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ABSTRACT: The antioxidant gallic acid (GA) has been incorporated into cotton (CO) and polyamide (PA) through two different vehicles, that is, liposomes and mixed micelles, and their respective absorption/desorption processes have been studied. Moreover, in vitro percutaneous absorption tests of different cosmetotextiles have been performed to demonstrate antioxidant penetration within the layers of the skin. When GA was embedded into the cosmetotextiles, it always promoted a reservoir effect that was much more marked than that observed for polyamide. Similar penetration was observed in the textiles treated with GA in mixed micelles or liposomes in such compartments of the skin as the stratum corneum, epidermis, and even the dermis. GA was detected in receptor fluid only when CO was treated with MM. This methodology may be useful in verifying how encapsulated substances incorporated into textile materials penetrate human skin. Indeed, such materials can be considered strategic delivery systems that release a given active compound into the skin at specific doses.
Journal of drug delivery. 01/2013; 2013:456248.
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ABSTRACT: Systems formed by mixtures of the phospholipids dioleoylphosphatidylcholine (DOPC) and dihexanoylphosphatidylcholine (DHPC) were characterized by use of differential scanning calorimetry, small angle X-ray scattering and two electron-microscopy techniques, freeze fracture electron microscopy and cryogenic transmission electron microscopy. These techniques allowed for the determination of the size, morphology, structural topology, self-assembly and thermotropic behavior of the nanostructures present in the mixtures. The interaction between the two phospholipids provides curvatures, irregularities and the increase of thickness and flexibility in the membrane. These effects led to the formation of different aggregates with a differential distribution of both phospholipids. The effect of these systems on the skin in vivo was evaluated by measurement of the biophysical skin parameters. Our results show that the DOPC/DHPC application induces a decrease in the permeability and in the hydration of the tissue. These effects in vivo are related to different microstructural changes promoted by these systems in the skin in vitro, published in a recent work. The fundamental biophysical analyses of DOPC/DHPC systems contribute to our understanding of the mechanisms that govern their interaction with the skin.
Biophysics of Structure and Mechanism 12/2012; · 2.44 Impact Factor
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ABSTRACT: Bicellar systems are a fascinating category of versatile lipid assemblies that comprise bilayered disk-shaped nanoaggregates formed in water by long and short alkyl chain phospholipids. Bicelles bridge the gap between micelles and lipid vesicles by combining the attractive properties of both systems. These structures have recently been proposed in dermatological, cosmetic and pharmaceutical applications. Two new binary bicellar systems composed of cholesterol sulphate (SCHOL) and long-chain phospholipids (dimyristoyl-phosphatidylcholine, DMPC, or dipalmitoyl-phosphatidylcholine, DPPC) are characterised herein by differential scanning calorimetry, fluorescence spectroscopy, X-ray scattering and microscopy. Additionally, a comparative study on skin treated with the new SCHOL systems (DMPC/SCHOL and DPPC/SCHOL) and classic DHPC systems (DMPC/DHPC and DPPC/DHPC) was performed. These studies were conducted to determinate how deeply bicelles penetrate into the skin and the extension of their effect on the phase behaviour of stratum corneum (SC) lipids using attenuated total reflectance-Fourier transform infrared spectroscopy and two-photon excitation fluorescence microscopy. Our results show that SCHOL modified the typical discoidal morphology and the phase behaviour of the systems, inducing coexistence of two phases, liquid-ordered and ripple phases. The effect of the systems on SC lipids depends on their composition and is related to the fluidity of the SC lipid alkyl chains. Thus, systems with DMPC induced more disorder in SC lipids than systems with DPPC, and SCHOL did not modify the lipid arrangement. Perdeuterated systems in the infrared spectroscopy technique supported a different distribution in the tissue for every system. DMPC systems were primarily at the first layers of the SC, whereas DPPC systems were more widely distributed. Systems with SCHOL had enhanced distribution and penetration of bicellar systems throughout the SC.
