Shape-dependent Ag-doped hydroxyapatite nanofillers for enhanced mechanical and antibacterial chitosan membranes

Natural biomaterial-derived membranes show great potential for guided bone regeneration (GBR) and bone tissue engineering due to excellent biocompatibility and degradability. While incorporating inorganic nanoparticles like hydroxyapatite (HA) is a common strengthening strategy, the systematic impact of nanoparticle morphology on the integrated performance of composite membranes remains a critical, yet underexplored, knowledge gap. Here, we developed chitosan (CS)-based composite membranes incorporating hydroxyapatite (HA) nanoparticles of four morphologies: large lamellar (LHA), small lamellar (SHA), wire-like (WHA), and rod-like (RHA). Additionally, HA’s capacity as an ion carrier enabled the loading of silver (Ag) to impart antibacterial properties. High-aspect-ratio fillers (LHA, WHA) promoted crack deflection and energy dissipation, achieving tensile strengths up to 82.47 ± 4.10 MPa and toughness up to 28.61 ± 5.02 MJ·m −3 —significantly outperforming pure CS membranes. This reinforcement mechanism extended to other matrices, such as sodium alginate. Simultaneously, the Ag-loaded HA (Ag-HA) composite membranes synergistically enhanced osteogenic activity (alkaline phosphatase) and exhibited strong antibacterial efficacy. These findings elucidate morphology–size–performance correlations, providing a framework for designing multifunctional GBR biomaterials with enhanced mechanical properties, osteogenesis, and antimicrobial capabilities.