Fabrication and evaluation of bioresorbable PLLA/magnesium and PLLA/magnesium fluoride hybrid composites for orthopedic implants

Polymers, such as poly-l-lactide (PLLA) were the first materials to be used as commercial biodegradable and bioresorbable implant materials. However, the limitations were focused on low mechanical properties and acid degradation by-products which were concerned as the source of inflammation. In this work, hybrid composites incorporated PLLA with 3-7 wt% magnesium and magnesium fluoride particles were developed to overcome drawbacks mentioned above as novel bioresorbable orthopedic implants. The morphology, mechanical and thermal properties, in vitro degradation and cytotoxicity assessment were analyzed by SEM, DSC, UTM, pH value monitoring and MTT. It was found that the tensile strength was slightly decreased with addition of Mg particles. The tensile fracture morphologies indicated that the interface adhesion between Mg particles and PLLA matrix could be contributed to the influence on mechanism property. The addition of Mg and MgF2 into PLLA was effective in neutralizing the acid environment caused by degradation by-products, which was reflected by a close pH value to body fluid. Moreover, cell viability showed better cytocompatibility of composites with the beneficial Mg ions release. Therefore, PLLA/magnesium and PLLA/magnesium fluoride hybrid composites had a promising potential for orthopedic implant application.