Degradable calcium deficient hydroxyapatite/poly(lactic-glycolic acid copolymer) bilayer scaffold through integral molding 3D printing for bone defect repair

A novel method was developed for calcium deficient hydroxyapatite (CDHA) scaffold 3D printing, through which a bilayer scaffold was fabricated by the integral molding of individual CDHA and poly(lactic-glycolic acid copolymer) (PLGA). The hydration reaction of α-tricalcium phosphate (TCP) was utilized to form CDHA, and a mixed solution of gelatin, glycerine and glutaraldehyde was applied as the dispersant and adhesive. The concentration of the glutaraldehyde (1‰(v/v)) and the mixing ratio of α-TCP (0.6, 0.8, 1.0 and 1.2 g ml−1) were studied with regard to the effect on the forming ability of the CDHA ink. The influence of α-TCP proportion (0.6, 0.8, 1.0 and 1.2 g ml−1) on the formation of CDHA was also researched in phase analysis, morphology and compressive strength measurements. The CDHA/PLGA bilayer scaffold was fabricated with a good combination of the two components by 3D printing. The in vitro degradation, cytotoxicity and cell proliferation behavior were studied. Meanwhile, the in-vivo performances in terms of surgical safety, biodegradation and osteogenic capacity were investigated with a cortical bone defect model in a rabbit femur. The results showed that the CDHA/PLGA bilayer scaffold had excellent biocompatibility and no cytotoxicity. The scaffolds were successfully implanted and presented remarkable osteogenic capacity within 6 months through analyses in radiography and histology. In conclusion, the method has a potential clinical application in diverse bone repair practices by varied 3D-printing fabrication.