Preparation and Characterization of 3D Printed Ink from Hydroxyapatite and Corn Starch for Bone Scaffolds Fabrication

The work aims to prepare 3D printing ink from hydroxyapatite using corn starch as a binder for scaffold. Hydroxyapatite synthesis, the eggshell was washed with distilled water several time and dried at room temperature. The calcium oxide was prepared from the heated eggshell powder at 900°C in the air pressure. The calcium nitrate solution was mixed with di-ammonium hydrogen orthophosphate solution by the magnetic stirrer. The precipitate of the mixed solution was washed with distilled water and dried at 90°C in the oven. The hydroxyapatite and corn starch as a 3D printing ink precursor were studied the crystal structure by X-ray diffractometer (XRD). The results show that the hydroxyapatite synthesized from eggshell has a pure phase and hexagonal structure. At the same time, the crystal structure of corn starch has an amorphous phase of αamylase. Then, the 3D printing ink was prepared from a mixing of hydroxyapatite powder and corn starch by ball milling method with a ratio of 97:3. The prepared 3D printing ink was printed the scaffold with a cylinder shape through the extruder of a 3D printer. The scaffold was heated with a furnace in the range of 1000-1200°C. The crystal structure of the scaffold before and after heat treatment was studied by XRD. The compressive strength of scaffold after heat treatment was studied by the universal testing machine. The results show that the 3D printing ink prepared from hydroxyapatite and corn starch can print the cylindrical scaffold. The XRD result indicated the partial transformation of hydroxyapatite into tricalcium phosphate after heat treatment at 1200°C. The compressive strength result of the scaffold was increased with increasing heating temperature. From this experiment, 3D printing ink from hydroxyapatite and corn starch can successfully prepare and print the scaffold for bone tissue engineering applications.