Synthesis, characterization and in vitro biocompatibility study of strontium titanate ceramic: A potential biomaterial.

Abstract

Strontium (Sr), a mineral element present in trace in the human body, has significant effect on bone remodelling. Sr containing ceramics have huge potential to heal bone defects and improve osseointegration of implants. In this study, perovskite oxide - strontium titanate (SrTiO₃) was synthesized and explored its potential for biomedical applications. The phase pure SrTiO₃ powder was synthesized from solid state reaction of strontium carbonate (SrCO₃) and titanium dioxide (TiO₂) at 1200 °C for 2 h. The as synthesized SrTiO₃ powder, pure hydroxyapatite (HAp) and SrTiO₃-50 wt% HAp (SH50) premixed powders were sintered at different temperatures varies from 1100 to 1400 °C in air. The sintered samples were characterized using X-ray diffraction (XRD) for phases and scanning electron microscopy (SEM) for microstructure analysis. XRD results revealed no dissociation of HAp or reaction with SrTiO₃ during sintering. The sintered samples were studied for mechanical properties, wettability, and biocompatibility. The relative density of the sintered SrTiO₃ increases with increasing sintering temperature. The relative density of SrTiO₃ was increased from 77% to 98% with increase in sintering temperature from 1250 to 1400 °C. The substantial improvement of hardness and compressive strength was observed for sintered SrTiO₃ compared to HAp of similar porosity level. The hardness and compressive strength of SrTiO₃ sintered at 1250 °C found ~6 and ~3.5 times higher than sintered HAp. In vitro dissolution study carried out in phosphate buffer solution at 37 °C, confirmed the release of Sr²⁺ ion from the bulk SrTiO₃ sintered at 1250 °C. The in vitro cell materials interaction showed cytocompatibility of sintered SrTiO₃ and SrTiO₃-HAp composite. In summary, excellent biocompatibility of SrTiO₃ with superior mechanical properties confirmed its potential as novel biomaterial for use in the repair of infected or aseptic bone defects.