Polydopamine-induced nanocomposite Ag/CaP coatings on the surface of titania nanotubes for antibacterial and osteointegration functions

The initial implant-associated infections and post aseptic loosening are the major obstacles for the clinical applications of titanium-based dental and orthopedic implants. To tackle these issues, the implant surface is engineered to possess combined osteointegration and antibacterial properties. Therefore, a mussel-inspired novel nano silver/calcium phosphate (CaP) composite coating was prepared on anodized Ti, in the expectation of its surface maintaining preferable biological performance and possessing long-term antibacterial ability. This approach involves three steps: (i) the anodic oxidation of Ti to enable it to have a TiO₂ nanotubular (TNT) surface structure, (ii) the self-polymerization of dopamine on TNT and the reduction of Ag and (iii) the modification of the Ag nanoparticles using polydopamine and further being immersed in SBF for the biomimetic mineralization of CaP. The surface morphology and microstructure of this novel coating was fully characterized. The Ag/CaP coatings displayed obvious antibacterial effects to S. aureus bacteria and relatively good in vitro cytocompatibility to MG63 cells. Compared with the pristine Ti, the cells cultured on the coated Ti showed enhanced ALP activities.