Electrophoretic deposition of graphene oxide on plasma electrolytic oxidized-magnesium implants for bone tissue engineering applications

Biodegradable magnesium (Mg) alloys have been widely used in fabrication of biomedical orthopedic implants owing to their similar characteristics to natural bone. In order to create a strong connection to the bone and to prevent inflammation, these implants should have a high corrosion resistance in physiological environment. In this study, Graphene oxide (GO) layer was produced on a plasma electrolytic oxidation (PEO) coating of AZ91 Mg alloy by electrophoretic deposition (EPD) process. The field emission scanning electron microscopy (FE-SEM) micrographs of the coating surfaces and cross sections showed that PEO coating had porous structure which considerably changed after EPD treatment and its micropores and microcracks were sealed by GO particles. Also, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR) results confirmed the formation of GO layers on MgO coating after PEO/EPD process. The corrosion behavior was studied by conducting potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in simulated body fluid (SBF) solution. Potentiodynamic tafel curve measurements demonstrated that the corrosion current density of the MgO/GO coating decreased by 56 and 708 times compared to PEO coating and bare substrate, respectively. Moreover, the EIS results indicated that the value of | Z|(f -> 0) of the MgO/GO coating (1.64x10(6) Omega.cm(2)) was slightly higher than PEO coating (8.21x10(4) Omega.cm(2)), attributed to the formation of a GO film as the top layer preventing infiltration of aggressive solution into the AZ91 substrate. (C) 2018 Elsevier Ltd. All rights reserved. Selection and/or Peer-review under responsibility of INN International Conference/Workshop on Nanotechnology and Nanomedicine'' NTNM2017.