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Raffaele Mezzenga - One of the best experts on this subject based on the ideXlab platform.
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a macroscopic h and cl ions pump via reconstitution of ecclc membrane proteins in lipidic cubic Mesophases
Proceedings of the National Academy of Sciences of the United States of America, 2016Co-Authors: Chiara Speziale, Livia Salvati Manni, Cristina Manatschal, Ehud M Landau, Raffaele MezzengaAbstract:Functional reconstitution of membrane proteins within lipid bilayers is crucial for understanding their biological function in living cells. While this strategy has been extensively used with liposomes, reconstitution of membrane proteins in lipidic cubic Mesophases presents significant challenges related to the structural complexity of the lipid bilayer, organized on saddle-like minimal surfaces. Although reconstitution of membrane proteins in lipidic cubic Mesophases plays a prominent role in membrane protein crystallization, nanotechnology, controlled drug delivery, and pathology of diseased cells, little is known about the molecular mechanism of protein reconstitution and about how transport properties of the doped Mesophase mirror the original molecular gating features of the reconstituted membrane proteins. In this work we design a general strategy to demonstrate correct functional reconstitution of active and selective membrane protein transporters in lipidic Mesophases, exemplified by the bacterial ClC exchanger from Escherichia coli (EcClC) as a model ion transporter. We show that its correct reconstitution in the lipidic matrix can be used to generate macroscopic proton and chloride pumps capable of selectively transporting charges over the length scale of centimeters. By further exploiting the coupled chloride/proton exchange of this membrane protein and by combining parallel or antiparallel chloride and proton gradients, we show that the doped Mesophase can operate as a charge separation device relying only on the reconstituted EcClC protein and an external bias potential. These results may thus also pave the way to possible applications in supercapacitors, ion batteries, and molecular pumps.
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controlling molecular transport and sustained drug release in lipid based liquid crystalline Mesophases
Journal of Controlled Release, 2014Co-Authors: Alexandru Zabara, Raffaele MezzengaAbstract:Lipid-based lyotropic liquid crystals, also referred to as reversed liquid crystalline Mesophases, such as bicontinuous cubic, hexagonal or micellar cubic phases, have attracted deep interest in the last few decades due to the possibility of observing these systems at thermodynamic equilibrium in excess water conditions. This becomes of immediate significance for applications in the colloidal environment, such as in the food, cosmetic and pharmaceutical arenas. One possible application regarded as very promising is that of controlled delivery of functional ingredients. Different crystallographic structures of the lipid Mesophase give access to different diffusion coefficients and distinct diffusion modes. It becomes thus crucial to engineer the space group of the Mesophase in a controlled way, and ideally, in a stimuli-responsive manner. In this article we review the state of the art on diffusion and molecular transport in lipid-based Mesophases and we discuss recent contributions to the controlled delivery of molecules and colloids through these systems. In particular we focus on the different available strategies relying on either endogenous or exogenous stimuli to induce changes in the symmetry and transport properties of lipid-based Mesophases and we discuss the impact and implications this may have on controlled drug delivery.
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reconstitution of ompf membrane protein on bended lipid bilayers perforated hexagonal Mesophases
Chemical Communications, 2014Co-Authors: Alexandru Zabara, Renata Negrini, Patric Baumann, Ozana Onacafischer, Raffaele MezzengaAbstract:Membrane proteins have been reconstituted on lipid bilayers with zero mean-curvature (cubic phases or vesicles). Here we show that reconstitution of pore-forming membrane proteins can also occur on highly curved lipidic bilayers of reverse hexagonal Mesophases, for which the mean-curvature is significantly different from zero. We further show that the membrane protein provides unique topological interconnectivities between the aqueous nanochannels, significantly enhancing Mesophase transport properties.
