| 1. |
|
|
| 2. |
- Almqvist, Nils, et al.
(författare)
-
Elasticity and adhesion force mapping reveals real-time clustering of growth factor receptors and associated changes in local cellular rheological properties
- 2004
-
Ingår i: Biophysical Journal. - 0006-3495 .- 1542-0086. ; 86:3, s. 1753-1762
-
Tidskriftsartikel (refereegranskat)abstract
- Cell surface macromolecules such as receptors and ion channels serve as the interface link between the cytoplasm and the extracellular region. Their density, distribution, and clustering are key spatial features influencing effective and proper physical and biochemical cellular responses to many regulatory signals. In this study, the effect of plasma-membrane receptor clustering on local cell mechanics was obtained from maps of interaction forces between antibody-conjugated atomic force microscope tips and a specific receptor, a vascular endothelial growth factor (VEGF) receptor. The technique allows simultaneous measurement of the real-time motion of specific macromolecules and their effect on local rheological properties like elasticity. The clustering was stimulated by online additions of VEGF, or antibody against VEGF receptors. VEGF receptors are found to concentrate toward the cell boundaries and cluster rapidly after the online additions commence. Elasticity of regions under the clusters is found to change remarkably, with order-of-magnitude stiffness reductions and fluidity increases. The local stiffness reductions are nearly proportional to. receptor density and, being concentrated near the cell edges, provide a mechanism for cell growth and angiogenesis.
|
|
| 3. |
- Almqvist, Nils, et al.
(författare)
-
Micromechanical and structural properties of a pennate diatom investigated by atomic force microscopy
- 2001
-
Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 202:3, s. 518-532
-
Tidskriftsartikel (refereegranskat)abstract
- The mechanisms behind natural nanofabrication of highly structured silicas are increasingly being investigated. We have explored the use of a standard Nanoscope III Multimode atomic force microscope (AFM) to study the silica shell of diatoms. The delicate structures of the shell surface of the diatom Navicula pelliculosa (Breb.) Hilse were imaged and the shell's micromechanical properties were measured semi-quantitatively with a resolution down to approximately 10 nm. The technique to measure elasticity and hardness with the AFM was demonstrated to be useable even on these hard glass-like surfaces, Different experimental configurations and evaluation methods were tested, They gave a consistent result of the shell micromechanical properties, The first results showed that the diatom shell's overall hardness and elasticity was similar to that of known silicas. However, regions with different mechanical proper ties were distinguished. The elastic modulus varied from 7 to 20 GPa, from 20 to 100 GPa and from 30 to hundreds of GPa depending on the location. In general, the hardness measurements showed similar spatial differences, The hardness values ranged from 1 to 12 GPa but one specific part of the shell was even harder. Hence, certain localized regions of the shell were significantly harder or more elastic. These regions coincide with known characteristic features and mechanisms appearing at the different stages of the shell's growth. These results show that this method serves as a complementary tool in the study of silica biomineralization, and can detect eventual crystalline phases.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Mechler, A., Kokavecz, J., Heszler, P., Lal, R.
(författare)
-
Surface energy maps of nanostructures: Atomic force microscopy and numerical simulation study
- 2003
-
Ingår i: Appl. Physics Letters 82, no 21, pp 3740 – 3742, American Inst. of Physics (2003).. ; 82:21
-
Tidskriftsartikel (refereegranskat)
|
|
