Mechanical properties and bioactivity of porous PLGA/TiO2 nanoparticle-filled composites for tissue engineering scaffolds

Poly(lactide-co-glycolide) (PLGA) foams and PLGA/titanium dioxide (TiO2) nanoparticle-filled composite foams (porosity > 90%) were produced by thermally induced solid–liquid phase separation (TIPS) and subsequent solvent sublimation. The scaffolds exhibit bimodal and anisotropic pore structures, with tubular macropores (approximately 100 μm in diameter) interconnected by a network of micropores. Quasi-static compression testing and dynamic mechanical analysis were carried out and the results were correlated to the microstructure observed by SEM, confirming the strong anisotropic behaviour of the foams. A study of the collapse mechanism of the foams porous structure revealed that when compressed in the main pore direction, the scaffolds failure mechanism involves an initial “accommodation” of large regions of the porous structure, followed by the collapse of individual pores in different modes. The bioactivity of the scaffolds was demonstrated by immersion in simulated body fluid (SBF) for up to 28 days. Formation of hydroxyapatite crystals on the scaffold surface was confirmed by X-ray diffraction analysis.