Preparation of a Zn/hydroxyapatite/chitosan composite coating with an antibacterial ability and cytocompatibility on a NiTi alloy

Zn has been extensively used to prevent microbial infections in orthopedic implants; however, high amounts of Zn inhibit cell proliferation. This study investigated the ability to decrease the cytotoxicity of Zn-doped coatings on NiTi shape memory alloys (NiTi SMAs) while maintaining their antibacterial activity. The Zn-3(PO4)(2) distributed in the chitosan coating, annotated as ZHAP, was obtained by electrophoretic deposition in a chitosan solution with Zn acetate acid and hydroxyapatite particles. The ZHAP inhibited bacterial growth and exhibited a good antibacterial activity (86 %) against Staphylococcus aureus. In addition, the MG63-cell adhesion and cytocompatibility with ZHAP were better than those with the Zn-doped coating due to the precipitation of Zn-3(PO4)(2) which decreased the release of Zn2+ ions from the chitosan matrix. The coatings did not affect neither the superelasticity (< 0.5 % residual strain) nor the shape memory ability (100 % recovery rate) of the NiTi SMAs.