An injectable hydroxyapatite/poly(lactide-co-glycolide) composite reinforced by micro/nano-hybrid poly(glycolide) fibers for bone repair.

Porous nanocomposite of hydroxyapatite/poly(lactide-co-glycolide) (HA/PLGA) is conventionally used in bone tissue engineering but seldom in load-bearing orthopedic applications due to poor mechanical property. This study aimed to fabricate an injectable ternary composite by incorporating different contents of poly(glycolide) (PGA) fibers (0, 30, 50 and 70wt%) into the nanocomposite HA/PLGA matrix as reinforcing fillers for bone tissue repair. The fibers were obtained from melt-spinning and fiber diameter ranged from 70nm to 191μm. The injectability, mechanical strength, solidification rate and cytotoxicity of injectable composites were characterized. All composites achieved the acceptable injectability under an injection force of 100N. The mechanical properties of composites were gradually enhanced by increasing PGA fiber contents. The compression strength of composite with 70wt% content of PGA fibers was up to 31.1MPa, which was four times stronger than that of composite without PGA fibers. In the solidification rate analysis, the compression strength of composites with 50 or 70wt% PGA fibers in immersion time of only 45min was similar to that of composite without fibers in immersion time of 4-5h. The MTT test showed that exceeding 70% cells could survive in the fourfold dilution of extract, and its cytotoxicity focused on the first 4h after immersing. This study have revealed that the PGA fiber-reinforced HA/PLGA composite is a promising candidate for orthopedic applications.