Physical Chemistry Chemical Physics 09/2012; 14(42):14523-33. · 3.57 Impact Factor
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ABSTRACT: In this work a new composition (dioleylphosphatidylcholine, DOPC, and dihexanoylphosphocholine, DHPC) is used to form the bicellar system and to evaluate their effect on stratum corneum (SC) lipids. Through this article, "bicellar system" will refer to a lipid binary system in which lipids are self-assembled forming different nanostructures. DOPC/DHPC system is characterized by dynamic light scattering and cryo-transmission electron microscopy showing two different nanostructures: unilamellar vesicles and tubular structures. In order to study the SC lipid organization attenuated total reflectance Fourier transform infrared spectroscopy, freeze-substitution applied to transmission electron microscopy and X-ray scattering are used. This work compares for the first time the use of two different X-ray scattering methods, transmission with synchrotron radiation and grazing incidence with conventional source, for skin studies. Our results indicate that vesicle-shaped structures remain adhered to the SC surface being unable to penetrate into the skin probably due to their large and voluminous size, while a proportion of structures could have interaction with SC lipids increasing the lamellar organization. Thus, the different nanostructures present in the system have different effects on SC lipids. The appropriate combination of both effects and the possibility to incorporate drugs offer a range of possibilities for the DOPC/DHPC system in development for skin care products.
Molecular Pharmaceutics 03/2012; 9(3):482-91. · 4.78 Impact Factor
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ABSTRACT: Bicelles are discoidal phospholipid nanostructures at high lipid concentrations. Under dilute conditions, bicelles become larger and adopt a variety of morphologies. This work proposes a strategy to preserve the discoidal morphology of bicelles in environments with high water content. Bicelles were formed in concentrated conditions and subsequently encapsulated in liposomes. Later dilution of these new structures, called bicosomes, demonstrated that lipid vesicles were able to isolate and protect bicelles entrapped inside them from the medium. Characterization of systems before and after dilution by dynamic light-scattering spectroscopy and cryo-transmission electron microscopy showed that free bicelles changed in size and morphology, whereas encapsulated bicelles remained unaltered by the effect of dilution. Free and entrapped bicelles (containing the paramagnetic contrast agent gadodiamide) were injected into rat brain lateral ventricles. Coronal and sagittal visualization was performed by magnetic resonance imaging. Whereas rats injected with free bicelles did not survive the surgery, those injected with bicosomes did, and a hyperintensity effect due to gadodiamide was observed in the cerebrospinal fluid. These results indicate that bicosomes are a good means of preserving the morphology of bicelles under dilution conditions.
Biophysical Journal 07/2010; 99(2):480-8. · 3.65 Impact Factor
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ABSTRACT: This work evaluates the relation between the composition and the self-assembly of some lipid aggregates with their effects on the skin. To this end, liposomes, bicelles and micelles formed by dipalmitoylphosphatidylcholine (DPPC), dimyristoylphosphatidylcholine (DMPC) and dihexanoylphosphatidylcholine (DHPC) were characterized by electron microscopy and dynamic light scattering techniques, and applied on the skin. The results revealed that nanostructures with similar assembly but different composition caused different effects on the skin parameters. In general, samples containing DMPC affected the barrier function to a greater extent than systems containing DPPC. Additionally, our results showed that samples with the same lipid composition but different assembly exerted different effects on the skin. Liposomes decreased or did not modify the transepidermal water loss (TEWL), while bicelles and micelles increased this parameter. Hydration of the skin diminished especially after the application of micellar and bicellar samples. In vitro experiments showed structures like vesicles inside cutaneous SC (stratum corneum) incubated with DPPC/DHPC bicelles. These structures were not detected in SC samples incubated with DMPC/DHPC bicelles probably due to the different thermotropic behavior of DMPC and DPPC at physiological temperatures. Results reported in this work should be considered in terms of design of more efficient and specific skin delivery systems.
Molecular Pharmaceutics 06/2009; 6(4):1237-45. · 4.78 Impact Factor
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ABSTRACT: The eosinophil cationic protein (ECP) is an antipathogen protein involved in the host defense system. ECP displays bactericidal and membrane lytic capacities [Carreras et al. (2003) Biochemistry 42, 6636-6644]. We have now characterized in detail the protein-membrane interaction process. All observed fluorescent parameters of the wild type and single-tryptophan-containing mutants, as well as the results of decomposition analysis of protein fluorescence, suggest that W10 and W35 belong to two distinct spectral classes I and III, respectively. Tryptophan residues were classified and assigned to distinct structural classes using statistical approaches based on the analysis of tryptophan microenvironment structural properties. W10 belongs to class I and is buried in a relative nonpolar, nonflexible protein environment, while W35 (class III) is fully exposed to free water molecules. Tryptophan solvent exposure and the depth of the protein insertion in the lipid bilayer were monitored by the degree of protein fluorescence quenching by KI and brominated phospholipids, respectively. Results indicate that W35 partially inserts into the lipid bilayer, whereas W10 does not. Further analysis by electron microscopy and dynamic light scattering indicates that ECP can destabilize and trigger lipid vesicle aggregation at a nanomolar concentration range, corresponding to about 1:1000 protein/lipid ratio. No significant leakage of the vesicle aqueous content takes place below that protein concentration threshold. The data are consistent with a membrane destabilization "carpet-like" mechanism.
