| 1. |
- Tymchenko, Nina, 1977, et al.
(författare)
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A novel cell force sensor for quantification of traction during cell spreading and contact guidance
- 2007
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Ingår i: Biophysical Journal. - : Elsevier BV. - 1542-0086 .- 0006-3495. ; 93, s. 335-345
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we present a ridged, microfabricated, force sensor that can be used to investigate mechanical interactions between cells exhibiting contact guidance and the underlying cell culture substrate, and a proof-of-function evaluation of the force sensor performance. The substrates contain arrays of vertical pillars between solid ridges that were microfabricated in silicon wafers using photolithography and deep reactive ion etching. The spring constant of the pillars was measured by atomic force microscopy. For time-lapse experiments, cells were seeded on the pillared substrates and cultured in an on-stage incubator on a microscope equipped with re. flected differential interference contrast optics. Endothelial cells (ECs) and. broblasts were observed during attachment, spreading, and migration. Custom image analysis software was developed to resolve cell borders, cell alignment to the pillars and migration, displacements of individual pillars, and to quantify cell traction forces. Contact guidance classifi. cation was based on cell alignment and movement angles with respect to microfabricated ridges, as well as cell elongation. In initial investigations made with the ridged cell force sensor, we have observed contact guidance in ECs but not in. broblast cells. A difference in maximal amplitude of mechanical forces was observed between a contact-guided and non-contact-guided, but mobile, EC. However, further experiments are required to determine the statistical significance of this observation. By chance, we observed another feature of cell behavior, namely a reversion of cell force direction. The direction of forces measured under rounded. broblast cells changed from outwards during early cell attachment to inwards during further observation of the spreading phase. The range of forces measured under. broblasts (up to 138 nN) was greater than that measured in EC (up to 57 nN), showing that the rigid silicon sensor is capable of resolving a large range of forces, and hence detection of differences in traction forces between cell types. These observations indicate proof-of-function of the ridged cell force sensor to induce contact guidance, and that the pillared cell force sensor constructed in rigid silicon has the necessary sensitivity to detect differences in traction force vectors between different cell phenotypes and morphologies.
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| 2. |
- Wallentin, Carl-Johan, et al.
(författare)
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Network analysis of bicyclo 3.3.1 nonanes: the diol, the dione and the acetal
- 2009
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 11:9, s. 1837-1841
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Tidskriftsartikel (refereegranskat)abstract
- The solid state structure of endo,endo-bicyclo[3.3.1]nonane-2,6-diol, rac-2, shows a hydrogen bonded, three-connected, chiral 3D-net with utg-topology, distinctively different from those formed by the so called tubuland diols, e.g. 2,6-dimethylbicyclo[3.3.1]nonane-exo2, exo-6-diol, rac-5, that crystallise as three-connected, chiral etanets and from the qtz-net formed by weaker hydrogen bonds in the bicyclo[3.3.1]nonane-2,6-dione, 3. The protected bicyclo[3.3.1]nonane2,6-dione, bis-2,6-ethylenedioxy acetal, 4, has a structure governed by weaker forces and can be interpreted as close packed stacks.
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| 3. |
- Wallentin, Carl-Johan, et al.
(författare)
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Synthetic and crystallographic studies of bicyclo 3.3.1 nonane derivatives: from strong to weak hydrogen bonds and the stereochemistry of network formation
- 2012
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Ingår i: CrystEngComm. - : Royal Society of Chemistry (RSC). - 1466-8033. ; 14:1, s. 178-187
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Tidskriftsartikel (refereegranskat)abstract
- The syntheses and crystal structures of four unsaturated bicyclo[3.3.1] nonane derivatives containing various functionalities are presented and their intermolecular interactions examined. The impact of unsaturation on crystal structures and intermolecular networks of the six membered rings was found to be significant compared to the saturated analogues. Thus, unsaturated diol rac-1, in striking contrast to its saturated analogue rac-6, does not crystallise with spontaneous resolution. The hydrogen bonds in the starting bicyclononane diene diol rac-1, and the weaker hydrogen bonds in the dienone rac-2, and the bromo and nitrile derivatives, rac-3, rac-4 and (+)-4, respectively, were found significant for the overall structure. The two bromine atoms in rac-3 have significant halogen-halogen interactions. In several structures 2D nets can be identified and overall structures can be interpreted as close packing of these layers. The crystal structures were also subject to independent analysis by Hirshfeld surfaces, and this method provided additional insights, especially for the structural role of the unsaturation. The possible relation between chiral networks and conglomerate formation is discussed.
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