L-poly(lactic acid) (PLLA) is a biodegradable material with multiple biomedical application potentials, especially as a membrane for guided bone regeneration. In terms of its low strength and poor osteogenic activity, improving these two properties is the key to resolve the limitations of PLLA for bone-associated applications. Herein, an orientation-strengthening technology (OST) was developed to reinforce PLLA's mechanical strength by introducing biocompatible β-tricalcium phosphate (β-TCP) to improve the crystallinity of PLLA, allowing for the formation of a highly oriented architecture to acquire an advanced membrane with high mechanical property. Furthermore, the addition of β-TCP nanoparticles significantly promotes the osteogenic activity of the composites. The tensile strength of the membrane containing 5 wt % β-TCP was 220 MPa, which was 4-folds that of the native polylactic acid fabricated via the conventional method. The oriented microstructure enhanced both the mechanical strength and the osteogenic activity of the material. The parallel grooves on the material surface are similar to the mineralized collagen fibers on the bone surface, which promoted the growth and differentiation of osteoblasts, with β-TCP further contributing to the osteoconductive effect. The combination of β-TCP and orientation-strengthening effect endows the material with higher mechanical properties and bioactivities, which provides an advanced manufacturing strategy for the preparation of PLLA-based materials for bone repair.
Keywords: L-polylactic acid; high strength; organic/inorganic composite; orientation enhancement; osteogenic activity.