Fabrication of novel bioactive hydroxyapatite-chitosan-silica hybrid scaffolds: Combined the sol-gel method with 3D plotting technique.

Sol-gel derived organic/inorganic hybrids, in which organic and inorganic components form co-networks at the molecular level, have demonstrated great potential for providing improved mechanical properties and biological functions in tissue engineering applications. Here, a novel bioactive hydroxyapatite-chitosan-silica hybrid (HA-CSH) scaffold was successfully fabricated by combining the sol-gel method and 3D plotting technique. Physiochemical characterization confirmed that chitosan was hybridized homogeneously with the inorganic phase on nanoscale. The obtained scaffolds possessed precisely controllable and interconnected porous structures. The nano-sized HA formed in situ and dispersed uniformly in the hybrid network, which reduced the water absorption and increased the mechanical strength of the hybrid scaffold under humidity condition as compared to chitosan-silica hybrid (CSH) scaffold. Compression tests showed that the 3D plotted hybrid scaffolds under wet conditions had compressive strengths of 10-13 MPa and elastic moduli of 21-27 MPa and thus met the mechanical requirements of human trabecular bone. Studies on the mineralization process under simulated body fluid (SBF) conditions confirmed that the introduction of HA obviously increased the biological activity of hybrid scaffolds. In vitro cell results indicated that the HA-CSH scaffold not only supported adhesion and proliferation of mouse bone mesenchymal stem cells (mBMSCs), but also improved the osteoinductivity. The alkaline phosphatase activity and mineral deposition on the HA-CSH scaffold were higher than those on the CSH scaffold. These results suggested that the 3D plotted HA-CSH scaffold may be a promising bioactive material for bone tissues regeneration.