Cell attachment and biocompatibility of polytetrafluoroethylene (PTFE) treated with glow-discharge plasma of mixed ammonia and oxygen

Abstract

The plasma generated from a gas mixture of NH3 plus O2 (NH3 + O2) has been used to impart unique chemical and biological characteristics to polytetrafluoroethylene (PTFE). PTFE treated with NH3 + O2 plasma was physiochemically distinct from surfaces treated with plasma of either NH3 or O2 alone, as determined by electron spectroscopy for chemical analysis (ESCA). The contact angle analysis revealed that the PTFE surfaces became less hydrophobic after plasma treatments. ESCA results indicate the presence of oxygen-containing groups and nitrogen-containing groups at the plasma-treated surfaces. PTFE treated with NH3 + O2 plasma resisted the attachment of platelets and leukocytes in a manner similar to untreated PTFE; however, the attachment of bovine aorta endothelial cells was substantially increased. Once attached, these cells grew to confluency. The increased endothelial cell attachment was higher than that observed following plasma treatment with each gas used separately, which could be attributed to the considerable amount of CF(OR)2-CF2 formed on the NH3 + O2 plasma-treated PTFE surface. At 14 days after subcutaneous implantation in rats, the PTFE wafers treated with NH3 + O2 plasma demonstrated less encapsulation and lower levels of inflammatory cells compared to controls. Collectively, the results suggest that NH3 + O2 plasma treatment imparts a unique character to PTFE and could be useful in certain in vivo applications.

XPS characterization of PTFE after treatment with RF oxygen and nitrogen plasma

“…C-C bond was not detected on the surface at all. A rather low concentration of nitrogen found on the PTFE surface (as compared with the results obtained by other authors [7,12,17] ) is probably due to extremely weak interaction of nitrogen positive ions in our plasma. For instance, at our experimental conditions we used inductively coupled plasma at a rather high pressure which is characterized by low kinetic energy of ions at the surface, while other authors used capacitively coupled plasma at lower pressure.…”

“…Free radicals that are created on a polymer surface during treatment in nitrogen plasma can react with oxygen and furthermore, free radicals that remain on the surface after the treatment will react with oxygen when the surface is exposed to the atmosphere. [1,12] When treating PTFE foil in nitrogen plasma for 10 min the N-concentration at the surface is little lower -about 2.5 at.%.…”

“…Defluorination process of the surface during the plasma treatment, which resulted in a decrease of F/C ratio was observed by other authors as well. [11,12] Defluorinaton was interpreted to be a consequence of a physical sputtering of PTFE by ions from the plasma. [7] Most of them have used more ionic plasma.…”

Adhesion of mouse fibroblasts on hexamethyldisiloxane surfaces with wide range of wettability

“…Many studies using plasma-treated polymer surfaces with Ar, O 2 , NH 3 , or N 2 reported increasing the surface wettability and improving the cell adhesion or spreading 9,10 . In most studies, however, the ranges of surface wettability employed were narrow; 46-67degrees 7 ,…”

Application of Low-Temperature Plasma Processes for Biomaterials

“…Similar to metals and metal alloys, cell attachment on polymers can also be modulated by plasma treatment. The application of glow-discharge plasma of mixed ammonia and oxygen on polytetrafluoroethylene surfaces reduced the hydrophobicity and increased the attachment of aorta endothelial cells (Chen et al, 2003). Furthermore, an oxygen plasma has been shown to improve surface attachment of mouse fibroblasts L-929 on thermoplastic polyetherurethane used for gastric implants (Schlicht et al, 2010).…”