Bioinspired sandwich-structured PLA scaffolds via additive manufacturing: Optimizing mechanical properties and printing efficiency for bone tissue engineering

Bone tissue engineering is based on scaffolds that mimic the hierarchical structure of natural bone to promote tissue regeneration. This study introduces a novel (sandwich-scaffold) approach, which is produced by fused filament fabrication (FFF) to produce polylactic acid (PLA) scaffolds with customized mechanical properties. Unlike traditional scaffolds with a single infill percentage, sandwich designs involve different infill percentages across the layer, combining an outer layer with a porous core or vice versa to simulate cortical and trabecular bone structures. Scaffolds were fabricated using single infill percentages (20–80%) and sandwich specimens (80/20/80%, 20/80/20%, 70/30/70%, 30/70/30%, 60/40/60% and 40/60/40%) and the impact strength, specific impact strength, weight, and printing times of the samples were evaluated. The results showed that the sandwich scaffolds, with the 80/20/80% structure, achieved an optimal balance of mechanical strength (impact strength up to 5.63 kJ/m 2 ) and weight (13.01 gr), which is similar to the biomechanical properties of human bones. The 80/20/80% sandwich samples showed the highest specific impact strength (7.12 J·m/kg). This was due to the high-density outer shell and porous cores, which improved energy absorption while reducing weight. The printing time analysis showed that the sandwich scaffolds with low infill percentages in the core were more time-efficient than the single-layer scaffolds with high infill percentages. These results highlight the sandwich scaffolds produced by the FFF method for bone tissue development, providing improved mechanical performance, weight optimization, and structural similarity to natural bone.