Effects of Ion Implantation on Protein Adsorption onto Silicone Rubber

AbstractA study has been made on the surface wettability, atomic ratio, chemical structure, chemical bonding states and plasma protein adsorption of ion implanted silicone rubbers. C+-, N2+-, 02+-, Ar+- and Na+-ion implantations were performed at an energy of 150 keV at room temperature. The doses ranged from 1x1012 to 1x1017 ions/cm2. Ion implantation caused the surface roughness to increase by 1–5 times. Surface wettability was estimated by means of a sessile drop method using water. With increasing ion dose, the contact angle of water decreased from 98.9° to 48.5°. However, if the sample was in the air, the contact angle of water returned to its initial valve in time elapsed. The results of XPS measurements showed that implanted elements were incorporated in a gaussian like distribution and host elements were redistributed in the polymer matrix. No change of binding energies of 01s, CIS, Si2p and Si2p can be observed upon ion implantation. Results of FT-IR-ATR showed that C+-, N2+-, 02+-, and Ar+-ion implantation decomposed the original chemical bonds to form the new radicals. The amounts of new radicals are related to doses of implanted ions. In contrast, Na+-ion implantation hardly formed new radicals. The amount of albumin adsorbed onto 02+-, Ar+-, N2+-, and C+- ion implanted silicone is less than that on unimplanted specimens, but more fibrinogen is adsorbed. Na+-ion implantation produced an increase in the amount of adsorbed albumin as the dose increased. In summary, Na+ion implantation produces effects that are attributable to the additional implanted constituent in the surface of the silicone, and 02+-, N2+-, C+-, and Ar+-ion implantations primarily cause radiation effects on silicone rubber.