Physicochemical and Osteoinductive Comparison of 2D Spin-Coated Films and 3D Porous Solvent-Cast Scaffolds of Poly(3-Hydroxybutyrate- co -3-Hydroxyvalerate) (PHBV)/ Polybutylene Adipate Terephthalate (PBAT) Blends

This aim of this study is to investigate the structure-property-function relationship of PBAT/PHBV blends by comparing rapid spin coating and porogen-assisted solvent casting. Spin coating induces "kinetic trapping", creating fully amorphous 2D films. Conversely, solvent casting allows PHBV crystallization, forming semicrystalline 3D porous scaffolds. While both 50:50 blends exhibit cocontinuous morphologies, they remain structurally distinct. Despite similar chemistries, spin-coated films show enhanced hydrophilicity due to high nanoscale roughness (Wenzel model). Biological evaluations confirm that both systems are noncytotoxic. Notably, spin-coated films, particularly the 50:50 blend, exhibit enhanced in vitro biocompatibility and rapid initial proliferation. However, their 2D nature eventually leads to contact inhibition. In contrast, the 3D porous 50:50 solvent-cast scaffold supports logarithmic proliferation, yielding a ∼160% increase in ALP activity and 228% higher terminal mineralization. Ultimately, while the 50:50 spin-coated blend serves as a resource-efficient, bioactive surface coating, the 50:50 solvent-cast scaffold provides the optimal 3D biomimetic niche for bone tissue engineering.