RESUMEN

Some biological properties of violacein are believed to be associated with their interactions with lipid surfaces, encouraging research on the identification of membrane sites capable of drug binding. In this study, we investigated the interaction of violacein with cell membrane models represented by Langmuir monolayers of selected lipids: one representing healthy cellular membranes: dipalmitoylphosphatidylcholine, DPPC, and the other one representing tumorigenic cellular membranes, dipalmitoylphosphatidylserine, DPPS. It is shown that even small amounts of the compound affect the surface pressure-area isotherms as well as the surface vibrational spectra of the lipid monolayers, which points to a significant interaction. Such effects depend on the electrical charge of the monolayer-forming molecules, with the drug activity being particularly distinctive for negatively charged lipids in relation to zwitterionic lipids. Morphological analysis also suggests that violacein at the air-water interface is homogenized when incorporated in both lipids. Although the interaction of violacein with the lipids affects viscoelastic and structural properties of the Langmuir monolayer, it is not present permeability through lipid bilayers, as investigated using liposomes. These results therefore may have important implications in understanding how violacein acts on specific sites of the cellular membrane, and evidence the fact that the lipid composition of the monolayer modulates the interaction with the lipophilic drug.

Asunto(s)

1,2-Dipalmitoilfosfatidilcolina/química , Aire/análisis , Indoles/química , Liposomas/química , Fosfatidilserinas/química , Agua/química , Elasticidad , Interacciones Hidrofóbicas e Hidrofílicas , Liposomas/ultraestructura , Microscopía de Fuerza Atómica , Electricidad Estática , Propiedades de Superficie , Viscosidad

RESUMEN

The evaporation of liquid droplets deposited on a substrate is a very complex phenomenon. Driven by capillary and Marangoni flows, particle-particle and particle-substrate interactions, the deposits they leave are vestiges of such complexity. We study the formation of patterns during the evaporation of liposome suspension droplets deposited on a hydrophobic substrate at different temperatures. We observed that as we change the temperature of the substrate, a morphological phase transition occurs at a given temperature Tm. This temperature corresponds to the gel-fluid lipid melting transition of the liposome suspension. Optical microscopy and atomic force microscopy are used to study the morphology of the patterns. Based on the radial density profiles we found that all structures can be classified into two groups: patterns composed by nearly uniform deposition (below Tm) and prominent structures containing randomly distributed voids (above Tm).

Asunto(s)

1,2-Dipalmitoilfosfatidilcolina/química , Gotas Lipídicas/química , Liposomas/química , Fosfatidilgliceroles/química , Calorimetría , Interacciones Hidrofóbicas e Hidrofílicas , Gotas Lipídicas/ultraestructura , Liposomas/ultraestructura , Tamaño de la Partícula , Transición de Fase , Propiedades de Superficie , Temperatura

RESUMEN

The formation of significant proportions of liposomes during the preparation of dispersed cubic phase particles presents a problem in trying to understanding cubosome behavior with a view to use in applications such as drug delivery. In this study, the variables impacting on liposome formation during cubosome production were interrogated. Bottom-up (BU) and top-down (TD) approaches were employed to prepare submicron sized liquid crystalline dispersions (cubosomes) of phytantriol in water with varying amounts of Pluronic(®)F127 (F127) as a stabilizer. In the BU approach, ethanol was used as a hydrotrope and was later removed using a rotary evaporator, whereas in the TD approach the bulk liquid gel was dispersed using ultrasonication. We aimed at finding the optimum ratio of phytantriol-to-F127 resulting in stable, liposome-free dispersions, whether this depends on the preparation method and the resulting morphology of the particles. The average particle size and zeta potential of the samples were measured using dynamic light scattering (DLS). Cryogenic transmission electron microscopy (Cryo-TEM) images showed a substantial number of liposomes in addition to cubosomes in the dispersion containing 4-1 (w/w) phytantriol-to-F127 prepared by the BU approach compared to very low liposome content with the TD approach. The effects of the amount of F127 in both approaches, amount of ethanol on the BU method and temperature on the TD method were investigated using small-angle X-ray scattering (SAXS). The cubosomes displayed cubic double-diamond (Pn3m) internal structure with a lattice parameter of approximately 6nm. In summary using the TD approach, with 4:1 phytantriol:F127 provided stable cubosome dispersion with minimal liposome co-existence.

