Enhancement of Corrosion Resistance and Biological Performances of Cu-Incorporated Hydroxyapatite/TiO2 Coating by Adjusting Cu Chemical Configuration and Hydroxyapatite Contents

To simultaneously enhance the antibacterial efficacy and cell biocompatibility of titanium (Ti)-based orthopedic implants, Cu-incorporated hydroxyapatite (HA)/TiO2 coatings have been fabricated via the micro-arc oxidation method in an aqueous solution containing calcium lactate ((CH3CHOHCOO)2Ca) and sodium dihydrogen phosphate (NaH2PO4) along with different contents of ethylenediaminetetraacetic acid copper(II) disodium salt (Na2Cu-EDTA). Microstructural characterization reveals that with the addition of 2 g/L of Na2Cu-EDTA, the resultant coating contains uniformly distributed HA phase depositions with a high Cu+-to-Cu2+ ratio relative to those in the electrolytes containing 5 and 10 g/L of Na2Cu-EDTA, which contain reduced amounts of HA depositions with Cu species mainly existing as Cu2+. Further, electrochemical responses and in vitro biological tests were conducted to assess corrosion resistance, antibacterial capability, and cell biocompatibility. It is revealed that the Cu-incorporated HA/TiO2 composite coating produced by 2 g/L of Na2Cu-EDTA exhibits enhanced corrosion resistance, antibacterial capability, and cell biocompatibility relative to those fabricated in the electrolytes containing 5 and 10 g/L of Na2Cu-EDTA, which is mainly attributed to the increased amount of HA components and the chemical configurations of the Cu specie.