Evaluation of in vitro bioactivity and MG63 Oesteoblast cell response for TiO₂ coated magnesium alloys

The present investigation reports TiO₂ coating on magnesium alloy AZ31 by sol–gel method via dip coating technique. TiO₂ coated surface was characterized by thin film X-ray diffraction (TF-XRD), Fourier transform infrared red (FT-IR) spectroscopy, scanning electron microscopy (SEM) with energy-dispersive X-ray (EDX) spectroscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM) techniques. From TF-XRD results, the peaks at 2θ values of 25.14, 32.12, 68.73 and 70.11 confirm the presence of TiO₂. The TiO₂ is crystalline in nature and the crystallite size is about 32.4 nm. SEM-EDX, TEM and AFM show that the coated surface is uniform and nanoporous. FT-IR analysis shows that the peak in the range of 692 cm⁻¹ is assigned to Ti–O–Ti stretching vibration. Contact angle measurements show that the coating is hydrophilic in nature. Bioactivity of the coating in simulated body fluid (SBF) was also examined, the hydroxyl functionalized surface greatly enhances the hydroxyapatite growth. The potentiodynamic polarization studies prove that the corrosion resistance of the TiO₂ coated surface after immersion in SBF for 7 days is improved dramatically. Cell adhesion studies confirm the increased cell attachment on TiO₂ coated surface when compared to uncoated alloy, due to less amount of Mg ion release from the substrate in the culture medium.