Formation of Silk Monolayers

1992 ◽  
Vol 292 ◽  
Author(s):  
Wayne S. Muller ◽  
Lynne A. Samuelson ◽  
Stephen A. Fossey ◽  
David L. Kaplan
Keyword(s):  
Silk Fibroin ◽  
Membrane Properties ◽  
Electron Diffraction Data ◽  
Attenuated Total Reflectance ◽  
Spectrometric Analysis ◽  
Molecular Architecture ◽  
Langmuir Blodgett ◽  
Transmission Electron ◽  
Pressure Area ◽  
Ellipsometry Data

AbstractCast silk membranes exhibit useful properties. However, there is limited control over the molecular architecture in these structures. The Langmuir-Blodgett technique can enhance the control of the membrane structure and allow improved control over membrane properties. We have formed natural silk monolayers using the Langmuir technique. Silk fibroin, regenerated from Bombvx mori cocoons, formed stable monolayers evident from pressure/area isotherms. Multilayers of the silk fibroin monolayers were deposited on a number of substrates and characterized. Transmission Electron Microscopy (TEM) and ellipsometry data provide basic information about the physical characteristics of the monolayer. Preliminary analysis of electron diffraction data of the monolayer indicate polycrystalline structure, consistent with the known structure of silk. Infrared spectrometric analysis of the monolayer using Attenuated Total Reflectance (ATR) gave wavenumbers for Amide I, II, III and V bands which compare with the silk II conformation reported for cast silk membranes.

PREPARATION AND CHARACTERIZATION OF ORGANIC THIN FILM OF STEARIC ACID/PYRAZOLINE NANOPARTICLES

2006 ◽  
Vol 05 (02n03) ◽  
pp. 199-205
Author(s):  
YOUNG SOO KANG ◽  
SUN WHA OH ◽  
JONG HWA SUH
Keyword(s):  
Stearic Acid ◽  
Organic Thin Films ◽  
Solid Substrate ◽  
Organic Thin Film ◽  
Blodgett Film ◽  
Optical Absorbance ◽  
Langmuir Blodgett ◽  
Pressure Area

The organic thin films of stearic acid/pyrazoline nanoparticles were prepared by transferring Langmuir monolayer of stearic acid/pyrazoline nanoparticle onto the solid substrate. The complex of stearic acid/pyrazoline nanoparticle was studied with pressure–area isotherm at the air/water interface and identified with linearly increasing optical absorbance around 370 nm by increasing the number of deposited layers. The in situ domain structure and molecular orientation of the complex were measured with BAM. The surface morphology of the Langmuir–Blodgett film was observed with AFM. The dispersion of pyrazoline nanoparticle in the film was studied with TEM.

Molecular Organization of Nonlinear Organic Films Laminated by Langmuir-Blodgett Method

2005 ◽  
Vol 492-493 ◽  
pp. 115-122 ◽  
Author(s):  
Saburo Uchida ◽  
Vijay T. Chitnis ◽  
Hideo Furuhashi ◽  
Toshio Yoshikawa ◽  
Akinori Maeda ◽  
...  
Keyword(s):  
Surface Pressure ◽  
Nonlinear Optical ◽  
Epitaxial Films ◽  
Operating Conditions ◽  
Molecular Organization ◽  
Optimum Operating ◽  
Monolayer Formation ◽  
Langmuir Blodgett ◽  
Molecular Arrangement ◽  
Pressure Area

In the 21st century, the optical computation is likely to be the basic technology for processing lots of information at high speed. The aim of the present research work is to develop optical logic gates or memory chips. For this purpose, we have examined the suitability of organic nonlinear optical dye material Vanadyl-phthalocyanine (VOPc). Large single crystals of this material have been fabricated by using Molecular Beam Epitaxy (MBE) technique. The epitaxial films were formed on the substrate under optimum operating conditions. However, the epitixial growth is observed only up to a limited thickness. Above this thickness, the films become non-epitaxial, which can be improved by annealing. The reformation of the epitaxial films has been confirmed. We have also reported the effects of the environment of high temperature on the multilayered tetra-tert-butyl-Vanadyl-phthalocyanine ((t-bu)4VOPc) films, formed by Langmuir-Blodgett (LB) method. The solvent used to dissolve ((t-bu)4VOPc) was 1,2-dichloroethane. The monolayer on the surface of the water was transferred to a glass substrate by the vertical dipping method. If the multilayered stack is too thick, the molecular arrangement of the film may get disturbed. The improvement in the molecular arrangement of the LB films was examined and confirmed by measuring it’s nonlinear optical susceptibility, using Maker Fringe Method. Monolayer formation on water surface depends on the surface pressure-area isotherm. If this monolayer formation is not perfect, multiplayer stacks cannot be formed. The molecular films were aligned almost perpendicular to the substrate, as estimated from the limiting molecular area of surface pressure-area isotherm. The molecular organization of the monolayer on the substrate and the molecular structure of the multilayered ((t-bu)4VOPc) films are discussed.

