Metal-Catechol Network (MCN) Based Bioactive Surface Engineering of Iron Reinforced Hydroxyapatite Nanorods for Bone Tissue Engineering

: Hydroxyapatite (HAp) is a calcium phosphate-based inorganic constitute in bones and teeth. The synthesis of nanostructured rods that mimic the natural bone apatite has attracted significant attention. Unfortunately, pristine HAp is unsuitable for clinical translation due to its brittleness, limited strength, uncontrolled leaching, and poor surface properties. These limitations necessitate size reduction, surface modification, and ion incorporation to expand their scope in bone reconstruction. Herein, iron-reinforced hydroxyapatite nanorods (Fe-HAp) were used as an inorganic component, and catechol-modified gelatin methacryloyl was employed as a surface functional modifier agent. Our study highlighted that Fe-doped HAp nanomaterials are more promising for developing bioactive surfaces than other ion-incorporated nanomaterials due to their metal-catechol network (MCN) surface engineering. Nanostructural, surface chemistries, cytocompatibility, and matrix mineralization characteristics of Fe-HAp and Fe-HAp/MCN nanorods have been comparatively studied. The results support that MCN-coated nanorod surfaces improved HAp cytocompatibility, bioactivity, and phase compatibility between organic/inorganic nanomaterials, which could be crucial for bone reconstruction.