Biomimetic characterization reveals enhancement of hydroxyapatite formation by fluid flow in gellan gum and bioactive glass composite scaffolds

This study presents production and biomimetic characterization of macroporous composite scaffolds based on gellan gum and nanoparticulate bioactive glass (GG-BAG) under conditions relevant for bone tissue engineering. Formation of hydroxyapatite (HAp) within the scaffolds was investigated in the simulated body fluid (SBF) during 14 days in two biomimetic bioreactors: perfusion bioreactor (1.1 ml/min SBF flowrate) and a bioreactor with coupled dynamic compression and SBF perfusion (5% strain, 0.68 Hz, 1 h on/1 h off, 1.1 ml/min SBF flowrate). HAp formation was evaluated by scanning electron microscopy (FE-SEM), energy dispersive X-ray (EDS) analysis, Fourier transform infrared spectroscopy (FTIR), and X-ray powder diffraction (XRPD). The superficial SBF velocity of 100 mu m/s in perfusion bioreactors induced the formation of abundant cauliflower-like HAp crystals throughout the scaffold interior and flake-like crystals on external surfaces resulting in improved mechanical properties as compared to the initial scaffolds. The obtained results indicate potentials of macro-porous GG-BAG scaffolds in conjunction with perfusion bioreactors for bone tissue engineering demonstrating high bioactivity suited for cultures of osteogenic cells.