Rapid Reversible Photoswitching of Integrin‐Mediated Adhesion at the Single‐Cell Level

Adhesion forces and mechanics in mannose-mediated acanthamoeba interactions

“…It is noteworthy that force spectroscopy on acanthamoebae requires a few modifications to the classical Single-Cell Force Spectroscopy experiment used for mammalian cells. There, the cell is typically glued to the cantilever [26, 32] and contact times of several minutes can easily be probed with the cell as an almost spherical object at the cantilever [33]. This is not possible for acanthamoebae due to their strong motility, which pushes the cantilever up and pulls it down.…”

Potential‐Responsive Surfaces for Manipulation of Cell Adhesion, Release, and Differentiation

“…Cell adhesion can be modulated dynamically by applying negative and positive potentials to surfaces functionalized with tailored monolayers. [13] RGD peptides have been immobilized on various substrates,s uch as hydrogels, [14] gold, [15] or glass [16] and these sequences can be modified to either promote or inhibit cell adhesion.To realize dynamic control of cell adhesion onto substrates during cell cultivation, stimuli-controlled switchable RGD surfaces have been developed and rely on the cleavage of the RGD ligands from the surface in response to electrochemical potential, [17,18] light, [19,20] and enzymes. The higher accessibility of the peptide under ap ositive applied potential causes phenotypic changes in the cells that are hallmarks of osteogenesis,w hereas lower accessibility of the peptide promoted by negative potentials leads to adipogenesis.…”

High‐Frequency Mechanostimulation of Cell Adhesion

“…[14] Them olar ratio of c(RGDfK)-azobenzene and PEG2000 was set to 1:99, which provides suitable adhesion conditions for fibroblast cells. [7,15] Thec (RGDfK)-azobenzene packing density on the substrates was 1.07 AE 0.33 molecules nm À2 ,a sd etermined with UV-vis spectroscopy.F igure 1b illustrates the working principle of the c(RGDfK)-coupled push-pull azobenzene monolayer.T he azobenzene remains in the trans configuration as long as the light is switched off.I rradiation at 530 nm induces photoisomerization of the push-pull azobenzenes [16] and ar eversion to the trans configuration takes place within afew milliseconds. [17][18][19] As azobenzenes can still change their configuration under significant external loads, [20] we assume that the re-isomerization still occurs when integrins have bound to the c-(RGDfK) headgroup of the push-pull azobenzene.D uring configuration switching,t he azobenzene molecules change their lengths from 9 in the trans configuration to 5.5 in the cis.…”

“…Theb istability of regular azobenzenes,w hich function by either exposing or hiding adhesion ligands via kinking the azobenzene units, [7] also impairs efficient force transduction to adhesion sites.…”

“…[7] Figure 2a shows as ketch of the experimental setup.After immobilizing acell on atipless cantilever,t he cantilever-bound cell is brought into contact with the sample and the detection system of an atomic force microscope is used to determine the forces necessary to detach the cell. Figure 2b shows force-distance curves for the detachment of ac ell adhering to the RGD push-pull azobenzene-decorated surface for our two experimental situations,t hat is,w hen the surface is inactive (light OFF) and when it is active,t hat is,t he push-pull azobenzenes are oscillating (light ON).…”