Microstructure, wear, and corrosion properties of PEEK-based composite coating incorporating titania- and copper-doped mesoporous bioactive glass nanoparticles

Abstract

Poor wear- and corrosion-resistance of 316L SS implants are critical problems in orthopedic implants. This study aims to improve the wear- and corrosion-resistance of 316L SS through surface coating. In this study, a bilayer composite coating consisting of polyether ether ketone (PEEK) as the first layer, and titania (TiO₂)- and Cu-doped mesoporous bioactive glass nanoparticles (Cu-MBGNs) were deposited as the second layer on a 316L SS via electrophoretic deposition (EPD). Scanning electron microscopy (SEM) images of the bilayer composite coating showed the distribution of TiO₂ and Cu-MBGNs within the PEEK matrix. Energy dispersive spectroscopy (EDS) analysis confirmed the presence of TiO₂ and Cu-MBGNs in the bilayer composite coating. Fourier transform infrared spectroscopy (FTIR) identified the functional groups attributed to the PEEK, TiO₂ and Cu-MBGNs. X-ray diffraction (XRD) analysis confirmed the presence of TiO₂ (anatase) and Cu-MBGNs in the bilayer composite coating. The coating exhibited a strong antibacterial effect against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). Incorporating TiO₂/Cu-MBGNs into the bilayer composite coating significantly modified the surface of 316L SS by improving the wear- and corrosion-resistance. Pin on disc test revealed that the specific wear rate of ∼(0.4570 ± 0.009) × 10⁻⁶ mm³ Nm⁻¹ of the PEEK coating decreased to (0.0482 ± 0.007) × 10⁻⁶ mm³ Nm⁻¹ on incorporating TiO₂/Cu-MBGNs in PEEK coating under a normal load of 10 N in Dulbecco's Modified Eagle Medium (DMEM). Furthermore, electrochemical impedance spectroscopy (EIS) results revealed that the impedance value of the bilayer composite coating remained ∼4.56 × 10⁵ Ω cm² compared to 8.81 × 10³ Ω cm² of 316L SS after 24 h immersion in phosphate-buffered saline (PBS). Thus, this study demonstrated that the wear- and corrosion-resistance of 316L SS can be improved by incorporating TiO₂/Cu-MBGNs in PEEK-based composite coatings for orthopedic applications.