Effect of TiO2 addition on adhesion and biological behavior of BCP-TiO2 composite films deposited by magnetron sputtering

The present investigation focuses on the deposition of biphasic calcium phosphate (BCP) and titania (TiO2) composite films on Ti-6Al-4V substrates using radio frequency (RF) magnetron sputtering. Three different compositions such as 100% BCP, 25% TiO2-75% BCP and 50% TiO2-50% BCP films were fabricated, and the physical, mechanical and biological behaviors of the films were analyzed. Post deposition, the films were annealed at 700 °C for 2 h to induce the crystallinity and to study its effect on different properties. The wettability was found to be 95°(±3°) for 100% BCP, 73°(±2°) for 25% TiO2-75% BCP and 35°(±1°) for 50% TiO2-50% BCP films, indicating improvement in wettability with an increase of TiO2 weight percent in the composite films. The value of critical load (Lc2) for 100 BCP film improved from 8.7 N to 14.8 N (25 TiO2-BCP) and >19 N (50 TiO2-BCP film), indicating improvement in bonding strength with TiO2 addition. The fetal bovine serum (FBS) adsorption decreased from 7.11 ± 0.25 to 4.42 ± 0.17 μg/cm2 with TiO2 weight percent from 0 to 50%. Cell adhesion and proliferation significantly improved in 100% BCP, 25% TiO2-75% BCP and 50% TiO2-50% BCP films as compared to uncoated Ti-6Al-4V. The maximum cell proliferation was found on the surface of 50% TiO2-50% BCP film (210.1 ± 6.5%) after 6 days of incubation. However, after annealing all the films exhibited less cell adhesion and cytocompatibility presumably due to change in composition. Globular apatite structure was observed on all modified surfaces after 7 days immersion in simulated body fluid (SBF); however, the growth rate was higher for 50 TiO2-BCP films. All these results revealed that the addition of TiO2 in BCP film (without annealing) is advantageous for improving the bonding strength as well as the bioactivity of implants, which can be used for long-term dental and orthopedic applications.