scholarly journals Micellization Behaviour of Linear and Nonlinear Block Copolymers Based on Poly(n-hexyl isocyanate) in Selective Solvents

Polymers ◽  
2020 ◽  
Vol 12 (8) ◽  
pp. 1678
Author(s):  
Aggelos Vazaios ◽  
Athanasios Touris ◽  
Mikel Echeverria ◽  
Georgia Zorba ◽  
Marinos Pitsikalis
Keyword(s):  
Block Copolymers ◽  
Self Assembly ◽  
Structural Parameters ◽  
The Self ◽  
Copolymer Composition ◽  
Force Microscopy ◽  
Selective Solvents ◽  
Atomic Force ◽  
Spherical Micelles ◽  
Macromolecular Architecture

Block copolymers have attracted significant scientific and economic interest over the last decades due to their ability to self-assemble into ordered structures both in bulk and in selective solvents. In this work, the self-assembly behaviour of both linear (diblocks, triblocks and pentablocks) and nonlinear (miktoarm stars and a block-graft) copolymers based on poly(n-hexyl isocyanate), PHIC, were studied in selective solvents such as n-heptane and n-dodecane. A variety of experimental techniques, namely static and dynamic light scattering, dilute solution viscometry and atomic force microscopy, were employed to study the micellar structural parameters (e.g., aggregation number, overall micellar size and shape, and core and shell dimensions). The effect of the macromolecular architecture, the molecular weight and the copolymer composition on the self-assembly behaviour was studied. Spherical micelles in equilibrium with clusters were obtained from the block copolymers. Thermally stable, uniform and spherical aggregates were found from the triblock copolymers. The poly(n-hexyl isocyanate)-b-polyisoprene-b-poly(n-hexyl isocyanate),-HIH copolymers tend to adopt closed loop conformation, leading to more elongated cylindrical-type structures upon increasing the concentration. Clustering effects were also reported in the case of the pentablock terpolymers. The topology of the blocks plays an important role, since the poly(n-hexyl isocyanate)-b-polystyrene-b-polyisoprene-b-polystyrene-b-poly(n-hexyl isocyanate), HSISH terpolymer shows intermicellar fusion of spherical micelles, leading to the formation of extended networks. The formation of spherical micelles in equilibrium with clusters was obvious in the case of the miktoarm stars, whereas the block-graft copolymer shows the existence of mainly unimolecular micelles.

Clathrin-Inspired Coating and Stabilization of Liposomes by DNA Self-Assembly

2019 ◽  
Author(s):  
Kevin N. Baumann ◽  
Luca Piantanida ◽  
Javier García-Nafría ◽  
Diana Sobota ◽  
Kislon Voïtchovsky ◽  
...  
Keyword(s):  
Self Assembly ◽  
Mechanical Stability ◽  
Lipid Vesicles ◽  
The Self ◽  
Force Microscopy ◽  
Atomic Force ◽  
Cryo Electron Microscopy ◽  
Further Development ◽  
Liposome Surface ◽  
Dna Coating

The self-assembly of the protein clathrin on biological membranes facilitates essential processes of endocytosis in biological systems and has provided a source of inspiration for materials design by the highly ordered structural appearance. By mimicking the architecture of clathrin self-assemblies to coat liposomes with biomaterials, new classes of hybrid carriers can be derived. Here we present a method for fabricating DNA-coated liposomes by hydrophobically anchoring and subsequently growing a DNA network on the liposome surface which structurally mimics clathrin assemblies. Dynamic light scattering (DLS), ζ-potential and cryo-electron microscopy (cryo-EM) measurements independently demonstrate successful DNA coating. Nanomechanical measurements conducted with atomic force microscopy (AFM) show that the DNA coating enhances the mechanical stability of the liposomes relative to uncoated ones. Furthermore, we provide the possibility to reverse the coating process by triggering the disassembly of the DNA coating through a toehold-mediated displacement reaction. Our results describe a straightforward, versatile, and reversible approach for coating and stabilizing lipid vesicles by an interlaced DNA network. This method has potential for further development towards the ordered arrangement of tailored functionalities on the surfaces of liposomes and for applications as hybrid nanocarrier.

