Enhanced in vitro biocompatibility and corrosion resistance of orthopedic NiTi by titanium carbonitride-hydroxyapatite composite finish: the role of HA nanoparticles

Abstract

The application of appropriate surface modification technologies is a key solution for addressing the growing demands for efficient biomaterials. In the current research, a comparative insight was rendered into the overall properties of the TiC/N and TiC/N + hydroxyapatite (HA) coatings deposited on the NiTi by single-pot plasma electrolytic saturation (PES) and PES-electrophoretic deposition (PES-EPD) strategies, respectively. The coatings were deposited from a bath containing urea, triethanolamine, ammonium nitrate, and HA. HA was added to the bath in the form of a suspension of 20 g/L HA nanoparticles in cetrimonium bromide. The PES and PES-EPD processes were conducted under optimum operating voltages of 450 and 470 V, respectively. The grazing incidence X-ray diffraction (GI-XRD) diffractograms showed that the only difference between the phase composition of the layers was the presence of the HA phase in the PES-EPD-derived film. The surface of TiC/N films obtained by the PES was rougher, containing more porosity. The results illustrated the enhanced in vitro biomineralization ability and in vitro osteoblast compatibility of the TiC/N + HA layers compared to HA-free ones. Furthermore, the outcomes of the electrochemical impedance spectroscopy (EIS) assay demonstrated the constructive contribution of the HA to the enhanced corrosion resistance of the coatings. The application of developed hybrid technology for surface finish of NiTi by TiC/N + HA can yield useful results in novel orthopedic implant design.