Metal Oxide Substituted Polyurethane foams for enhanced craniofacial bone repair: Exploring the properties of Cerium, Zirconium and Copper doped Zinc oxide nanoparticles as potential additive for bone regeneration and angiogenesis.

Zinc oxide containing bone regenerative scaffolds have great potential in bone tissue engineering since zinc oxide has multifunctional properties and is one of the most researched metal oxide. Zinc oxide have been synthesized via different methods and in different morphologies such as nanowires, rods and nanoparticles. It is a known antibacterial agent and can promote cell growth, differentiation, and angiogenesis. Within this thesis, cerium, zirconium and copper doped zinc oxides were synthesized using eco-friendly continuous hydrothermal flow system. The nanoparticles were characterized and change in particle size and morphology was seen. The zirconium doping resulted in smallest particle size i.e. from 83 nm (ZnO_2) to 45 nm (ZrZnO5). The porous polyurethane-hydroxyapatite scaffolds containing doped zinc oxides were fabricated using freeze extraction salt leaching process. The 1% CeZnO5, ZrZnO5 and CuZnO5 was added to polyurethane-hydroxyapatite scaffold. The cell seeding efficiency data revealed 60% cell adhesion for PU-HA-CeZnO5 scaffold, 45% cell adhesion for PU-HA-ZrZnO5 and 80% for PU-HA-CuZnO5 scaffolds when compared with PU only or PU-HA and PU-HA-ZnO_2. The cell metabolic activity assay revealed highest cell metabolic activity for scaffolds incorporated with doped zinc oxide nanoparticles. The raised ALP levels were also detected with doped zinc oxide incorporated scaffolds which is an early marker for bone regeneration. The current data suggested that the doped zinc oxide nanoparticles can be used as additives for bone regenerative applications and angiogenesis.