The Experts below are selected from a list of 5589 Experts worldwide ranked by ideXlab platform
Thomas R Weikl - One of the best experts on this subject based on the ideXlab platform.
-
binding constants of membrane anchored receptors and ligands a general theory corroborated by monte carlo simulations
Journal of Chemical Physics, 2015Co-Authors: Guangkui Xu, Reinhard Lipowsky, Jinglei Hu, Thomas R WeiklAbstract:Adhesion processes of biological membranes that enclose cells and cellular organelles are essential for immune responses, tissue formation, and signaling. These processes depend sensitively on the binding constant K2D of the membrane-anchored receptor and ligand proteins that mediate adhesion, which is difficult to measure in the “two-dimensional” (2D) membrane environment of the proteins. An important problem therefore is to relate K2D to the binding constant K3D of soluble variants of the receptors and ligands that lack the membrane anchors and are free to diffuse in three dimensions (3D). In this article, we present a general theory for the binding constants K2D and K3D of rather stiff proteins whose main degrees of freedom are translation and rotation, along membranes and around anchor points “in 2D,” or unconstrained “in 3D.” The theory generalizes previous results by describing how K2D depends both on the average separation and thermal Nanoscale Roughness of the apposing membranes, and on the length...
-
binding constants of membrane anchored receptors and ligands depend strongly on the Nanoscale Roughness of membranes
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Reinhard Lipowsky, Thomas R WeiklAbstract:Cell adhesion and the adhesion of vesicles to the membranes of cells or organelles are pivotal for immune responses, tissue formation, and cell signaling. The adhesion processes depend sensitively on the binding constant of the membrane-anchored receptor and ligand proteins that mediate adhesion, but this constant is difficult to measure in experiments. We have investigated the binding of membrane-anchored receptor and ligand proteins with molecular dynamics simulations. We find that the binding constant of the anchored proteins strongly decreases with the membrane Roughness caused by thermally excited membrane shape fluctuations on Nanoscales. We present a theory that explains the Roughness dependence of the binding constant for the anchored proteins from membrane confinement and that relates this constant to the binding constant of soluble proteins without membrane anchors. Because the binding constant of soluble proteins is readily accessible in experiments, our results provide a useful route to compute the binding constant of membrane-anchored receptor and ligand proteins.
Joseph Zyss - One of the best experts on this subject based on the ideXlab platform.
-
enhanced second harmonic generation by metal surfaces with Nanoscale Roughness Nanoscale dephasing depolarization and correlations
Physical Review Letters, 2004Co-Authors: Mark I Stockman, David J Bergman, Cristelle Anceau, Sophie Brasselet, Joseph ZyssAbstract:On the basis of spectral-expansion Green's function theory, we theoretically describe the topography, polarization, and spatial-coherence properties of the second-harmonic (SH) local fields at rough metal surfaces. The spatial distributions of the fundamental frequency and SH local fields are very different, with highly enhanced hot spots of the SH. The spatial correlation functions of the amplitude, phase, and direction of the SH polarization all show spatial decay on the Nanoscale in the wide range of the metal fill factors. This implies that SH radiation collected from even nanometer-scale areas is strongly depolarized and dephased, i.e., has the nature of hyper-Rayleigh scattering, in agreement with recent experiments. The present theory is applicable to nanometer-scale nonlinear-optical illumination, probing, and modification.
-
enhanced second harmonic generation by metal surfaces with Nanoscale Roughness Nanoscale dephasing depolarization and correlations
Physical Review Letters, 2004Co-Authors: Mark I Stockman, David J Bergman, Cristelle Anceau, Sophie Brasselet, Joseph ZyssAbstract:polarization, and spatial-coherence properties of the second-harmonic (SH) local fields at rough metal surfaces. The spatial distributions of the fundamental frequency and SH local fields are very different, with highly enhanced hot spots of the SH. The spatial correlation functions of the amplitude, phase, and direction of the SH polarization all show spatial decay on the Nanoscale in the wide range of the metal fill factors. This implies that SH radiation collected from even nanometer-scale areas is strongly depolarized and dephased, i.e., has the nature of hyper-Rayleigh scattering, in agreement with recent experiments. The present theory is applicable to nanometer-scale nonlinear-optical illumination, probing, and modification.
