Surface Energy and Work of Adhesion of Titania-related Materials

The interaction between metal surface and cell/tissue is important for the biocomptibilty of metallic implants, and surface modification has been studied extensively to alter its surface characteristics, and improve biocompatibility. Titanium oxide (TiOx) films were deposited by electron-beam evaporation system using TiO2 as a source material. The films deposited by various thickness and growth rate were investigated by X-ray photoelectron spectra and atomic force microscopy. TiOx films were etched subsequently by different plasma to obtain different surface morphology. The composition of TiOx films were changed from nonstoichiometric to stoichiometric due to etching process, and the surface roughness of TiOx films was increased. TiOx films were further modified by selfassembled monolayer (SAM) of silanes. TiOx films became hydrophobicity by the SAM modification process and highly hydrophilic by ultraviolet (UV) irradiation. Surface modification of TiOx films (like plasma etching, SAM and UV irradiation) has proven to be indispensable for improved hemocompatibility, as assessed by work of adhesion calculations and x-ray photoemission spectroscopy.