Hierarchically Porous TPMS β-TCP Scaffolds to Overcome Stiffness Mismatch in Bone Regeneration

Bone tissue engineering scaffolds must satisfy a delicate balance of requirements, such as sufficient mechanical strength to support physiological loads, while presenting an elastic modulus low enough to avoid stress-shielding effects on surrounding bone tissue, alongside adequate porosity to enable cell infiltration, vascularization and tissue ingrowth. Triply Periodic Minimal Surface (TPMS) architectures offer a promising design strategy for addressing this trade-off, as their smooth, continuous geometries allow precise control over porosity and mechanical response through unit cell parameters. However, these TPMS-based ceramic scaffolds could have elastic modulus higher than the one of the bone, preventing proper mechanical stimulation and eventually leading to implant failure. This thesis investigates the development of β-tricalcium phosphate (β-TCP) TPMS scaffolds fabricated via Digital Light Processing (DLP), with hierarchical porosity obtained through the incorporation of PMMA particles as a sacrificial microporogen agent. Increasing PMMA content was used to systematically introduce and tune microporosity within the scaffold matrix, complementing the macroporosity inherent to the TPMS geometry. The hierarchical pore structure was characterized to establish the relationship between PMMA loading and resulting porosity at both scales. The results demonstrate that increasing microporosity keeps an adequate mechanical performance, featuring β-TCP TPMS scaffolds with tunable porosity as an attractive solution in the field of regenerative medicine.