Derek L Patton - One of the best experts on this subject based on the ideXlab platform.
-
superhydrophobic hybrid inorganic organic thiol ene surfaces fabricated via spray deposition and photopolymerization
ACS Applied Materials & Interfaces, 2013Co-Authors: Bradley J Sparks, Ethan F T Hoff, Li Xiong, James T Goetz, Derek L PattonAbstract:We report a simple and versatile method for the fabrication of superhydrophobic inorganic–organic thiol-ene coatings via sequential spray-deposition and photopolymerization under ambient conditions. The coatings are obtained by spray-deposition of UV-curable hybrid inorganic–organic thiol-ene resins consisting of pentaerythritol tetra(3-mercaptopropionate) (PETMP), triallyl isocyanurate (TTT), 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (TMTVSi), and hydrophobic fumed silica nanoparticles. The spray-deposition process and nanoparticle agglomeration/dispersion provide surfaces with hierarchical morphologies exhibiting both micro- and Nanoscale Roughness. The wetting behavior, dependent on the concentration of TMTVSi and hydrophobic silica nanoparticles, can be varied over a broad range to ultimately provide coatings with high static water contact angles (>150°), low contact angle hysteresis, and low roll off angles (<5°). The cross-linked thiol-ene coatings are solvent resistant, stable at low...
Reinhard Lipowsky - One of the best experts on this subject based on the ideXlab platform.
-
binding constants of membrane anchored receptors and ligands a general theory corroborated by monte carlo simulations
Journal of Chemical Physics, 2015Co-Authors: Guangkui Xu, Reinhard Lipowsky, Jinglei Hu, Thomas R WeiklAbstract:Adhesion processes of biological membranes that enclose cells and cellular organelles are essential for immune responses, tissue formation, and signaling. These processes depend sensitively on the binding constant K2D of the membrane-anchored receptor and ligand proteins that mediate adhesion, which is difficult to measure in the “two-dimensional” (2D) membrane environment of the proteins. An important problem therefore is to relate K2D to the binding constant K3D of soluble variants of the receptors and ligands that lack the membrane anchors and are free to diffuse in three dimensions (3D). In this article, we present a general theory for the binding constants K2D and K3D of rather stiff proteins whose main degrees of freedom are translation and rotation, along membranes and around anchor points “in 2D,” or unconstrained “in 3D.” The theory generalizes previous results by describing how K2D depends both on the average separation and thermal Nanoscale Roughness of the apposing membranes, and on the length...
-
binding constants of membrane anchored receptors and ligands depend strongly on the Nanoscale Roughness of membranes
Proceedings of the National Academy of Sciences of the United States of America, 2013Co-Authors: Reinhard Lipowsky, Thomas R WeiklAbstract:Cell adhesion and the adhesion of vesicles to the membranes of cells or organelles are pivotal for immune responses, tissue formation, and cell signaling. The adhesion processes depend sensitively on the binding constant of the membrane-anchored receptor and ligand proteins that mediate adhesion, but this constant is difficult to measure in experiments. We have investigated the binding of membrane-anchored receptor and ligand proteins with molecular dynamics simulations. We find that the binding constant of the anchored proteins strongly decreases with the membrane Roughness caused by thermally excited membrane shape fluctuations on Nanoscales. We present a theory that explains the Roughness dependence of the binding constant for the anchored proteins from membrane confinement and that relates this constant to the binding constant of soluble proteins without membrane anchors. Because the binding constant of soluble proteins is readily accessible in experiments, our results provide a useful route to compute the binding constant of membrane-anchored receptor and ligand proteins.
Russell J Composto - One of the best experts on this subject based on the ideXlab platform.
