3D-printed biodegradable composite poly(lactic acid)-based scaffolds with a shape memory effect for bone tissue engineering

In this study, 3D-printed biodegradable poly(lactic acid) (PLA) and hybrid PLA scaffolds doped with magnetite nanoparticles (PLA/Fe₃O₄) and having gyroid structure were investigated at various infill densities (100%, 70%, 50%, or 30%). Effects of infill density on the composition, structure, and mechanical properties (Young’s modulus, compression, and tensile strength) of the scaffolds and a shape memory effect were documented. Raman spectroscopy was used to detect the characteristic molecular bonds of PLA and magnetite. X-ray diffraction confirmed higher crystallinity of the materials printed with Fe₃O₄ addition. PLA/Fe₃O₄ composites showed ferrimagnetic behavior. Mechanical properties of PLA/Fe₃O₄ composite scaffolds with 50% porosity fall within the range of corresponding mechanical properties of native cancellous bone, and therefore these scaffolds hold promise for the repair of bone defects. Additionally, 3D-printed materials’ various sizes and shapes were tested to achieve shape recovery up to 85% for composite porous scaffolds with gyroid structure and up to 100% for nonporous pure PLA ribbons (the supporting walls). Furthermore, a decrease in the infill density of the gyroid scaffolds resulted in a higher shape recovery rate. A proposed mechanism of the shape memory effect in the printed scaffolds was also discussed. These findings suggest that the developed 3D-printed PLA/Fe₃O₄ scaffolds, with tunable mechanical properties and shape memory capabilities, offer significant potential for advanced biomedical applications, including personalized bone repair and regeneration.