Improved In Vitro and In Vivo Biocompatibility on Dual Plasma Modified titanium Surfaces

Ti-6Al-4V is widely used in present orthopedic applications, owing to a combination of good mechanical properties and excellent corrosion resistance. However, long-term success of Ti-6Al-4V implants and the completeness of their osteointegration still need to be addressed. Since the biofunctionality of the implant is strongly affected by its surface characteristics, to promote osteointegration, considerable efforts have focused on modifying the surface of the implants. In this study, we employed carbon-nitrogen dual plasma immersion ion implantation (PIII) to treat Ti-6Al-4V alloys. As a non-line-of-sight technique, PIII is especially suitable for biomedical implants with a complex geometry. The in-vitro studies indicate that as compared with only carbon PIII treatment and untreatment, carbon-nitrogen dual PIII treatment effectively promotes osteoblasts adhesion and proliferation on Ti alloy surfaces. The cytocompatibility enhancements may be attributed to rough surface morphology and introduction of carbon and nitrogen groups under high-energy ion bombardment. These surface signals can then stimulate osteoblasts response at the early stage of cell-material interaction. A comparison of surfaces with PIII treatment and without PIII treatment in animal model shows the importance of PIII treatment in bone growth. A larger amount of new bone is formed on ion-implanted titanium compared to unimplanted titanium after 1 to 12 weeks of implantation into rat femur. Especially the carbon-nitrogen dual PIII treated sample behaves the highest volumes of new bone. It might be caused by the fact that osteoblasts on titanium are activated to accelerate bone tissue formation when carbon and nitrogen ions are implanted. Collectively, these results suggest that the use of carbon-nitrogen dual PIII to Ti-6Al-4V alloys may be potentially applied for future clinical use.