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a reverse micellar Mesophase of face centered cubic fm3m symmetry in phosphatidylcholine water organic solvent ternary systems
Langmuir, 2013Co-Authors: Isabelle Martiel, Laurent Sagalowicz, Raffaele MezzengaAbstract:We report the formation of a reverse micellar cubic Mesophase of symmetry Fm3m (Q(225)) in ternary mixtures of soy bean phosphatidylcholine (PC), water, and an organic solvent, including cyclohexane, (R)-(+)-limonene, and isooctane, studied by small-angle X-ray scattering (SAXS) and oscillatory shear rheology at room temperature. The Mesophase structure consists of a compact packing of remarkably large reverse micelles in a face-centered cubic (fcc) lattice, a type of micellar packing not yet reported for reverse micellar Mesophases. Form factor fitting in the pure L2 phase and in the Fm3m-L2 coexistence region yields quantitative estimations of the PC interface rigidity. The compact Fm3m structure results mainly from release of lipid tail frustration and hard-sphere interactions between monodisperse micelles, as suggested by a comparison with the Fd3m structure found in the PC/water/α-tocopherol system.
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twofold light and magnetic responsive behavior in nanoparticle lyotropic liquid crystal systems
Langmuir, 2012Co-Authors: Jijo J Vallooran, Stephan Handschin, Sreenath Bolisetty, Raffaele MezzengaAbstract:We demonstrate the dual magnetic and light responsive nature of hybrid Mesophases constituted by Fe3O4 nanoparticles dispersed in lipid-based lyotropic liquid crystals (LC). When subjected to an external magnetic field in the Mesophase isotropic state, the nanoparticles aggregate and orient along the magnetic field direction, and upon cooling the system through the disorder–order transition the aggregates drive the orientation of the Mesophase via heterogeneous nucleation; furthermore, order–disorder transitions in the lipidic Mesophase can be triggered by Fe3O4-induced photothermal effect under visible light exposure. Both the orientational order and the photothermal effect of the hybrid Mesophase can be tuned by the nanoparticle content, offering a general route for controlled assembly of complex fluids with combined magnetic and light responsiveness.
Jose Luis Serrano - One of the best experts on this subject based on the ideXlab platform.
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bent core liquid crystal phases promoted by azo containing molecules from monomers to side chain polymers
RSC Advances, 2014Co-Authors: Nelida Gimeno, Inmaculada C Pintre, Marta Martinezabadia, Jose Luis SerranoAbstract:New bent-core monomethacrylates and their side-chain polymers containing the 3,4′-biphenylene moiety as a central core and both all-ester and azo-ester lateral structures have been prepared and characterized. Attractive results concerning the scarcely studied side-chain homo- and copolymers, synthesized either by in situ polymerization in the Mesophase or ATRP in solution, are reported. The research is focused on the synthesis of these materials and the effect that structural changes, such as the number of aromatic rings (5 or 6), the presence of –NN– versus –COO– links on the lateral structures, and the relative positions of the reactive groups, have on the liquid crystal properties of these new bent-core based-materials. The mesomorphic behavior of these low and high-molecular compounds, and also of the synthetic intermediates with bulky terminal bromo-substituents, have been characterized by POM, XRD, DSC and electrooptic studies, showing that the majority of these new molecules have the ability to organize forming non classical lamellar or columnar Mesophases. Significant stabilization of the lamellar SmCP Mesophase ranges is achieved upon polymerization in comparison to the monomers and interestingly the vitrification of these supramolecular organizations occurs at room temperature.
