Bacterial repellence from polyethylene terephthalate surface modified by acetylene plasma immersion ion implantation–deposition

There is an increasing interest in developing new methods to reduce bacterial adhesion onto polymeric materials used in biomedical implants. The antibacterial adsorption behavior on polyethylene terephthalate (PET) treated by plasma immersion ion implantation–deposition (PIII–D) using acetylene (C2H2) at different working pressures is investigated. The surface structure of the treated PET is determined by Rutherford backscattering spectrometry (RBS), laser Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The results show the formation of thin hydrogenated amorphous carbon (a-C:H) films with different structures and chemical bonds on the PET surface. The ability of Staphylococcus aureus (SA) and Staphylococcus epidermidis (SE) to adhere to PET is quantitatively determined by plate counting and Gamma-ray counting of the 125I-labeled bacteria in vitro. The adhesion efficiency of SA on the a-C:H film deposited at 0.5 Pa of working pressure is about 16% of that on the untreated PET surface, and the adhered bacterial concentration of SE on the carbon film deposited at 1.0 Pa is about 1/6 of that of the PET surface. Bacterial adhesion onto a-C:H films is influenced by the structures and chemical bonds of the materials. The reduction in bacterial adhesion can be explained by the free energy of adhesion (ΔFAdh), which predicts whether microbial adhesion is energetically favorable (ΔFAdh<0) or not (ΔFAdh>0). Our results show that bacterial adhesion is energetically unfavorable on the a-C:H films deposited at 0.5 and 1.0 Pa, and this study suggests one possible method to repel bacteria from polymeric surfaces.