scholarly journals A platform for light-controlled formation of free-stranding lipid membranes

2020 ◽  
Vol 17 (163) ◽  
pp. 20190740 ◽  
Author(s):  
Nikolay V. Ryzhkov ◽  
Ekaterina V. Skorb
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Science And Technology Studies ◽  
Separation Distance ◽  
Layer By Layer ◽  
Net Charge ◽  
Novel Approach ◽  
Layer Deposition ◽  
Transmembrane Channels

The engineering of artificial cells is one of the most significant scientific challenges. Thus, controlled fabrication and in situ monitoring of biomimetic nanoscale objects are among the central issues in current science and technology. Studies of transmembrane channels and cell mechanics often require the formation of lipid bilayers (LBs), their modification and their transfer to a particular place. We present here a novel approach for remotely controlled manipulation of LBs. Layer-by-layer deposition of polyethyleneimine and poly(sodium 4-styrenesulfonate) on a nanostructured TiO 2 photoanode was performed to obtain a surface with the desired net charge and to enhance photocatalytic performance. The LB was deposited on top of a multi-layer positive polymer cushion by the dispersion of negative vesicles. The separation distance between the electrostatically linked polyelectrolyte cushion and the LB can be adjusted by changing the environmental pH, as zwitter-ionic lipid molecules undergo pH-triggered charge-shifting. Protons were generated remotely by photoanodic water decomposition on the TiO 2 surface under 365 nm illumination. The resulting pH gradient was characterized by scanning vibrating electrode and scanning ion-selective electrode techniques. The light-induced reversible detachment of the LB from the polymer-cushioned photoactive substrate was found to correlate with suggested impedance models.

In Situ Spectroscopic Approach to Atomic Layer Deposition

2002 ◽  
Vol 745 ◽  
Author(s):  
Martin M. Frank ◽  
Yves J. Chabal ◽  
Glen D. Wilk
Keyword(s):  
Infrared Spectroscopy ◽  
Atomic Layer Deposition ◽  
Aluminum Oxide ◽  
Atomic Layer ◽  
Gate Oxide ◽  
Silicon Surfaces ◽  
Oxide Growth ◽  
Layer By Layer ◽  
Layer Deposition

ABSTRACTThere is great need for a mechanistic understanding of growth chemistry during atomic layer deposition (ALD) of films for electronic applications. Since commercial ALD reactors are presently not equipped for in situ spectroscopy, we have constructed a model reactor that enables single-pass transmission infrared spectroscopy to be performed in situ on a layer-by-layer basis. We demonstrate the viability of this approach for the study of aluminum oxide growth on silicon surfaces, motivated by alternative gate oxide applications. Thanks to submonolayer dielectric and adsorbate sensitivity, we can quantify oxide thicknesses and hydroxyl areal densities on thermal and chemical SiO2/Si(100) substrates. Methyl formation and hydroxyl consumption upon initial trimethylaluminum (TMA) reaction can also be followed. We verify that in situ grown Al2O3 films are compatible in structure to films grown in a commercial ALD reactor.

Magnetic Nanoparticle–Polyelectrolyte Interaction: A Layered Approach for Biomedical Applications

2008 ◽  
Vol 8 (8) ◽  
pp. 4033-4040 ◽  
Author(s):  
John E. Wong ◽  
Akhilesh K. Gaharwar ◽  
Detlef Müller-Schulte ◽  
Dhirendra Bahadur ◽  
Walter Richtering
Keyword(s):  
Magnetic Nanoparticles ◽  
Magnetic Nanoparticle ◽  
Layer By Layer ◽  
Layer Deposition ◽  
Dimethylammonium Chloride ◽  
Modified Magnetic Nanoparticles ◽  
Post Modification ◽  
Nanoparticle Core ◽  
Modification Of The Surface

This study describes the surface modification of magnetic nanoparticles using two different approaches. The first approach consists of an in situ modification of the surface during the precipitation of the magnetic nanoparticles while the second approach consists of a post-modification of the surface after the formation of the magnetic nanoparticles. In the latter case, we adopted the Layer-by-Layer assembly of polyelectrolyte multilayers of poly(diallyl-dimethylammonium) chloride and poly(styrenesulfonate) to build a polymeric shell around the magnetic nanoparticle core, thereby intentionally conferring to this hybrid core–shell the same charge as the charge of the polyelectrolyte deposited in the last layer. Electrophoretic measurements reveal charge reversal indicating successful Layer-by-Layer deposition while magnetization studies show that the superparamagnetic behavior is not much affected by the presence of polyelectrolytes on the modified magnetic nanoparticles. Fourier transform infrared and thermogravimetry analysis results underline that the various polyelectrolytes employed, in both the methodologies adopted, were successfully bound to the nanoparticles.

scholarly journals AlN epitaxy on SiC by low-temperature atomic layer deposition via layer-by-layer, in situ atomic layer annealing

RSC Advances ◽  
2019 ◽  
Vol 9 (22) ◽  
pp. 12226-12231 ◽  
Author(s):  
Wei-Chung Kao ◽  
Wei-Hao Lee ◽  
Sheng-Han Yi ◽  
Tsung-Han Shen ◽  
Hsin-Chih Lin ◽  
...  
Keyword(s):  
Low Temperature ◽  
Atomic Layer Deposition ◽  
Epitaxial Growth ◽  
Atomic Layer ◽  
Layer By Layer ◽  
Schematic Diagram ◽  
Layer Deposition ◽  
Processing Cycle

The schematic diagram of the processing cycle including the atomic layer annealing (ALA) to achieve low-temperature epitaxial growth of AlN on SiC.

