scholarly journals van der Waals forces influencing adhesion of cells

2015 ◽  
Vol 370 (1661) ◽  
pp. 20140078 ◽  
Author(s):  
K. Kendall ◽  
A. D. Roberts
Keyword(s):  
Cell Adhesion ◽  
Surface Energy ◽  
Adhesion Molecules ◽  
Adhesion Force ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Surface Molecules ◽  
Molecular Adhesion ◽  
Surface Active ◽  
Water Cut

Adhesion molecules, often thought to be acting by a ‘lock and key’ mechanism, have been thought to control the adhesion of cells. While there is no doubt that a coating of adhesion molecules such as fibronectin on a surface affects cell adhesion, this paper aims to show that such surface contamination is only one factor in the equation. Starting from the baseline idea that van der Waals force is a ubiquitous attraction between all molecules, and thereby must contribute to cell adhesion, it is clear that effects from geometry, elasticity and surface molecules must all add on to the basic cell attractive force. These effects of geometry, elasticity and surface molecules are analysed. The adhesion force measured between macroscopic polymer spheres was found to be strongest when the surfaces were absolutely smooth and clean, with no projecting protruberances. Values of the measured surface energy were then about 35 mJ m −2 , as expected for van der Waals attractions between the non-polar molecules. Surface projections such as abrasion roughness or dust reduced the molecular adhesion substantially. Water cut the measured surface energy to 3.4 mJ m −2 . Surface active molecules lowered the adhesion still further to less than 0.3 mJ m −2 . These observations do not support the lock and key concept.

Pull-In Instability of Functionally Graded Cantilever Nanoactuators Incorporating Effects of Microstructure, Surface Energy and Intermolecular Forces

2018 ◽  
Vol 10 (08) ◽  
pp. 1850091 ◽  
Author(s):  
Mohamed A. Attia ◽  
Salwa A. Mohamed
Keyword(s):  
Residual Stress ◽  
Surface Energy ◽  
Boundary Conditions ◽  
Van Der Waals ◽  
Surface Elasticity ◽  
Van Der Waals Forces ◽  
Functionally Graded ◽  
Surface Residual Stress ◽  
Electrically Actuated ◽  
Classical Boundary

In this paper, an integrated non-classical continuum model is developed to investigate the pull-in instability of electrostatically actuated functionally graded nanocantilevers. The model accounts for the simultaneous effects of local-microstructure, surface elasticity and surface residual in the presence of fringing field as well as Casimir and van der Waals forces. The modified couple stress and Gurtin–Murdoch surface elasticity theories are employed to conduct the scaling effects of microstructure and surface energy, respectively, in the context of Euler–Bernoulli beam hypothesis. Bulk and surface material properties are varied according to the power-law distribution through the beam thickness. The physical neutral axis position for mentioned FG nanobeams is considered. Hamilton principle is employed to derive the nonlinear size-dependent governing equations and the non-classical boundary conditions. The resulting nonlinear differential equations are solved utilizing the generalized differential quadrature method (GDQM). In addition, the non-classical boundary conditions of nanocantilever beams due to surface residual stress are exactly implemented. After validation of the obtained results by previously available data in the literature, the influences of different geometrical and material parameters on the pull-in instability of the FG nanocantilevers are examined in detail. It is concluded that the pull-in behavior of electrically actuated FG micro/nanocantilevers is significantly influenced by the material distribution, material length scale parameter, surface elasticity constant, surface residual stress, initial gap, slenderness ratio, Casimir, and van der Waals forces. The obtained results can be considered for modeling and analysis of electrically actuated FG nanocantilevers.

scholarly journals Cadherins, Selectins, and Integrins in CAM-DR in Leukemia

2020 ◽  
Vol 10 ◽  
Author(s):  
Hye Na Kim ◽  
Yongsheng Ruan ◽  
Heather Ogana ◽  
Yong-Mi Kim
Keyword(s):  
Drug Resistance ◽  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Cell Adhesion Molecules ◽  
Intracellular Signaling ◽  
Myeloid Leukemia ◽  
Lymphoblastic Leukemia ◽  
Leukemia Cells ◽  
Surface Molecules

