Influence of zirconia nanoparticles on the surface and electrochemical behaviour of polypyrrole nanocomposite coated 316L SS in simulated body fluid

Current efforts of recent implant technology have been aimed principally at the improvement of corrosion resistance and biocompatibility. The present study demonstrates that the electro polymerisation of pyrrole and incorporation of zirconia (ZrO2) nanoparticles can be successfully combined to produce bioactive polypyrrole nanocomposite coatings for orthopaedic implants. Polypyrrole/ZrO2 nanocomposite coatings were electrochemically synthesised by cyclic votametric technique on 316L stainless steel (SS) in aqueous solution of oxalic acid. The existence of ZrO2 nanoparticles in polypyrrole (PPy) matrix was confirmed by Fourier Transform Infrared (FT-IR) spectroscopy and X ray diffraction (XRD) analysis. The surface morphology of coated 316L SS substrates was observed using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Transmission Electron Microscopy (TEM). Micro hardness of coated 316L SS was examined using Vickers hardness method. The electrochemical studies were carried out using cyclic polarisation and electrochemical impedance spectroscopy (EIS) measurements. In order to describe the biocompatibility, contact angle measurements and in vitro characterisation 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 due to their hydrophilic, smooth, compact and less porous surface morphology than that of pure polypyrrole coatings.