USING POLY(ETHYLENE IMINE) TO GRAFT POLY(ETHYLENE GLYCOL) OR POLYSACCHARIDE TO POLYSTYRENE

A novel method of grafting poly(ethylene glycol) (PEG) or polysaccharide to polystyrene has been developed. The non-charged, hydrophilic polymer is firstly grafted to poly(ethylene imine). After prior oxidation of the solid surface, the graft copolymer is subsequently adsorbed. Analysis by electron spectroscopy for chemical analysis and ellipsometry indicates a trains-and-loops arrangement of the copolymer on the surface with densely packed PEG or polysaccharide chains oriented towards the bulk water phase. Ellipsometry also shows that whereas the PEG grafting is fast, the polysaccharide grafting is more sluggish. Attachment of both graft copolymers is completely irreversible, as seen also by ellipsometry. The surfaces obtained are highly protein repellent, as shown by enzyme-linked immunosorbent assay using fibrinogen and immunoglobulin G as model proteins.