Improved physicochemical properties of structurally modified titanium coated with zein-mesoporous bioactive glass nanoparticles-Commiphora wightii for orthopaedic applications

Abstract

Titanium (Ti) is an ideal implant material due to its strength, biocompatibility, and corrosion resistance. Ti is often structurally modified to overcome its inert nature. Nanostructures (pores, rods, tubes, etc.) formed on the surface of Ti followed by bioactive and antibacterial coatings can be exploited for many biomedical applications. A combination of zein (a biopolymer with low elastic modulus), mesoporous bioactive glass nanoparticles (MBGNs, a bioactive material) and Commiphora wightii (CW, an antibacterial herb) could result in a multi-functional coating for osteogenic purposes. Zein, not only reduces the stress shielding effect at the bone-implant interface but also acts as a binder for MBGNs and CW particles in the matrix and facilitates their uniform dispersion in the coating. In this work, zein nanoparticles (ZNPs), MBGNs, and CW were deposited on electrochemically synthesized titania nanotubes (TNTs) via electrophoretic deposition (EPD). A uniform and adherent composite coating named ZNPs/MBGNs/CW was obtained. The in-vitro bioactivity test in the simulated body fluid (SBF) revealed the formation of a biologically active calcium-deficient apatitic layer (cd-HA) on the coating surface. The electrophoretically deposited composite coating was also resistant to corrosion in SBF. Furthermore, the viability of MG-63 cells was tested in which coating displayed 100 % viability after 14 days of incubation. The presence of natural herb CW inhibited the growth of gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria. Hence, the results demonstrate that the ZNPs/MBGNs/CW composite coating system may be a strong candidate for orthopaedic applications.

Keywords: Antibacterial; Bioactive; Coating; Electrophoretic; Herb; Mesoporous; Titania nanotubes; Zein.