Biomimetic structural design and performance study of 3D-printed graded minimal surface bone scaffolds with enhanced bioactivity

Bone bionics and structural engineering have played a vital role in bone regeneration, with artificial scaffolds generating widespread interest. However, the mechanical properties and bone regeneration potential of biomimetic structures remain unclear. Herein, biodegradable polymer composites based on poly(butylene adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA) were 3D-printed into lattice structures as tissue engineering scaffolds. For structural design, graded diamond (D) minimal surfaces were proposed and designed to mimic the natural bone structure. The graded topologies were realized by designing gradient thickness either radially from center to edge or vertically from top to bottom. The mechanical performance of these graded samples displayed better load-carrying and energy absorption capacity than the uniform counterparts. No obvious damage was detected in the internal microstructure of the compressed samples using computed tomography. Subsequently, platelet-rich plasma (PRP), containing diverse cytokines, was loaded on the graded scaffolds. The PRP-loaded D-scaffold reported improved in vitro cell proliferation and osteoblast differentiation. Finally, femoral condyle defect repair results indicated that the PRP-loaded D-scaffold effectively promoted early-stage bone regeneration. Overall, this work provides insights into fabricating artificial scaffolds with bioactive factors and biomimetic lattice structures.