The interaction between leukemia cells and the bone microenvironment is known to provide drug resistance in leukemia cells. This phenomenon, called cell adhesion-mediated drug resistance (CAM-DR), has been demonstrated in many subsets of leukemia including B- and T-acute lymphoblastic leukemia (B- and T-ALL) and acute myeloid leukemia (AML). Cell adhesion molecules (CAMs) are surface molecules that allow cell–cell or cell–extracellular matrix (ECM) adhesion. CAMs not only recognize ligands for binding but also initiate the intracellular signaling pathways that are associated with cell proliferation, survival, and drug resistance upon binding to their ligands. Cadherins, selectins, and integrins are well-known cell adhesion molecules that allow binding to neighboring cells, ECM proteins, and soluble factors. The expression of cadherin, selectin, and integrin correlates with the increased drug resistance of leukemia cells. This paper will review the role of cadherins, selectins, and integrins in CAM-DR and the results of clinical trials targeting these molecules.

scholarly journals Surface energy and wettability of van der Waals structures

Nanoscale ◽  
2016 ◽  
Vol 8 (10) ◽  
pp. 5764-5770 ◽  
Author(s):  
Meenakshi Annamalai ◽  
Kalon Gopinadhan ◽  
Sang A. Han ◽  
Surajit Saha ◽  
Hye Jeong Park ◽  
...  
Keyword(s):  
Surface Energy ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
Layered Materials ◽  
2D Layered Materials ◽  
Dipole Interactions

Our study shows that the surface energy of all 2D layered materials is undoubtedly dominated by London–van der Waals forces with little contribution from dipole–dipole interactions.

scholarly journals Cell adhesion molecules: detection with univalent second antibody.

1980 ◽  
Vol 87 (3) ◽  
pp. 703-707 ◽  
Author(s):  
W R Springer ◽  
S H Barondes
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Cell Adhesion Molecules ◽  
In Vitro Assay ◽  
Cell Surface Molecules ◽  
Rabbit Antibody ◽  
Vitro Assay ◽  
Surface Molecules ◽  
Cell Cell

Identification of cell surface molecules that play a role in cell-cell adhesion (here called cell adhesion molecules) has been achieved by demonstrating the inhibitory effect of univalent antibodies that bind these molecules in an in vitro assay of cell-cell adhesion. A more convenient reagent, intact (divalent) antibody, has been avoided because it might agglutinate the cells rather than blocking cell-cell adhesion. In this report, we show that intact rabbit immunoglobulin directed against certain cell surface molecules of Dictyostelium discoideum blocks cell-cell adhesion when the in vitro assay is performed in the presence of univalent goat anti-rabbit antibody. Under appropriate experimental conditions, the univalent second antibody blocks agglutination induced by the rabbit antibody without significantly interfering with its effect on cell-cell adhesion. This method promises to be useful for screening monoclonal antibodies raised against potential cell adhesion molecules because: (a) it allows for the screening of large numbers of antibody samples without preparation of univalent fragments; and (b) it requires much less antibody because of the greater affinity of divalent antibodies for antigens.

scholarly journals Bravo/Nr-CAM is closely related to the cell adhesion molecules L1 and Ng-CAM and has a similar heterodimer structure.

1992 ◽  
Vol 118 (5) ◽  
pp. 1259-1270 ◽  
Author(s):  
J F Kayyem ◽  
J M Roman ◽  
E J de la Rosa ◽  
U Schwarz ◽  
W J Dreyer
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Neural Development ◽  
Cell Adhesion Molecules ◽  
Transmembrane Domain ◽  
Chain Structure ◽  
Cell Interactions ◽  
Cdna Clones ◽  
Coding Region ◽  
Surface Molecules

