Novel bio-nanocomposite scaffolds for tissue engineering application

Abstract: Polymer nanocomposite scaffolds of polylactic acid and poly(ε-caprolactone) with chitosan-modified montmorillonite were prepared, characterized and tested for biodegradability, bioresorbability and biocompatibility for possible application in bone tissue engineering. Bone is a typical complex and hierarchical tissue consisting of the polymer collagen and nano hydroxyapatite crystals. The standard treatment for bone damage and repair is the use of bone grafts which, so far, have led to complications associated with infection, scarring, donor-site morbidity and the need for secondary surgeries. The construction of artificial bone, through the engineering of polymeric materials with cells and growth factors, is a promising approach to solving some of these issues. Composites in particular, best mimic the natural functions of bone since it is also a nanocomposite material. The polymer nanocomposite scaffolds developed in this work were prepared by the solvent casting and particulate leaching method. The properties of the materials were studied by scanning electron microscopy, energy dispersive x-ray spectroscopy, fourier transform infra-red, x-ray diffraction and dynamic mechanical analysis. Highly porous, three-dimensional scaffolds with pore sizes of up to 400 μm and porosities greater than 80% were obtained. Electron microscopy showed structures with interconnecting pore networks, while elemental analysis from energy dispersive x-ray spectroscopy confirmed the absence of any toxic elements that could have resulted from the preparation procedures. The introduction of the clay particles into the polymer matrices produced a combination of partially intercalated and exfoliated structures. The elastic modulus of the polymer nanocomposites was significantly improved by the clay particles inclusion, giving modulus values of up to 36 GPa. Biodegradation and bioresorption studies, which were performed in simulated physiological conditions, showed an increase in the degradation and resorption rates due to the presence of montmorillonite in the nanocomposite scaffolds when compared to the neat polymers. For biocompatibility testing, the polymeric materials were cultured with human foetal osteoblast cells. An improvement in the...D.Phil. (Chemistry