Interplay Between Long-Range And Short-Range Interactions In Polymer Self-Assembly And Cell Adhesion
01 Jan 2008-
TL;DR: In this paper, reversible gelation of associating polymers and ligand-receptor interactions in membrane adhesion was studied, and the energy barrier of the adhesion as a result of membrane bending deformations and the double-well adhesion potential was calculated.
Abstract: Interplay between long-range and short-range interactions is a common theme in soft and biological matter, which results in complicated self-assembly behaviors. We study two examples of this interplay: reversible gelation of associating polymers and ligand-receptor interactions in membrane adhesion. In associating polymer solutions, the competition between the conformation flexibility of polymer chains and the enthalpic monomer interactions results in phase-separated micro-structures at the mesoscopic scale; both gelation and the microphase order-disorder transition are manifestations of this self-assembly. We further establish that reversible gelation is similar to the glass transition: both are characterized by ergodicity breaking, aperiodic micro-structures, and non-equilibrium relaxations over a finite temperature range. In the study of ligand-receptor interactions between surfaces, we emphasize the interplay between specific ligand-receptor binding, and generic physical interactions. We find that both the finite spatial extension of receptors and their mobilities affect their binding affinity. As a special case of the interplay between receptor binding and generic interactions, we study the dynamics of membrane adhesion that is mediated by receptor binding but fulfilled through membrane deformations. We calculate the energy barrier of the adhesion as a result of membrane bending deformations and the double-well adhesion potential, and analyze the different scenarios according to the shape of the adhesion potential by scaling arguments.
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01 Mar 1996
TL;DR: In this paper, a mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented, which traverses the weak- to strong-segregation regimes, is free of traditional approximations.
Abstract: A mean-field phase diagram for conformationally symmetric diblock melts using the standard Gaussian polymer model is presented. Our calculation, which traverses the weak- to strong-segregation regimes, is free of traditional approximations. Regions of stability are determined for disordered (DIS) melts and for ordered structures including lamellae (L), hexagonally packed cylinders (H), body-centered cubic spheres (QIm3m), close-packed spheres (CPS), and the bicontinuous cubic network with Ia3d symmetry (QIa3d). The CPS phase exists in narrow regions along the order−disorder transition for χN ≥ 17.67. Results suggest that the QIa3d phase is not stable above χN ∼ 60. Along the L/QIa3d phase boundaries, a hexagonally perforated lamellar (HPL) phase is found to be nearly stable. Our results for the bicontinuous Pn3m cubic (QPn3m) phase, known as the OBDD, indicate that it is an unstable structure in diblock melts. Earlier approximation schemes used to examine mean-field behavior are reviewed, and compa...
1,256 citations
554 citations
Posted Content•
TL;DR: It is shown that a system with competing interactions on different length scales, relevant to the formation of stripes in doped Mott insulators, undergoes a self-generated glass transition which is caused by the frustrated nature of the interactions and not related to the presence of quenched disorder.
Abstract: Using our previous results for the configurational entropy of a stripe glass as well as a variational result for the bare surface tension of entropic droplets we show that there is no disagreement between the numerical simulations of Grousson et al. and our theory. The claim that our theory disagrees with numerical simulations is based on the assumption that the surface tension is independent of the frustration parameter Q of the model. However, we show in this Reply that it varies strongly with Q and that the resulting Q-dependence of the kinetic fragility agrees with the one obtained by Grousson et al. We believe that this answers the questions raised in the Comment by Grousson et al.
127 citations
TL;DR: In this paper, eine Einfiihrung in einige aktuelle Forschungsaspekte aus dem Bereich der Biophysik zu geben is discussed.
Abstract: Das Ziel dieses Buches ist es, eine Einfiihrung in einige aktuelle Forschungsaspekte aus dem Bereich der Biophysik zu geben. Der Inhalt des Buches umfaBt folgende Teilgebiete: den Einsatz der Mikrolithographie zur DNA-Trennung, die Modellierung der Faltung, Struktur und Dynamik von Proteinen, neuere theoretische Ansátze zur Proteinfaltung, die Physik der Organellen, Mechanismen molekularer Motorén, die Dynamik von Mikrotubuli, Formübergange und Fluktuationen von Membránén, Vesikeln und Zellen, die Biophysik des Gehirns und seiner Neuronen, weiterhin werden die sensorische Signalverarbeitung, molekulare evolutionsbiologische Strategien und potentielle Anwendungen, die Musterbildung beim Wachstum bakterieller Kolonien und Evolutionsmodelle erotteti. Das Buch, das aus einer Sommerschule und einem Workshop hervorgegangen ist, richtet sich an fortgeschrittene Studenten und an Doktoranden der Physik, Chemie und Biologie (z.T. sind mathematische Kenntnisse erforderlich!), aber auch an Forscher, die sich mit biophysikalischen Fragestellungen beschaftigen und einen aktuellen Einstieg in die angesprochenen modernen Forschungsfelder der Biophysik suchen. Die Artikel sind
18 citations
Journal Article•
TL;DR: The selectivity of cell-cell and cell-tissue adhesion is determined by specific short range forces between cell surface proteins, which function as constraint reaction spaces facilitating the local assembly of actin stress fibers and control cell signalling processes.