NANOSTRUCTURES FROM DESIGNER PEPTIDES

COSMOS ◽  
2008 ◽  
Vol 04 (02) ◽  
pp. 173-183
Author(s):  
BOON TEE ONG ◽  
PARAYIL KUMARAN AJIKUMAR ◽  
SURESH VALIYAVEETTIL
Keyword(s):  
Atomic Force Microscopy ◽  
Solid State ◽  
Self Assembly ◽  
Size Range ◽  
The Self ◽  
Mica Surface ◽  
Force Microscopy ◽  
Solution Structures ◽  
Atomic Force

The present article reviews the self-assembly of oligopeptides to form nanostructures, both in solution and in solid state. The solution structures of the peptides were examined using circular dichroism and dynamic light scattering. The solid state assembly was examined by adsorbing the peptides onto a mica surface and analyzing it using atomic force microscopy. The role of pH and salt concentration on the peptide self-assembly was also examined. Nanostructures within a size range of 3–10 nm were obtained under different conditions.

scholarly journals Cation-Specific Effects on the Self-Assembly of Collagen Molecules Mediated by Acetate on Mica Surface Observed with Atomic Force Microscopy

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Zhiwei Wang ◽  
Qi Xiao ◽  
Xuan Song ◽  
Yunfei Wan ◽  
Jie Zhu
Keyword(s):  
Atomic Force Microscopy ◽  
Self Assembly ◽  
Ionic Concentration ◽  
Collagen Fibrils ◽  
The Self ◽  
Mica Surface ◽  
Force Microscopy ◽  
Specific Effects ◽  
Atomic Force ◽  
Base Method

The well-organized collagen layers on mica surface have drawn extensive attention for its essential applications and studies on the process of self-assembly as a model system. In this work, collagen extracted from fish scales by acid-base method was used to explore the self-assembly characters, and atomic force microscopy was applied to observe the collagen assembled on mica surface mediated by acetate with four different cations, including K+, Na+, Mg2+, and Ca2+. It showed that cations might influence the interaction between collagen fibrils and mica surface at high ionic concentration. And a similar network structure was acquired with uniform pore size for four kinds of acetates; nearly ranged collagen fibrils in the same direction were collected in Mg2+ solutions, while flat films with some fibrils were achieved in K+ solutions. The Hofmeister series and Collins’ model were adapted to explain the effects of cations and acetate on the self-assembly of collagen. These results and analysis would be helpful for directing the pattern of collagen assembly on a solid surface with a potential application in food science and engineering.

scholarly journals Self-assembly and wetting properties of gold nanorod–CTAB molecules on HOPG

2019 ◽  
Vol 10 ◽  
pp. 696-705 ◽  
Author(s):  
Imtiaz Ahmad ◽  
Floor Derkink ◽  
Tim Boulogne ◽  
Pantelis Bampoulis ◽  
Harold J W Zandvliet ◽  
...  
Keyword(s):  
Self Assembly ◽  
Cetyltrimethylammonium Bromide ◽  
Pyrolytic Graphite ◽  
The Self ◽  
Gold Nanorod ◽  
Force Microscopy ◽  
Wetting Properties ◽  
Atomic Force ◽  
Highly Ordered Pyrolytic Graphite ◽  
Self Assembled

The formation of self-assembled superstructures of cetyltrimethylammonium bromide (CTAB) after drying on a nonwetting highly ordered pyrolytic graphite (HOPG) surface have been investigated using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Although SEM did not reveal coverage of CTAB layers, AFM showed not only CTAB assembly, but also the dynamics of the process on the surface. The self-assembled layers of CTAB molecules on the HOPG terraces prior to nanorod deposition were shown to change the wettability of the surface, and as a result, gold nanorod deposition takes place on nonwetting HOPG terraces.

scholarly journals Self-Assembly Investigations of Sulfonated Poly(methyl methacrylate-block-styrene) Diblock Copolymer Thin Films

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Claudia Piñón-Balderrama ◽  
César Leyva-Porras ◽  
Roberto Olayo-Valles ◽  
Javier Revilla-Vázquez ◽  
Ulrich S. Schubert ◽  
...  
Keyword(s):  
Thin Films ◽  
Block Copolymers ◽  
Methyl Methacrylate ◽  
Self Assembly ◽  
Volume Fraction ◽  
Degree Of Polymerization ◽  
Solvent Vapor ◽  
Poly Methyl Methacrylate ◽  
Force Microscopy ◽  
Atomic Force

