The influence of polyethylene terephthalate surfaces modified by silver ion implantation on bacterial adhesion behavior

The prevention of medical device related infection remains an important concern because of the high risk of complications. Efforts to prevent bacterial colonization of biomaterials have focused on surface modification. This paper investigates the antibacterial behavior of polyethylene terephthalate (PET) surfaces modified by ion implantation with silver ions (Ag+). PET films were modified by silver ion implantation at a dose of 1 × 1016 ions/cm2. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface structure and composition. The results indicate that silver was successfully implanted into the surface of the PET. The static contact angle of water decreased from an original value of 83.5° to 67.6° following Ag+ implantation, which suggests that the hydrophilic property of the modified PET is improved. The quantity of Staphylococcus epidermis (SE) adhered onto the different PET films was quantitatively determined using colony forming units (CFU) plate counting in vitro. The results indicate that the quantity of SE adhered onto PET films implanted with Ag+ is 5.3 × 106 CFU/ml, but the quantity of SE adhered onto virgin PET films is 2.23 × 107 CFU/ml. The releasing concentration of silver ions from the implanted PET is 0.22 mg/ml over 2 h. The release of antibacterial silver ions may be an important reason for less SE adhered to the PET surface modified by Ag+ implantation. The free energy of adhesion (DFAdh) of SE on the PET surfaces modified by Ag+ implantation is positive, which means that this adhesion is energetically unfavorable.