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.

An instrument for time-resolved and anomalous simultaneous small- and wide-angle X-ray scattering (SWAXS) at NSRRC

2006 ◽  
Vol 39 (6) ◽  
pp. 871-877 ◽  
Author(s):  
Ying-Huang Lai ◽  
Ya-Sen Sun ◽  
U-Ser Jeng ◽  
Jhih-Min Lin ◽  
Tsang-Lang Lin ◽  
...  
Keyword(s):  
Lipid Membrane ◽  
Quantum Wires ◽  
Grazing Incidence ◽  
Anomalous Scattering ◽  
Wide Angle ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

A SWAXS (small- and wide-angle X-ray scattering) instrument was recently installed at the wiggler beamline BL17B3 of the National Synchrotron Radiation Research Center (NSRRC), Taiwan. The instrument, which is designed for studies of static and dynamic nanostructures and correlations between the nano (ormeso) structure (SAXS) and crystalline structure (WAXS), provides a flux of 1010–1011photon s−1at the sample at energies between 5 and 14 keV. With a SAXS area detector and a WAXS linear detector connected to two data acquisition systems operated in master–slave mode, the instrument allows one to perform time-resolved as well as anomalous scattering measurements. Data reduction algorithms have been developed for rapid processing of the large SWAXS data sets collected during time-resolved measurements. The performance of the instrument is illustrated by examples taken from different classes of ongoing projects: (i) time-resolved SAXS/WAXS/differential scanning calorimetry (DSC) with a time resolution of 10 s on a semicrystalline poly(hexamethylene terephthalate) sample, (ii) anomalous SAXS/WAXS measurements on a nanoparticulate PtRu catalyst, and (iii) grazing-incidence SAXS of a monolayer of oriented semiconductor quantum wires, and humidity-controlled ordering of Alamethicin peptides embedded in an oriented lipid membrane.

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 GISAXS studies of mesoporous films using a standard laboratory diffractometer

2014 ◽  
Vol 70 (a1) ◽  
pp. C883-C883
Author(s):  
Milen Gateshki ◽  
Alexander Kharchenko ◽  
Patricia Kidd
Keyword(s):  
Photon Counting ◽  
Grazing Incidence ◽  
Low Noise ◽  
Mesoporous Films ◽  
X Ray ◽  
Noise Characteristics ◽  
X Ray Scattering ◽  
Silica Thin Film ◽  
Sample Structure ◽  
Set Up

With the increasing number of GISAXS (Grazing-Incidence Small-Angle X-ray Scattering) applications for the investigation of materials surface nano-structures, comes the demand for a mainstream laboratory capability to run alongside the more established synchrotron facilities. GISAXS poses considerable challenges when scaling the method to fit a multipurpose laboratory instrument, including the achievement of good angular resolution at small scattering radius, the reduction of scatter from the direct beam and the observation of low intensity signals. We have developed a hardware solution that addresses these challenges. The recent availability of small size pixel (55 micron) photon counting detectors with very low noise characteristics has enabled the implementation of new 2D imaging GISAXS hardware for a standard 1.8KW laboratory X-ray source. In this work we present a number of results that illustrate the capabilities of the new experimental set-up based on a standard multipurpose diffractometer. We present GISAXS images and analysis of a mesoporous silica thin film with close-packed hexagonal type ordering of the pores. In [1] we have reported reflectometry results and analysis of this sample structure. The addition of GISAXS information demonstrates the versatility of the multipurpose diffractometer and the strength in combining methods on one instrument. Strongly scattering Ti-filled silica mesoporous films illustrate the relative ease with which GISAXS signals can be recorded, including even the weak signal below the critical angle of the sample (fig.1). The scattering patterns from both samples exhibit subtle departures from a simple symmetry, suggesting that the films may exhibit residual strain. Thin films with vertical mesopores provide their own challenges in the observation of scatter close and parallel to the specularly reflected beam. We present results in which scattering from Co-filled mesopore structures with 37nm pitch can be clearly resolved.

scholarly journals Evaluation of Strategies for Improving Proteolytic Resistance of Antimicrobial Peptides by Using Variants of EFK17, an Internal Segment of LL-37

