In Vitro Biocompatibility, Radiopacity, and Physical Property Tests of Nano-Fe(3)O(4) Incorporated Poly-l-lactide Bone Screws

The aim of this study was to fabricate biodegradable poly-l-lactic acid (PLLA) bone screws containing iron oxide (Fe(3)O(4)) nanoparticles, which are radiopaque and 3D-printable. The PLLA composites were fabricated by loading 20%, 30%, and 40% Fe(3)O(4) nanoparticles into the PLLA. The physical properties, including elastic modulus, thermal properties, and biocompatibility of the composites were tested. The 20% nano-Fe(3)O(4)/PLLA composite was used as the material for fabricating the 3D-printed bone screws. The mechanical performance of the nano-Fe(3)O(4)/PLLA bone screws was evaluated by anti-bending and anti-torque strength tests. The tissue response and radiopacity of the nano-Fe(3)O(4)/PLLA bone screws were assessed by histologic and CT imaging studies using an animal model. The addition of nano-Fe(3)O(4) increased the crystallization of the PLLA composites. Furthermore, the 20% nano-Fe(3)O(4)/PLLA composite exhibited the highest thermal stability compared to the other Fe(3)O(4) proportions. The 3D-printed bone screws using the 20% nano-Fe(3)O(4)/PLLA composite provided excellent local tissue response. In addition, the radiopacity of the 20% nano-Fe(3)O(4)/PLLA screw was significantly better compared with the neat PLLA screw.