Comparative study on physicochemical properties of macroporous hydroxyapatite coatings on 316L stainless steel implants using sol-gel and inverse opal templating

This study focuses on enhancing metallic implant biocompatibility by fabricating a three-dimensional ordered macroporous hydroxyapatite (HAP) architecture through inverse opal technology. Utilizing colloidal crystal templates on 316L stainless steel, specifically with polystyrene and polymethyl methacrylate, successful fabrication was achieved through H 2 O 2 plus H 2 SO 4 etching. The calcination process at different temperatures (350, 500 and 700°C) resulted in distinct HAP structures, and the sample was calcined at 500°C (HAP500), exhibiting superior physicochemical properties, including enhanced crystallinity, surface roughness and wettability. Biological experiments demonstrated that HAP500 significantly promoted mesenchymal stem cell adhesion and proliferation compared to HAP350 and bare 316LSS, suggesting its potential as a highly effective medical device for bone implantation.