348-0715. ; 41:10, s. 1090-1092
  • Tidskriftsartikel (refereegranskat)abstract
    • Lipid compositions with the ability to self-assemble into biocompatible nano- and mesostructured functional materials have many potential uses in modem medicine. By using two-component lipid systems, it is possible to tune the structure formation and related functional properties, e.g., the encapsulation and extended release of small molecules and peptides, by simply varying the ratio of the lipid building blocks. This is shown in detail for the binary phosphatidylcholine and diglyceride lipid systems, which are currently being used in multiple programs for the development of novel pharmaceuticals and marketed products.
  •  
40.
  • Valldeperas Badell, Maria, et al. (författare)
  • Sponge Phases and Nanoparticle Dispersions in Aqueous Mixtures of Mono- and Diglycerides
  • 2016
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 32:34, s. 8650-8659
  • Tidskriftsartikel (refereegranskat)abstract
    • The lipid liquid crystalline sponge phase (1,3) has the advantages that it is a nanoscopically bicontinuous bilayer network able to accommodate large amounts of water and it is easy to Manipulate due to its fluidity. This paper reports on the detailed characterization of L3 phases with water channels large enough to encapsulate bioactive macromolecules such as proteins. The aqueous phase behavior of a novel lipid mixture system, consisting of diglycerol monooleate (DGMO), and a mixture of mono-, di- and triglycerides (Capmul GMO50) was studied. In addition, sponge -like nanoparticles (NPs) stabilized by Polysorbate 80 (P80) were prepared based on the DGMO/GMO-50 system, and their structure was correlated with the phase behavior of the corresponding bulk system. These NPs were characterized by dynamic light scattering (DLS), angle X-ray scattering (SAXS) cryo-transmission electron microscopy (Cryo-TEM) and small angle X-ray scattering (SAXS) to determine their size, shape, and DGMO/GMO-50 ratio. In addition, the effect of P80 as stabilizer was investigated. We found that the NPs have aqueous pores with diameters up to 13 nm, similar to the ones in the bulk phase.
  •  
41.
  • Valldeperas, Maria, et al. (författare)
  • Encapsulation of Aspartic Protease in Nonlamellar Lipid Liquid Crystalline Phases
  • 2019
  • Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495. ; 117:5, s. 829-843
  • Tidskriftsartikel (refereegranskat)abstract
    • Encapsulation of proteins within lipid inverse bicontinuous cubic phases (Q2) has been widely studied for many applications, such as protein crystallization or drug delivery of proteins for food and pharmaceutical purposes. However, the use of the lipid sponge (L3) phase for encapsulation of proteins has not yet been well explored. Here, we have employed a lipid system that forms highly swollen sponge phases to entrap aspartic protease (34 kDa), an enzyme used for food processing, e.g., to control the cheese-ripening process. Small-angle x-ray scattering showed that although the L3 phase was maintained at low enzyme concentrations (≤15 mg/mL), higher concentration induces a transition to more curved structures, i.e., transition from L3 to inverse bicontinuous cubic (Q2) phase. The Raman spectroscopy data showed minor conformational changes assigned to the lipid molecules that confirm the lipid-protein interactions. However, the peaks assigned to the protein showed that the structure was not significantly affected. This was consistent with the higher activity presented by the encapsulated aspartic protease compared to the free enzyme stored at the same temperature. Finally, the encapsulation efficiency of aspartic protease in lipid sponge-like nanoparticles was 81% as examined by size-exclusion chromatography. Based on these results, we discuss the large potential of lipid sponge phases as carriers for proteins.
  •  
42.
  • Valldeperas, Maria, et al. (författare)
  • Enzyme encapsulation in nanostructured self-assembled structures : Toward biofunctional supramolecular assemblies
  • 2019
  • Ingår i: Current Opinion in Colloid & Interface Science. - : Elsevier. - 1359-0294 .- 1879-0399. ; 44, s. 130-142
  • Forskningsöversikt (refereegranskat)abstract
    • Enzymes have come into use for many new applications outside their natural biological environment, taking advantage of their high efficiency and selectivity as biocatalysts. Such new application often requires encapsulation to preserve the structure and activity of the enzyme, but also to regulate and control the activity. Here, we will discuss two types of encapsulation, soft matrices consisting of polar lipid liquid crystals and hard ordered mesoporous silica matrices. For both types of matrices, the challenge is to control the pore size of the matrices and the interaction with the matrix interface. Here, the polar lipid liquid crystals offer larger flexibility than silica, but on the other hand, it is considerably more sensitive to the environment.
  •  
43.
  • Valldeperas, Maria, et al. (författare)
  • Interfacial properties of lipid sponge-like nanoparticles and the role of stabilizer on particle structure and surface interactions
  • 2019
  • Ingår i: Soft Matter. - : ROYAL SOC CHEMISTRY. - 1744-683X .- 1744-6848. ; 15:10, s. 2178-2189
  • Tidskriftsartikel (refereegranskat)abstract
    • The advantage of using nonlamellar lipid liquid crystalline phases has been demonstrated in many applications, such as drug delivery, protein encapsulation and crystallisation. We have recently reported that a mixture of mono-and diglycerides is able to form sponge-like nanoparticles (L-3-NPs) with large enough aqueous pores to encapsulate macromolecules such as proteins. Here we use small angle neutron scattering (SANS) to reveal morphology, structural and chemical composition of these polysorbate 80 (P80) stabilized sponge phase nanoparticles, not previously known. Our results suggest that L-3-NPs have a core-shell sphere structure, with a shell rich in P80. It was also found that even if P80 is mostly located on the surface, it also contributes to the formation of the inner sponge phase structure. An important aspect for the application and colloidal stability of these particles is their interfacial properties. Therefore, the interfacial behaviour of the nanoparticles on hydrophilic silica was revealed by Quartz crystal microbalance with dissipation (QCM-D) and neutron reflectivity (NR). Adsorption experiments reveal the formation of a thin lipid layer, with the dimension corresponding to a lipid bilayer after L-3-NPs are in contact with hydrophilic silica. This suggests that the diglycerol monoleate/ Capmul GMO-50/P80 particles reorganize themselves on this surface, probably due to interactions between P80 head group and SiO2.
