Biocompatibility and bioactivity of PDLLA/TiO2 and PDLLA/TiO2/Bioglass® nanocomposites

Biocompatibility and bioactivity of polymer matrix composites containing titanium dioxide (TiO2) nanoparticles were investigated. The solvent casting method was used to prepare poly (d,l-lactic acid) (PDLLA) films with 0 and 20 wt.% TiO2 nanoparticles and with 20 wt.% TiO2 mixed with 5 wt.% micrometre-sized (< 5 μm) Bioglass® particles. The samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy Dispersive X-ray (EDX) analyses. A Zygo® light interferometer was used to examine the surface roughness of the samples. The bioactivity and the surface reactivity of the materials were determined by investigating the formation of hydroxyapatite (HA) on the surface of samples upon immersion in simulated body fluid (SBF) for up to 28 days. Heterogeneous distributed HA crystals were found on composite films containing TiO2 after 21 days exposure to SBF. Cell cytotoxicity and viability were determined by using live/dead and MTS assay on osteoblast-like MG-63 cells. The PDLLA films containing different concentrations of TiO2 and Bioglass® particulate inclusions showed no effect on cell viability in live/dead assay after incubation period of 7 days. All three groups of samples demonstrated significant increase in relative metabolic activity in MTS assay after 7 days incubation (while a slower proliferation rate was obtained for cells on the PDLLA film containing both TiO2 and Bioglass® compared to the Thermanox® control). The bioactive behaviour of the nanocomposites may make them attractive materials for fabrication of tissue engineering scaffolds.