A free-energy model for cell settling behavior on nanostructured surfaces, as proposed by Buch-Månson et al. (A) Scanning-electron-microscopy micrograph of cells suspended on top of nanostructure arrays in ‘top’ state (scale bar 5 μm). (B) Scanning-electron-microscopy micrograph of cells engulfing nanostructure arrays in ‘bottom’ state (scale bar 2 μm). (C) Illustration of membrane behavior as described by the model. (D) The change in free energy for the membrane – surface interaction, as a function of nanostructure density. In this model, if the overall change in free energy is greater than zero, the system favors cell settling in the ‘top’ state, and vice versa. Depending on the substrate and cell properties, the model predicts that the transition point between states will occur at different nanostructure densities. Adapted with permission.[117] Copyright 2015, John Wiley and Sons.