Biochemistry 02/2007; 46(3):720-33. · 3.42 Impact Factor
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ABSTRACT: Polarised optical microscopy (POM) and X-ray diffraction techniques were applied to intercellular lipids extracted from wool to study their structural arrangement in order to determine their role in the diffusion properties of wool fibre. Intercellular wool lipids (IWL) arranged as concentrated liposomes were shown to be a good intercellular lipid model, allowing their study by X-ray diffraction techniques. The results confirm that intercellular lipids of wool fibre are organised in a lamellar structure of 5.0-8.0 nm width, termed beta-layer, which had been assumed to be lipids arranged as a bilayer. Structurally, internal wool lipids are distributed at least in two domains at low temperatures: an ordered phase made up of ceramides and free fatty acids (FFA) alone, arranged in crystal orthorhombic states separately, and a liquid crystal state when mixed together. At 40 degrees C there is a reversible phase transition produced by the melt of the crystal orthorhombic states, whereas the liquid crystal state remains until 65 degrees C.
Chemistry and Physics of Lipids 08/2004; 130(2):159-66. · 2.57 Impact Factor
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ABSTRACT: Thermotropic physicochemical techniques such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and electron paramagnetic resonance (EPR) were applied to liposomes made up of internal wool lipids. These vesicles can be regarded as a model of wool membranes. Differences in fluidity obtained from EPR allow us to deduce a high rigidity of the polar external section of the vesicle in contrast to the high fluidity of the hydrophobic internal section, which accounts for the thermotropic properties of the liposome. The coincidence of the thermotropic changes obtained with the EPR, FTIR, and DSC techniques allows us to infer a reversible phase transition temperature in the range of 30−40 °C, indicating a transition from a mixture of hexagonal gel−liquid crystal state to a single liquid crystal state.
04/2000;
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ABSTRACT: Referencia OEPM: P9901541.-- Fecha de solicitud: 09/07/1999.-- Titular: Consejo Superior de Investigaciones Científicas (CSIC). Composiciones y uso extracto de lípidos internos de la lana en la preparación de productos para el tratamiento y cuidado de la piel. Se describe el uso de extractos de los lípidos internos de las fibras de lana, con un contenido en ceramidas de al menos un 15% en peso, para preparar composiciones, farmacéuticas o cosméticas para el tratamiento y cuidado de la piel. Los extractos objeto de la invención manifiestan excelentes cualidades para mejorar de manera sostenida y prolongada el efecto de barrera de la piel contra las agresiones externas, así como una buena capacidad para mantener el grado de hidratación de la misma. Dichas cualidades son incluso superiores a las que se obtienen con composiciones lipídicas que contienen ceramida III, que imitan la propia del stratum corneum de la piel humana. Peer reviewed
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ABSTRACT: 10 pages, 9 figures. Bicelles are discoidal aggregates formed by a flat dimyristoyl-glycero-phosphocholine (DMPC) bilayer, stabilized by a rim of dihexanoylglycero-phosphocholine (DHPC) in water. Given the structure, composition and the dimensions of these aggregates around 10–50 nm diameter, their use for topical applications is a promising strategy. This work evaluates the effect of DMPC/DHPC bicelles with molar ratio (2/1) on intact skin. Biophysical properties of the skin, such as transepidermal water loss (TEWL), elasticity, skin capacitance and irritation were measured in healthy skin in vivo. To study the effect of the bicellar systems on the microstructure of the stratum corneum (SC) in vitro, pieces of native tissue were treated with the aforementioned bicellar system and evaluated by freeze substitution applied to transmission electron microscopy (FSTEM). Our results show that bicelles increase the TEWL, the skin elastic parameters and, decrease skin hydration without promoting local signs of irritation and without affecting the SC lipid microstructure. Thus, a permeabilizing effect of bicelles on the skin takes place possibly due to the changes in the phase behaviour of the SC lipids by effect of phospholipids from bicelles. The authors would like to thank Pedro González from Transtechnics S.L. for providing technical and financial support for this project. We acknowledge Dr. Ana Linares for her expert assistance on the NMR experiments and to Sonia Ruiz and Elisenda Casals for helping in TEM. We are also indebted to the volunteers who participated in this trial. Peer reviewed
