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Failures of small internal diameter vascular grafts have been caused by the lack of a stable endothelial lining to form on their artificial surfaces. Polymer surfaces can be optimized by means of proper treatment to allow a homogeneous and uniform coverage in artificial prosthesis applications. Several solutions were studied to improve cell attachment and growth on artificial materials. In the present study, polyethyleneterephthalate (PET) surfaces were treated by plasma processes with oxygen and ammonia and also in the presence of a gas mixture to verify the effect of functional groups grafting onto the endothelial cell growth. Related surface chemical modifications were investigated by X-ray photoelectron spectroscopy (XPS). Then using cytotoxicity and cytocompatibility tests, the biocompatibility of the modified PET surfaces was assessed by studying the behavior of human umbilical vein endothelial cells (HUVEC). The results showed that plasma-treated PET samples have no toxic effect on HUVEC. The cytocompatibility tests revealed an increase in cell growth with incubation time and the presence of well-spread and flattened cells (SEM analyses). Thus it is reported that plasma treatments can improve PET biocompatibility to HUVEC.

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Titanium dioxide nanopowders doped with different amounts of Fe ions were prepared by coprecipitation method. Obtained materials were characterized by structural (XRD), morphological (TEM and SEM), optical (UV/vis reflection and photoluminescence, and Raman), and analytical techniques (XPS and ICP-OES). XRD analysis revealed rutile crystalline phase for doped and undoped titanium dioxide obtained in the same manner. Diameter of the particles was 5–7 nm. The presence of iron ions was confirmed by XPS and ICP-OES. Doping process moved absorption threshold of TiO2into visible spectrum range. Photocatalytic activity was also checked. Doped nanopowders showed normal and up-converted photoluminescence.