Fabrication of silicon nitride Nanowires@Carboxylated carbon nanotubes scaffolds inducing hydroxyapatite plane connection growth for bone defect repair

Hydroxyapatite (HA) is an essential inorganic component of bone tissue. However, the low strength and poor stability of HA limit the application in implantable materials. Herein, we report a strategy to fabricate SW@CNT by grafting carbon nanotubes (CNT) on the surface of silicon nitride nanowires (SW). Subsequently, carboxylic groups were introduced to the surface of SW@CNT to form hydrophilic SW@CCNT. Then, the honeycomb-like HA grows in the SW@CCNT network structure in a plane connection pattern to fabricate SW@CCNT/HA, which is similar to the natural bone structure. Specifically, the SW@CCNT network was embedded in SW@CCNT/HA, which enhances the cohesion of SW@CCNT/HA. Meanwhile, the hydrophilic SW@CCNT promotes the HA growth in a plane connection pattern, which effectively enhances the interfacial bonding strength of HA. Compared to SW@CNT/HA, the tensile strength, elastic modulus and elongation of SW@CCNT/HA were increased by 237.75 %, 245.17 %, and 158.65 %, respectively. Moreover, SW@CCNT/HA exhibited 8.26 % higher bone volume fraction and 65.43 % higher bone mineral density than SW@CNT/HA at 12 weeks, indicating significantly enhanced bone regeneration and mineralization capacity. Summarily, the network scaffolds with mechanical strength and bone regeneration properties provided a promising strategy for enhancing HA applied to bone defect repair.