  •  
44.
  • Vandoolaeghe, Pauline, et al. (författare)
  • Interaction between Lamellar (Vesicles) and Nonlamellar Lipid Liquid-Crystalline Nanoparticles as Studied by Time-Resolved Small-Angle X-ray Diffraction
  • 2009
  • Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 25:7, s. 3999-4008
  • Tidskriftsartikel (refereegranskat)abstract
    • The kinetics of structure change when dispersions of two different types of lipid-based liquid-crystalline phases, one lamellar and one reversed, are mixed has been investigated using synchrotron small-angle X-ray diffraction and ellipsometry. The systems studied were (i) cubic-phase nanoparticles (CPNPs) based on glycerol monooleate (GMO) stabilized with a nonionic block copolymer, Pluronic F-127; (ii) CPNPs based on phytantriol (PtOH) stabilized with D-alpha-Tocopheryl polyethylene glycol 1000 succinate (Vitamin E TPGS); and (iii) hexagonal-phase nanoparticles (HPNPs) based on a lipid mixture of diglycerol monooleate/glycerol dioleate, stabilized by Pluronic F-127. Time-resolved small-angle X-ray diffraction was used to track structural changes within nonlamellar nanoparticles when they interact with uni- and multilamellar vesicles of dioleoylphosphatidylcholine and dipalmitoylphatidylcholine. The results are very dependent on the type of nanoparticles under investigation. For GMO-based CPNPs, a strong interaction is observed on mixing with vesicular dispersions that leads to large changes in unit size dimensions as well as a later transition from cubic to lamellar structure. These results are in good agreement with previous studies on the interaction of GMO-based CPNPs with planar bilayers using neutron reflectivity, where the diffraction peak shifted with time upon mixing. The structural changes are much less prominent for the PtOH-based CPNPs and the HPNPs upon mixing with phospholipid vesicles. These results are correlated with those from measurement studying interactions between the liquid-crystalline nanoparticles and supported phospholipid bilayers by ellipsometry. Also, here the GMO-based CPNPs show more pronounced and rapid adsorption and interaction with the supported bilayer surface than do the other types of nonlamellar nanoparticles. The interaction also depends on the bilayer properties, where significantly slower lipid mixing is observed for a bilayer in the gel state compared to a bilayer in the liquid-crystalline phase. This study is not only relevant for drug-delivery applications but also shows the potential of synchrotron small-angle X-ray diffraction in studying time-dependent structural changes as a consequence of the interaction between different lipid self-assembled aggregates in complex systems.
  •  
45.
  •  
46.
  • Wadsäter, Maria, et al. (författare)
  • Formation of Highly Structured Cubic Micellar Lipid Nanoparticles of Soy Phosphatidylcholine and Glycerol Dioleate and Their Degradation by Triacylglycerol Lipase
  • 2014
  • Ingår i: ACS Applied Materials and Interfaces. - : American Chemical Society (ACS). - 1944-8244 .- 1944-8252. ; 6:10, s. 7063-7069
  • Tidskriftsartikel (refereegranskat)abstract
    • Lipid nanoparticles of reversed internal phase structures, such as cubic micellar (I-2) 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 (I-2) 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 12 structure to structures of less negative curvature (2D hexagonal, bicontinuous cubic, and sponge), ultimately resulting in the formation of multilamellar vesicles.
  •  
47.
  • Wadsäter, Maria, et al. (författare)
  • Nonlamellar lipid liquid crystalline model surfaces for biofunctional studies
  • 2013
  • Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 9:37, s. 8815-8819
  • Tidskriftsartikel (refereegranskat)abstract
    • Nonlamellar lipid liquid crystalline (LC) bulk phases and dispersions show promise as functional nanostructured materials for potential use as controlled release matrices e. g. in pharmaceuticals. Herein, methods for preparing and characterizing thin films of lipid liquid crystalline phases on solid surfaces are presented. The thickness, hydration phase structure and surface topography of spin-coated films of mixtures of soy phosphatidylcholine and glycerol dioleate are characterized by means of spectroscopic ellipsometry, small angle X-ray diffraction and atomic force microscopy. Besides being useful as bioadhesive drug delivery systems, the lipid nonlamellar LC films produced may also be exploited as model surfaces for studying properties such as bioadhesion and biodegradation.
  •  
48.
  • Wadsäter, Maria, et al. (författare)
  • Structural effects of the dispersing agent polysorbate 80 on liquid crystalline nanoparticles of soy phosphatidylcholine and glycerol dioleate
  • 2015
  • Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 11:6, s. 1140-1150
  • Tidskriftsartikel (refereegranskat)abstract
    • Well-defined, stable and highly structured I-2 (Fd (3) over barm) 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 Fd (3) over barm 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.
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49.
  • Wadsäter, Maria, et al. (författare)
  • The lipolytic degradation of highly structured cubic micellar nanoparticles of soy phosphatidylcholine and glycerol dioleate by phospholipase A and triacylglycerol lipase.
  • 2018
  • Ingår i: Chemistry and Physics of Lipids. - : Elsevier. - 0009-3084 .- 1873-2941. ; 211, s. 86-92
  • Tidskriftsartikel (refereegranskat)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.
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