-
model surfaces engineered with Nanoscale Roughness and rgd tripeptides promote osteoblast activity
Journal of Biomedical Materials Research Part A, 2004Co-Authors: Ahmed Elghannam, Paul Ducheyne, Makarand V Risbud, Christopher S Adams, Irving M Shapiro, David G Castner, Stephen L Golledge, Russell J CompostoAbstract:Cell adhesion to biomaterials is a prerequisite for tissue integration with the implant surface. Herein, we show that we can generate a model silica surface that contains a minimal-length arginine-glycine-aspartic acid (RGD) peptide that maintains its biological activity. In the first part of this study, attachment of MC3T3-E1 osteoblast-like cells was investigated on silicon oxide, amine terminated substrates [i.e., 3-aminopropyl triethoxysilane (APTS)], grafted RGD, and physisorbed RGD control. The APTS layer exhibited Nanoscale Roughness and presented amine functional groups for grafting a minimal RGD tripeptide devoid of any flanking groups or spacers. Contact angle measurements indicated that the hydrophobicity of the APTS surface was significantly lower than that of the surface with grafted RGD (RGD-APTS). Atomic force microscopy showed that surfaces covered with RGD-APTS were smoother (Ra = 0.71 nm) than those covered with APTS alone (Ra = 1.59 nm). Focusing mainly on cell morphology, experiments showed that the RGD-APTS hybrid provided an optimum surface for cell adhesion, spreading, and cytoskeletal organization. Discrete focal adhesion plaques were also observed consistent with successful cell signaling events. In a second set of experiments, smooth, monolayers of APTS (Ra = 0.1 nm) were used to prepare arginine-glycine-aspartic acid-serine (RGDS)-APTS and arginine-glycine-glutamic acid-serine (RGES)-APTS (control) substrates. Focusing mainly on cell function, integrin and gene expression were all enhanced for rate osteosarcoma cells on surfaces containing grafted RGDS. Both sets of studies demonstrated that grafted molecules of RGD(S) enhance both osteoblast-like cell adhesion and function.
-
model surfaces engineered with Nanoscale Roughness and rgd tripeptides promote osteoblast activity
Journal of Biomedical Materials Research Part A, 2004Co-Authors: Ahmed Elghannam, Paul Ducheyne, Makarand V Risbud, Christopher S Adams, Irving M Shapiro, David G Castner, Stephen L Golledge, Russell J CompostoAbstract:Cell adhesion to biomaterials is a prerequisite for tissue integration with the implant surface. Herein, we show that we can generate a model silica surface that contains a minimal-length arginine-glycine-aspartic acid (RGD) peptide that maintains its biological activity. In the first part of this study, attachment of MC3T3-E1 osteoblast-like cells was investigated on silicon oxide, amine terminated substrates [i.e., 3-aminopropyl triethoxysilane (APTS)], grafted RGD, and physisorbed RGD control. The APTS layer exhibited Nanoscale Roughness and presented amine functional groups for grafting a minimal RGD tripeptide devoid of any flanking groups or spacers. Contact angle measurements indicated that the hydrophobicity of the APTS surface was significantly lower than that of the surface with grafted RGD (RGD–APTS). Atomic force microscopy showed that surfaces covered with RGD–APTS were smoother (Ra = 0.71 nm) than those covered with APTS alone (Ra = 1.59 nm). Focusing mainly on cell morphology, experiments showed that the RGD–APTS hybrid provided an optimum surface for cell adhesion, spreading, and cytoskeletal organization. Discrete focal adhesion plaques were also observed consistent with successful cell signaling events. In a second set of experiments, smooth, monolayers of APTS (Ra = 0.1 nm) were used to prepare arginine-glycine-aspartic acid-serine (RGDS)–APTS and arginine-glycine-glutamic acid-serine (RGES)–APTS (control) substrates. Focusing mainly on cell function, integrin and gene expression were all enhanced for rate osteosarcoma cells on surfaces containing grafted RGDS. Both sets of studies demonstrated that grafted molecules of RGD(S) enhance both osteoblast-like cell adhesion and function. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 68A: 615–627, 2004
