Nanocomposite Ti/hydrocarbon plasma polymer (Ti/ppCH) films were deposited by DC magnetron sputtering of titanium target in a mixture of argon and hexane. The titanium content was controlled by adjusting argon/hexane ratio in the working gas. OES and QCM were used to monitor the deposition process. Chemical and structural properties were analyzed by X-ray photoelectron spectroscopy (XPS), Rutherford back-scattering spectrometry combined with elastic recoil detection analysis (RBS/ERDA), X-ray diffraction (XRD), optical emission spectroscopy (OES) and atomic force microscopy (AFM).
The concentration of titanium increases with the amount of argon and reaches 20 at. %. A high extent of oxidation is detected with titanium bound mainly in TiO2. Minor contribution from titanium carbide and sub-stoichiometric titania. Furthermore, high hydrogen content is detected in the films rich with titanium. The resultant films are heterogeneous with inorganic regions of nanometer scale distributed within plasma polymer matrix. No crystalline structure is observed by XRD. The wettability increased proportionally to the content of Ti in the films. Films sputtered in pure hexane (less than 1 at. % of Ti) or pure argon (20 at. % of Ti) on microscopic glass slides or polystyrene culture dishes were seeded with human osteoblast-like MG 63 cells or bovine pulmonary artery endothelial CPAE cells. In MG 63 cells, the cell population densities on days 1, 3 and 7 after seeding, the cell spreading area on day 1, the formation of talin-containing focal adhesion plaques as well as the concentrations of talin and osteocalcin (per mg of protein) were similar in cells on both Ti/ppCH films as comparable to the values in cells on the tissue culture polystyrene. However, in CPAE cells, the cell population densities, cell spreading area and the concentration of von Willebrand factor were higher in cells on argon-sputtered than in hexane-sputtered films. Thus, both types of films could be used for coating bone implants, and the argon-sputtered film for the enhancement of endothelialization of blood contacting artificial materials.
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