Osteoblastic cell response to Al2O3-Ti composites as bone implant materials

Alumina-titanium (Al2O3-Ti) composites with enhanced mechanical and corrosion properties have been recently developed for potential applications in orthopaedics and hard tissue replacements. However, before any clinical use, their interactions with biological environment must be examined.

The aim of this study, therefore, was to assess the biocompatibility of three Al2O3-Ti composites having 25, 50, and 75 volume percentages of titanium. These materials were made by spark plasma sintering (SPS), and MC3T3-E1 cells were cultured onto the sample discs to evaluate the cell viability, proliferation, differentiation, mineralization, and adhesion. Furthermore, the apatite formation ability and wettability of the composites were analysed. Pure Ti (100Ti) and monolithic Al2O3 (0Ti) were also fabricated by SPS and biological characteristics of the composites were compared with them.

The results showed that cell viability to 75Ti (95.0%), 50Ti (87.3%), and 25Ti (63.9%) was superior when compared with 100Ti (42.7%). Pure Al2O3 also caused very high cell viability (89.9%). Furthermore, high cell proliferation was seen at early stage for 50Ti, while the cells exposed to 75Ti proliferated more at late stages. Cell differentiation was approximately equal between different groups, and increased by time. Matrix mineralization was higher on the composite surfaces rather than on 0Ti and 100Ti. Moreover, the cells adhered differently to the surfaces of different biomaterials where more spindle-shaped configuration was found on 100Ti, slightly enlarged cells with dendritic shape and early pseudopodia were observed on 75Ti, and more enlarged cells with long dendritic extensions were found on 0Ti, 25Ti, and 50Ti. The results of EDS analysis showed that both Ca and P deposited on the surfaces of all materials, after 20 days of immersion in SBF.

Our in-vitro findings demonstrated that the 75Ti, 50Ti, and 25Ti composites have high potential to be used as load-bearing orthopedic materials.