Reversible Trilayer Formation at the Air−Water Interface from a Mixed Monolayer Containing a Cationic Lipid and an Anionic Porphyrin

Pérez-Morales, Marta; Pedrosa, José M.; Martín‐Romero, María T.; Moebius, D.; Camacho, Luis

doi:10.1021/jp037282k

Cited by 35 publications

(61 citation statements)

References 36 publications

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“…[32] This experimental technique can provide valuable information on the orientation of the chromophore molecules located at the air/water interface. [11,34,35] Figure 6 shows the normalised reflection spectra per MB molecule) is the surface area of methylene blue. The normalised reflection spectra clearly show possible changes of orientation and/or association of the dye.…”

Section: Uv/vis Reflection Spectroscopymentioning

confidence: 99%

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Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

et al. 2010

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Adsorption of methylene blue (MB) onto a dimyristoylphosphatidic acid (DMPA) Langmuir air/water monolayer is studied by molecular dynamics (MD) simulations, UV reflection spectroscopy and surface potential measurements. The free-energy profile associated with MB transfer from water to the lipid monolayer shows two minima of -66 and -60 kJ mol(-1) for its solid and gas phase, respectively, corresponding to a spontaneous thermodynamic process. From the position of the free-energy minima, it is possible to predict the precise location of MB in the interior of the DMPA monolayer. Thus, MB is accommodated in the phosphoryl or carbonyl region of the DMPA Langmuir air/water interface, depending on the isomorphic state (solid or gas phase, respectively). Reorientation of MB, measured from the bulk solution to the interior of the lipid monolayer, passes from a random orientation in bulk solution to an orientation parallel to the surface of the lipid monolayer when MB is absorbed.

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Section: Uv/vis Reflection Spectroscopymentioning

confidence: 99%

“…The detailed procedure has been thoroughly described in previous papers, to which the reader interested in mathematical details is referred. [11,34,35] The MB polar angle can be related with the orientational factor as Equation (5):…”

Section: Uv/vis Reflection Spectroscopymentioning

confidence: 99%

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

et al. 2010

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“…36 This technique gives us valuable information on the organization, density, and orientation of the chomophore molecules located at the air-water interface. 3,19,41,44 Reflection spectra ∆R of SP:DMPA ) 1:1 monolayers on the water subphase at different surface pressures are shown in Figure 5A.…”

Section: Methodsmentioning

confidence: 99%

“…1,2 In this sense, the air-water interface is an ideal model for these purposes, as it is easy to prepare in a pure state and also because the surface coverage can be smoothly adjusted by using the Langmuir trough technique. 3 However, Langmuir monolayers are interesting not only in a fundamental way but also as a means to build an ordered system on mesoscopic length scales. 4 The domains observed in Langmuir monolayers at high surface pressures indicate the formation of large structures.…”

Section: Introductionmentioning

confidence: 99%

Control of the Lateral Organization in Langmuir Monolayers via Molecular Aggregation of Dyes

et al. 2010

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This paper shows that it is possible to construct well-defined 2D structures at the air-water interface in which the lateral organization is controlled by means of the preparation of mixed films, and selecting the components so that there are attractive interactions between them. The goal here is to establish the lateral connection between components through self-aggregation of the dye. This can be achieved by selecting a suitable balance between the sizes of the hydrophobic and polar groups. In such a way, the domain structure depends on the ability of the tilt dye to fill the available area. Thus, the molecular organization and the domain morphology of mixed films containing dimyristoyl-phosphatidic acid (DMPA) and the hemicyanine dye, 4-[4-(dimethylamino)styryl]-1-docosylpyridinium bromide (SP), have been studied by using Grazing Incidence X-ray Diffraction (GIXD), Brewster angle microscopy (BAM), and reflection spectroscopy at the air-water interface. For this mixed system, the formation of circular domains with bright horizontal regions and dark vertical regions was observed. Furthermore, depending on the temperature, it is observed as branches grow from circular domains, whose brightness depends on the growth direction. Thus, BAM images allow us to observe some branches that, as their growth direction changes, their brightness also changes simultaneously. The GIXD experiment permits us to relate the circular domains with an orthorhombic phase and the branches grown from the circles with an Overbeck phase. In both cases, the formed structures are induced by the hemicyanine aggregation. Circular BAM domain textures have been simulated by using the Fresnel equations for biaxial anisotropic materials.

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“…The study of mixed films of dissimilar components [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] is of practical interest due to the fact that a great number of compounds of technological interest need a film former. Phthalocyanines (Pc), porphyrins (P), metallo-porphyrins (MP) and metallophthalocyanines (MPc) are an example.…”

Section: Introductionmentioning

confidence: 99%

Phase separation in mixed monolayers of arachidic acid and a phthalocyanine of zinc

Torrent‐Burgués

2012

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Mixed Langmuir and Langmuir-Blodgett films of dissimilar components, arachidic acid and a phthalocyanine of zinc, have been investigated. These compounds form mixed films with phase separation, with domains at the sub-micro scale which are detected by AFM in LB films but not observed by BAM. These domains present different contrast in the surface potential images obtained with SP-AFM and in the friction images. The analysis of the isotherms and of the AFM images, at several compositions, reveals that the components are immiscible. The difference in height between the arachidic acid and the phthalocyanine of zinc phases is in accordance with the heights of the molecules, and points to the presence of a monolayer in the zinc phthalocyanine phase. AFM has revealed as a necessary technique to elucidate the miscibility in mixed films at the nanometric scale. UV-Vis spectroscopy shows changes in the spectra bands of LB films in respect to those in solution, due to the organization of the molecules in the LB film.

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Reversible Trilayer Formation at the Air−Water Interface from a Mixed Monolayer Containing a Cationic Lipid and an Anionic Porphyrin

Cited by 35 publications

References 36 publications

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

Methylene Blue Adsorption on a DMPA Lipid Langmuir Monolayer

Control of the Lateral Organization in Langmuir Monolayers via Molecular Aggregation of Dyes

Phase separation in mixed monolayers of arachidic acid and a phthalocyanine of zinc

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