A novel platform for simultaneous mechanical stimulation and characterization of single cells based on dielectric elastomers and atomic force microscopy

We have developed a novel set-up to simultaneously 1) apply static and dynamic deformations to adherent cells in culture 2) optically image cells under fluorescence microscopy and 3) assay the near-membrane mechanical properties with atomic force microscopy. In this system, the cell culture substrate is formed by a film of dielectric elastomer which can be eletroactuated. The geometry and position of the actuating electrodes and the applied potential can be manipulated to obtain specific strain fields over the cell culture chamber. We have modeled the electro-mechanical behavior of the actuated elastomer film and using optical markers we have established an experimental procedure to optimize and quantify the strain at the adherent cells. This cell culture device has been integrated together with a commercial atomic force microscope coupled with an inverted optical microscope equipped for fluorescence. This novel set-up allows us to temporally assess, with sub-micron spatial resolution, single cell topography and elasticity, as well as ion fluxes, all during static or cyclically applied deformations. Preliminary results on fibrobalsts (3T3 NIH) show reproducible and reversible increase in cell elastic modulus as a response to 4% applied uni-axial stretch; additionally high resolution elasticity maps of an area of40x40 mm on a single fibroblast could be obtained while stretching a single cell. When measuring cardiomyocites from mouse embryo, profiles of Ca2þ intracellular concentration could be also monitored while applying static and dynamic stretches. This study provides proof-of-concept for this set-up as a flexible experimental platform to investigate mechano-transduction mechanisms at the single cell level.