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

• 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.

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 500 μm. 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.