Abstract: The selectivity of cell-cell and cell-tissue adhesion is determined by specific short range forces between cell surface proteins. Long range entropic interfacial forces (mediated by repeller molecules and membrane undulations) and adhesion-induced elastic stresses in the cell envelope serve the fine control of the strength and duration of adhesion. The initial step of cell adhesion exhibits typical features of a first order wetting transition resulting in the formation of tight adhesion domains by lateral phase separation of receptors. External lift forces can cause shrinking and unbinding of adhesion sites if the receptors are immobile but induce domain growth if they are mobile. Strong adhesion domains (resisting nano-Newton forces) can form by commitment of some 10,000 receptors enabling cells to control adhesion strength rapidly by varying the receptor and repeller densities on cell surfaces through endocytosis and exocytosis. The adhesion domains can function as constraint reaction spaces facilitating the local assembly of actin stress fibers and control cell signalling processes as shown for the activation of immunological responses by immunological synapses.
12 citations
References
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TL;DR: The Knitting Pattern as mentioned in this paper is a block copolymer that was discovered by Reimund Stadler and his coworkers and reflects a delicate free-energy minimization that is common to all blockcopolymer materials.
Abstract: Block copolymers are all around us, found in such products as upholstery foam, adhesive tape and asphalt additives. This class of macromolecules is produced by joining two or more chemically distinct polymer blocks, each a linear series of identical monomers, that may be thermodynamically incompatible (like oil and vinegar). Segregation of these blocks on the molecular scale (5–100 nm) can produce astonishingly complex nanostructures, such as the “knitting pattern” shown on the cover of this issue of PHYSICS TODAY. This striking pattern, discovered by Reimund Stadler and his coworkers, reflects a delicate free‐energy minimization that is common to all block copolymer materials.
2,824 citations
"Interplay Between Long-Range And Sh..." refers background in this paper
...Melts of block copolymers are attractive from both theoretical and experimental standpoints, as they undergo microphase transitions and produce diverse ordered microstructures (Hamley, 1998, 2004; Bates and Fredrickson, 1990, 1999)....
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2,416 citations
"Interplay Between Long-Range And Sh..." refers background in this paper
...TK is often termed the ideal glass transition temperature and is conceptually identified with the underlying thermodynamic glass transition at which the viscosity of the supercooled liquid diverges (Kauzmann, 1948; Adam and Gibbs, 1965; Monasson, 1995; Debenedetti and Stillinger, 2001)....
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TL;DR: The results suggest a new class of synthetic thin-shelled capsules based on block copolymer chemistry, and both the membrane bending and area expansion moduli of electroformed polymersomes (polymer-based liposomes) fell within the range of lipid membrane measurements.
Abstract: Vesicles were made from amphiphilic diblock copolymers and characterized by micromanipulation. The average molecular weight of the specific polymer studied, polyethyleneoxide-polyethylethylene (EO40-EE37), is several times greater than that of typical phospholipids in natural membranes. Both the membrane bending and area expansion moduli of electroformed polymersomes (polymer-based liposomes) fell within the range of lipid membrane measurements, but the giant polymersomes proved to be almost an order of magnitude tougher and sustained far greater areal strain before rupture. The polymersome membrane was also at least 10 times less permeable to water than common phospholipid bilayers. The results suggest a new class of synthetic thin-shelled capsules based on block copolymer chemistry.
2,338 citations
TL;DR: Rolling of leukocytes on vascular endothelial cells, an early event in inflammation, can be reproduced in vitro on artificial lipid bilayers containing purified CD62, a selectin also named PADGEM and GMP-140 that is inducible on endothelial Cells.
2,242 citations
"Interplay Between Long-Range And Sh..." refers background in this paper
...On the other hand, it is known that in the rolling of leukocyte cells (Lawrence and Springer, 1991; Springer, 1994), the longer but weaker selectin ligands mediate rolling of the cells, while the shorter but stronger integrin receptors result in the final strong adhesion; the interplay between longer-tethered ligands and shorter-tethered ligands is key to the successful immunological response (Qi et al....
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..., 2004; Cuvelier and Nassoy, 2004), and substrate-supported monolayer and bilayer membranes (Sackmann, 1996; Tanaka and Sackmann, 2005) allow better characterization of the specific and non-specific interactions because of the absence of complicating factors such as chemical signaling and deformability of biological cells in vivo (Lawrence and Springer, 1991; Dustin et al., 1996; Finger et al., 1996; Kuo and Lauffenburger, 1993; Eniola et al., 2003)....
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Book•
01 Jan 1998
TL;DR: The self consistent field theory of block copolymers has been studied in this article, where the authors describe the behavior of blockcopolymers in a variety of ways: 1. Melt Phase Behaviour of Block Copolymers 2. Block copolymer in Dilute Solution 3. Block Copylmers in Semidilute Solution 4.
Abstract: 1. Introduction 2. Melt Phase Behaviour of Block Copolymers 3. Block Copolymers in Dilute Solution 4. Block Copolymers in Semidilute and Concentrated Solutions 5. Solid State Structure of Block Copolymers 6. Blends Containing Block Copolymers Appendix: The Self Consistent Field Theory
1,606 citations
"Interplay Between Long-Range And Sh..." refers background in this paper
...Microphase transitions in block-copolymer systems have been extensively studied, both theoretically and experimentally (Bates and Fredrickson, 1990; Hamley, 1998)....
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...Melts of block copolymers are attractive from both theoretical and experimental standpoints, as they undergo microphase transitions and produce diverse ordered microstructures (Hamley, 1998, 2004; Bates and Fredrickson, 1990, 1999)....
[...]
...In addition, such structures were also obtained (as a rule) in dynamicdensity-functional calculations (Fraaije et al., 1997; Maurits and Fraaije, 1997; Hamley, 1998)....
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