Microscopic analysis of the surface functionalization of polymer particles and subsequent grafting of polymer chains from the surface

2012 ◽  
Vol 61 (6) ◽  
pp. 367-380
Author(s):  
V. Mittal ◽  
N. B. Matsko
Keyword(s):  
Surface Functionalization ◽  
Microscopic Analysis ◽  
Polymer Chains ◽  
Polymer Particles

Novel three-dimensional long-term bone marrow culture system using polymer particles with grafted epoxy-polymer-chains supports the proliferation and differentiation of hematopoietic stem cells

2011 ◽  
Vol 236 (11) ◽  
pp. 1342-1350 ◽  
Author(s):  
Yukio Hirabayashi ◽  
Yoshihiro Hatta ◽  
Jin Takeuchi ◽  
Isao Tsuboi ◽  
Tomonori Harada ◽  
...  
Keyword(s):  
Stromal Cells ◽  
Culture System ◽  
3D Structure ◽  
Three Dimensional ◽  
Hematopoietic Cells ◽  
3D Culture ◽  
Polymer Chains ◽  
Polymer Particles ◽  
Hematopoietic Stem ◽  
3D Culture System

Hematopoiesis occurs in the bone marrow, where primitive hematopoietic cells proliferate and differentiate in close association with a three-dimensional (3D) hematopoietic microenvironment composed of stromal cells. We examined the hematopoietic supportive ability of stromal cells in a 3D culture system using polymer particles with grafted epoxy polymer chains. Umbilical cord blood-derived CD34+ cells were co-cultivated with MS-5 stromal cells. They formed a 3D structure in the culture dish in the presence of particles, and the total numbers of cells and the numbers of hematopoietic progenitor cells, including colony-forming unit (CFU)-Mix, CFU-granulocyte-macrophage, CFU-megakaryocyte and burst-forming unit-erythroid, were measured every seven days. The hematopoietic supportive activity of the 3D culture containing polymer particles and stromal cells was superior to that of 2D culture, and allowed the expansion and maintenance of hematopoietic progenitor cells for more than 12 weeks. Various types of hematopoietic cells, including granulocytes, macrophages and megakaryocytes at different maturation stages, appeared in the 3D culture, suggesting that the CD34+ cells were able to differentiate into a range of blood cell types. Morphological examination showed that MS-5 stromal cells grew on the surface of the particles and bridged the gaps between them to form a 3D structure. Hematopoietic cells slipped into the 3D layer and proliferated within it, relying on the presence of the MS-5 cells. These results suggest that this 3D culture system using polymer particles reproduced the hematopoietic phenomenon in vitro, and might thus provide a new tool for investigating hematopoietic stem cell–stromal cell interactions.

Chiral helical substituted polyacetylene grafted on hollow polymer particles: preparation and enantioselective adsorption towards cinchona alkaloids

2019 ◽  
Vol 10 (32) ◽  
pp. 4441-4448 ◽  
Author(s):  
Xueyong Yong ◽  
Youping Wu ◽  
Jianping Deng
Keyword(s):  
Cinchona Alkaloids ◽  
Polymer Chains ◽  
Carboxyl Groups ◽  
Polymer Particles ◽  
Helical Polymer ◽  
Enantioselective Adsorption

Hollow polymer particles tethering chiral helical polymer chains and functional carboxyl groups were prepared and applied in enantioselective adsorption.

scholarly journals Particle packing into loose networks for tough and sticky composite gels

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Taka-Aki Asoh ◽  
Tatsuya Yamamoto ◽  
Hiroshi Uyama
Keyword(s):  
Polymer Network ◽  
Particle Packing ◽  
Polymer Chains ◽  
Stimuli Responsive ◽  
Polymer Particles ◽  
Composite Gels ◽  
Composite Gel ◽  
High Level ◽  
External Stimuli ◽  
Stimuli Responsive Polymer

Abstract Hydrogel is an attractive material, but its application is limited due to its low mechanical strength. In this study, a tough composite gel could be prepared by synthesizing polymer particles within a polymer network having relatively loose cross-linking. Since the polymer network acts as a dispersion stabilizer during the synthesis of the hydrophobic polymer particles, a large amount of particles could be introduced into the gel without agglomeration. It was suggested that the high level of toughness was induced by the adsorption and desorption of the polymer chains on the surface of the finely packed particles. By using a stimuli-responsive polymer network, elasticity and plasticity of composite gels could be controlled in response to external stimuli, and adhesion on the gel surface could also be modulated.

scholarly journals Ionic Inter-Particle Complexation Effect on the Performance of Waterborne Coatings

Polymers ◽  
2021 ◽  
Vol 13 (18) ◽  
pp. 3098
Author(s):  
Maialen Argaiz ◽  
Fernando Ruipérez ◽  
Miren Aguirre ◽  
Radmila Tomovska
Keyword(s):  
Density Functional ◽  
Resonance Energy ◽  
Density Functional Theory Calculations ◽  
Tensile Tests ◽  
Polymer Chains ◽  
Mechanical Resistance ◽  
Polymer Particles ◽  
Waterborne Coatings ◽  
Ionic Complexation ◽  
Oppositely Charged

