Role of superhydrophobicity in the biological activity of fibronectin at the cell-material interface

Protein adsorption and cellular behavior depend strongly on the wettability of substrates. Such studies are scarce for surfaces exhibiting extreme values of contact angles. Fibronectin (FN) adsorption and adhesion of MC3T3-E1 cells were investigated on superhydrophobic polystyrene (SH-PS) surfaces and compared with the corresponding smooth polystyrene (PS) substrate and the control glass. The FN surface density was lower on the SH-PS than on PS, and the adsorbed protein showed altered conformation of cell adhesion domains, as obtained by ELISA with monoclonal antibodies. Cell adhesion occurred on the SH-PS without the formation of mature focal adhesions, as assessed by immunofluorescence for vinculin, talin and paxillin. Correspondingly, the development of the actin cytoskeleton was delayed and without the presence of defined F-actin fibers. FAK phosphorylation was reduced on SH-PS, as compared with PS and the control glass. Also, cell contractility was diminished on the SH-PS as revealed by phosphorylation of myosin light chain (pMLC). Likewise, FN reorganization and secretion were impaired on the superhydrophobic surfaces. Cell proliferation was significantly lower in SH-PS as compared with PS up to 21 days of culture.