The correlation between osteopontin adsorption and cell adhesion to mixed self-assembled monolayers of varying charges and wettability.

Osteopontin (OPN) is a key mediator of cell interactions with biomaterials. However, few studies have been dedicated to studying cell adhesion on OPN-adsorbed substrates with controlled charge and wettability. Here, amino-carboxyl (NH2/COOH) and hydroxyl-methyl (OH/CH3) mixed self-assembled monolayers (SAMs) of varying charges and wettability, respectively, were used as controllable model surfaces to study OPN adsorption and subsequent mesenchymal stem cell (MSC) adhesion. The amount of OPN adsorbed onto the NH2/COOH mixed SAMs appeared to monotonically depend on the surface charge, whereas only a moderately hydrophilic surface was conducive to OPN adsorption on OH/CH3 mixed SAMs. The results correlated well with cell spreading on OPN-coated surfaces in a serum-free medium culture. In addition, the OH/CH3 mixed SAMs with moderate wettability tended to promote β1, β3, αv and α5 integrins, indicating that wettability may guide cell adhesion by mediating the integrins signaling pathway. This work will have reference value for designing biologically responsive substrate surfaces.