Protein adsorption on various plasma-treated polyethylene terephthalate substrates.

Protein adhesion and cell response to plasma-treated polymer surfaces were studied. The polymer polyethylene terephthalate (PET) was treated in either an oxygen plasma to make the surface hydrophilic, or a tetrafluoromethane CF(4) plasma to make the surface hydrophobic. The plasma source was radiofrequency (RF) discharge. The adsorption of albumin and other proteins from a cell-culture medium onto these surfaces was studied using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The cellular response to plasma-treated surfaces was studied as well using an MTT assay and scanning electron microscopy (SEM). The fastest adsorption rate was found on the hydrophilic oxygen plasma-treated sample, and the lowest was found on the pristine untreated sample. Additionally, the amount of adsorbed proteins was higher for the oxygen-plasma-treated surface, and the adsorbed layer was more viscoelastic. In addition, cell adhesion studies support this finding because the best cell adhesion was observed on oxygen-plasma-treated substrates.

Covalent Binding of Heparin to Functionalized PET Materials for Improved Haemocompatibility.

The hemocompatibility of vascular grafts made from poly(ethylene terephthalate) (PET) is insufficient due to the rapid adhesion and activation of blood platelets that occur upon incubation with whole blood. PET polymer was treated with NHx radicals created by passing ammonia through gaseous plasma formed by a microwave discharge, which allowed for functionalization with amino groups. X-ray photoelectron spectroscopy characterization using derivatization with 4-chlorobenzaldehyde indicated that approximately 4% of the -NH2 groups were associated with the PET surface after treatment with the gaseous radicals. The functionalized polymers were coated with an ultra-thin layer of heparin and incubated with fresh blood. The free-hemoglobin technique, which is based on the haemolysis of erythrocytes, indicated improved hemocompatibility, which was confirmed by imaging the samples using confocal optical microscopy. A significant decrease in number of adhered platelets was observed on such samples. Proliferation of both human umbilical vein endothelial cells and human microvascular endothelial cells was enhanced on treated polymers, especially after a few hours of cell seeding. Thus, the technique represents a promising substitute for wet-chemical modification of PET materials prior to coating with heparin.

Oxygen-rich coating promotes binding of proteins and endothelialization of polyethylene terephthalate polymers.

The formation of endothelial cell monolayer on prosthetic implants has not sufficiently explored. The main reasons leading to the development of thrombosis and/or intimal hyperplasia is the lack of endothelialization. In the present work, we have studied the influence of oxygen and fluorine plasma treatment of polyethylene terephthalate (PET) polymers on human microvascular endothelial cell adhesion and proliferation. We characterized the polymer surface, wettability, and oxidation potential upon plasma treatment. Moreover, binding of serum and media compounds on PET surface was monitored by Quartz crystal microbalance method, X-ray photoelectron spectroscopy, and atomic force microscopy. Cell adhesion and morphology was assessed by light and scanning electron microscopy. The influence of plasma treatment on induction of cellular oxidative stress and cell proliferation was evaluated. The results obtained showed that treatment with oxygen plasma decreased the oxidation potential of the PET surface and revealed the highest affinity for binding of serum components. Accordingly, the cells reflected the best adhesion and morphological properties on oxygen-treated PET polymers. Moreover, treatment with oxygen plasma did not induce intracellular reactive oxygen species production while it stimulated endothelial cell proliferation by 25% suggesting the possible use of oxygen plasma treatment to enhance endothelialization of synthetic vascular grafts.