scholarly journals Synthesis, Characterization and Biological Properties of Intercalated Kaolinite Nanoclays: Intercalation and Biocompatibility

2019 ◽  
Vol 19 (1) ◽  
pp. 83-99 ◽  
Author(s):  
B. Yilmaz ◽  
E. T. Irmak ◽  
Y. Turhan ◽  
S. Doğan ◽  
M. Doğan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Human Lymphocytes ◽  
Biological Properties ◽  
Attenuated Total Reflectance ◽  
X Ray Diffraction ◽  
Cytotoxic Effects ◽  
X Ray ◽  
Human Risk ◽  
Transmission Electron ◽  
Reflectance Ftir

AbstractThe aims of the present study were to synthesize the intercalated kaolinite samples with dimethylsulfoxide (DMSO), glutamic acid (GA), succinimide (SIM), cetylpyridiniumchloride (CPC), and hexadecyltrimethylammoniumchloride (HDTMA+); to characterize by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR), and to determine the hemocompatibility and the cytotoxic effects of the intercalated kaolinite nanoclays on human lymphocytes. It was found that the intercalation with DMSO did not cause any decrease in cell viability until its maximum concentration (500 µg/mL), however, the intercalation with SIM, CPC, and (HDTMA+) causd important decreases in lymphocyte viabilities. It was determined that no significant decrease was observed in protein content of the lymphocyte cells exposed to the kaolinite nanoclays except the ones intercalated with SIM. Furthermore, the pristine kaolinite nanoclays which were intercalated with DMSO, GA, and SIM exhibited high hemocompatibility and the nanoclays intercalated with CPC and (HDTMA+) were highly hemocompatibile for the amounts below 125 and 500 µg/mL, respectively. All the results of this work can serve for the human risk assesment of intercalated nanoclays.

Structural and Morphological Characterization of Ultrathin Films of an Asymmetric Polydiacetylene

1996 ◽  
Vol 440 ◽  
Author(s):  
H. C. Wang ◽  
D. W. Cheong ◽  
J. Kumar ◽  
C. Sung ◽  
S. K. Tripathy
Keyword(s):  
Second Harmonic ◽  
Morphological Characterization ◽  
Lb Films ◽  
Force Microscopy ◽  
Langmuir Blodgett ◽  
Glass Substrates ◽  
Atomic Force ◽  
Transmission Electron ◽  
Air Water Interface

AbstractA soluble, asymmetrically substituted polydiacetylene, poly(BPOD), has been reported to form stable monolayers at the air-water interface by the Langmuir-Blodgett (LB) technique [2]. Preformed polydiacetylene has been deposited onto hydrophobic substrates as multilayers to form second order nonlinear optical thin films. Second harmonic generation was found to increase with the number of layers. From previous atomic force microscopy (AFM) studies backbone orientation along the dipping direction with an interchain spacing of about 5 A° was indicated [2].The film morphology and preferential molecular orientation of these LB films are further investigated by transmission electron microscopy (TEM). A specifically tailored sample preparation method for the ultrathin LB films was used. Multilayer films were deposited on hydrophobic collodion covered glass substrates for this purpose. Electron diffraction was employed to study the crystalline organization of mono and multilayers of LB films as well as cast films.

scholarly journals Effect of Tetramethylammonium Hydroxide on Nucleation, Surface Modification and Growth of Magnetic Nanoparticles

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Ângela L. Andrade ◽  
José D. Fabris ◽  
José D. Ardisson ◽  
Manuel A. Valente ◽  
José M. F. Ferreira
Keyword(s):  
Zeta Potential ◽  
Magnetite Nanoparticles ◽  
Heat Dissipation ◽  
Tetramethylammonium Hydroxide ◽  
Precipitation Method ◽  
Attenuated Total Reflectance ◽  
X Ray Diffraction ◽  
Experimental Conditions ◽  
Transmission Electron ◽  
Magnetite Particles

