scholarly journals Conformation of Peptides in Lipid Membranes Studied by X-Ray Grazing Incidence Scattering

2004 ◽  
Vol 87 (1) ◽  
pp. 396-407 ◽  
Author(s):  
Alexander Spaar ◽  
Christian Münster ◽  
Tim Salditt
Keyword(s):  
Lipid Membranes ◽  
Grazing Incidence ◽  
X Ray

scholarly journals Structural Study of the Hydration of Lipid Membranes Upon Interaction With Mesoporous Supports Prepared by Standard Methods and/or X‐Ray Irradiation

2021 ◽  
Vol 8 ◽  
Author(s):  
Benedetta Marmiroli ◽  
Barbara Sartori ◽  
Adriana R. Kyvik ◽  
Imma Ratera ◽  
Heinz Amenitsch
Keyword(s):  
Structural Study ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Subsequent Development ◽  
Grazing Incidence ◽  
Mesoporous Films ◽  
X Ray ◽  
Sensing Applications ◽  
Model Lipid Membranes ◽  
Biological Studies

Mesoporous materials feature ordered tailored structures with uniform pore sizes and highly accessible surface areas, making them an ideal host for functional organic molecules or nanoparticles for analytical and sensing applications. Moreover, as their porosity could be employed to deliver fluids, they could be suitable materials for nanofluidic devices. As a first step in this direction, we present a study of the hydration of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) model lipid membranes on solid mesoporous support. POPC was selected as it changes the structure upon hydration at room temperature. Mesoporous films were prepared using two different templating agents, Pluronic P123 (PEO–PPO–PEO triblock copolymer where PEO is polyethylene oxide and PPO is polypropylene oxide) and Brij 58 (C16H33(EO)20OH where EO is ethylene oxide), both following the conventional route and by X-ray irradiation via deep X-ray lithography technique and subsequent development. The same samples were additionally functionalized with a self-assembly monolayer (SAM) of (3-aminopropyl)triethoxysilane. For every film, the contact angle was measured. A time resolved structural study was conducted using in situ grazing incidence small-angle X-ray scattering while increasing the external humidity (RH), from 15 to 75% in a specially designed chamber. The measurements evidenced that the lipid membrane hydration on mesoporous films occurs at a lower humidity value with respect to POPC deposited on silicon substrates, demonstrating the possibility of using porosity to convey water from below. A different level of hydration was reached by using the mesoporous thin film prepared with conventional methods or the irradiated ones, or by functionalizing the film using the SAM strategy, meaning that the hydration can be partially selectively tuned. Therefore, mesoporous films can be employed as “interactive” sample holders with specimens deposited on them. Moreover, thanks to the possibility of patterning the films using deep X-ray lithography, devices for biological studies of increasing complexity by selectively functionalizing the mesopores with biofunctional SAMs could be designed and fabricated.

Nanosilica Formation at Lipid Membranes Induced by Silaffin Peptides

2009 ◽  
Vol 1187 ◽  
Author(s):  
Michael Kent ◽  
Jaclyn K. Murton ◽  
Sushil Satija ◽  
Ivan Kuzmenko ◽  
Blake Simmons
Keyword(s):  
Amorphous Silica ◽  
Lipid Membranes ◽  
Langmuir Monolayers ◽  
Local Environment ◽  
Grazing Incidence ◽  
Peptide Sequence ◽  
X Ray ◽  
Ambient Temperatures ◽  
Peptide Adsorption ◽  
Specific Species

AbstractDiatoms are unicellular eukaryotic algae found in fresh and marine water. Each cell is surrounded by an outer shell called a frustule that is composed of highly structured amorphous silica. Diatoms are able to transform silicic acid into these sturdy intricate structures at ambient temperatures and pressures, whereas the chemical synthesis of silica-based materials typically requires extremes of temperature and pH. Cationic polypeptides, termed silica affinity proteins (or silaffins) recently identified from dissolved frustules of specific species of diatoms are clearly involved and have been shown to initiate the formation of silica in solution. The relationship between the local environment of catalytic sites on these peptides, which can be influenced by the amino acid sequence and the extent of aggregation, and the observed structure of the silica is not understood. Moreover, the activity of these peptides in promoting silicification at lipid membranes has not yet been clarified. In this work we developed a model system to address some of these questions. We studied peptide adsorption to Langmuir monolayers and subsequent silicification using X-ray reflectivity and grazing incidence X-ray diffraction. The results demonstrate the lipid affinity of the parent sequences of several silaffin peptides. Further, the results show that the membrane-bound peptides promote the formation of interfacial nanoscale layers of amorphous silica at the lipid-water interface that vary in structure according to the peptide sequence.

