Fibronectin adsorption and cell adhesion to mixed monolayers of tri(ethylene glycol)- and methyl-terminated alkanethiols

Surface chemistries that prevent protein adsorption and render surfaces nonadhesive have emerged as promising biomaterial modifications for minimizing host-implant inflammatory responses and providing a nonspecific background for the presentation of bioactive motifs to elicit directed cellular responses. Oligo(ethylene glycol) moieties (-(CH2CH2O)(n)-, abbreviated as EG.) have proven to be the most protein-resistant functionality and remain the standard for comparison. In the present study, we analyzed fibronectin (FN) adsorption and cell adhesion to CH3/EG(3) mixed self-assembled monolayers. In contrast to previous studies with ellipsometry and surface plasmon resonance spectroscopy, we demonstrate significant radiolabeled FN adsorption onto EG(3)-containing surfaces, including pure EG(3) Monolayers. These FN-coated surfaces supported FN density-dependent increases in fibroblast adhesion strength. However, while FN adsorbed irreversibly to CH3-terminated surfaces, adsorbed FN was removed from EG(3) monolayers and the corresponding cell adhesion eliminated by long-term (16 h) incubation in either protein-free or serum-containing solutions. Once the adsorbed FN was eluted, EG(3) monolayers remained nonadhesive, even in the presence of serum-containing media. These results provide new insights into the interactions between cells and synthetic, nonadhesive surfaces.