Heteroepitaxy of Strained and Not-Strained Ferroelectric Superlattices and their Electric Properties.

1995 ◽  
Vol 401 ◽  
Author(s):  
Hitoshi Tabata ◽  
Masakazu Hamada ◽  
Tomoji Kawai
Keyword(s):  
Dielectric Constant ◽  
Essential Role ◽  
Ferroelectric Properties ◽  
Coulomb Force ◽  
In Situ Monitoring ◽  
Laser Deposition ◽  
Layer By Layer ◽  
Ferroelectric Films ◽  
Layer Deposition

AbstractBismuth based artificial superlattices have been formed by a layer-by-layer laser deposition with in-situ monitoring of RHEED. The Bi2O2/WO6, Bi2O2/SrTa2O9, Bi2O2/SrTa2O9 /SrTiO3 and Bi2O2/SrTa2O9/BaTiO3 are constructed epitaxially by a single, double and triple perovskite layers sandwiched by Bi2O2 layers, respectively. The dielectric constant increases with increasing the number of perovskite layers. And the D-E hysteresis loop (ferroelectric properties) appears along the c-axis direction in odd perovskite layers (n=l and 3). We have also formed the SrTiO3/BiWO6/SrTiO3 multi layers. With this combination, the STO layers are isolated by the BWO layers. The dimensionality of STO layer can be controlled by changing the thickness of BWO layers. Below the BWO thickness of 500 Å, the εr increases monotonously with decreasing the BWO thickness. Therefore, the the coulomb force, which is in proportion to inverse of the distance, plays an essential role for the dielectric constant. The formation of “artificially constructed ferroelectric films” by a layer-by-layer deposition method will be discussed ad an essential approach to elucidate the mechanism of ferroelectricity.

Observation of Concanavalin-A receptors on hydrated planar erythrocyte membrane film by in situ electron microscopy

1983 ◽  
Vol 41 ◽  
pp. 608-609
Author(s):  
Neng-Bo He ◽  
S.W. Hui
Keyword(s):  
Lipid Bilayers ◽  
Erythrocyte Membrane ◽  
Lipid Membranes ◽  
Surface Film ◽  
Biological Membranes ◽  
Electron Microscopic Observation ◽  
Electron Microscopic ◽  
Black Lipid Membranes ◽  
Fine Mesh ◽  
Planar Films

Monolayers and planar "black" lipid membranes have been widely used as models for studying the structure and properties of biological membranes. Because of the lack of a suitable method to prepare these membranes for electron microscopic observation, their ultrastructure is so far not well understood. A method of forming molecular bilayers over the holes of fine mesh grids was developed by Hui et al. to study hydrated and unsupported lipid bilayers by electron diffraction, and to image phase separated domains by diffraction contrast. We now adapted the method of Pattus et al. of spreading biological membranes vesicles on the air-water interfaces to reconstitute biological membranes into unsupported planar films for electron microscopic study. hemoglobin-free human erythrocyte membrane stroma was prepared by hemolysis. The membranes were spreaded at 20°C on balanced salt solution in a Langmuir trough until a surface pressure of 20 dyne/cm was reached. The surface film was repeatedly washed by passing to adjacent troughs over shallow partitions (fig. 1).

Epitaxial growth manner and structure of superconducting oxide films

1990 ◽  
Vol 48 (4) ◽  
pp. 2-3
Author(s):  
Yoshichika Bando ◽  
Takahito Terashima ◽  
Kenji Iijima ◽  
Kazunuki Yamamoto ◽  
Kazuto Hirata ◽  
...  
Keyword(s):  
Ultrathin Films ◽  
Film Surface ◽  
High Energy ◽  
Epitaxial Films ◽  
Layer By Layer ◽  
Initial Growth ◽  
In Situ Growth ◽  
High Quality ◽  
Activated Reactive Evaporation

The high quality thin films of high-Tc superconducting oxide are necessary for elucidating the superconducting mechanism and for device application. The recent trend in the preparation of high-Tc films has been toward “in-situ” growth of the superconducting phase at relatively low temperatures. The purpose of “in-situ” growth is to attain surface smoothness suitable for fabricating film devices but also to obtain high quality film. We present the investigation on the initial growth manner of YBCO by in-situ reflective high energy electron diffraction (RHEED) technique and on the structural and superconducting properties of the resulting ultrathin films below 100Å. The epitaxial films have been grown on (100) plane of MgO and SrTiO, heated below 650°C by activated reactive evaporation. The in-situ RHEED observation and the intensity measurement was carried out during deposition of YBCO on the substrate at 650°C. The deposition rate was 0.8Å/s. Fig. 1 shows the RHEED patterns at every stage of deposition of YBCO on MgO(100). All the patterns exhibit the sharp streaks, indicating that the film surface is atomically smooth and the growth manner is layer-by-layer.

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