Controlling cell adhesion on polyurethanes.

Cell attractive or non-attractive surface properties of polyurethane devices can be controlled by treating them with zirconium tetra(tert-butoxide). This gives reactive interfacial zirconium complex species that can be used subsequently to bond cell attractive peptides such as arg-gly-asp (RGD) or cell non-attractive organics such as polyethylene glycol (PEG) to the device surface. Control of the surface properties of the polyurethane occurs on the nanoscale, and does not compromise the physical properties of the polymer. Interfacial Zr complex formation occurs at N-H sites of the polyurethane; therefore surface loadings of the Zr complex depend on the spatial separation of these N-H groups in the polymer backbone. A complex loading of 110 ± 15 pmol cm-2 is achieved on poly(hexamethylenehexylene)urethane, and 40 ± 10 pmol cm-2 is bound on the medically relevant polyurethane, tecoflex®. About 25% and 10% of these polymer surfaces, respectively, can be covered by RGD via the zirconium complex interface; because of its greater size, about 100% of both polymer surfaces is covered by PEG. The response of 3T3 fibroblasts to surface-treated and untreated tecoflex® is described.