Ultrasmall sized calcium phosphate nanoclusters based organic-inorganic biofiber for accelerated bone fracture healing

Amorphous calcium phosphate (CaP) is the precursor of minerals in bone, and this precursor phase has been suggested to exist in the form of nanoclusters. In vitro experiments have demonstrated a strong ability of these CaP nanoclusters in mineralizing collagen matrix, suggesting their potential applications in bone fracture healing. It is however difficult to obtain stable CaP nanoclusters and control their release to bone fracture sites in vivo . In this work, we designed an organic-inorganic polyvinyl alcohol-arginine-calcium phosphate (PVA/Arg/CaP) biofiber. The as-prepared biofiber displays good mechanical performance and can continuously release CaP nanoclusters to mouse tibial fracture sites. These released CaP nanoclusters display good in vivo stability and can be directly utilized for collagen mineralization and bone regeneration, thus accelerating the healing process. The bone healing ability is confirmed by in vivo experiments, and the regenerated bones possess satisfactory mineral content and mechanical performance comparable with that of normal ones. The discovery not displays a promising avenue of bone fracture healing, but also provides insight into the bone mineralization process.