The performance of waterborne (meth)acrylic coatings is critically affected by the film formation process, in which the individual polymer particles must join to form a continuous film. Consequently, the waterborne polymers present lower performance than their solvent-borne counter-polymers. To decrease this effect, in this work, ionic complexation between oppositely charged polymer particles was introduced and its effect on the performance of waterborne polymer films was studied. The (meth)acrylic particles were charged by the addition of a small amount of ionic monomers, such as sodium styrene sulfonate and 2-(dimethylamino)ethyl methacrylate. Density functional theory calculations showed that the interaction between the selected main charges of the respective functional monomers (sulfonate–amine) is favored against the interactions with their counter ions (sulfonate–Na and amine–H). To induce ionic complexation, the oppositely charged latexes were blended, either based on the same number of charges or the same number of particles. The performance of the ionic complexed coatings was determined by means of tensile tests and water uptake measurements. The ionic complexed films were compared with reference films obtained at pH at which the cationic charges were in neutral form. The mechanical resistance was raised slightly by ionic bonding between particles, producing much more flexible films, whereas the water penetration within the polymeric films was considerably hindered. By exploring the process of polymer chains interdiffusion using Fluorescence Resonance Energy Transfer (FRET) analysis, it was found that the ionic complexation was established between the particles, which reduced significantly the interdiffusion process of polymer chains. The presented ionic complexes of sulfonate–amine functionalized particles open a promising approach for reinforcing waterborne coatings.

Enzyme immobilization on amphiphilic polymer particles having grafted polyionic polymer chains

2009 ◽  
Vol 48 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Masahiro Yasuda ◽  
Hibiki Nikaido ◽  
Wilhelm R. Glomm ◽  
Hiroyasu Ogino ◽  
Kosaku Ishimi ◽  
...  
Keyword(s):  
Enzyme Immobilization ◽  
Amphiphilic Polymer ◽  
Polymer Chains ◽  
Polymer Particles

scholarly journals Functionalization of Single-Walled Carbon Nanotubes with End-Capped Polystyrene via a Single-Step Diels–Alder Cycloaddition

Polymers ◽  
2021 ◽  
Vol 13 (7) ◽  
pp. 1169
Author(s):  
Maria-Malvina Stathouraki ◽  
Christos Pantazidis ◽  
Emmanouil Mygiakis ◽  
Apostolos Avgeropoulos ◽  
Georgios Sakellariou
Keyword(s):  
Carbon Nanotubes ◽  
Surface Functionalization ◽  
Cycloaddition Reaction ◽  
Single Walled Carbon Nanotubes ◽  
Terminal Group ◽  
Single Step ◽  
Diels Alder ◽  
Polymer Chains ◽  
Single Walled Carbon ◽  
Walled Carbon Nanotubes

A facile, single-step, [4+2] Diels–Alder cycloaddition reaction for the surface functionalization of single-walled carbon nanotubes (SWNTs) with end-capped polystyrene chains is presented. The thermal cycloaddition reaction took place at high temperature (~230 °C) without any catalyst between the sp2 network of carbon nanotubes, which acted as dienophile, and the diphenylethylene cyclobutene (DPE-CB) terminal group of the polystyrene chain. Anionic polymerization was employed for the synthesis of the polystyrene macromolecule, and successful and quantitative end-capping reaction with the DPE-CB molecule was confirmed by matrix-assisted laser desorption/ionization time of flight mass spectroscopy. Thermogravimetric analysis revealed the wt % of the grafted macromolecule on the CNT surface as well as the grafting density of the polymer chains on the SWNTs (0.027 chains nm−2). Direct evidence for the surface functionalization and the presence of thin polystyrene film was obtained by transmission electron microscopy (TEM) and by atomic force microscopy (AFM).

Preparatory Procedures for Electron Microscopic Analysis at the Molecular Level of Resolution

1978 ◽  
Vol 36 (3) ◽  
pp. 516-520
Author(s):  
F.J. Sjostrand
Keyword(s):  
Electron Microscope ◽  
Molecular Level ◽  
Microscopic Analysis ◽  
Resolving Power ◽  
Cellular Structures ◽  
Electron Microscopic ◽  
Systematic Analysis ◽  
Technical Developments ◽  
Thin Sectioning ◽  
Obvious Reason

In the 1940's and 1950's electron microscopy conferences were attended with everybody interested in learning about the latest technical developments for one very obvious reason. There was the electron microscope with its outstanding performance but nobody could make very much use of it because we were lacking proper techniques to prepare biological specimens. The development of the thin sectioning technique with its perfectioning in 1952 changed the situation and systematic analysis of the structure of cells could now be pursued. Since then electron microscopists have in general become satisfied with the level of resolution at which cellular structures can be analyzed when applying this technique. There has been little interest in trying to push the limit of resolution closer to that determined by the resolving power of the electron microscope.

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