Revisiting the Brewster Angle Microscopy: The relevance of the polar headgroup

Roldán‐Carmona, Cristina; Giner‐Casares, Juan J.; Pérez-Morales, Marta; Martín‐Romero, María T.; Camacho, Luis

doi:10.1016/j.cis.2012.02.002

Cited by 42 publications

(49 citation statements)

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“…Current interpretation ascribes to the head group the ruling role in determining the shapes of the domains, while chain length has only an impact on smaller details of their form . For the racemate no special shape is observed but rather a cholesteric texture …”

Section: Resultsmentioning

confidence: 96%

“…Nevertheless, quantitative predictions of large‐scale chirality based on that at the molecular scale remains a debated problem whose solution requires sophisticated techniques . Considering that the shape of the domains is mainly determined by the interactions between the polar head groups, the morphological differences between figures d and e in Table strongly suggest that specific interactions (electrostatic interactions, hydrogen bonding) between the d ‐DPPC head groups and 1 take place. We could suppose that also the lipophilic chains, whose spatial arrangement is in turn influenced by the chiral polar head, contribute to the specific interaction altering the monolayer organization of one enantiomer with respect to the other and favoring homochiral interaction in condensed phases.…”

Section: Resultsmentioning

confidence: 99%

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Separation of Enantiomers of a Phospholipid in Langmuir Monolayers by a New Selector

et al. 2015

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Section: Resultsmentioning

confidence: 96%

Section: Resultsmentioning

confidence: 99%

Separation of Enantiomers of a Phospholipid in Langmuir Monolayers by a New Selector

et al. 2015

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“…This applies to some cases of bulky, radiation absorbing headgroups being weakly hydrated and as a result causing stronger modification of the water refracting index. 37 However, the last of the three scenarios should be rejected as an explanation for the molecules studied herein, since the headgroup of sterols, being the single hydroxyl, does not fulfill the above-mentioned requirements. On the other hand, to resolve unambiguously between the first two possibilities, i.e., whether the molecular tilt is responsible for the observed anisotropy, we must refer to the results acquired with the technique based on synchrotron radiation scattering.…”

Section: ■ Experimental Sectionmentioning

confidence: 96%

Crucial Role of the Double Bond Isomerism in the Steroid B-Ring on the Membrane Properties of Sterols. Grazing Incidence X-Ray Diffraction and Brewster Angle Microscopy Studies

et al. 2015

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Three cholesterol precursors-desmosterol, zymosterol, and lanosterol-were comprehensively characterized in monolayers formed at the air/water interface. The studies were based on registration of the surface pressure (π)-area (A) isotherms complemented with in situ analysis performed with application of modern physicochemical techniques: grazing incidence X-ray diffraction (GIXD) and Brewster angle microscopy (BAM). In this approach we were interested in the correlation between molecular structures of the studied sterols found in the cholesterol biosynthetic pathway and their membrane properties. Our results revealed that only desmosterol behaves in Langmuir monolayers comparably to cholesterol, the molecules of which arrange in the monolayers into a hexagonal lattice, while the two remaining sterols possess extremely different properties. We found that molecules of both zymosterol and lanosterol are organized on the water surface in the two-dimensional oblique unit cells despite the fact that they are oriented perpendicular to the monolayer plane. The comparison of chemical structures of the investigated sterols leads to the conclusion that the only structural motive that can be responsible for such unusual behavior is the double bond in the B sterol ring, which is located in desmosterol in a different position from in the other two sterols. This issue, which was neglected in the scientific literature, seems to have crucial importance for sterol activity in biomembranes. We showed that this structural modification in sterol molecules is directly responsible for their adaptation to proper functioning in biomembranes.

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“…17 The BAM images shown in Scheme 1C were recorded with the camera polarizer (analyzer) at 0 . Thus, the monolayer is considered as a biaxial materials with the complex refractive indices of N q ¼ n q À ik q (q^x, y and z), where n q is the real part of the refractive index, and k q is the absorption coefficient of the monolayer (see details in the ESI †).…”

Section: The Origin Of the Domain Anisotropy Observed By Bam: In-planmentioning

confidence: 99%

Aggregation and structural study of the monolayers formed by an amphiphilic thiapentacarbocyanine

et al. 2015

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Exotic assemblies with unique photophysical features can be built based on organic dyes at the air-liquid interface. Langmuir monolayers of N,N 0 -dioctadecylthiapentacarbocyanine (OTCC) at air-water and airsolid interfaces have been studied. A single type of domain and presumably of one single aggregate type has been found by Brewster angle microscopy. Peanut-shaped domains with internal anisotropy have been observed. However, this structure leads to a complex absorption spectrum which shows 4 bands, two red-shifted (822 nm and 757 nm), and two blue-shifted (600 nm and 530 nm) with respect to the monomer band (665 nm). Our results confirm that all the absorption components are polarized in approximately the same direction. The absence of an emission spectrum indicates that this interfacial aggregate cannot be classified as a simple J-aggregate. Moreover, these bands cannot relate to Davydov splitting, given that all of them have the same polarization direction. We propose possible explanations based on a strong exciton-phonon interaction, and/or the formation of aggregates with different coherent lengths within the domain. The basic exciton model cannot explain this behavior. The coherent aggregate described in this study is proposed as a unique dye supramolecular structure obtained by assembly at the air-liquid interface.

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Revisiting the Brewster Angle Microscopy: The relevance of the polar headgroup

Cited by 42 publications

References 50 publications

Separation of Enantiomers of a Phospholipid in Langmuir Monolayers by a New Selector

Separation of Enantiomers of a Phospholipid in Langmuir Monolayers by a New Selector

Crucial Role of the Double Bond Isomerism in the Steroid B-Ring on the Membrane Properties of Sterols. Grazing Incidence X-Ray Diffraction and Brewster Angle Microscopy Studies

Aggregation and structural study of the monolayers formed by an amphiphilic thiapentacarbocyanine

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