Dielectric barrier discharge plasma treatment of ultrahigh molecular weight polyethylene in different discharge atmospheres at medium pressure: A cell-biomaterial interface study

Nonthermal plasma activation of ultrahigh molecular weight polyethylene (UHMWPE) is performed in different discharge atmospheres (helium, nitrogen, argon, and air) using a parallel-plate dielectric barrier discharge reactor at medium pressure. Obtained samples are characterized via water contact angle, x-ray photoelectron spectroscopy (XPS), and atomic force microscopy. Plasma treatments were found to significantly alter the samples' surface chemical and physical characteristics. Before conducting a biocompatibility study, the influence of postplasma sterilization processes (ethanol rinsing/UV exposure) on the plasma treatment effects were studied. XPS studies showed that samples' surface chemical composition is least affected by UV exposure, thus making this process the most adequate for sterilization. In-vitro evaluation of biocompatibility was carried out by studying human foreskin fibroblast interaction with untreated and plasma treated surfaces. Cell attachment and viability on all plasma treated UHMWPE were found to be significantly higher in comparison to plain UHMWPE; this was further confirmed by the overall cell morphology. This increased cell viability on treated samples can be explained by the increased wettability on these samples. In this study, a somewhat higher cell proliferation was observed on argon plasma treated surface (water contact angle = 52°) after 7 days culture.