Physicochemical, mechanical, dielectric, and biological properties of sintered hydroxyapatite/barium titanate nanocomposites for bone regeneration.

Bone implants fabricated using nanocomposites containing hydroxyapatite and barium titanate showed piezoelectricity, osteoconductive, osteoinductive, and osteointegration properties for bone regeneration applications. In our present study, hydroxyapatite (HA) and barium titanate (BT) nanopowders were synthesized using high-energy ball-milling (HEBM)-assisted solid-state reaction with precursors of calcium carbonate and ammonium dihydrogen phosphate, and barium carbonate and titanium oxide powder mixtures, respectively. Hexagonal HA and tetragonal BT phases were formed after calcination at 700 and 1000 °C, respectively. Subsequently, HA/BT nanocomposites with different weight percentages of HA and BT were prepared by ball-milling, then compacted and sintered at two different temperatures to endow these bioceramics with better mechanical, dielectric, and biological properties for bone regeneration. Microstructure, crystal phases, and molecular structure characterizations of these sintered HA/BT nanocomposite compacts (SHBNCs) were performed using field-emission scanning electron microscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy, respectively. Bulk density was evaluated using the Archimedes method. HA/BT nanocomposites with increased BT content showed enhanced dielectric properties, and the dielectric constant (εr) value for 5HA/95BT was ~182 at 100 Hz. Mechanical properties such as Vicker's hardness, fracture toughness, yield strength, and diametral tensile strength were also investigated. The hemolysis assay of SHBNCs exhibited hemocompatibility. The effect of these SHBNCs as implants on the in vitro cytocompatibility and cell viability of MG-63 osteoblast-like cells was assessed by MTT assay and live/dead staining, respectively. 15HA/85BT showed increased metabolic activity with a higher number of live cells than BT after the culture period. Overall, the sintered HA/BT nanocomposite compacts can be used as orthopedic implants for bone regeneration applications.