scholarly journals Polyhedra Self-Assembled from DNA Tripods and Characterized with 3D DNA-PAINT

Science ◽  
2014 ◽  
Vol 344 (6179) ◽  
pp. 65-69 ◽  
Author(s):  
Ryosuke Iinuma ◽  
Yonggang Ke ◽  
Ralf Jungmann ◽  
Thomas Schlichthaerle ◽  
Johannes B. Woehrstein ◽  
...  
Keyword(s):  
Self Assembly ◽  
Fluorescent Microscopy ◽  
Three Dimensional ◽  
Super Resolution ◽  
Triangular Prism ◽  
Hexagonal Prism ◽  
General Strategy ◽  
Transmission Electron ◽  
Pentagonal Prism ◽  
Means Of Transmission

DNA self-assembly has produced diverse synthetic three-dimensional polyhedra. These structures typically have a molecular weight no greater than 5 megadaltons. We report a simple, general strategy for one-step self-assembly of wireframe DNA polyhedra that are more massive than most previous structures. A stiff three-arm-junction DNA origami tile motif with precisely controlled angles and arm lengths was used for hierarchical assembly of polyhedra. We experimentally constructed a tetrahedron (20 megadaltons), a triangular prism (30 megadaltons), a cube (40 megadaltons), a pentagonal prism (50 megadaltons), and a hexagonal prism (60 megadaltons) with edge widths of 100 nanometers. The structures were visualized by means of transmission electron microscopy and three-dimensional DNA-PAINT super-resolution fluorescent microscopy of single molecules in solution.

scholarly journals Protein Fibrillar Hydrogels for three-Dimensional Tissue Engineering

2009 ◽  
Vol 2009 ◽  
pp. 1-4 ◽  
Author(s):  
Hui Yan ◽  
Antti Nykanen ◽  
Janne Ruokolainen ◽  
David Farrar ◽  
Aline F. Miller
Keyword(s):  
Cell Culture ◽  
Self Assembly ◽  
Culture Media ◽  
Three Dimensional ◽  
Three Dimensions ◽  
Disease States ◽  
Environmental Responsiveness ◽  
Transmission Electron ◽  
Biological Compatibility ◽  
Oscillatory Rheology

Protein self-assembly into highly ordered fibrillar aggregates has attracted increasing attention over recent years, due primarily to its association with disease states such as Alzheimer's. More recently, however, research has focused on understanding the generic behavior of protein self-assembly where fibrillation is typically induced under harsh conditions of low pH and/or high temperature. Moreover the inherent properties of these fibrils, including their nanoscale dimension, environmental responsiveness, and biological compatibility, are attracting substantial interest for exploiting these fibrils for the creation of new materials. Here we will show how protein fibrils can be formed under physiological conditions and their subsequent gelation driven using the ionic strength of cell culture media while simultaneously incorporating cells homogeneously throughout the gel network. The fibrillar and elastic nature of the gel have been confirmed using cryo-transmission electron microscopy and oscillatory rheology, respectively; while cell culture work shows that our hydrogels promote cell spreading, attachment, and proliferation in three dimensions.

Effect of the Doping and the Al Content on the Microstructure and Morphology of Thin AlxGa1-xN Layers Grown by MOCVD.

1999 ◽  
Vol 595 ◽  
Author(s):  
J.H. Mazur ◽  
M. Benamara ◽  
Z. Liliental-Weber ◽  
W. Swider ◽  
J. Washburn ◽  
...  
Keyword(s):  
Thin Films ◽  
Schottky Diodes ◽  
Three Dimensional ◽  
Growth Front ◽  
Tem Analysis ◽  
Al Content ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Means Of Transmission ◽  
20 Nm

AbstractAlxGa1−xN {x=30% (doped and undoped), 45% (doped)} thin films were grown by MOCVD on ∼2 µm thick GaN layer using Al2O3 substrate. These films were designed to be the active parts of HFETs with nsí product of about 1016(Vs)−1. The layers were then studied by means of transmission electron microscopy (TEM) techniques. In this paper, it is shown that the AlxGa1−xN layer thickness was non-uniform due to the presence of Vshaped defects within the AlxGa1−xN films. The nucleation of these V-shaped defects has taken place about 20 nm above the AlxGa1−xN/aN interface. Many of these Vshaped defects were associated with the presence of the threading dislocations propagating from the GaN/Al2O3 interface. We show that the density of these V-shaped defects increases with the doping level and also with the Al mole fraction in the films. The formation mechanism of the V-shaped defects seems to be related to the concentration of dopants or other impurities at the ledges of the growing film. This suggestion is supported by high resolution TEM analysis. The growth front between the V-shaped defects in the lower Al concentration thin films was planar as compared with F99W3.77 the three-dimensional growth in the doped, higher Al concentration film. This interpretation of the origin of the V-shaped defects is consistent with the observed lowering of the Schottky barrier height in n-doped AlGaN/Ni Schottky diodes.

