Abstract: BACKGROUND: Bone tissue engineering scaffolds are prepared and applied to repair bone defects caused by osteosarcoma disease, which is the current hotspot of bone tissue engineering research.  
OBJECTIVE: To determine the ratio of chitosan/polylactic acid/hydroxyapatite/polyvinyl alcohol composite material, and optimize the mechanical properties of bone scaffolds.
METHODS:  The chitosan/polylactic acid/hydroxyapatite/polyvinyl alcohol bone scaffold was prepared using extrusion-based 3D printing technology. The maximum compressive strength was used as the evaluation index to design orthogonal experiments. The acetic acid concentration (1.5%, 2%, 2.5%, 3%), chitosan solution concentration (2%, 3%, 4%, 5%), hydroxyapatite:polylactic acid mass ratio (1:5, 1:6, 1:7, 1:8), and hydroxyapatite/polylactic acid:chitosan solution:polyvinyl alcohol gel mass volume ratio (1 g: 1 g: 0 mL, 2 g: 1 g: 1 mL, 2 g: 1 g: 1.2 mL, 2 g: 1 g: 1.4 mL) were independent variables to get the best material ratio. The mechanical properties, phase composition and bonding mode, porosity and degradation properties of the optimal ratio composite material were characterized.  
RESULTS AND CONCLUSION: (1) Orthogonal experiment results exhibited that the concentration of acetic acid was 3%; the concentration of chitosan solution was 5%; the mass ratio of hydroxyapatite:polylactic acid was 1:6; the hydroxyapatite/polylactic acid:chitosan solution:polyethylene alcohol gel was 2 g:1 g:1.4 mL. The composite material had good mechanical properties. (2) The composite material scaffold with the best ratio had good connectivity; the porosity was (52.0±1.5)%; and the maximum compressive strength reached 6 MPa. X-ray diffraction scanning and Fourier infrared spectroscopy test results demonstrated that the main bonding method of composite materials was physical blending. Composite scaffolds had certain degradation properties, but the weight loss rate was low during the test time, and degradation property needs to be further improved. (3) These findings indicate that the chitosan/polylactic acid/hydroxyapatite/polyvinyl alcohol composite scaffold has high porosity and good mechanical properties.

Key words: orthogonal experiment, analysis of variance, extrusion-based 3D printing, bone tissue engineering scaffold, mechanical properties, degradation property, weight loss rate, porosity