Enhancement of antibacterial properties and biocompatibility of polyethylene by silver and copper plasma immersion ion implantation

The surface antibacterial properties and biocompatibility of biopolymers can be enhanced by means of plasma immersion ion implantation (PIII). In the work described here, the effects of Cu and Ag PIII on polyethylene (PE) are investigated and compared. The growth and behavior of different cell lines on the modified surfaces are determined. Our data reveal that although the Ag elemental depth profiles are similar to those of Cu, there is a larger amount of surface Ag compared to Cu possibly due to the different charge states in the plasma. Photoluminescence is found to be enhanced after Cu and Ag PIII based on Raman studies. Antibacterial tests against E. coli show that the Ag PIII PE has better antibacterial properties than the Cu PIII one in spite of implantation using similar parameters. Based on cell assays, both the Ag PIII PE and Cu PIII PE samples exhibit excellent biocompatibility for bone cells. However, the Chinese hamster ovary (CHO) cells show a non-uniform distribution on the Cu PIII PE and Ag PIII PE surfaces after incubating for 2 days. Therefore, the PE surfaces after Cu and Ag PIII show little adhesion and biocompatibility for CHO cells.