scholarly journals Effect of the Doping and the Al Content on the Microstructure and Morphology of Thin AlxGa1−xN Layers Grown by MOCVD

2000 ◽  
Vol 5 (S1) ◽  
pp. 294-300
Author(s):  
J.H. Mazur ◽  
M. Benamara ◽  
Z. Liliental-Weber ◽  
W. Swider ◽  
J. Washburn ◽  
...  
Keyword(s):  
Thin Films ◽  
Schottky Diodes ◽  
Three Dimensional ◽  
Growth Front ◽  
Tem Analysis ◽  
Al Content ◽  
Transmission Electron ◽  
High Resolution Tem ◽  
Means Of Transmission ◽  
20 Nm

AlxGa1−xN {x=30% (doped and undoped), 45% (doped)} thin films were grown by MOCVD on ∼2 μm thick GaN layer using Al2O3 substrate. These films were designed to be the active parts of HFETs with nsμ product of about 1016(Vs)-1. The layers were then studied by means of transmission electron microscopy (TEM) techniques. In this paper, it is shown that the AlxGa1−xN layer thickness was non-uniform due to the presence of V-shaped defects within the AlxGa1−xN films. The nucleation of these V-shaped defects has taken place about 20 nm above the AlxGa1−xN/GaN interface. Many of these V-shaped defects were associated with the presence of the threading dislocations propagating from the GaN/Al2O3 interface. We show that the density of these V-shaped defects increases with the doping level and also with the Al mole fraction in the films. The formation mechanism of the V-shaped defects seems to be related to the concentration of dopants or other impurities at the ledges of the growing film. This suggestion is supported by high resolution TEM analysis. The growth front between the V-shaped defects in the lower Al concentration thin films was planar as compared with the three-dimensional growth in the doped, higher Al concentration film. This interpretation of the origin of the V-shaped defects is consistent with the observed lowering of the Schottky barrier height in n-doped AlGaN/Ni Schottky diodes.

Polymer Cyclization as a General Strategy for the Emergence of Hierarchical Nanostructures

2020 ◽  
Author(s):  
Chaojian Chen ◽  
Manjesh Kumar Singh ◽  
Katrin Wunderlich ◽  
Sean Harvey ◽  
Manfred Wagner ◽  
...  
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Hierarchical Structures ◽  
Structural Similarity ◽  
Vital Role ◽  
General Strategy ◽  
Wide Range ◽  
Linear Poly ◽  
Polymer Folding ◽  
Dynamics Simulations

The creation of synthetic polymer nanoobjects with well-defined hierarchical structures is important for a wide range of applications such as nanomaterial synthesis, catalysis, and therapeutics. Inspired by the programmability and precise three-dimensional architectures of biomolecules, here wedemonstrate the strategy of fabricating controlled hierarchical structures through self-assembly of folded synthetic polymers. Linear poly(2-hydroxyethyl methacrylate) of different lengths are folded into cyclic polymers and their self-assembly into hierarchical structures is elucidated by various experimental techniques and molecular dynamics simulations. Based on their structural similarity, macrocyclic brush polymers with amphiphilic block side chains are synthesized, which can self-assemble into wormlike structures and higher-ordered networks. Our work points out the vital role of polymer folding in macromolecular self-assembly and establishes a versatile approach for constructing biomimetic hierarchical assemblies.

