Facile fabrication of gradient bioactive coating with hierarchically porous structures and superior cell response

To better construct the interface between implant and natural bone, novel gradient nano-hydroxyapatite/polyamide (nHA/PA) composite coating with hierarchically porous structures was prepared using phase-inversion technique and particle-leaching processing. Scanning electron microscopy observation shows that the size of macropores on the surface ranges from 300 to 500μm. There are abundant micron/submicron-scale pores distributed on the walls of the macropores. Energy-dispersive X-ray spectroscopy analysis indicates that nHA component increases gradually at the interface from the porous transition region to nHA-rich coating layer and then keeps stable towards the coating surface. The osteoblast-like cells (MG63) were cultured on the samples. The results confirm that the samples with nHA-rich coatings and hierarchical structures are favorable to the attachment and proliferation of MG63 cells, and they are potentially attractive candidates for bone repair applications. •Gradient composite coating with hierarchically porous structures was obtained by phase-inversion technique and particle-leaching processing.•nHA content increases gradually at the interface from the transition region to nHA-rich coating.•Coating with hierarchical structures shows superior cytocompatibility.