Effect of TiO2 nanoparticle loading on Poly(l-lactic acid) porous scaffolds fabricated by TIPS

Porous nanocomposite scaffolds of poly(L-lactic acid) (PLA), loaded with TiO2 nanoparticles, were prepared by thermally induced phase-separation (TIPS). The preparation procedure induced crystalline polymer structures (with degree of crystallinity up to 51%) with no evidence of residual solvent, as confirmed by thermal analysis. Scaffold porosity, distribution of the nanofiller and shape of the pores were investigated by X-ray micro computed tomography (m-CT) and scanning electron microscopy (SEM). The produced scaffolds with porosity of 86 ± 2% have interconnected open tubular pores with diameter and length in the ranges 40e80 mm and 200e400 mm respectively. The inorganic TiO2 nano-additive is well dispersed in the scaffold walls, with only a small fraction of micrometric aggregates observable. All investigated polymer scaffolds display similar compressive moduli (between 2.1 and 2.8 MPa). Thermogravimetry (TGA), wide angle X-ray diffraction (XRD) and SEM analyses run on scaffolds subjected to in vitro mineralization tests showed that PLA scaffolds loaded with TiO2 develop an amount of hydroxyapatite four times higher than that of plain PLA, thus assessing that titania nanoparticles confer improved bioactivity to the scaffolds.