3D-FABRICATION OF HYDROXYAPATITE-POLYSACCHARIDE COMPOSITE SCAFFOLDS FOR BONE TISSUE ENGINEERING

The overarching goal of this research work is to synthesize and fabricate mechanically robust, dimensionally accurate, and porous bone tissue scaffolds for the clinical treatment of bone fractures, defects, and diseases. In pursuit of this goal, the objective of the work is to investigate the influence of hydroxyapatite (HA) as well as polysaccharide concentration on the mechanical properties of bone scaffolds, fabricated using pneumatic micro-extrusion (PME) additive manufacturing process. PME has emerged as a high-resolution method for the fabrication of a broad range of biological tissues. This research work tests the following central hypothesis: hydroxyapatite and polysaccharide significantly affect the mechanical properties of PME-fabricated bone scaffolds. A review of literature shows that while hydroxyapatite-polysaccharide composite scaffolds are biocompatible (allowing for mimicking the structure and the function of natural bone), identification of key material and fabrication factors as well as underlying failure mechanisms would be inevitable to achieve mechanically robust, porous bone scaffolds. In this study, based on designed experiments, the HA concentration as well as the polysaccharide concentration (amylose content) were changed in the range of 10-40 % and 7.5-15 %, respectively. Porous bone scaffolds were PME-fabricated using a micro-capillary nozzle having a diameter of 860 mu m. In addition, print speed and pneumatic flow pressure were set at 5 mm/s and 300 kPa, respectively. The material deposition was laminar and highly viscous on an unheated glass substrate. Subsequently, the fabricated scaffolds were oven-sintered at 37 degrees C. It was observed that the compression modulus of the scaffolds decreased with an increase in the HA concentration, while an increase in amylose content led to an increase in the scaffold stiffness. The outcomes of this work pave the way for the fabrication of complex, mechanically robust composite bone tissue scaffolds with tunable medical and functional properties.