Cell adhesion is an extremely dynamic process that gives cells the ability to adapt to changes in their environment, particularly also to mechanical changes and to external forces. Previous approaches to explore the response of cells to extracellular forces have been limited to applying mechanical stimuli through large-scale deformations that involve the cytoskeleton with the risk of inducing secondary signalling processes.
We here present an approach to successfully conduct reversible photoswitching of cell adhesion on surfaces through the rapid molecular oscillations of push-pull substituted azobenzenes. Push-pull azobenzenes carry out rapid molecular oscillations between the cis and the trans state when exposed to visible light. We utilized this switching concept to develop surfaces that “tickle” cellular integrin receptors push-pull azobenzenzenes that carry the cell adhesion ligand c(RGDfK) as a headgroup. With this system, we have shown that the oscillation of c(RGDfK)-ligands indeed leads to increased cell detachment forces and enhances the expression of adhesion-associated proteins such as vinculin, talin, zyxin, and paxillin, thus pointing at the involvement of mechanosensory processes in cells.
Such photoswitching approaches to switch cell adhesion provide a stepping stone toward greater exploration of mechanosensing-controlled cell adhesion mechanisms in biomaterials and might lead to completely novel strategies to device cells through their environment.
L. F. Kadem, M. Holz, K. G. Suana, Q. Li, C. Lamprecht, R. Herges, C. Selhuber-Unkel (2016): Rapid Reversible Photoswitching of Integrin-mediated Adhesion at the Single-Cell Level. Advanced Materials, 28:1799-1802.
L. F. Kadem, K. G. Suana, M. Holz, W. Wang, H. Westerhaus, R. Herges, C. Selhuber-Unkel: High Frequency Mechanostimulation of Cell Adhesion. Angewandte Chemie International Edition, in press.