Simultaneously constructing nanotopographical and chemical cues in 3D-printed polylactic acid scaffolds to promote bone regeneration

Topographical structures and bioactive surface coatings are effective in improving the biological function for bone regeneration. However, the simultaneous introduction of these benefits into three-dimensional (3D) porous scaffolds poses a daunting challenge. In this study, we proposed a simple yet effective approach to decorate 3D-printed polylactic acid (PLA) scaffolds with chemically modified nanotopographical patterns. The nanotopography was produced by etching the amorphous phase of PLA in an alcohol/alkali solution to expose dense lamellae. Subsequently, conformal decoration of polydopamine (PDA) was realized via self-assembly of catecholamines without changing the surface nanotopography. In vitro cell experiments including live and dead staining, cell morphology, cell growth, and alkaline phosphatase showed that the combination of nanotopography and PDA-coating led to a favorable enhancement of osteoblasts adhesion, spread and proliferation in 3D-printed scaffolds. The contribution of integrated patterns to bone regeneration was evaluated using a rat femur critical-sized defect model in vivo. Micro-CT evaluation and histological analysis demonstrated that the scaffold decorated with integrated pattens promoted osteogenesis more than the bare scaffolds and the scaffolds decorated with only nanotopography. Our proposed approach offers a promising method for improving bioactivity of 3D polymer scaffolds for bone tissue regeneration.