Corrosion and biological study on biofunctionalized porous coating on titanium produced by plasma electrolytic oxidation

Upon implantation of biomaterials in human body, the risk for electrochemical corrosion within the surrounding environment becomes a critical factor affecting implant biocompatibility. This study endeavors to develop a biofunctionalized and corrosion-resistant TiO2/hydroxyapatite coating using a cost-effective one-step plasma electrolytic oxidation (PEO) process. Initially, magnesium and zinc substituted hydroxyapatite (HA) particles were synthesized to enhance bioactivity and antibacterial properties compared to pure HA. The synthesized particles underwent characterization using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Subsequently, these synthesized particles were utilized in the Plasma Electrolytic Oxidation (PEO) coating process. Polarization and electrochemical impedance spectroscopy (EIS) tests, in addition to bioactivity and antibacterial activity assessments, were conducted to examine the corrosion resistance and biological response of the coatings. The results of biological tests on particle-containing PEO coatings on titanium demonstrated a significant improvement in the bioactivity and antibacterial activity of the biofunctionalized coatings caused by ion-substituted HA particles. Furthermore, polarization and EIS results indicated superior corrosion resistance in the biofunctionalized coatings. Electrochemical tests after one week of immersion in simulated body fluid (SBF) revealed the positive influence of apatite formation on the long-term corrosion behavior of coatings with ion-substituted particles.