Direct visualization of phase-separated domains in lipid membranes

1978 ◽  
Vol 36 (2) ◽  
pp. 290-291
Author(s):  
S. W. Hui ◽  
T. P. Stewart
Keyword(s):  
Lipid Membranes ◽  
Structural Information ◽  
Freeze Fracture ◽  
Biological Molecules ◽  
Vacuum Drying ◽  
Direct Visualization ◽  
X Ray Diffraction ◽  
Electron Microscopic ◽  
X Ray ◽  
Hydrocarbon Chains

Direct electron microscopic study of biological molecules has been hampered by such factors as radiation damage, lack of contrast and vacuum drying. In certain cases, however, the difficulties may be overcome by using redundent structural information from repeating units and by various specimen preservation methods. With bilayers of phospholipids in which both the solid and fluid phases co-exist, the ordering of the hydrocarbon chains may be utilized to form diffraction contrast images. Domains of different molecular packings may be recgnizable by placing properly chosen filters in the diffraction plane. These domains would correspond to those observed by freeze fracture, if certain distinctive undulating patterns are associated with certain molecular packing, as suggested by X-ray diffraction studies. By using an environmental stage, we were able to directly observe these domains in bilayers of mixed phospholipids at various temperatures at which their phases change from misible to inmissible states.

New Structure of CTAB Templated Silica Films as revealed by GISAXS coupled to HRTEM

2000 ◽  
Vol 628 ◽  
Author(s):  
Sophie Besson ◽  
Catherine Jacquiod ◽  
Thierry Gacoin ◽  
André Naudon ◽  
Christian Ricolleau ◽  
...  
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Grazing Incidence ◽  
Hexagonal Structure ◽  
X Ray Diffraction ◽  
Electronic Microscopy ◽  
Silica Films ◽  
X Ray ◽  
X Ray Scattering ◽  
Hexagonal Arrangement ◽  
Spherical Micelles

ABSTRACTA microstructural study on surfactant templated silica films is performed by coupling traditional X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM) to Grazing Incidence Small Angle X-Ray Scattering (GISAXS). By this method it is shown that spin-coating of silicate solutions with cationic surfactant cetyltrimethylammonium bromide (CTAB) as a templating agent provides 3D hexagonal structure (space group P63/mmc) that is no longer compatible with the often described hexagonal arrangement of tubular micelles but rather with an hexagonal arrangement of spherical micelles. The extent of the hexagonal ordering and the texture can be optimized in films by varying the composition of the solution.

X-Ray Fluorescence Spectrometer with Geometry of Grazing Incidence X-ray Radiation

2012 ◽  
Vol 1 (2) ◽  
pp. 78-82
Author(s):  
N.M. Novikovskii ◽  
◽  
V.M. Raznomazov ◽  
V.O. Ponomarenko ◽  
D.A. Sarychev ◽  
...  
Keyword(s):  
Grazing Incidence ◽  
X Ray ◽  
Fluorescence Spectrometer

Quantifying Multiple Crystallite Orientations and Crystal Heterogeneities in Complex Thin Film Materials

2019 ◽  
Author(s):  
Jonathan Ogle ◽  
Daniel Powell ◽  
Eric Amerling ◽  
Detlef Matthias Smilgies ◽  
Luisa Whittaker-Brooks
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Structural Design ◽  
Grazing Incidence ◽  
Crystallite Orientation ◽  
Miller Index ◽  
X Ray ◽  
X Ray Scattering ◽  
Orientation Distributions ◽  
Orientation Information

<p>Thin film materials have become increasingly complex in morphological and structural design. When characterizing the structure of these films, a crucial field of study is the role that crystallite orientation plays in giving rise to unique electronic properties. It is therefore important to have a comparative tool for understanding differences in crystallite orientation within a thin film, and also the ability to compare the structural orientation between different thin films. Herein, we designed a new method dubbed the mosaicity factor (MF) to quantify crystallite orientation in thin films using grazing incidence wide-angle X-ray scattering (GIWAXS) patterns. This method for quantifying the orientation of thin films overcomes many limitations inherent in previous approaches such as noise sensitivity, the ability to compare orientation distributions along different axes, and the ability to quantify multiple crystallite orientations observed within the same Miller index. Following the presentation of MF, we proceed to discussing case studies to show the efficacy and range of application available for the use of MF. These studies show how using the MF approach yields quantitative orientation information for various materials assembled on a substrate.<b></b></p>

Strain Relaxation and In-Situ Observation of Voiding in Passivated Aluminum Alloy Lines.

1993 ◽  
Vol 308 ◽  
Author(s):  
Paul R. Besser ◽  
Thomas N. Marieb ◽  
John C. Bravman
Keyword(s):  
Strain Relaxation ◽  
Grazing Incidence ◽  
Scanning Transmission Electron Microscope ◽  
In Situ Observation ◽  
X Ray ◽  
Scanning Transmission ◽  
Length Width ◽  
Measured Strain ◽  
Ray Geometry

ABSTRACTStrain relaxation in passivated Al-0.5% Cu lines was measured using X-ray diffraction coupled with in-situ observation of the formation and growth of stress induced voids. Samples of 1 μm thick Al-0.5% Cu lines passivated with Si3N4 were heated to 380ºC, then cooled and held at 150ºC. During the test, principal strains along the length, width, and height of the line were determined using a grazing incidence x-ray geometry. From these measurements the hydrostatic strain in the metal was calculated and strain relaxation was observed. The thermal cycle was duplicated in a high voltage scanning transmission electron microscope equipped with a backscattered electron detector. The 1.25 μm wide lines were seen to have initial stress voids. Upon heating these voids reduced in size until no longer observable. Once the samples were cooled to 150ºC, voids reappeared and grew. The measured strain relaxation is discussed in terms of void and θ-phase (Al2Cu) formation.

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