Electrophoretic Deposition of Carbon Nanotube and Graphene Composites on Anodized Stainless Steel for Biological Applications

Surface modification of a stainless steel 316L substrate (SS316L) via anodization and deposited composite of carbon nanotubes (CNTs) and graphene oxide (GO) for cell viability were demonstrated in this study. Anodized SS316L has periodic pits with a diameter of 70–150 nm at a range of anodization voltage of 40–60 V in ethylene glycol/perchloric acid. After anodization, SS316L were electrophoretically deposited with CNT, GO and CNT/GO. Scanning electron microscopy and Raman spectroscopy with an IG/ID ratio were utilized to determine the surface morphology and composition of carbon materials. For corrosion testing and cell cytotoxicity test, a potentiometry and the MTT assay method were used. It was found that the 60 V-anodized SS316L coated with composites of CNT/GO at a concentration of 0.5/0.5 mg/mL shows the highest corrosive resistance via potentio-dynamic polarization with a corrosion voltage at -0.14 V and a corrosive current at 5.9x10-7 A in ringer’s solution. Meanwhile, the anodized SS316L coated with only CNT or GO shows a poor corrosion resistance with a corrosion voltage lower than -0.32 V and a corrosive current at 1.57x10-6 A. For cytotoxicity tests with fibroblast L929 cells, all the anodized SS316Ls coated with composites of CNT/GO show the high cell viability in a range of 74–92% at a 20% MTT solution, indicating excellent biocompatibility. This work provides the possibility of using composites of carbon nanomaterials coated SS for various implant and cell attachment applications.