Biowaste-Based Hydroxyapatite Composite for Biomedical Application

Chin, Shi Jia (2022) Biowaste-Based Hydroxyapatite Composite for Biomedical Application. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The rise in orthopaedic and dental bone defects around the world is pressuring the bone tissue engineering to develop novel biomaterials or composite used in constructing bone scaffolds and fostering bone regeneration. Hence, the effect of bioglass reinforced hydroxyapatite composite was studied and evaluated in density, microstructure, hardness, fracture toughness and characterisation such as Fourier transform infrared spectroscopy (FTIR), Scanning electron microscope-Energy dispersive X-ray spectrometer (SEM-EDX) and X-ray diffraction (XRD). In this project sol-gel synthesis method was employed to prepare the bioglass powder with composition of 50SiO2: 25CaO: 25Na2O (mol%) from eggshells and rice husk as the source of calcium oxide and silica respectively. Then, the hydroxyapatite was synthesised by using wet chemical precipitation method using eggshells. Both bioglass powder and hydroxyapatite powder were successfully synthesised by using sol-gel synthesis method and wet chemical precipitation method respectively. The prepared powder was compressed and sintered at temperature of 1000℃ for bioglass, 1200℃ for all bioglass reinforced hydroxyapatite composite and cold isostatic pressed hydroxyapatite, and 1500℃ for uniaxially pressed hydroxyapatite. The result obtained showed that the sintered cold isostatic pressed hydroxyapatite has the highest density (3.09g/cm3), shrinkage percentage (32.88%) and hardness (5.07 GPa) among the sintered samples as it has more equiaxed grains and a Ca/P ratio (1.65) very close to the theoretical Ca/P ratio of hydroxyapatite (1.67). The XRD and FTIR result showed that pure phase of hydroxyapatite is present in sintered cold isostatic pressed hydroxyapatite. For bioglass reinforced hydroxyapatite composite, 20% bioglass reinforced hydroxyapatite composite made of hydroxyapatite powder with Ca/P ratio 4.2 exhibit better overall performance than other bioglass reinforced hydroxyapatite composites and the characterisation results identified the presence of pure phase hydroxyapatite. The bioglass reinforced hydroxyapatite composites made of hydroxyapatite powder with Ca/P ratio 4.2 also showed significant improvement in fracture toughness as compared to hydroxyapatite. Hence, 20% bioglass reinforced hydroxyapatite composite made of hydroxyapatite powder with Ca/P ratio 4.2 has high potential in the applications of constructing bone scaffolds and fostering bone regeneration. The uniaxially pressed green compact can be further compact by using cold isostatic pressing, since the cold isostatic pressed hydroxyapatite showed positive results. Then, cold isostatic pressed sample can be sintered at lower temperature or shorter sintering duration to reduce energy consumption, cost and save time.