This image, featured on the cover of Biophysical Journal, shows two micrometer-sized cells (in pink and blue) at the end of two micropipettes (the horizontal tubes). These cells are pushed against two vertical glass rods terminated by two tips, either sharp (right) or more rounded (left). This is an artist’s rendering by Julien Husson, researcher at the Hydrodynamics Laboratory (LadHyX*), faithfully reproducing the experiment he is conducting on the mechanical properties of the cells.
Thanks to this technique, the force applied to the cell (from a few tens of piconewtons to a few nanonewtons) and its deformation (from a few tens of nanometers to a few micrometers) can be finely measured to deduce its stiffness, an important parameter in the characterization of cancer cells, for example, in addition to the usual biological data. In their article, the researchers show that, depending on the surface used to probe the cells (sharp tip or rounded tip), it is essential to differentiate the contribution of the cell’s surface tension from the contribution of its viscoelastic interior, in order to best interpret the measurements.