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discotic liquid crystalline poly propylene imine dendrimers based on triphenylene
Journal of the American Chemical Society, 2005Co-Authors: Mark Mckenna, Joaquin Barbera, Mercedes Marcos, Jose Luis SerranoAbstract:The design, synthesis, and mesomorphic properties of a new series of homodendrimers consisting of the commercially available poly(propylene imine) (PPI) dendrimers (G = 1−5), PPI−(NH2)n (n = 4, 8, 16, 32, 64), functionalized with a discotic triphenylene moiety are reported. The liquid crystalline behavior was investigated by means of differential scanning calorimetry (DSC), polarizing-light optical microscopy (POM), and X-ray diffractometry (XRD). All of the homodendrimers showed mesomorphic properties, with the second to fifth generations giving a hexagonal columnar Mesophase (Colh) and the first generation a rectangular columnar Mesophase (Colr). The X-ray study reveals that these Mesophases show a highly ordered structure with segregation of triphenylenes and dendrimers into separate columns and a regular stacking distance inside the triphenylene columns. GPC analysis showed that the dendrimers had good monodispersity and MALDI-TOF studies of the first three generations gave good evidence that all of t...
Alexandru Zabara - One of the best experts on this subject based on the ideXlab platform.
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predicting the release profile of small molecules from within the ordered nanostructured lipidic bicontinuous cubic phase using translational diffusion coefficients determined by pfg nmr
Nanoscale, 2017Co-Authors: Thomas G Meikle, Alexandru Zabara, Calum J Drummond, Charlotte E Conn, Frances SeparovicAbstract:The ordered nanostructured lipidic bicontinuous cubic phase has demonstrated potential as a drug release material, due to its ability to encapsulate a wide variety of compounds, which may undergo sustained, diffusion controlled release over time. Control of drug release has been shown to depend on the nanostructural parameters of the lipid Mesophase. Herein, the diffusion and release of two amino acids, encapsulated within a range of different lipidic cubic Mesophases are investigated. Pulsed-field gradient NMR was used to determine the diffusion coefficient of the encapsulated amino acid, which was found to be correlated with the nanoscale diameter of the water channels within the cubic Mesophase. This information was used to predict the release profiles of encapsulated compounds from within the cubic Mesophase, which was verified by directly measuring the release of each amino acid in vitro. Predicted release profiles tracked reasonably close to the measured release profiles, indicating that NMR determined diffusion measurements can be used to predict release profiles.
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controlling molecular transport and sustained drug release in lipid based liquid crystalline Mesophases
Journal of Controlled Release, 2014Co-Authors: Alexandru Zabara, Raffaele MezzengaAbstract:Lipid-based lyotropic liquid crystals, also referred to as reversed liquid crystalline Mesophases, such as bicontinuous cubic, hexagonal or micellar cubic phases, have attracted deep interest in the last few decades due to the possibility of observing these systems at thermodynamic equilibrium in excess water conditions. This becomes of immediate significance for applications in the colloidal environment, such as in the food, cosmetic and pharmaceutical arenas. One possible application regarded as very promising is that of controlled delivery of functional ingredients. Different crystallographic structures of the lipid Mesophase give access to different diffusion coefficients and distinct diffusion modes. It becomes thus crucial to engineer the space group of the Mesophase in a controlled way, and ideally, in a stimuli-responsive manner. In this article we review the state of the art on diffusion and molecular transport in lipid-based Mesophases and we discuss recent contributions to the controlled delivery of molecules and colloids through these systems. In particular we focus on the different available strategies relying on either endogenous or exogenous stimuli to induce changes in the symmetry and transport properties of lipid-based Mesophases and we discuss the impact and implications this may have on controlled drug delivery.
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reconstitution of ompf membrane protein on bended lipid bilayers perforated hexagonal Mesophases
Chemical Communications, 2014Co-Authors: Alexandru Zabara, Renata Negrini, Patric Baumann, Ozana Onacafischer, Raffaele MezzengaAbstract:Membrane proteins have been reconstituted on lipid bilayers with zero mean-curvature (cubic phases or vesicles). Here we show that reconstitution of pore-forming membrane proteins can also occur on highly curved lipidic bilayers of reverse hexagonal Mesophases, for which the mean-curvature is significantly different from zero. We further show that the membrane protein provides unique topological interconnectivities between the aqueous nanochannels, significantly enhancing Mesophase transport properties.