Wüstite nanocrystals: Synthesis, structure and superlattice formation

2007 ◽  
Vol 22 (7) ◽  
pp. 1987-1995 ◽  
Author(s):  
Ming Yin ◽  
Zhuoying Chen ◽  
Brian Deegan ◽  
Stephen O’Brien
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Size Control ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Salt Crystal ◽  
Uniform Size ◽  
Nonpolar Solvents ◽  
Transmission Electron ◽  
State Kinetic

Monodisperse ligand-capped cubic wüstite FexO nanocrystals were prepared by a novel thermal decomposition method of iron (II) acetate in the presence of oleic acid as the surfactant. Controlled size distributions of cubic nanoparticles possessing the rock salt crystal structure were isolated in the range 10–18 nm. The influence of molar ratio of surfactant to precursor was investigated to understand size control and monodispersity. Using inexpensive, nontoxic metal salts as reactants, we were able to synthesize gram-scale quantities of relatively monodisperse nanocrystals in a single reaction, without further size selection, characterized by x-ray diffraction and transmission electron microscopy. The procedure enables the collection of samples of uniform size as a function of time, thus permitting a preliminary solid-state kinetic analysis of the reaction as a function of increasing particle size. Following controlled evaporation from nonpolar solvents, self-assembly into two-dimensional arrays, three-dimensional single-component superlattices, and binary superlattices with gold nanoparticles were observed and characterized.

scholarly journals Polymer Cyclization as a General Strategy for the Emergence of Hierarchical Nanostructures

2020 ◽  
Author(s):  
Chaojian Chen ◽  
Manjesh Kumar Singh ◽  
Katrin Wunderlich ◽  
Sean Harvey ◽  
Manfred Wagner ◽  
...  
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Hierarchical Structures ◽  
Structural Similarity ◽  
Vital Role ◽  
General Strategy ◽  
Wide Range ◽  
Linear Poly ◽  
Polymer Folding ◽  
Dynamics Simulations

The creation of synthetic polymer nanoobjects with well-defined hierarchical structures is important for a wide range of applications such as nanomaterial synthesis, catalysis, and therapeutics. Inspired by the programmability and precise three-dimensional architectures of biomolecules, here wedemonstrate the strategy of fabricating controlled hierarchical structures through self-assembly of folded synthetic polymers. Linear poly(2-hydroxyethyl methacrylate) of different lengths are folded into cyclic polymers and their self-assembly into hierarchical structures is elucidated by various experimental techniques and molecular dynamics simulations. Based on their structural similarity, macrocyclic brush polymers with amphiphilic block side chains are synthesized, which can self-assemble into wormlike structures and higher-ordered networks. Our work points out the vital role of polymer folding in macromolecular self-assembly and establishes a versatile approach for constructing biomimetic hierarchical assemblies.

scholarly journals Polymer Cyclization as a General Strategy for the Emergence of Hierarchical Nanostructures

2020 ◽  
Author(s):  
Chaojian Chen ◽  
Manjesh Kumar Singh ◽  
Katrin Wunderlich ◽  
Sean Harvey ◽  
Manfred Wagner ◽  
...  
Keyword(s):  
Self Assembly ◽  
Three Dimensional ◽  
Hierarchical Structures ◽  
Structural Similarity ◽  
Vital Role ◽  
General Strategy ◽  
Wide Range ◽  
Linear Poly ◽  
Polymer Folding ◽  
Dynamics Simulations

The creation of synthetic polymer nanoobjects with well-defined hierarchical structures is important for a wide range of applications such as nanomaterial synthesis, catalysis, and therapeutics. Inspired by the programmability and precise three-dimensional architectures of biomolecules, we report the strategy of fabricating controlled hierarchical structures through self-assembly of folded synthetic polymers. Linear poly(2-hydroxyethyl methacrylate) of different lengths are folded into cyclic polymers and their self-assembly into hierarchical structures is elucidated by various experimental techniques and molecular dynamics simulations. Based on their structural similarity, macrocyclic brush polymers with amphiphilic block side chains are synthesized, which can self-assemble into wormlike structures and higher-ordered networks. Our work points out the vital role of polymer folding in macromolecular self-assembly and establishes a versatile approach for constructing biomimetic hierarchical assemblies.

