Biomimetic calcium carbonate-calcium phosphate composite films with tunable cytological behaviors

Calcium phosphate salts, which have a similar composition with the mineral phase in natural bone, have been extensively studied for their applications in bone regeneration. However, another calcium-based mineral, calcium carbonate, which is also frequently found in biological materials, is seldom considered for this purpose despite their high biocompatibility and bioactivity. Herein, we report the performance of five types of biomimetic mineral films that are fabricated via the mineralization of calcium carbonate and calcium phosphate on chitin. These films have different in vitro degradation dynamics because of their varied stability. They also show distinct surface roughness, modulus and hardness. Cytological analyses reveal that, although these films all display high biocompatibility, they exhibit diverse osteogenic differentiation behavior, which can be attributed to their respective physicochemical properties. Real-time polymerase chain reaction assays suggest that the aragonite group can lead to higher expression of the six representative osteogenic genes, which even surpasses the amorphous calcium phosphate group and the aragonite-crystalline calcium phosphate composite group. These results illustrate that calcium carbonate and its composites with calcium phosphate are potential bone repair materials. We anticipate these mineral-based materials with controlled physiochemical properties, along with their specific fabrication techniques, can facilitate the design and production of mineral-based bone repair materials with optimized performance.