SrTiO₃-loaded SA/ε‑PL composite hydrogels with piezocatalytic and osteoimmune regulatory functions for infected bone repair

Abstract Bacterial infection and persistent local inflammation severely hinder the healing of bone defects, and conventional bone repair materials fail to achieve antibacterial treatment and bone regeneration regulation at the same time. As mechanical cues can modulate cell behaviors and osteogenesis, piezoelectric materials can convert ultrasound stimulation into bioelectrical signals and reactive oxygen species for bacteriostasis and osteogenic regulation. In this work, we prepared a composite hydrogel by incorporating strontium titanate into crosslinked sodium alginate/ε-polylysine networks. This material exhibits obvious pH-responsive release in acidic inflammatory microenvironments and realizes highly efficient sterilization under ultrasonic assistance. In vitro experiments confirm its outstanding biocompatibility. It effectively regulates macrophage polarization to relieve inflammatory responses and greatly promotes the osteogenic differentiation of bone marrow mesenchymal stem cells. This study establishes a feasible fabrication strategy for multifunctional therapeutic hydrogels and provides a promising platform for the comprehensive treatment of clinically infected bone defects.