Enhancing the mechanical and antibacterial properties of hydroxyapatite bioceramics by in situ graphene doping to promote osseointegration in infected bone defects

Abstract

Hydroxyapatite (HA) bioceramics are extensively utilized in the field of bone repair owing to their remarkable biocompatibility, bioactivity, and osteoconductivity. However, their applications in load-bearing bones are significantly limited because of their inherent brittleness. Achieving a suitable balance between mechanical strength and osteogenic activity remains a critical challenge. In this work, HA ceramics with in situ graphene doping were fabricated via ball-milling and vacuum sintering processes in a convenient way, thereby increasing their fracture toughness and flexural strength to the levels of natural cortical bone. Furthermore, in situ graphene doping imparted outstanding photothermal property to HA bioceramics, achieving wet temperatures exceeding 60 °C under near-infrared radiation at 808 nm and exhibiting excellent antibacterial efficacy with a bacteriostasis rate of approximately 96% against S. aureus. Additionally, HA bioceramics with in situ graphene doping promoted the proliferation and differentiation of bone marrow stem cells (BMSCs). The anti-infective capability and osseointegration potential of these doped HA bioceramics were further validated using an infected bone defect model in the rabbit femur. In summary, these findings indicate that in situ graphene doping holds immense potential for broadening the applications of HA bioceramics in the repair of load-bearing and infected bone defects.