Asunto(s)

Alcoholes Grasos/química , Liposomas/química , Polietilenos/química , Polipropilenos/química , Microscopía por Crioelectrón , Liposomas/ultraestructura , Microscopía Electrónica de Transmisión , Dispersión del Ángulo Pequeño , Difracción de Rayos X

RESUMEN

Cell backpacks, or micron-scale patches of a few hundred nanometers in thickness fabricated by layer-by-layer (LbL) assembly, are potentially useful vehicles for targeted drug delivery on the cellular level. In this work, echogenic liposomes (ELIPs) containing the anticancer drug doxorubicin (DOX) are embedded into backpacks through electrostatic interactions and LbL assembly. Poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA)n , and poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/SPS)n film systems show the greatest ELIP incorporation of the films studied while maintaining the structural integrity of the vesicles. The use of ELIPs for drug encapsulation into backpacks facilitates up to three times greater DOX loading compared to backpacks without ELIPs. Cytotoxicity studies reveal that monocyte backpack conjugates remain viable even after 72 h, demonstrating promise as drug delivery vehicles. Because artificial vesicles can load many different types of drugs, ELIP containing backpacks offer a unique versatility for broadening the range of possible applications for cell backpacks.

Asunto(s)

Liposomas/farmacología , Monocitos/citología , Animales , Cationes , Adhesión Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Doxorrubicina/farmacología , Recuperación de Fluorescencia tras Fotoblanqueo , Liposomas/ultraestructura , Ratones , Monocitos/efectos de los fármacos , Monocitos/metabolismo , Nanopartículas/química , Nanopartículas/ultraestructura , Tamaño de la Partícula

RESUMEN

Cancer is one of the leading causes of death worldwide. Although several drugs are used clinically, some tumors either do not respond or are resistant to the existing pharmacotherapy, thus justifying the search for new drugs. Ursolic acid (UA) is a triterpene found in different plant species that has been shown to possess significant antitumor activity. However, UA presents a low solubility in aqueous medium, which presents a barrier to its biological applications. In this context, the use of liposomes presents a promising strategy to deliver UA and allow for its intravenous administration. In this work, long-circulating and pH-sensitive liposomes containing UA (SpHL-UA) were developed, and their chemical and physicochemical properties were evaluated. SpHL-UA presented adequate properties, including a mean diameter of 191.1 ± 6.4 nm, a zeta potential of 1.2 ± 1.4 mV, and a UA entrapment of 0.77 ± 0.01 mg/mL. Moreover, this formulation showed a good stability after having been stored for 2 months at 4 °C. The viability studies on breast (MDA-MB-231) and prostate (LNCaP) cancer cell lines demonstrated that SpHL-UA treatment significantly inhibited cancer cell proliferation. Therefore, the results of the present work suggest the applicability of SpHL-UA as a new and promising anticancer formulation.

Asunto(s)

Fenómenos Químicos , Portadores de Fármacos/química , Liposomas/química , Triterpenos/química , Triterpenos/farmacología , Línea Celular Tumoral , Supervivencia Celular/efectos de los fármacos , Femenino , Humanos , Concentración de Iones de Hidrógeno/efectos de los fármacos , Concentración 50 Inhibidora , Liposomas/ultraestructura , Masculino , Tamaño de la Partícula , Ácido Ursólico

RESUMEN

To evaluate the process parameters for the production of plasmid DNA/cationic liposome (pDNA/CL) complexes in microfluidic systems, we studied two microfluidic devices: one with simple straight hydrodynamic flow focusing (SMD) and a second one with barriers in the mixing microchannel (patterned walls, PMD). A conventional bulk mixing method was used as a comparison to microfluidic mixing. The CL and the pDNA were combined at a molar positive/negative charge ratio of 6. The results showed that incorporating pDNA into the liposomal structures was different for the two microfluidic devices and that the temperature influenced the average size of complexes produced by the simple microfluidic device, while it did not influence the average complex size in the patterned wall device. Differences were also observed in pDNA probe accessibility in the complexes. The SMD yielded a similar quantity of non-electrostatic bound pDNA as that provided by the bulk mixing method. The complexes produced by the PMD had their pDNA probe accessibility decreased in 40% and achieved lower in vitro transfection levels in HeLa cells than the bulk mixing and simple microfluidic complexation methods. These differences are most likely due to different degrees of association between pDNA and CL, as controlled by the microfluidic devices. This study contributes to the development of rational strategies for controlling the formation of pDNA/CL complexes for further applications in gene and vaccine therapy.