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tuning in meso crystallized lysozyme polymorphism by lyotropic liquid crystal symmetry
Langmuir, 2011Co-Authors: Alexandru Zabara, Idit Amaryuli, Raffaele MezzengaAbstract:Lipid-based lyotropic liquid crystals (LLCs) show great potential for applications in fields as diverse as food technology, cosmetics, pharmaceutics, or structural biology. Recently, these systems have provided a viable alternative to the difficult process of membrane protein crystallization, owing to their similarities with cell membranes. Nonetheless, the process of in-meso crystallization of proteins still remains poorly understood. In this study, we demonstrate that in-meso crystal morphologies of lysozyme (LSZ), a model hydrophilic protein, can be controlled by both the composition and symmetry of the Mesophase, inferring a possible general influence of the LLC space group on the protein crystal polymorphism. Lysozyme was crystallized in-meso from three common LLC phases (lamellar, inverse hexagonal, and inverse bicontinuous cubic) composed of monolinolein and water. Different mixing ratios of Mesophase to crystallization buffer were used in order to tune crystallization both in the bulk Mesophase and in excess water conditions. Two distinct mechanisms of crystallization were shown to take place depending on available water in the Mesophases. In the bulk Mesophases, protein nuclei form and grow within structural defects of the Mesophase and partially dehydrate the system inducing order-to-order transitions of the liquid crystalline phase toward stable symmetries in conditions of lower hydration. The formed protein crystals eventually macrophase separate from the Mesophase allowing the system to reach its final symmetry. On the other hand, when excess water is available, protein molecules diffuse from the water channels into the excess water, where the crystallization process can take place freely, and with little to no effect on the structure and symmetry of the lyotropic liquid crystals.
Sabine Laschat - One of the best experts on this subject based on the ideXlab platform.
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headgroups versus symmetry in congruent ion pairs which one does the job in mesomorphic aryl guanidinium and aryl imidazolium sulphonates
Liquid Crystals, 2014Co-Authors: Martin Butschies, Markus Mansueto, Johannes Christian Haenle, Christof Schneck, Stefan Tussetschlager, Frank Giesselmann, Sabine LaschatAbstract:Ionic liquid crystals based on congruent ion pairs composed of mesogenic cations and anions of similar shape provide an attractive tool for the tuning of Mesophase properties. Here, the effect of the number and symmetry of lipophilic side chains and the type of head group on the phase type and thermal Mesophase properties was probed by the synthesis and investigation of two series of novel guanidinium and imidazolium sulphonates and compared with the corresponding iodides. Their mesomorphic properties were examined via differential scanning calorimetry, optical polarising microscopy and X-ray diffraction. While derivatives bearing only one alkoxy chain in either cation or anion with up to three alkoxy chains in total within the ion pairs display smectic A Mesophases, hexagonal columnar Mesophases were observed for all other compounds with four or five alkoxy chains totally irrespective of the head group. However, with increasing steric bulk, i.e. with a total of six alkoxy chains, the symmetry of the aryl...
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ionic liquid crystals derived from amino acids
Chemistry: A European Journal, 2013Co-Authors: Markus Mansueto, Wolfgang Frey, Sabine LaschatAbstract:Novel chiral amino acid derived ionic liquid crystals with amine and amide moieties as spacers between the imidazolium head group and the alkyl chain were synthesised. The key step in the synthesis utilised the relatively uncommon SO3 leaving group in a microwave-assisted reaction. The mesomorphic properties of the mesogens were determined by differential scanning calorimetry (DSC), polarising optical microscopy (POM) and X-ray diffraction. All liquid crystalline salts exhibit a smectic A Mesophase geometry with strongly interdigitated bilayer structures. An increase of the steric bulk of the stereogenic centre hindered the formation of Mesophases. In case of phenylalanine-derived derivatives a mesomorphic behaviour was observed for shorter alkyl chains as compared to other amino acid derivatives indicating an additional stabilising effect by the phenyl moiety.
