Molecular Self‐Assembly into Crystals at Air‐Liquid Interfaces

Weissbuch, Isabelle; Popovitz‐Biro, Ronit; Lahav, Meir; Leiserowitz, Leslie; Kjær, Kristian; Als‐Nielsen, J.

doi:10.1002/9780470141618.ch2

Cited by 20 publications

(3 citation statements)

References 83 publications

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“…Figure c gives the out-of-plane [(01 l ) + (11 l )] diffraction profile. The positions of peaks as a function of q z can be used to obtain the bilayer periodicity in the vertical direction, which in turn can be used to get the vertical tilt angle. , At room temperature, the bilayer periodicity comes out to be 5.23 nm. The bilayer thickness of the CdA multilayer with untilted molecules is 5.54 nm .…”

Section: Resultsmentioning

confidence: 99%

Low-Dimensionality Effects in the Melting of a Langmuir−Blodgett Multilayer

et al. 2008

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Low-dimensionality effects in the melting behavior of a cadmium arachidate Langmuir-Blodgett multilayer have been studied. Depth resolved information about structural changes occurring with temperature is obtained using in-plane X-ray diffraction under standing wave conditions. The surface region exhibits a distinctly different melting behavior as compared to the bulk of the film. While in the bulk of a 13-monolayer cadmium arachidate multilayer, the crystalline phase directly transforms to a tilted hexaticlike phase at 360 K, in the near surface region transformation occurs via an intermediate smectic phase. This behavior of the surface region is similar to that observed in two-dimensional crystals. Thus even in a thick Langmuir-Blodgett multilayer, the surface region exhibits low-dimensionality effects.

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Section: Resultsmentioning

confidence: 99%

Low-Dimensionality Effects in the Melting of a Langmuir−Blodgett Multilayer

et al. 2008

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“…The X-ray footprint area on the sample is inversely proportional to the incident angle of the X-rays. [40][41] Irrespective the usual phase problem of X-ray crystallography, the normalized reflectivity, R(Q z )/R F (Q z ), where R F (Q z ) is the Fresnel reflectivity from an ideal smooth surface, can usually be inverted to yield the laterally averaged electron density, 1(z), as a function of the vertical z coordinate. The inversion of R(Q z )/R F (Q z ) to yield 1(z) can be performed either by a model-independent method or by using a box model based on the molecular structure.…”

Section: Methodsmentioning

confidence: 99%

Physical–Chemical Properties and Transfection Activity of Cationic Lipid/DNA Complexes

et al. 2009

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Investigation of DNA interactions with cationic lipids is of particular importance for the fabrication of biosensors and nanodevices. Furthermore, lipid/DNA complexes can be applied for direct delivery of DNA-based biopharmaceuticals to damaged cells as non-viral vectors. To obtain more effective and safer DNA vectors, the new cationic lipids 2-tetradecylhexadecanoic acid-{2-[(2-aminoethyl)amino]ethyl}amide (CI) and 2-tetradecylhexadecanoic acid-2-[bis(2-aminoethyl)amino]ethylamide (CII) were synthesized and characterized. The synthesis, physical-chemical properties and first transfection and toxicity experiments are reported. Special attention was focused on the capability of CI and CII to complex DNA at low and high subphase pH values. Langmuir monolayers at the air/water interface represent a well-defined model system to study the lipid/DNA complexes. Interactions and ordering of DNA under Langmuir monolayers of the new cationic lipids were studied using film balance measurements, grazing incidence X-ray diffraction (GIXD) and X-ray reflectivity (XR). The results obtained demonstrate the ability of these cationic lipids to couple with DNA at low as well as at high pH value. Moreover, the observed DNA structuring seems not to depend on subphase pH conditions. An influence of the chemical structure of the lipid head group on the DNA binding ability was clearly observed. Both compounds show good transfection efficacy and low toxicity in the in vitro experiments indicating that lipids with such structures are promising candidates for successful gene delivery systems.

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“…Experiments were also performed at a synchrotron source. All x-ray scattering experiments were carried out at the BW1 (undulator) beam line at HASYLAB (Hamburg, Germany) using a dedicated liquid surface diffractometer (29,(32)(33)(34) with an incident x-ray wavelength of l ; 1.3 Å . A thermostated trough equipped with a Wilhelmy balance for measuring the surface pressure (p) and a barrier for changing the surface area was mounted on the diffractometer.…”

Section: Experimental Configurationmentioning

confidence: 99%

Interaction between Lipid Monolayers and Poloxamer 188: An X-Ray Reflectivity and Diffraction Study

Majewski

Ege

et al. 2005

Biophysical Journal

Self Cite

111

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The mechanism by which poloxamer 188 (P188) seals a damaged cell membrane is examined using the lipid monolayer as a model system. X-ray reflectivity and grazing-incidence x-ray diffraction results show that at low nominal lipid density, P188, by physically occupying the available area and phase separating from the lipids, forces the lipid molecules to pack tightly and restore the barrier function of the membrane. Upon compression to bilayer equivalent pressure, P188 is squeezed out from the lipid monolayer, allowing a graceful exit of P188 when the membrane integrity is restored.

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Molecular Self‐Assembly into Crystals at Air‐Liquid Interfaces

Cited by 20 publications

References 83 publications

Low-Dimensionality Effects in the Melting of a Langmuir−Blodgett Multilayer

Low-Dimensionality Effects in the Melting of a Langmuir−Blodgett Multilayer

Physical–Chemical Properties and Transfection Activity of Cationic Lipid/DNA Complexes

Interaction between Lipid Monolayers and Poloxamer 188: An X-Ray Reflectivity and Diffraction Study

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