Resonant Acoustic Mixing-Assisted Fabrication of Fused Deposition Modeling-Printed Shape Memory P(DLLA-TMC)/β-TCP/PDA...

Four-dimensional (4D) printing offers a promising strategy for fabricating shape-adaptive bone scaffolds capable of conforming to complex defect geometries; however, achieving stable fabrication, homogeneous dispersion of multifunctional components, and predictable osteogenic performance remains challenging. In this study, a solvent-free resonant acoustic mixing (RAM)-assisted strategy was introduced to fabricate fused deposition modeling (FDM)-printed shape memory P(DLLA-TMC)/β-tricalcium phosphate (β-TCP)/polydopamine (PDA) composite scaffolds. RAM enabled uniform dispersion of microscale β-TCP and nanoscale PDA within the polymer matrix under low-shear conditions, providing a robust basis for continuous filament extrusion and FDM-based 4D printing. The resulting ternary composite scaffolds exhibited suitable rheological behavior, improved compressive strength, enhanced surface hydrophilicity, and stable near-infrared-triggered photothermal shape memory performance. In vitro experiments demonstrated excellent cytocompatibility and significantly enhanced osteogenic differentiation, as evidenced by increased alkaline phosphatase activity, mineralized matrix deposition, and upregulated osteogenesis-related gene and protein expression. Furthermore, in vivo rat calvarial defect models confirmed that the composite scaffolds effectively promoted new bone formation and structural maturation. Collectively, this work establishes an integrated material-process-function framework for the scalable fabrication of multifunctional 4D-printed bone scaffolds and highlights the translational potential of RAM-assisted manufacturing for advanced bone tissue engineering applications.