Surface film characterizations and electrochemical behavior of type I collagen-immobilized interconnected porous Ti–Nb–Zr–Sn alloy scaffolds in simulated inflammatory environment

Inflammation in the tissue surrounding titanium (Ti)-based alloy implants can lead to increased acidity and the release of reactive oxygen species (e.g., H2O2), which can undermine the corrosion resistance of surface protective films. This study created 3D-printed interconnected porous Ti–24Nb–4Zr–8Sn (Ti2448) alloy scaffolds, over which was applied alkali treatment followed by type I collagen immobilization via natural cross-linker procyanidin. The samples were characterized in terms of polarization curves, surface film characterizations, and electrochemical impedance spectroscopy analysis under simulated inflammatory (SI) environment (150 mM H2O2-containing simulated body fluid with pH 5.2). The SI environment was shown to compromise the corrosion resistance of untreated Ti2448 scaffolds. The surface-treated samples presented a dense, homogeneous surface film of mainly TiO2 and Nb2O5, which moderated the adverse effects of SI environment. Electrochemical equivalent circuits of the surface-treated Ti2448 scaffolds under SI environment included two resistor-capacitor (RC) circuits, corresponding to a protective inner film and a less protective outer film. This might be the first study which proposed a unique surface treatment to provide a protective surface film over 3D-printed interconnected porous biomedical Ti2448 alloy scaffolds under SI environment.