Development of Innovative 3D Porous TiO2 Ceramic Scaffolds for Orthopeadic Applications

The development of scaffolds for replacement of injured and diseased hard tissues such as bones is highly desired in orthopaedic surgery. The porous structure of scaffold provide necessary framework for the bone cells to grow into the pores and integrate with host tissue, known as osteointegration. Thus porosity and pore size of biomaterial scaffolds play a critical role and also has great impact on mechanical properties. Particular attention has attracted TiO2 ceramic scaffolds due to its excellent mechanical properties compared to other ceramic materials, biocompatibility and good osteoconductivity. TiO2 scaffolds were produced via polymer foam replica method. Commercially available anatase powder, polyvinyl alcohol solution, ethylene glycol, ammonia solution and deionised water were used as raw materials for ceramic slurry preparation. Homogenisation of the slurry was conducted by stirring for different period of time. Particle size distribution, viscosity and pH of titania slurry were monitored during stirring. Cylindrical polyurethane foams with fully interconnected pore structure serves as a sacrificial template for the ceramic coating. After drying, the polymer was slowly burned out and scaffolds were sintered in air at different temperatures (above 1300°C) and holding times. Increasing sintering temperature to 1300 °C complete phase transition from anatase to rutile crystalline modification takes place and stable rutile modification has been obtained. By optimising thermal treatment regimes grain growth and collapse of struts can be controlled that may result in higher compressive strength. Effect of slurry parameters (pH, viscosity, particle size, solid content etc.) on characteristics of produced titania ceramic scaffolds (porosity, pore size, mechanical strength) were evaluated. Using replica method porous TiO2 ceramic with porosity >85% and pore size >100 μm were obtained. Scaffolds showed fully open and interconnected pore structure. Obtained pore size and porosity is wide enough to ensure cell migration throughout scaffold structure and ensure vascularisation