Degradation behaviors of three-dimensional hydroxyapatite fibrous scaffolds stabilized by different biodegradable polymers

For bone tissue engineering, three-dimensional (3D) macroporous bioceramic scaffolds are usually preferred because they can mimic the inorganic components in natural bone tissues. Among them, fibrous bioceramic scaffolds are more preferred due to their biomimetic morphology, while they are usually fragile without polymer coating. In this study, hydroxyapatite nanowires (HANW) were prepared using hydrothermal technique and shaped into 3D macroporous scaffolds via steps of dispersing in water, freeze-drying and sintering. Five biodegradable polymers of different features were applied to coat the HANW scaffolds, and the polymers were poly (L-lactide) (PLLA), polycaprolactone (PCL), poly(lactide-co-glycolide) (PLGA), poly(lactide-co-caprolactone) (PLCL) and gelatin. By optimzing the coating operation, the polymer coatings would not deform the fibrous structure of the HANW scaffold, and not cause cytotoxicity. All these polymers could stabilize and reinforce the HANW scaffold. Among them, the crystalline PLLA and the rigid gelatin could improve the mechanical properties of the polymer-coated HANW scaffolds more significant than the other three polymers. At the meantime, the PLLA or the gelatin coating could maintain the mechanical strengths of the composite scaffolds alongside degradation for a longer time than the other polymer coatings. In summary, a proper polymer coating could be helpful in obtaining 3D bioceramic fibrous scaffolds with improved performances targeting bone tissue engineering.