Electrochemical aspects and in vitro biocompatibility of polypyrrole/TiO₂ ceramic nanocomposite coatings on 316L SS for orthopedic implants

With a view to developing a smart coating combining both biocompatibility and corrosion resistance over bioimplants, polypyrrole/TiO₂ nanocomposite coatings were electrochemically synthesized by cyclic voltammetric technique on 316L stainless steel (SS) in an aqueous solution of oxalic acid. The presence of TiO₂ nanoparticles in polypyrrole (PPy) matrix was confirmed using FT-IR spectroscopy and XRD analysis. The surface morphology of coated 316L SS substrates was observed by the Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). Microhardness of coated 316L SS was examined by the Vickers hardness method. The electrochemical studies were carried out using Cyclic Polarization and Electrochemical Impedance Spectroscopy (EIS) measurements. In order to describe the biocompatibility, contact angle measurements and in vitro characterization were carried out in Simulated Body Fluid (SBF) solution. The results showed that the nanocomposite coatings exhibit superior biocompatibility and enhanced corrosion protection performance over 316L SS than that of pure polypyrrole coatings.