Electrolytic plasma processing (EPP) was used to create hydrophilic surface profiles on titanium. The wettability, surface morphology characteristics and chemical composition of the treated samples were studied as a function of EPP processing parameters. The EPP profiled surfaces comprised of a characteristic "hills and valleys" morphology because of continuous surface melting and freezing cycles. A bimodal surface profile was produced with 2-3 μm height hills and valleys with nano-roughness (≤200 nm). The produced profile resulted in a significant contact angle decrease (from 38.7° to 5.4°). Ratios of actual surface area to projection area (r) and fraction of solid surface remaining dry (φ) were obtained from profilometry. The surface characteristics and large r values produced by EPP were able to induce hemi-wicking. Hence, EPP produced superhydrophilic surfaces on Ti. The bioactivity of EPP treated Ti was evaluated using cell free and MC3T3 cells in-vitro studies. The treated Ti surface significantly increased the bioactivity and formed stoichiometric hydroxyapatite after immersion in a bone cell culture medium for 21 days. Cells' attachment and proliferation studies indicated that EPP treated surface significantly enhances the cells' adhesion and growth after 24 and 48 h compared to the untreated surface. The results show that Ti surface profiling by EPP constitutes a promising method to potentially improve bone implant bonding.
Keywords: Contact angle; Hydrophilicity; Hydroxyapatite nucleation; Surface profile; Surface roughness; Titanium.