Silver nanoparticles grafted onto PET: Effect of preparation method on antibacterial activity

Abstract

Incorporating silver nanoparticles (Ag NPs) into surface structure is one of the way to prepare antibacterial surfaces. This study focuses on preparation of antibacterial polymer surface by grafting polyethylene terephthalate (PET) with Ag NPs differing by method of preparation. Ag NP dispersions were synthesized by chemical (Ag NPCH), electrochemical (Ag NPE) and physical (Ag NPP) methods. They were characterized by transmission electron microscopy and UV–Vis spectroscopy. Ag NPs were grafted onto plasma treated PET using dithiol interlayer because of Ag high affinity to thiol groups. Success of grafting was determined by X–ray photoelectron and energy dispersive X-ray spectroscopies. Atomic force and scanning electron microscopes also showed presence of both thiol and Ag NPs on plasma treated PET. Prepared samples were subjected to antibacterial tests against Escherichia coli and Staphylococcus epidermidis. Ag NPE were the smallest and their amount grafted onto PET surface was the highest. Therefore, PET with Ag NPE would be expected to have the best antibacterial effect. However, the highest antibacterial activity (for both strains) turned out to be on PET grafted with Ag NPP because far greater NP amount was situated more in the volume of grafted layer than on PET surface itself.