A study on antibacterial properties of Ag+-implanted pyrolytic carbon

The bactericidal properties of Ag+-implanted pyrolitic carbon were investigated using Gram positive S. aureus and negative E. coli. The pyrolitic 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 samples were characterized by Rutherford Backscatter Spectrometry (RBS), Auger analysis (AES), and Scanning Electron Microscopy (SEM) respectively. The results show that the bactericidal ratios 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 ratio is over 97% when the ion dose exceeds that dose. RBS analysis shows that the silver atoms penetrate into the sample surface and forms an asymmetric Gaussian distribution so as to form a silver rich surface region which plays an important role in killing bacteria. AES analysis also confirms this distribution. SEM characterization shows that the surface morphology is another factor for killing bacteria.