Adsorption of a cell-adhesive oligopeptide on polymer surfaces irradiated by ion beams.

The adsorption behavior of H-Arg-Gly-Asp-OH (RGD) oligopeptide on ion-irradiated polymer surfaces has been studied. The RGD-incubated surfaces of poly(ethylene terephtalate) (PET) and poly(hydroxymethylsiloxane) (PHMS) thin films, before and after irradiation with 50 keV Ar+ to 1x10(15) ions/cm2, were investigated by X-Ray Photoelectron Spectroscopy and Atomic Force Microscopy. It was found that no significant adsorption occurs on PET, while a measurable amount of RGD is preferentially adsorbed onto irradiated PHMS surfaces. The evaluated surface coverage was found to range between 5 and 12%. In situ adsorption measurements performed by using the Quartz Crystal Microbalance with Dissipation monitoring technique showed that the irradiation induced remarkable changes of mass uptake with respect to the unirradiated surfaces, mostly attributed to the change in the water adsorption capability of the irradiated surfaces. The adsorption results are discussed in terms of the ion-induced changes on the morphology, chemical structure and composition, surface free energy and surface charge.