In Situ Formation Mechanism and Osteogenic Performance of Dislocation-Rich Fibrous Octacalcium Phosphate Mediated by Silk Fibroin

Octacalcium phosphate (OCP) is a biodegradable material with excellent biocompatibility and osteoinductive activity, showing great promise in bone repair applications. Although silk fibroin (SF) demonstrates osteogenic potential and SF-modified OCP has shown enhanced mineralization and osteogenesis in vitro, the underlying regulatory mechanism remains unclear. In this study, by combining cryo-transmission electron microscopy analysis and density functional theory (DFT) calculations, the SF-modified OCP is revealed that possesses a higher density of dislocations. The hydrophobic amino acid sequence of SF induced the formation of edge dislocations via an “adsorption-epitaxy-extrusion” mechanism, accompanied by changes in adsorption energy, which facilitated the transformation of OCP into hydroxyapatite (HAp) and enhanced osteoinduction. In vitro experiments further confirmed that SF-modified OCP enhanced cytocompatibility, promoted ALP and ARS activity, upregulated osteogenic gene expression, and strengthened osteogenic protein expression. This work proposed a novel strategy for modulating defect structures in bioceramics through organic molecules and demonstrated the potential of dislocation-engineered SF-OCP for bone defect repair.