Tayloring the Photocatalytical Activity of Anatase TiO2 Thin Film Electrodes by Three-Dimensional Mesoporosity

2010 ◽  
Vol 162 ◽  
pp. 91-113 ◽  
Author(s):  
Bernhard Neumann ◽  
Thorsten Brezesinsky ◽  
Bernd Smarsly ◽  
Helmut Tributsch
Keyword(s):  
Thin Film ◽  
Self Assembly ◽  
Three Dimensional ◽  
Great Influence ◽  
X Ray Diffraction ◽  
Porous Films ◽  
X Ray ◽  
Transmission Electron ◽  
Evaporation Induced Self Assembly ◽  
Thin Film Electrodes

Mesoporous titanium dioxide (m-TiO2) thin film electrodes were synthesized by evaporation-induced self-assembly (EISA), utilizing a novel type of amphiphilic block copolymer as template. The ordered network of pores shows an accessible inner volume that results in a huge BET-surface and a distinct transparency. According to X-ray diffraction analyses the mesoporous films are highly crystalline after calcination at 550°C. 1D and 2D small-angle X-ray scattering and transmission electron microscopy investigations prove the high quality of the mesopore texture over micrometer-sized areas. These well-defined, crystalline m-TiO2 films show an increased photoactivity for overall water splitting and oxidation of formic acid as compared to porous films prepared in the same manner without a template. The performance of the electrodes was analyzed by measuring the photocurrent and the mass signal of liberated gas by electrochemical mass spectroscopy (EMS). These experiments reveal that film morphology have a great influence to the I-V characteristic of photoelectrodes. An appropriate crystallization temperature is indispensable to obtain an optimum between crystallinity, morphology and photoactivity and to prevent collapse of the mesopore architecture.

Fabrication of Scattering Spheres-Embedding Three-Dimensional Ordered Macroporous Titania and Application in Dye-Sensitized Photoanode

2012 ◽  
Vol 554-556 ◽  
pp. 395-398 ◽  
Author(s):  
Cheng An Tao ◽  
Jian Fang Wang ◽  
Yin Long ◽  
Ya Nan Lv ◽  
Guang Tao Li
Keyword(s):  
Self Assembly ◽  
Colloidal Crystal ◽  
Three Dimensional ◽  
Solid Material ◽  
X Ray Diffraction ◽  
Colloidal Spheres ◽  
Nanoparticle Dispersions ◽  
Transmission Electron ◽  
Colloidal Crystal Template ◽  
Ordered Macroporous

Scattering spheres-embedding three-dimensional ordered macroporous (3DOM) titania(TiO2) was fabricated, by the route of colloidal spheres self-assembly, infiltration and template removal. The procedures of 3DOM structure preparation were characterized by transmission electron microscope (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD). The silica@PMMA core-shell spheres were prepared and self-assembled into colloidal crystal template. Solid material was deposited in the colloidal crystal template by spin-coating of titania nanoparticle dispersions. Subsequently, the samples were heated to 400 °C to form anatase TiO2and to remove the polymer of template, which resulted in macroporous structure with a silica sphere in each lattice pore. The conventional TiO2film, 3DOM TiO2photoanodes were also fabricated. It was found that SiO2-embedding 3DOM photoanode has the higher photocurrent efficiency than both of TiO2 film and 3DOM, because there are scattering spheres in its lattice pores which enhance the light scattering and improve the light harvest of the dye.

Ultrastructural Analysis of the Salivary Glands of Gromphadorhina Portentosa (Schaum)

1977 ◽  
Vol 35 ◽  
pp. 638-639
Author(s):  
P.J. Dailey
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Salivary Glands ◽  
Secretory Vesicles ◽  
The Past ◽  
Transmission Electron ◽  
Means Of Transmission ◽  
Gromphadorhina Portentosa ◽  
Scanning Electron ◽  
Topographical Relief

The structure of insect salivary glands has been extensively investigated during the past decade; however, none have attempted scanning electron microscopy (SEM) in ultrastructural examinations of these secretory organs. This study correlates fine structure by means of SEM cryofractography with that of thin-sectioned epoxy embedded material observed by means of transmission electron microscopy (TEM).Salivary glands of Gromphadorhina portentosa were excised and immediately submerged in cold (4°C) paraformaldehyde-glutaraldehyde fixative1 for 2 hr, washed and post-fixed in 1 per cent 0s04 in phosphosphate buffer (4°C for 2 hr). After ethanolic dehydration half of the samples were embedded in Epon 812 for TEM and half cryofractured and subsequently critical point dried for SEM. Dried specimens were mounted on aluminum stubs and coated with approximately 150 Å of gold in a cold sputtering apparatus.Figure 1 shows a cryofractured plane through a salivary acinus revealing topographical relief of secretory vesicles.

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