Incorporation of Zn/Sr-Ga based LDH particles into Si-HAp coatings to control the corrosion of Nitinol alloys

Abstract

Metallic implants, especially Nitinol, have numerous biomedical applications; however, they have inherent drawbacks, such as poor corrosion and wear resistance and suffer from nickel ion leaching. To address these challenges, this paper explores the use of silicon-substituted hydroxyapatite (Si-HAp) coatings with incorporated Zn/Sr-Ga based Layered Double Hydroxide (LDH) particles deposited by electrophoretic deposition (EPD). The synthesized Zn/Sr-Ga based LDH particles were investigated as both passive and active fillers in Si-HAp coatings. An anodization pre-treatment of the Nitinol substrates was performed to improve adhesion between the substrate and the coating. The EPD parameters were also optimized to prepare homogeneous and stable Si-HAp coatings loaded with Zn/Sr-Ga LDH particles. The morphology, composition, and electrochemical properties of the Si-HAp composite coatings were characterized using different techniques. Electrochemical impedance spectroscopy (EIS) and polarization studies demonstrated a significant improvement of the corrosion resistance properties of Si-HAp coatings with Zn/Sr-Ga LDH particles, compared to pure Si-HAp coatings and Nitinol substrate. The LDH@Si-HAp-coated sample showed the lowest nickel release, indicating the potential of LDH to reduce toxicity and enhance the strength of Nitinol implants.