The effects of surface topography of nanostructure arrays on cell adhesion

Nanostructure arrays have drawn much attention and are promising as new biomaterials in the field of biomedicine. In recent years, numerous experimental studies on the cell behavior of nanostructured arrays (NSs) have been published, describing a wide variety of experimental results. But there are only a few theoretical analyses that elucidate the mechanisms of interactions between cells and nanostructures. Here we present a quantitative thermodynamic model to elucidate the effects of surface topography of nanostructure arrays on cell adhesion. Based on the established model, we studied the equilibrium state of cell adhesion by analyzing the change in free energy during the adhesion process. Theoretical results showed that cell adhesion mode is actually determined by the balance between adhesion energy and deformation energy of the cell membrane. According to the calculated results, a phase diagram of the cell adhesion has been constructed, which can clarify the interrelated effects of the radius and surface distribution density of nanopillars. We can identify the relation between the surface topography of nanostructure arrays and the cell adhesion mode from the phase. The effects of geometry and surface density distribution of nanopillars on cell adhesion studied by a quantitative thermodynamic model showed that high (low) surface distribution density and large (small) radius result in the "Top" ("Bottom") mode.