Characterization, Bioactivity and Antibacterial Properties of Copper-Based TiO2 Bioceramic Coatings Fabricated on Titanium

Abstract

The bioactive and anti-bacterial Cu-based bioceramic TiO 2 coatings have been fabricated on cp-Ti (Grade 2) by two-steps. These two-steps combine micro-arc oxidation (MAO) and physical vapor deposition-thermal evaporation (PVD-TE) techniques for dental implant applications. As a first step, all surfaces of cp-Ti substrate were coated by MAO technique in an alkaline electrolyte, consisting of Na 3 PO 4 and KOH in de-ionized water. Then, as a second step, a copper (Cu) nano-layer with 5 nm thickness was deposited on the MAO by PVD-TE technique. Phase structure, morphology, elemental amounts, thickness, roughness and wettability of the MAO and Cu-based MAO coating surfaces were characterized by XRD (powder-and TF-XRD), SEM, EDS, eddy current device, surface profilometer and contact angle goniometer, respectively. The powder-and TF-XRD spectral analyses showed that Ti, TiO 2 , anatase-TiO 2 and rutile-TiO 2 existed on the MAO and Cu-based MAO coatings' surfaces. All coatings' surfaces were porous and rough, owing to the presence of micro sparks through MAO. Furthermore, the surface morphology of Cu-based MAO was not changed. Also, the Cu-based MAO coating has more hydrophilic properties than the MAO coating. In vitro bioactivity and in vitro antibacterial properties of the coatings have been investigated by immersion in simulated body fluid (SBF) at 36.5 • C for 28 days and bacterial adhesion for gram-positive (S. aureus) and gram-negative (E. coli) bacteria, respectively. The apatite layer was formed on the MAO and Cu-based MAO surfaces at post-immersion in SBF and therefore, the bioactivity of Cu-based MAO surface was increased to the MAO surface. Also, for S. aureus and E. coli, the antibacterial properties of Cu-based MAO coatings were significantly improved compared to one of the uncoated MAO surfaces. These results suggested that Cu-based MAO coatings on cp-Ti could be a promising candidate for biomedical dental implant applications.TiO 2 -based coatings have been suggested to improve corrosion resistance, bioactivity and biocompatibility of implant surfaces. They have recently received great attention for the biomedical applications owing to their more stable chemical composition [11,12]. TiO 2 were fabricated on cp-Ti by various surface coating methods including sol-gel [13], anodic oxidation [14], magnetron sputtering [15], electrophoretic deposition [16], acid etching [17,18], laser surface treatment [19], plasma spraying [20,21] and micro arc oxidation [22][23][24][25] etc. However, certain problems like non-homogenous structure, micro-structural control problems, micro-cracks formation, the presence of phase impurity, poor adhesion strength were observed in these methods except for MAO technique [26][27][28]. Thus, implant application areas of the coatings produced by these techniques are limited.Micro-arc oxidation (MAO) is one of the most applicable methods to deposit a porous and rough bioceramic layer on valve metals such as Ti, Al, Mg, and Zr surfaces [3,[29][30][31]. The MAO coating promotes bioacti...

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