Enhancing the osteogenic capability of additively manufactured Ti6Al4V scaffolds: uniform internal/external composite coating while maintaining mechanical performance

Abstract

Additively manufactured Ti6Al4V scaffolds, characterized by interconnected porosity and high specific surface area, are gradually replacing solid implants in orthopedic surgery. However, the complete removal of residual Ti6Al4V particles from both the internal and external surfaces of the scaffolds and the improvement of the uniformity in biological performance remain significant challenges. The proposed combined method of flowing acid etching and anodic oxidation effectively removed residual Ti6Al4V particles from all surfaces of the scaffold and enabled the formation of TiO₂ nanotubes on both its inner and outer surfaces. This process facilitated the construction of a micro-/nano-composite structure that uniformly covers the entire scaffold. Importantly, the post-treatment process did not compromise the designed mechanical properties of the scaffolds. Subsequent in vitro and in vivo studies demonstrated that the removal of residual Ti6Al4V particles, combined with the construction of micro-/nano-composite structures on all scaffold surfaces, significantly enhanced osteogenic activity. This strategy can be broadly applied to the post-processing of additively manufactured Ti6Al4V scaffolds to achieve simultaneous particle removal and osteogenic surface modification while preserving the mechanical integrity dictated by the design.