Optimization of 3D printing parameters for PLGA/HA scaffolds using the Taguchi method

PLGA/HA is a promising material for 3D printed bioresorbable bone scaffolds, but the effects of fused filament fabrication parameters on monotonic and cyclic mechanical performance of resulting structures are unknown. Furthermore, the evolution of mechanical properties and dimensional stability under prolonged exposure to temperature and cell culture immersion conditions is also poorly investigated. This study first applied a Taguchi L9 orthogonal array to evaluate the effects of layer height, nozzle temperature, print speed, and cooling fan speed on the flexural properties of 90:10 wt% PLGA/HA scaffolds. Statistical analysis revealed that flexural strength, modulus, and deflection at failure were significantly influenced by specific printing parameters, while energy absorption showed no significant dependence (p > 0.05). At 50% print porosity, flexural strength and modulus increased by 20% and 50%, respectively, under the optimal settings (0.12 mm layer height and 205 °C nozzle temperature), reaching 45.0 MPa and 1807.80 MPa. Differential scanning calorimetry revealed significant effects on second-cycle glass transition (p = 0.0029), first-cycle cold crystallization (p = 0.0086), second-cycle cold crystallization (p = 0.0177), and first-cycle crystallinity (p = 0.0177), with favorable transitions aligning with mechanical maxima. Fatigue samples were printed using parameters that provided maximum flexural strength, and tests in PBS at 37 °C showed an endurance limit of 1.2 MPa at 10⁶ cycles. In-vitro degradation over 60 days caused swelling of the scaffold by more than 20%, while the strength and the modulus decreased by 76% and 65% respectively, still above lower levels for trabecular bone. Consequently, optimization of 3D print parameters resulted in attaining improved mechanical properties of PLGA/HA, making scaffolds printed under these conditions viable for partial load bearing bone tissue regeneration applications.