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ABSTRACT: 5 pages, 3 figures. Disperse dyes are very hydrophobic molecules that in their commercial form are usually milled in the presence of large amounts of dispersing agents (synthetic surfactants). Other dispersing agents are added as auxiliaries during the dyeing process. These synthetic surfactants were substituted for liposomes prepared with phosphatidylcholine, a well-known biological surfactant of natural origin which is environmentally friendly, and liposomes were studied as a dispersing agent in polyester dyeing. The physicochemical behaviour of dye dispersion was analysed by two experimental measurements: the aggregation process of dye particles by filtration of dispersion and the determination of the turbidity ratio. The results obtained show the usefulness of liposomes as a dispersing auxiliary in a dyeing process, avoiding aggregation of dye molecules at high temperatures. Moreover, polyester dyeing shows similar final exhaustions, approximately 90%, at different kinetics, when liposomes are used. The authors are indebted to Ms I. Yuste and Mr G. von Knorring for technical support. Thanks are also due to EMEQUIMICA for supplying auxiliary products and to Mr S. Serra from Tints Enrich SL for his support and technical advice. Peer reviewed
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ABSTRACT: 9 pages, 7 figures.-- PMID: 17292323 [PubMed].-- Online version published Dec 23, 2006. A new arrangement of proteins and lipids of stratum corneum (SC) cornified envelope (CE) is proposed. The chemical analysis of CE revealed the presence of free fatty acids (FFA), ceramides (Cer), and important percentages of glutamic acid/glutamine (Glx) and serine (Ser) residues. The molecular structure of these components suggests the existence of covalent links not only between Cer and Glx but also between FFA and Ser. The protein distribution of extracellular surface of CE, i.e., the proteins that could be involved in the bonds with lipids, was studied using post- and preembedding immunolabeling electron microscopy. Some loricrin (protein rich in Ser) was detected in the outermost part of the CE protein layer. The external arrangement of some domains of this protein may give rise to form linkages with FFA, yielding further insight into the CE arrangement in which Cer–Glx bonds and FFA–Ser bonds would be involved. Although the importance of fatty acids in the cohesion and barrier function of SC has been widely demonstrated, their role could be associated not only to the presence of these lipids in the intercellular lamellae but also in the CE, in the same way that Cer. The authors would like to thank Pedro González from Transtechnics S.L. for providing technical and financial support for this project. We are also grateful to Dr. Jaime Notario for providing human skin samples from the Universitary Hospital “Principes de España”, Barcelona, Spain. We also thank Sonia Ruíz and Marta Taulés for helping in TEM work and Mr. G. von Knorring for expert technical assistance. Peer reviewed
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ABSTRACT: 9 pages, 4 figures, 1 table.-- Online version available Dec 3, 2007. This work describes the effects of the inclusion of ceramides with different chain lengths in the structure of bicelles formed by dimyristoylphosphocholine (DMPC) and dihexanoylphosphocholine (DHPC). By using a number of physical techniques we observed that the bicellar structures were affected by both the concentration and the type of ceramide. The P-31 nuclear magnetic resonance showed that inclusion of the short chain ceramide in the system slightly affects the phosphorus resonance whereas the inclusion of the long chain ceramide promotes the differentiation of the peaks. The decrease in the ceramide chain length is associated with a less miscibility in DMPC. The values of d-spacing obtained by small angle X-ray scattering suggest that ceramides are organized in domains along the DMPC bilayer. The bicellar system studied supported the inclusion of 10 mol% of the long chain ceramide. This inclusion increased the particle size but did not affect the integrity of the structures. Freeze-fracture electron microscopy and dynamic light scattering techniques showed small bicelles with diameters around 15–20 nm and a low polydispersity index for this system. The inclusion of 10 mol% of the short chain ceramide in the bicellar system resulted in the formation of aggregates with two different morphologies: small rounded structures 15–20 nm in diameter and elongated structures 40 nm in length. The inclusion of 20 mol% of either of these two ceramides resulted in the formation of bigger structures in the range of 60–100 nm together with small bicelles. This work was supported by a PhD grant subsidized by C.S.I.C. Peer reviewed
