Synergistic regulation of piezoelectricity and bioactivity in xSrTiO3·BG–KNN ceramics for bone regeneration

Piezoelectric biomaterials that convert mechanical stimulation into bioelectrical signals are attractive for bone regeneration because they mimic the native electromechanical environment of bone. In this study, a series of bioactive piezoelectric ceramics, x SrTiO 3 ·BG-KNN ( x  = 0, 0.03, 0.06, 0.09), were fabricated via a solid-state reaction route by incorporating strontium titanate and 45S5 bioactive glass. The influence of SrTiO 3 content on phase structure, microstructure, piezoelectric output, and in vitro biocompatibility was systematically investigated. Among all compositions, 0.06 mol% Sr-doped sample exhibited an optimized microstructure with moderate porosity and refined grains, resulting in the highest piezoelectric coefficient (67 pC/N) and enhanced electrical output (Voc ≈ 1.2 V, Isc ≈ 30 nA) with minimal frequency dependence. All samples demonstrated good cytocompatibility (>80% cell viability) and good hemocompatibility (<1% hemolysis), supported by sustained bioactive Si ion release (1–2 mg/L). These results indicate that 0.06SrTiO 3 ·BG-KNN is a promising multifunctional piezoelectric bioceramic promising candidate for bone repair.