A study on biocompatibility and bactericidal properties of pyrolytic carbon by silver ion implantation

The biocompatibility and bactericidal properties of Ag+-implanted pyrolytic carbon were investigated by means of Staphylococcus aureus and Escherichia coli bacteria and some biocompatible experiments. The pyrolytic carbon samples were implanted by silver ions with the dose ranging from 5 × 1014 to 5 × 1018 ions/cm2 at an energy of 70 keV. The silver distribution in pyrolytic carbon was characterized by Rutherford Backscattering Spectrometry (RBS).The results show that the bactericidal rate for both S. aureus and E. coli increase with the ion dose when the silver ion dose is under the saturated dose of 5 × 1017 ions/cm2. The bactericidal rate is over 97% when the ion dose exceeds that value. In comparison with the reference sample, Ag+-implanted pyrolytic carbon shows a good biocompatibility and without biotoxication by means of cytotoxicity, hemolysis and platelet tests. RBS analyses show that silver atoms penetrate into the sample surface and form a silver-rich surface region which plays an important role in killing bacteria. When the ion dose is not exceed 1 × 1016 ions/cm2, the structure of Ag+-implanted pyrolytic carbon is kept unchanged maintaining the original biocompatibility.