Design and characterization of surfaces presenting mechanical nanoheterogeneities for a better control of cell–material interactions

Development of microfabrication technologies allowed creating surfaces with subcellular topographic and chemical features, which led to an improved control of cell reaction in contact with biomaterials. More recently, it was discovered that cells were also sensitive to mechanical properties of their substrate. This study aims at evaluating cell behavior in contact with surfaces presenting mechanical cues at the nanometer scale. However, control of the mechanical properties of such surface remains challenging. The adopted strategy consists in creating rigid topographic features prepared by colloidal lithography of 500 nm silica particles on a glass substrate, and covering it with a soft layer of polydimethylsiloxane (PDMS) by spin-coating. X-ray photoelectron spectroscopy analysis shows that the PDMS layer ensures a homogeneous surface chemistry, while spin-coating parameters can be adjusted to obtain a limited topography. Presence of mechanical contrast is confirmed by force–distance measurements obtained by atomic force microscopy. Finally, morphology and proliferation of MC3T3 preosteoblasts cultured during 3 days on the obtained substrates is shown to be influenced by the presence of mechanical heterogeneities at the subcellular level.