2008 ◽  
Vol 53 (2) ◽  
pp. 593-602 ◽  
Author(s):  
Adam A. Strömstedt ◽  
Mukesh Pasupuleti ◽  
Artur Schmidtchen ◽  
Martin Malmsten
Keyword(s):  
Lipid Membranes ◽  
Lipid Membrane ◽  
Antimicrobial Properties ◽  
Peptide Sequence ◽  
Proteolytic Degradation ◽  
Human Neutrophil Elastase ◽  
Helix Formation ◽  
Proteolytic Resistance ◽  
Model Lipid Membranes ◽  
Protease Cleavage Sites

ABSTRACT Methods for increasing the proteolytic stability of EFK17 (EFKRIVQRIKDFLRNLV), a new peptide sequence with antimicrobial properties derived from LL-37, were evaluated. EFK17 was modified by four d-enantiomer or tryptophan (W) substitutions at known protease cleavage sites as well as by terminal amidation and acetylation. The peptide variants were studied in terms of proteolytic resistance, antibacterial potency, and cytotoxicity but also in terms their adsorption at model lipid membranes, liposomal leakage generation, and secondary-structure behavior. The W substitutions resulted in a marked reduction in the proteolytic degradation caused by human neutrophil elastase, Staphylococcus aureus aureolysin, and V8 protease but not in the degradation caused by Pseudomonas aeruginosa elastase. For the former two endoproteases, amidation and acetylation of the terminals also reduced proteolytic degradation but only when used in combination with W substitutions. The d-enantiomer substitutions rendered the peptides indigestible by all four proteases; however, those peptides displayed little antimicrobial potency. The W- and end-modified peptides, on the other hand, showed an increased bactericidal potency compared to that of the native peptide sequence, coupled with a moderate cytotoxicity that was largely absent in serum. The bactericidal, cytotoxic, and liposome lytic properties correlated with each other as well as with the amount of peptide adsorbed at the lipid membrane and the extent of helix formation associated with the adsorption. The lytic properties of the W-substituted peptides were less impaired by increased ionic strength, presumably by a combination of W-mediated stabilization of the largely amphiphilic helix conformation and a nonelectrostatic W affinity for the bilayer interface. Overall, W substitutions constitute an interesting means to reduce the proteolytic susceptibility of EFK17 while also improving antimicrobial performance.

Structural Study of Thin Amorphous SiO2 and Si3N4 Films by the Grazing Incidence X-Ray Scattering (GIXS) Method

1999 ◽  
Vol 18 (1-2) ◽  
pp. 99-107 ◽  
Author(s):  
Shigeo Sato, ◽  
Ryoji Kakiuchi, ◽  
Masato Yoshiya, ◽  
Eiichiro Matsubara, ◽  
Masatoshi Saito, ◽  
...  
Keyword(s):  
Structural Study ◽  
Grazing Incidence ◽  
Amorphous Sio2 ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

X-Ray Reflectivity and Diffraction Studies of Doxorubicin Binding to Model Lipid Membranes

2020 ◽  
Vol 10 (3) ◽  
pp. 618-624
Author(s):  
Natalia Novikova ◽  
Mikhail Kovalchuk ◽  
Oleg Konovalov ◽  
Nina Stepina ◽  
Alexandr Rogachev ◽  
...  
Keyword(s):  
Lipid Membranes ◽  
X Ray ◽  
Model Lipid Membranes

Resolving the structural interactions between antimicrobial peptides and lipid membranes using small-angle scattering methods: the case of indolicidin

Soft Matter ◽  
2018 ◽  
Vol 14 (43) ◽  
pp. 8750-8763 ◽  
Author(s):  
Josefine Eilsø Nielsen ◽  
Victoria Ariel Bjørnestad ◽  
Reidar Lund
Keyword(s):  
Small Angle ◽  
Lipid Membranes ◽  
Cytoplasmic Membrane ◽  
Theoretical Modelling ◽  
Anionic Lipid ◽  
X Ray ◽  
Charge Densities ◽  
Model Lipid Membranes ◽  
Angle Scattering ◽  
Structural Interactions

Using small angle X-ray and neutron scattering and theoretical modelling we have elucidated the structure of the antimicrobial peptide, indolicidin, and the interaction with model lipid membranes of different anionic lipid compositions mimicking charge densities found in the cytoplasmic membrane of bacteria.

Structural study of TiB2 film by grazing incidence X-ray diffraction

1990 ◽  
Vol 186 (2) ◽  
pp. L33-L37 ◽  
Author(s):  
E. Matsubara ◽  
Y. Waseda ◽  
S. Takeda ◽  
Y. Taga
Keyword(s):  
Structural Study ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray
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