Effects of molecular interactions at various polymer brush surfaces on fibronectin adsorption induced cell adhesion

The effects of protein adsorption on the polymer brush surfaces with well-defined chemical structures and physical properties were examined with respect to initial protein adsorption, structural changes to the adsorbed proteins, and subsequent cell adhesion. Four polymer brush surfaces with different hydrophilicities and charge states were prepared. The molecular interaction forces during adsorption-desorption processes of protein on the polymer brush surfaces depending on the chemical structure of the polymer were determined. Crucially, these molecular interactions affected the adsorption behavior and structural changes of fibronectin (FN), a cell-adhesive protein, used in this study. Adsorption of FN onto the zwitterionic polymer and anionic polymer surfaces was difficult, however significant protein adsorption to the hydrophobic and cationic surfaces was observed. Further, the structural changes to the adhered FN on these surfaces were significant. Subsequent cell adhesion experiments revealed that the adhered cell density was correlated with the amount of adsorbed FN and the degree of FN structural change. In addition, the cationic surface inhibited cell proliferation behavior. These results indicate that cellular responses can be indirectly regulated by controlling the molecular interactions which induced the structural change of adsorbed proteins via the material surface properties.