Poly(methyl methacrylate-block-styrene) block copolymers (BCs) of low dispersity were selectively sulfonated on the styrenic segment. Several combinations of degree of polymerization and volume fraction of each block were investigated to access different self-assembled morphologies. Thin films of the sulfonated block copolymers were prepared by spin-coating and exposed to solvent vapor (SVA) or thermal annealing (TA) to reach equilibrium morphologies. Atomic force microscopy (AFM) was employed for characterizing the films, which exhibited a variety of nanometric equilibrium and nonequilibrium morphologies. Highly sulfonated samples revealed the formation of a honeycomb-like morphology obtained in solution rather than by the self-assembly of the BC in the solid state. The described morphologies may be employed in applications such as templates for nanomanufacturing and as cover and binder of catalytic particles in fuel cells.

scholarly journals Structural and Nanotribological Properties of a BODIPY Self-Assembly

2021 ◽  
Vol 9 ◽  
Author(s):  
Shanchao Tan ◽  
Wendi Luo ◽  
Yongjie Zhang ◽  
Xiang-Kui Ren ◽  
Yuhong Liu ◽  
...  
Keyword(s):  
Self Assembly ◽  
Density Functional ◽  
Supramolecular Assembly ◽  
Dft Method ◽  
The Self ◽  
Scanning Tunneling ◽  
Tunneling Microscopy ◽  
Force Microscopy ◽  
Atomic Force ◽  
Assembly Mechanism

Boron-dipyrromethenes (BODIPY) are promising functional dyes, whose exceptional optical properties are closely related to their supramolecular assembly. Herein, the self-assembly of a BODIPY derivative functionalized with uracil groups is explicitly and thoroughly investigated by using scanning tunneling microscopy (STM). Based on the simulation and calculation by density functional theory (DFT) method, it can be concluded that the construction of ordered self-assembly structure is attributed to the formation of hydrogen bonds between uracil groups. Moreover, the nanotribological property of the self-assembly on HOPG surface is measured by using atomic force microscopy (AFM). The effort on self-assembly of the BODIPY derivative could enhance the understanding of surface assembly mechanism.

scholarly journals Observing Effects of Calcium/Magnesium Ions and pH Value on the Self-Assembly of Extracted Swine Tendon Collagen by Atomic Force Microscopy

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Xuan Song ◽  
Zhiwei Wang ◽  
Shiyu Tao ◽  
Guixia Li ◽  
Jie Zhu
Keyword(s):  
Atomic Force Microscopy ◽  
Metal Ions ◽  
Self Assembly ◽  
Food Packaging ◽  
Ph Value ◽  
The Self ◽  
Solution Ph ◽  
Collagen Concentration ◽  
Force Microscopy ◽  
Atomic Force

Self-assembly of extracted collagen from swine trotter tendon under different conditions was firstly observed using atomic force microscopy; then the effects of collagen concentration, pH value, and metal ions to the topography of the collagen assembly were analyzed with the height images and section analysis data. Collagen assembly under 0.1 M, 0.2 M, 0.3 M CaCl2, and MgCl2 solutions in different pH values showed significant differences (P < 0.05) in the topographical properties including height, width, and roughness. With the concentration being increased, the width of collagen decreased significantly (P < 0.05). The width of collagen fibers was first increased significantly (P < 0.05) and then decreased with the increasing of pH. The collagen was assembled with network structure on the mica in solution with Ca2+ ions. However, it had shown uniformed fibrous structure with Mg2+ ions on the new cleaved mica sheet. In addition, the width of collagen fibrous was 31~58 nm in solution with Mg2+ but 21~50 nm in Ca2+ solution. The self-assembly collagen displayed various potential abilities to construct fibers or membrane on mica surfaces with Ca2+ ions and Mg2+ irons. Besides, the result of collagen self-assembly had shown more relations among solution pH value, metal ions, and collagen molecular concentration, which will provide useful information on the control of collagen self-assembly in tissue engineering and food packaging engineering.

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