Electrochemically-assisted deposition on TiO2 scaffold for tissue engineering : an apatite bio-inspired crystallization pathway

The interactions among inorganic materials and biological environments occurring at the nanoscale level are crucial to understand the mechanisms behind the bioactivity of biomaterials and for their better design. In the present study, we prepare TiO2 and TiO2/hydroxyapatite (HA) scaffolds for Tissue Engineering (TE) via a sol–gel/polymeric spongemethod. The obtained architectures have a biomimetic morphology (trabecular bone) and an average pore dimension of 100 mm. Moreover, we introduce a versatile electrochemically assisted deposition method for non-conductive substrates that allows the formation of a stable coating on the pore walls of the scaffolds with the morphology and phase composition determined by SEM and DRIFTS. Both the materials properties are strictly correlated to the scaffold composition: pure TiO2 scaffolds are coated with amorphous calcium carbonate while onto TiO2/HA scaffolds we observe the growth of octacalcium phosphate nanocrystals. The bioactivity of the TiO2-based scaffolds is then predicted examining the apatite formation on their surface in simulated body fluid. The presence of apatite crystals is observed only for pure TiO2 scaffolds due to the transformation of amorphous calcium carbonate into crystalline biomimetic HA: a novel bio-inspired crystallization pathway toward the bioactivity of scaffold for TE.