Nanoparticles of magnetite (Fe3O4) were obtained by reacting ferric chloride with sodium sulphite, through the reduction-precipitation method. The effects of adding tetramethylammonium hydroxide (TMAOH) during or after the precipitation of the iron oxide were studied in an attempt to obtain well-dispersed magnetite nanoparticles. Accordingly, the following experimental conditions were tested: (i) precipitation in absence of TMAOH (sample Mt), (ii) the same as (i) after peptizing with TMAOH (Mt1), (iii) TMAOH added to the reaction mixture during the precipitation of magnetite (Mt2). Analyses with transmission electron microscopy (TEM), X-ray diffraction, Mössbauer spectroscopy, attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), zeta potential, and magnetization measurements up to 2.5 T revealed that magnetite was normally formed also in the medium containing TMAOH. The degree of particles agglomeration was monitored with laser diffraction and technique and inspection of TEM images. The relative contributions of Néel and Brownian relaxations on the magnetic heat dissipation were studied by investigating the ability of suspensions of these magnetite nanoparticles to release heat in aqueous and in hydrogel media. Based on ATR-FTIR and zeta potential data, it is suggested that the surfaces of the synthesized magnetite particles treated with TMAOH become coated with (CH3)4N+cations.

scholarly journals Influence of the Casting Concentration on the Mechanical and Optical Properties of FA/CaCl2-Derived Silk Fibroin Membranes

2020 ◽  
Vol 21 (18) ◽  
pp. 6704
Author(s):  
Alexander Kopp ◽  
Laura Schunck ◽  
Martin Gosau ◽  
Ralf Smeets ◽  
Simon Burg ◽  
...  
Keyword(s):  
Silk Fibroin ◽  
Tensile Testing ◽  
Biomedical Applications ◽  
Toxic Chemicals ◽  
Membrane Properties ◽  
Limited Extent ◽  
Dissolution Method ◽  
Process Output ◽  
Silkworm Bombyx Mori

In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live–dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.

Streptavidin-Phycoerythrin Conjugated Proteins Bound to Biotin on Langmuir-Blodgett Films of Biotinylated Lipid Monolayers

1990 ◽  
Vol 218 ◽  
Author(s):  
Lynne A. Samuelson ◽  
D. L. Kaplan ◽  
K. A. Marx ◽  
P. Miller ◽  
D. M. Galotti ◽  
...  
Keyword(s):  
Specific Binding ◽  
Lipid Monolayers ◽  
Interface Pressure ◽  
Monolayer Films ◽  
Protein Charge ◽  
Langmuir Blodgett ◽  
Surface Recognition ◽  
Langmuir Blodgett Films ◽  
Pressure Area ◽  
Structure Research

AbstractStudies involving the specific and non-specific surface recognition of biotin on biotinylated LB lipid monolayers by streptavidin and avidin conjugated phycoerythrin are presented. Both streptavidin and avidin conjugates were injected under the monolayer and found to preferentially adsorb to the biotinylated monolayers at the air-water interface. Pressure-area isotherms displayed a biotin-streptavidin/avidin complex dependent increase in surface pressure at expanded areas indicating protein adsorption. The binding of protein was confirmed by transferring the monolayer films to solid supports and measuring the characteristic intense phycoerythrin fluorescence at 576 nm. The effect of protein charge, monolayer packing density and structure, and activation of the tetramer proteins towards specific and non-specific binding are discussed. These results suggest a novel and general methodology for the two-dimensional ordering of protein monolayers with potential bioelectronic, optical and protein structure research applications.

Models of Magnesium Oxide (111) Surface Reconstructions Obtained from Direct Phasing of Transmission Electron Diffraction Data

1997 ◽  
Vol 3 (S2) ◽  
pp. 1039-1040
Author(s):  
R. Plass ◽  
K. Egan ◽  
C. Collazo-Davila ◽  
D. Grozea ◽  
E. Landree ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Diffraction ◽  
Electron Diffraction Data ◽  
Vacuum Furnace ◽  
Transmission Electron Diffraction ◽  
Transmission Electron ◽  
Surface Reconstructions ◽  
Reflection Electron Microscopy ◽  
Plane Disk ◽  
Flowing Oxygen

It has long been thought that (111) surfaces of rock salt oxides microfacet to neutral surfaces upon annealing because of the very large energies involved in bulk terminating a layer of like ions. However in a recent reflection electron microscopy (REM) study Gajdardziska-Josifovska et al. found that MgO(lll) surfaces annealed in flowing oxygen furnaces at 1500°C not only did not microfacet, but displayed a √3×√3R30° surface periodicity that was stable in air. To determine the structure of this unusually stable surface MgO (111) transmission electron microscopy (TEM) samples were annealed in a vacuum furnace in the present study and their transmission electron diffraction (TED) patterns were analyzed with direct phasing methods.The TEM samples were prepared by orienting a MgO single crystal and sawing lmm wafers along a (111) plane. Disk samples were then ultrasonically drilled, dimpled, mechanically polished and/or hot nitric acid etched, and milled with 5 KeV Ar+ ions.

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