Performance of ZnO-Incorporated Hydroxyapatite/Polymethyl Methacrylate Tri-Component Composite Bone Scaffolds Fabricated from Varying Sources of Hydroxyapatite

Considering the popularity of hydroxyapatite (HA)-based scaffolds and the varied sources of HA synthesis, their impact on the properties of the developed scaffolds needs to be properly explored. Moreover, conventional gas foaming process yields scaffolds with excellent pore morphology, but with closed pores which are inadequate for efficient osteoinduction. To address these issues, porous hydroxyapatite (HA)/polymethyl methacrylate (PMMA)/zinc oxide (ZnO)-based tri-component composite scaffolds are fabricated by a novel modified gas foaming process from both chemically synthesized HA and natural HA derived from galline and bovine bone bio-wastes. The role of the varying sources of HA on the physico-chemical, mechanical and biological properties of the developed scaffolds is investigated. For this purpose, the scaffolds developed by maintaining a constant composition of HA and PMMA at 70:30 (w/w) and ZnO at 5 wt.% are characterized. The developed scaffolds show stability in their chemical properties and interconnected macro porous network with a maximum porosity of 81.93 +/- 1.2%, average pore size of 149 +/- 5 mu m and maximum hydraulic permeability of (2.36 +/- 0.09) x 10(3) mu m(2) for synthetic HA-based scaffolds. A maximum compressive strength, hardness and cell viability of 16.70 +/- 0.6 MPa, 32.4 +/- 0.9 HD and 98 +/- 3.2%, respectively, and maximum protein adsorption are recorded for bovine bone-derived HA-based scaffolds. All the scaffolds are found to be bioactive in nature, while galline bone-derived HA-based scaffolds show maximum biodegradation with 8.1 +/- 0.15% weight loss in SBF. The results obtained indicate that apart from the porosity and permeability, synthetic HA-based scaffolds reveal poor chemical, mechanical and biological properties compared to natural HA-based scaffolds. The study concludes that the properties of a composite scaffold rely significantly on the parent material (HA). Based on the extensive comparative investigation, bovine bone-derived HA-based composite scaffold is found to have improved properties for growth and proliferation of bone cells.