Contact angle lowering of polystyrene surface by silver-negative-ion implantation for improving biocompatibility and introduced atomic bond evaluation by XPS

Negative-ion implantation technique is expected as an effective surface modification method for insulators of polymer, since in negative-ion implantation into insulators the charge-up potential of the surface is in several volts. Polystyrene dishes were implanted with Ag − ions in an ion energy range under 30 keV in order to bring hydrophilic property to their surface for improving surface biocompatibility of cell adhesion property, and contact angles to water were measured. Contact angle was found to be lowered to 73° by the Ag-ion implantation from an original value of 86°, and it decreased with increase in both ion dose and ion energy below 20 keV. Atomic bonds of C–O, CO, and OC–O were introduced by ion implantation, these were increased in number with increase in dose and energy of implantation. These atomic bonds were considered to bring the hydrophilic property to the polystyrene surface. Human umbilical vascular endothelial cell (HUVEC) was cultured on each sample with a 199 medium. The cell growth and attachment were observed only for Ag-implanted surfaces.