Development & Characterisation of Nanocomposites for Bone Tissue Engineering

The aim of this thesis was to develop a bioactive and resorbable nanoscale composite that mimics the properties of bone and will have the potential to regenerate bone. In conventional composites, the polymer phase can mask the bioactive phase and often degrades faster than the ceramic phase due to the weak interfacial bonding between the polymer and ceramic. Here in this thesis an organic/inorganic nanocomposite with stronger interfacial bonding between the two phases has been produced using the sol-gel route. Glasses containing SiO2 and CaO were used as the inorganic while the amino acid poly-γ−glutamic acid (γ−PGA) was used as the organic. This is the first time an inorganic/organic hybrid with enzymatically degradable polymer covalently crosslinked to the inorganic has been produced. Several factors contributed to the homogeneity of the nanocomposites; most important of all was the extent of integration (homogeneity and phase miscibility) of the organic into the inorganic sol. The main focus of this thesis was to synthesise this new material and to develop an understanding of the nanoscale interactions of the two phases. The chemical structure of the nanocomposites were characterised with Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR) and the nanostructure was characterised with scanning and transmission electron microscopy (SEM and TEM). Bioactivity studies of the nanocomposites in simulated body fluid (SBF) showed that the nanocomposites containing calcium were bioactive. Initial in vitro cell response studies also showed that the nanocomposites were not toxic to cells. Nanocomposites were also foamed to create the first porous bioactive inorganic/organic scaffolds with covalent bonding between the organic and inorganic. Micro-computed tomography (μCT) was used to non-destructively image and quantify the internal pore structure of the bioactive nanocomposite scaffolds. The three-dimensional images of the scaffolds show that the nanocomposites have large macropores with multiple connections between them giving a suitable pore structure for tissue engineering