Diverse cell-surface molecules of the nervous system play an important role in specifying cell interactions during development. Using a method designed to generate mAbs against neural surface molecules of defined molecular weight, we have previously reported on the surface protein, Bravo, found in the developing avian retinotectal system. Bravo is immunologically detected on developing optic fibers in the retina, but absent from distal regions of the same fibers in the tectum. We have isolated cDNA clones encompassing the entire coding region of Bravo, including clones containing five alternative sequences of cDNA. These putative alternatively spliced sequences encode stretches of polypeptide ranging in length from 10-93 amino acids and are predicted to be both extra- and intracellular. The deduced primary structure of Bravo reveals that, like the cell adhesion molecules (CAMs) chicken Ng-CAM and mouse L1, Bravo is composed of six Ig-like domains, five fibronectin type III repeats, a transmembrane domain, and a short cytoplasmic region. Recently, the cDNA sequence of a related molecule, Nr-CAM, was reported and its possible identity with Bravo discussed (Grumet, M., V. Mauro, M. P. Burgoon, G. E. Edelman, and B. A. Cunningham. 1991. J. Cell Biol. 113:1399-1412). Here we confirm this identity and moreover show that Bravo is found on Müller glial processes and end-feet in the developing retina. In contrast to the single polypeptide chain structure of Nr-CAM reported previously, we show that Bravo has a heterodimer structure composed of an alpha chain of M(r) 140/130 and a beta chain of 60-80 kD. As with L1 and Ng-CAM, the two chains of Bravo are generated from an intact polypeptide by cleavage at identical locations and conserved sites within all three molecules (Ser-Arg/Lys-Arg). The similar domain composition and heterodimer structure, as well as the 40% amino acid sequence identity of these molecules, defines them as an evolutionarily related subgroup of CAMs. The relationship of Bravo to molecules known to be involved in cell adhesion and process outgrowth, combined with its pattern of expression and numerous potential isoforms, suggests a complex role for this molecule in cell interactions during neural development.

Cell Adhesion Molecules: Selectins and Integrins

1999 ◽  
Vol 19 (5-6) ◽  
pp. 41 ◽  
Author(s):  
Francisco Sanchez-Madrid ◽  
Roberto González-Amaro
Keyword(s):  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Cell Adhesion Molecules

ROCK2 Regulates the Expression of Cell Adhesion Molecules and Cell-to-Cell Adhesion in Vascular Endothelial Cells

Diabetes ◽  
2018 ◽  
Vol 67 (Supplement 1) ◽  
pp. 476-P
Author(s):  
YUSUKE TAKEDA ◽  
KEIICHIRO MATOBA ◽  
DAIJI KAWANAMI ◽  
YOSUKE NAGAI ◽  
TOMOYO AKAMINE ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Cell Adhesion ◽  
Adhesion Molecules ◽  
Cell Adhesion Molecules ◽  
Vascular Endothelial Cells ◽  
Vascular Endothelial ◽  
Cell To Cell Adhesion

Self-Assembly of a Chiral Cubic Three-Connected Net from the High Symmetry Molecules C60 and SnI4

2020 ◽  
Author(s):  
Daniel B. Straus ◽  
Robert J. Cava
Keyword(s):  
Organic Synthesis ◽  
Self Assembly ◽  
Van Der Waals ◽  
Van Der Waals Forces ◽  
High Symmetry ◽  
Molecular Chirality ◽  
Chiral Materials ◽  
Self Assembled ◽  
Chiral Centers

The design of new chiral materials usually requires stereoselective organic synthesis to create molecules with chiral centers. Less commonly, achiral molecules can self-assemble into chiral materials, despite the absence of intrinsic molecular chirality. Here, we demonstrate the assembly of high-symmetry molecules into a chiral van der Waals structure by synthesizing crystals of C<sub>60</sub>(SnI<sub>4</sub>)<sub>2</sub> from icosahedral buckminsterfullerene (C<sub>60</sub>) and tetrahedral SnI4 molecules through spontaneous self-assembly. The SnI<sub>4</sub> tetrahedra template the Sn atoms into a chiral cubic three-connected net of the SrSi<sub>2</sub> type that is held together by van der Waals forces. Our results represent the remarkable emergence of a self-assembled chiral material from two of the most highly symmetric molecules, demonstrating that almost any molecular, nanocrystalline, or engineered precursor can be considered when designing chiral assemblies.

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