Corrosion Protection of Nano-biphasic Calcium Phosphate Coating on Titanium Substrate

Abstract

Background: Increasing the bioactivity of metallic implants is necessary for biomaterial applications where hydroxyapatite (HA) is used as a surface coating. In industry, HA is currently coated by plasma spraying, but this technique has a high cost and produces coating with short-term stability. Objectives: In the present study, electrophoretic deposition (EPD) was used to deposit nano-biphasic calcium phosphate compound (β-tri-calcium phosphate (β-TCP) /hydroxyapatite (HA)) bio-ceramics on the titanium surface. The microstructural, chemical compositions and bioactivity of the β- TCP/HA coatings were studied in a simulated body fluid solution (SBF). Methods: Scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR) were used. Additionally, the antibacterial effect was studied by the agar diffusion method. The corrosion behavior of the β-TCP/HA coating on titanium surface (Ti) in the SBF solution at 37oC was investigated by means of electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization tests. Results: The Ti surface modification increased its biocompatibility and corrosion resistance in the simulated body fluid. The antibacterial inhibition activity of the β-TCP/HA bio-ceramic was enhanced by electroless silver deposition. The enhanced properties could be attributed to the use of nano-sized biphasic calcium phosphates in a low-temperature EPD process. Conclusions: The β-TCP/HA and β-TCP/HA/Ag coatings well protect Ti from the corrosion in SBF and endow Ti with biocompatibility. The β-4-TCP/HA/Ag/Ti substrate shows good antibacterial activity.