AFM study of the interaction of collagen with polystyrene and plasma-oxidized polystyrene

Adsorption of collagen on polystyrene (PS) and plasma-oxidized PS (PSox) wa s investigated using atomic force microscopy (AFM) as the main tool. The ex tent of alteration produced by the AFM tip upon scanning at controlled load ing forces in water was used to obtain semiquantitative information on the properties of the interfacial phase. This information was completed by obse rving the extent of reorganization of the adsorbed collagen layer after dry ing. The PSox surface was altered by scanning at high loading force in wate r. This behavior, which was not observed on PS, was attributed to the prese nce of a solvated polyelectrolyte layer at the surface of PSox, as demonstr ated by previous works. Collagen adsorbed on PS gathered together under the action of the AFM tip while no perturbation was observed for collagen adso rbed on PSox. After drying at low rate of a thin adsorbed collagen layer, a netlike structure was formed on PS, in contrast with PSox. These differenc es were attributed to the formation of a dense, mechanically strong mat of collagen molecules adsorbed on PSox and/or to anchoring of collagen molecul ar ends in the swollen surface layer of PSox, in contrast with PS.