Effect of Adding Nanocrystalline Cellulose on Reducing Micro-Crack of Three-Dimensional Printed Hydroxyapatite/Collagen Composite

Large bone defects can not be recovered by self-repair meanwhile, bone scaffold with biomimetic material is needed. The biomimetic materials are hydroxyapatite/collagen as inorganic and organic material. The study on printed hydroxyapatite/collagen has been conducted. However, the crack occurred after printing and drying. The novelty of the research is addition of nanocrystalline cellulose (NCC) into the HA/collagen composite to reduce microcrack. The hydroxyapatite/collagen/NCC composite scaffold was printed with 3D bioprinting which was a modification in bracket and cartridge with print speed and layer height of 10 mm/min and 0.5 mm. The cracking process that occurred in the hydroxyapatite/collagen material was investigated using Mi-View microscope. Furthermore, the scaffold of hydroxyapatite/collagen/NCC composite with composition 70/15/15 (%w/v) was examined using the Vickers hardness test, Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope (SEM), energy dispersive X-ray (EDX), and thermogravimetric analysis/derivative thermogravimetry (TGA/DTG). After the printing process, shrinkage occurs on the X, Y, and Z axes with values of 14, 15.1 and 20.5%. Moreover, the hardness value was 0.002 to 0.003 HV with the detection of hydroxyapatite, collagen, and NCC. The crystallinity of hydroxyapatite/collagen/NCC was 28%. The presence of NCC in the composite material can maintain a uniform three-dimensional network structure with a dominant composition of oxygen (47.77%), calcium (36.62%), and phosphate (12.8%). The TGA/DTG represented the amount of weight loss of 23.46% with an initial temperature of 610 °C and maximum temperature of 650 °C. Therefore, hydroxyapatite/collagen/NCC is promising material for bone tissue engineering.