High performance composites of bioactive glass fiber-reinforced degradable PCL-b-PLLA for load-bearing bone repair

Abstract

High performance is necessary for materials to repair load-bearing bones. The elastic moduli of conventional metals, such as stainless steel and titanium alloys, are significantly higher than those of human cancellous and cortical bones, leading to severe stress shielding effects and requiring secondary surgery for removal. The insufficient mechanical strength of biodegradable polymers or hydroxyapatite-blended biodegradable polymers limits their application in load-bearing bone repair. In this study, we developed bioactive glass fiber-reinforced biodegradable polymer composites for the repair of load-bearing bones. The biodegradable polymer matrix was a poly(ε-caprolactone)-b-poly(L-lactide) diblock copolymer. Bioactive glass 13-93 was melt-spun into continuous fibers and subsequently laminated with diblock copolymers through hot pressing. The melt-spinning of bioactive glass fibers and composite manufacturing were investigated. Composites with 30 wt% and 50 wt% glass fibers were prepared; mechanical testing revealed that the elastic modulus of the composite plates containing 50 wt% bioactive glass fibers was as high as approximately 5 GPa, which exceeded that of human cancellous bone and approached the range of cortical bone modulus. Biocompatibility tests revealed that the composites were not cytotoxic and promoted osteoblast mineralization. With the addition of bioactive glass fibers, the composites exhibited excellent antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). Thus, the bioactive glass fiber-reinforced PCL–PLLA composites are favorable for load-bearing bone repair.