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counterion effects on the columnar Mesophases of triphenylene substituted 18 crown 6 ethers is flatter better
Chemistry: A European Journal, 2010Co-Authors: Martin Kaller, Christopher Deck, Annette Meister, Gerd Hause, Angelika Baro, Sabine LaschatAbstract:The twisted lateral tetraalkyloxy ortho-terphenyl units in dibenzo[18]crown-6 ethers 1 a–f were readily converted into the flat tetraalkyloxytriphenylene systems 2 a–f by oxidative cyclization with FeCl3 in nitromethane. Reactions of the latter with potassium salts gave complexes KX⋅2, which displayed mesomorphic properties. The aromatization increased both the clearing and melting points; the Mesophase stabilities, however, were mainly influenced by the respective anions upon complexation with various potassium salts. In contrast, the alkyl chain lengths played only a secondary role. Among the potassium complexes of triphenylene-substituted crown ethers KX⋅2, only those with the soft anions I− and SCN− displayed Mesophases with expanded phase temperature ranges of 93 °C and 132 °C (for KX⋅2 e), respectively, as compared to the corresponding o-terphenyl-substituted crown ether complexes KI⋅1 e (ΔT=51 °C) and KSCN⋅1 e (plastic crystal phase). Anions such as Br−, Cl−, and F− decreased the Mesophase stability, and PF6− led to complete loss of the mesomorphic properties of KPF6⋅2 although not for KPF6⋅1. For crown ether complexes KX⋅2 (X=F, Cl, Br, I, BF4, and SCN), columnar rectangular Mesophases of different symmetries (c2 mm, p2 mg, and p2 gg) were detected. In contrast to findings for the twisted o-terphenyl crown ether complexes KX⋅1, the complexation of the flat triphenylene crown ethers 2 with KX resulted in the formation of organogels. Characterization of the organogel of KI⋅2 e in CH2Cl2 revealed a network of fibers.
Calum J Drummond - One of the best experts on this subject based on the ideXlab platform.
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predicting the release profile of small molecules from within the ordered nanostructured lipidic bicontinuous cubic phase using translational diffusion coefficients determined by pfg nmr
Nanoscale, 2017Co-Authors: Thomas G Meikle, Alexandru Zabara, Calum J Drummond, Charlotte E Conn, Frances SeparovicAbstract:The ordered nanostructured lipidic bicontinuous cubic phase has demonstrated potential as a drug release material, due to its ability to encapsulate a wide variety of compounds, which may undergo sustained, diffusion controlled release over time. Control of drug release has been shown to depend on the nanostructural parameters of the lipid Mesophase. Herein, the diffusion and release of two amino acids, encapsulated within a range of different lipidic cubic Mesophases are investigated. Pulsed-field gradient NMR was used to determine the diffusion coefficient of the encapsulated amino acid, which was found to be correlated with the nanoscale diameter of the water channels within the cubic Mesophase. This information was used to predict the release profiles of encapsulated compounds from within the cubic Mesophase, which was verified by directly measuring the release of each amino acid in vitro. Predicted release profiles tracked reasonably close to the measured release profiles, indicating that NMR determined diffusion measurements can be used to predict release profiles.
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exploring the structural relationship between encapsulated antimicrobial peptides and the bilayer membrane mimetic lipidic cubic phase studies with gramicidin a
RSC Advances, 2016Co-Authors: Calum J Drummond, Thomas G Meikle, Charlotte E Conn, Frances SeparovicAbstract:Lipid based bicontinuous cubic Mesophases provide a low-cost, robust membrane mimetic nanomaterial which allows for the incorporation of membrane peptides and proteins. However, the relationship between the mesostructure of the host lipidic bicontinuous Mesophase, the chemical structure of its constituents, and the secondary structure of encapsulated biomolecules is complex, and at present largely unclear. Here we have examined the effects of adding gramicidin A′, an anti-microbial peptide, to lipidic bicontinuous cubic phases composed of a number of different lipids. We demonstrate, using a combination of synchrotron small angle X-ray scattering and circular dichroism, that fundamental physicochemical parameters of the lipid Mesophase impact both the structural response to peptide addition, and the conformation of the encapsulated peptide. We have rationalised the results with reference to hydrophobic mismatch, the putative lateral pressure profile and the intrinsic surface curvature of each lipid system. Results should be of use for several applications of hybrid peptide-lipid materials including peptide based drug delivery and the design of in meso crystallization trials.
