Corrosion behavior of collagen-immobilized interconnected porous titanium alloy scaffold in simulated inflammatory environments

摘要

The implantation of metallic biomaterials in the human body can lead to inflammation of the surrounding tissue. Inflammatory cells attach to the implant surface and release reactive oxygen species (ROS, e.g., H 2O2), leading to a decrease in the ambient pH, which in turn affects the corrosion resistance of the implant. In our previous study, we have demonstrated that 3D-printed interconnected porous Ti-24Nb- 4Zr-8Sn (Ti244 8) alloy scaffold immobilized with type I collagen promotes osteogenesis. However, the corrosion (or electrochemical) behavior of Ti2448 alloy scaffold under inflammatory conditions remains unclear. Therefore, this study was to evaluate how simulated infla mmatory (SI) conditions (containing H 2O2 and lower pH) affect the corrosion behavior of 3D -printed porous Ti2448 scaffolds immobilized with type I collagen. Unique surface treatment process, combining alkali treatment and the following type I collagen immobilization via natural crosslinker procyanidin, was applied to electron beam melting process -produced interconnected porous Ti2448 scaffolds. Surface characteristics (including oxide thickness and chemical composition) and electrochemical behavior (by meas uring polarization curves and electrochemical impedance spectra) were studied under SI environments containing H 2O2 and lower pH. Results showed that alkali treatment created a dense passive film (thickness 200~400 nm) on the surface of Ti2448 scaffolds an d then improved the corrosion resistance, in terms of increasing the generation rate and protectiveness of surface passive film, regardless of the pH (7.4 and 5.2) and H 2O2 concentration (0 and 150 mM) in the SI environments. Immobilization of type I colla gen on Ti2448 scaffolds not only enhanced the osteogenesis but also slightly increased the corrosion resistance in SI environments. We concluded that the presence of acidic pH and H 2O2 decreased the corrosion resistance of the untreated Ti2448 alloy scaffo lds, while the proposed surface treatment improved its corrosion resistance.