Eu-Doped TiO2 Coatings via One-Step In Situ Preparation Enhance Macrophage Polarization and Osseointegration of Implants

The controllable regulation of immune and osteogenic processes plays a critical role in the modification of biocompatible materials for tissue regeneration. In this study, titanium dioxide-europium coatings (MAO/Eu) were prepared on the surface of a titanium alloy (Ti-6Al-4V) via a one-step process combining microarc oxidation (MAO) and in situ doping. The incorporation of Eu significantly improved the hydrophilic and mechanical properties of the TiO2 coatings without altering their morphology. The presence of Eu effectively stimulated calcium influx in macrophages and activated β-catenin through the wnt/β-catenin signaling pathway. Consequently, macrophage M2 polarization was accelerated through the overexpression of prostaglandin E2 (PGE2). Additionally, Ca2+ promoted the osteogenic differentiation of MC3T3-E1 cells through the synergistic upregulation of transcription factors (e.g., AP-1, BMP-2). In vivo studies demonstrated that MAO/Eu coatings significantly enhanced osseointegration compared with the titanium alloy group. Therefore, MAO/Eu shows promising potential as an ideal coating for implants that offers effective immunomodulatory strategies and improves bone integration.