Asunto(s)

ADN/metabolismo , Técnicas de Transferencia de Gen , Inmunoterapia Activa , Liposomas/síntesis química , Técnicas Analíticas Microfluídicas/instrumentación , Plásmidos/metabolismo , Cationes , Ensayo de Cambio de Movilidad Electroforética , Fluorescencia , Células HeLa , Humanos , Hidrodinámica , Liposomas/química , Liposomas/ultraestructura , Tamaño de la Partícula , Reología , Temperatura , Transfección

RESUMEN

It is desirable and challenging to prevent E-resveratrol (E-RSV) from photoisomerizing to its Z-configuration to preserve its biological and pharmacological activities. The aim of this research was to evaluate the photostability of E-RSV-loaded supramolecular structures and the skin penetration profile of chemically and physically stable nanoestructured formulations. Different supramolecular structures were developed to act as carriers for E-RSV, that is, liposomes, polymeric lipid-core nanocapsules and nanospheres and solid lipid nanoparticles. The degrees of photostability of these formulations were compared with that of an ethanolic solution of E-RSV. The skin penetration profiles of the stable formulations were obtained using vertical diffusion cells (protected from light and under UVA radiation) with porcine skin as the membrane, followed by tape stripping and separation of the viable epidermis and dermis in a heated water bath. Photoisomerization was significantly delayed by the association of resveratrol with the nanocarriers independently of the supramolecular structure. Liposomes were the particles capable of maintaining E-RSV concentration for the longest time. On the other hand, E-RSV-loaded liposomes reduced in size showing low physical stability under UVA radiation. In the dark, the skin penetration profiles were very similar, but under UVA radiation the E-RSV-loaded nanocarriers showed increasing amounts in the total epidermis.

Asunto(s)

Dermis/metabolismo , Epidermis/metabolismo , Liposomas/química , Nanocápsulas/química , Nanopartículas/química , Estilbenos/metabolismo , Estilbenos/efectos de la radiación , Administración Cutánea , Animales , Permeabilidad de la Membrana Celular , Cromatografía Líquida de Alta Presión , Cámaras de Difusión de Cultivos , Estabilidad de Medicamentos , Etanol , Cinética , Liposomas/efectos de la radiación , Liposomas/ultraestructura , Microscopía Electrónica de Transmisión , Nanocápsulas/efectos de la radiación , Nanocápsulas/ultraestructura , Nanopartículas/efectos de la radiación , Nanopartículas/ultraestructura , Tamaño de la Partícula , Fotólisis , Resveratrol , Estilbenos/química , Porcinos , Rayos Ultravioleta

RESUMEN

In this work, didecyldimethylammonium bromide (DDAB) and 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) (2.5:1) were used to prepare liposomes coated with polyacrylic acid (PAA) using "in situ" polymerization with 2.5, 5 and 25 mM of acrylic acid (AA). The PAA concentrations were chosen to achieve partially to fully covered capsules, and the polymerization reaction was observed with real-time monitoring using dynamic light scattering (NanoDLS). The DDAB:DOPE liposomes showed stability in the tested temperature range (25-70°C), whereas the results confirmed the success of the polymerization according to superficial charge (zeta potential of +66.7±1.2 mV) results and AFM images. For the liposomes that were fully coated with PAA (zeta potential of +0.3±3.9 mV), cytotoxicity was independent of the concentration of albumin. Cationic liposomes and nanocapsules of the stable liposomes coated with PAA were obtained by controlling the surface charge, which was the most important factor related to cytotoxicity. Thus, a potential, safe drug nanocarrier was successfully developed in this work.

Asunto(s)

Supervivencia Celular/efectos de los fármacos , Materiales Biocompatibles Revestidos/síntesis química , Portadores de Fármacos/síntesis química , Liposomas/química , Nanocápsulas/química , Células 3T3 , Resinas Acrílicas/química , Animales , Cationes/química , Materiales Biocompatibles Revestidos/metabolismo , Materiales Biocompatibles Revestidos/farmacología , Portadores de Fármacos/metabolismo , Portadores de Fármacos/farmacología , Luz , Liposomas/metabolismo , Liposomas/farmacología , Liposomas/ultraestructura , Ratones , Microscopía de Fuerza Atómica , Nanocápsulas/ultraestructura , Fosfatidiletanolaminas/química , Polimerizacion , Compuestos de Amonio Cuaternario/química , Reología/efectos de los fármacos , Dispersión de Radiación , Electricidad Estática

