Comparative study of calcium phosphate formation on sol-gel and solid-state synthesized calcium titanate surfaces

The variation of calcium phosphate formation rate on calcium titanate surfaces synthesized via sol-gel (CTSol) and solid-state reaction (CTS-S) at 600 °C for 10 h, were investigated using DSC, FTIR, XRD, DLS-Zeta potential, FESEM-EDS, BET, and ICP-OES, focusing on the relationship between surface morphology and calcium phosphate formation ability. Both powders had meso-porosities with a mean pore diameter of 45 and 54 nm, respectively. While CTSol particles had a diameter of about 100–250 nm, CTS-S had nanosized particles (35–40 nm) with the configuration of parent P25 TiO₂. CTS-S had a higher specific surface area (26.14 m². g⁻¹), pore volume (0.36 cm³.g⁻¹), and pore size (D = 54.51 nm) than CTSol (11.09 m². g⁻¹, 0.12 cm³.g⁻¹, D = 44.97 nm). By submerging disk-shaped samples in SBF solution, their bioactivity was evaluated for up to 14 days. Both samples formed calcium phosphate at similar rates. Despite having a smaller surface area, CTSol makes up for it with a higher rate of Ca²⁺ dissolution. Whereas the calcium phosphate initial particles on the surface of CTS-S were spherical, the needle-like features on the surface of CTSol were created by immersion in SBF.