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linking molecular ion structure solvent mesostructure the solvophobic effect and the ability of amphiphiles to self assemble in non aqueous liquids
Faraday Discussions, 2013Co-Authors: Emmy C Wijaya, Tamar L Greaves, Calum J DrummondAbstract:Sixteen non-ionic molecular solvents have been found to exhibit the solvophobic effect and to support the formation of amphiphile self-assembly Mesophases. The solvents were low molecular weight polar solvents which contained various combinations of amine, hydroxyl or ether moieties with relatively small proportions of hydrocarbon unit constituents. The studied amphiphiles were hexadecyltrimethylammonium bromide (CTAB), hexadecylpyridinium bromide (C16PyrBr) and tetraethylene glycol monohexadecyl ether (C16E4). Lyotropic liquid crystal Mesophases with lamellar, normal hexagonal and normal bicontinuous cubic, with ordered one-, two- and three-dimensional periodic structure respectively, were identified in CTAB and C16PyrBr systems by using cross-polarised optical microscopy (CPOM). Mesophase diversity and thermal stability ranges correlated to the Gordon parameter (G) value, a proxy for the solvent cohesive energy density. Infrared spectroscopy confirmed that all the studied molecular solvents were associative liquids. Solvent mesostructure was studied by synchrotron small angle X-ray scattering. The small sub-set of neat solvents which were mesostructured, with polar and non-polar domain segregation, displayed the lowest G values, and amongst the lowest Mesophase diversity and thermal stability ranges. It has been established that the G value is a good indicator of whether or not a molecular solvent is likely to behave as a co-surfactant, residing within the amphiphile–solvent interfacial region of self-assembled objects, thereby influencing specific Mesophase structure formation. Structure–property behaviour has been explored and shows that beneficial solvent features for serving as amphiphile-self assembly media, with the potential for rich Mesophase diversity, include the presence of hydroxyl > amine > ether moieties, while methyl moieties have an adverse effect larger than that of methylene moieties.
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positron annihilation lifetime spectroscopy pals as a characterization technique for nanostructured self assembled amphiphile systems
Journal of Physical Chemistry B, 2009Co-Authors: Aurelia W Dong, C Pascualizarra, Steven J Pas, Anita J Hill, Ben J Boyd, Calum J DrummondAbstract:Positron annihilation lifetime spectroscopy (PALS) has potential as a novel rapid characterization method for self-assembly amphiphile systems; however, a lack of systematic correlation of PALS parameters with structural attributes has limited its more widespread application. In this study, using the well-characterized phytantriol/water and the phytantriol/vitamin E acetate/water self-assembly amphiphile systems, the impact of systematic structural changes controlled by changes in composition and temperature on PALS parameters has been studied. The PALS parameters (orthopositronium (oPs) lifetime and intensity signatures) were shown to be sensitive to the molecular packing and mobility of the self-assembled lipid molecules in various lyotropic liquid crystalline phases, enabling differentiation between liquid crystalline structures. The oPs lifetime, related to the molecular packing and mobility, is correlated with rheological properties of the individual Mesophases. The oPs lifetime links the lipid chain packing and mobility in the various Mesophases to resultant macroscopic properties, such as permeability, which is critical for the use of these Mesophase structures as diffusion-controlled release matrices for active liposoluble compounds.