RESUMEN

Membrane-modification effects, induced by ultraviolet (UV) irradiation in diacetylenic liposomes, were analyzed upon contact with cells, biological membranes, and proteins. Liposomes formulated with mixtures of unsaturated 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine and saturated 1,2-dimyristoyl-sn-glycero-3-phosphocholine, in a 1:1 molar ratio, were compared with those that were UV-irradiated and analyzed in several aspects. Membrane polymerization inherence on size stability was studied as well as its impact on mitochondrial and microsomal membrane peroxidation induction, hemolytic activity, and cell viability. Moreover, in order to gain insight about the possible irradiation effect on interfacial membrane properties, interaction with bovine serum albumin (BSA), lysozyme (Lyso), and apolipoprotein (apoA-I) was studied. Improved size stability was found for polymerized liposomes after a period of 30 days at 4°C. In addition, membrane irradiation had no marked effect on cell viability, hemolysis, or induction of microsomal and mitochondrial membrane peroxidation. Interfacial membrane characteristics were found to be altered after polymerization, since a differential protein binding for polymerized or nonpolymerized membranes was observed for BSA and Lyso, but not for apoA-I. The substantial contribution of this work is the finding that even when maintaining the same lipid composition, changes induced by UV irradiation are sufficient to increase size stability and establish differences in protein binding, in particular, reducing the amount of bound Lyso and BSA, without increasing formulation cytotoxicity. This work aimed at showing that the usage of diacetylenic lipids and UV modification of membrane interfacial properties should be strategies to be taken into consideration when designing new delivery systems.

Asunto(s)

Membrana Dobles de Lípidos/química , Membrana Dobles de Lípidos/farmacología , Liposomas/química , Liposomas/farmacología , Polimerizacion/efectos de la radiación , Unión Proteica/efectos de la radiación , Animales , Apolipoproteína A-I/metabolismo , Bovinos , Línea Celular Transformada , Supervivencia Celular/efectos de los fármacos , Dimiristoilfosfatidilcolina/química , Diinos/química , Eritrocitos/efectos de los fármacos , Hemólisis/efectos de los fármacos , Membrana Dobles de Lípidos/metabolismo , Membrana Dobles de Lípidos/efectos de la radiación , Peroxidación de Lípido/efectos de los fármacos , Liposomas/metabolismo , Liposomas/efectos de la radiación , Liposomas/ultraestructura , Ratones , Microscopía Electrónica de Rastreo , Muramidasa/metabolismo , Tamaño de la Partícula , Fosfatidilcolinas/química , Albúmina Sérica/metabolismo , Rayos Ultravioleta

RESUMEN

S-layer proteins from Lactobacillus kefir and Lactobacillus brevis are able to adsorb on the surface of positively charged liposomes composed by Soybean lecithin, cholesterol and stearylamine. The different K values for S-layer proteins isolated from L. kefir and L. brevis (4.22 x 10(-3) and 2.45 x 10(2) microM(-1) respectively) indicates that the affinity of the glycosylated protein isolated from L. kefir is higher than the non-glycosylated one. The attachment of S-layer proteins counteracts the electrostatic charge repulsion between stearylamine molecules in the membrane surface, producing an increase in the rigidity in the acyl chains as measured by DPH anisotropy. Laurdan generalized polarization (GP) shows that glycosylated causes a GP increase, attributed to a lowering in water penetration into the head groups of membrane phospholipids, with charge density reduction, while the non-glycosylated does not affect it. The octadecyl-rhodamine results indicate that S-layer coated liposomes do not show spontaneous dequenching in comparison with control liposomes without S-layer proteins, suggesting that S-layer protein avoid spontaneous liposomal fusion. It is concluded that the increase in stability of liposomes coated with S-layers proteins is due to the higher rigidity induced by the S-layer attachment by electrostatic forces.

Asunto(s)

Proteínas Bacterianas/química , Liposomas/química , Glicoproteínas de Membrana/química , Lípidos de la Membrana/química , Algoritmos , Técnica de Fractura por Congelación , Lactobacillus/química , Levilactobacillus brevis/química , Liposomas/ultraestructura , Microscopía Electrónica de Transmisión , Modelos Químicos , Modelos Moleculares , Especificidad de la Especie