Bioactive and Electrically Conductive Nanocomposite Bone Biomaterials
Abstract
Electrically conductive carbon-based materials are emerging as potential biomaterials for bone tissue engineering. Their incorporation into organic-inorganic nanocomposites mimics the structural composition and electrically conductive nature of bone.
The aim of this research was to design bone biomaterials from gelatin-based polymers, tertiary bioactive glasses (BG) via a sol-gel method, and multiwall carbon nanotubes (MWCNT). The incorporation of calcium into organic-inorganic nanocomposites plays an essential role in the development of bioactive bone biomaterials. Calcium chloride and calcium ethoxide were investigated as calcium sources in gelatin-BG-MWCNT nanocomposites. The resulting surface elemental distribution was homogeneous, but the swelling, degradation and porosity properties of nanocomposites differed due to the fate of calcium ions within the organic-inorganic network. Mineralization on the surfaces of nanocomposites was observed after treatment in simulated body fluid. Favorable cell adhesion, spreading, and viability were observed on nanocomposites, with calcium ethoxide having more advantageous properties. Furthermore, an alternative synthesis strategy comprising gelatin methacryloyl (GelMA), sol-gel derived tertiary BG containing calcium ethoxide as calcium source, and MWCNT was developed to create nanocomposite organic-inorganic hydrogels. Using this strategy, biomaterials possessed mechanical and electrically conductive properties as a function of MWCNT loading. In addition, suitable electro-mechanical responses similar to that found in endogenous bone were observed without affecting their bioactive and biocompatibility properties. Nanocomposite hydrogels also supported mouse embryo multipotent mesenchymal progenitor (10T1/2) cells and drove differentiation into an osteogenic lineage.
Mesenchymal stem cells derived from human-induced pluripotent stem cells (iMSCs) were also able to attach to GelMA-BG-MWCNT nanocomposite hydrogels. Cell adhesion onto the surfaces of nanocomposite was improved when hydrogels were coated with fibronectin and seeding pre-differentiated iMSCs. Increased osteogenic differentiation and the formation of mature mineral deposition were observed in hydrogels with increasing MWCNT concentration. Overall, the data presented in this thesis demonstrated that nanocomposites containing MWCNT could potentially become promising bioactive biomaterials for bone repair and regeneration applications.