Development of multifunctional composite coatings by electrophoretic deposition on biomedical implants

Electrophoretic deposition (EPD) is a powerful technique to assemble metals, polymers, ceramics, and composite materials into 2D, 3D, and intricately shaped coatings. These materials can be deposited via EPD at room temperature without affecting their chemical structures. Furthermore, EPD can be used to deposit multifunctional (i.e., bioactive, antibacterial, etc). or multi-structured biomedical coatings to improve mechanical properties, confer suitable biological aspects and provide controlled release of therapeutic agents. Ti-6Al-4V alloy is typically accepted as one of the best in vitro and in vivo bone replacement biomaterials, due to its excellent balance between biomechanical and biofunctional properties. Despite its desirable properties, Ti implants cannot develop a biologically active bonding with the adjacent bone tissue. Moreover, there is always a risk of implant failure due to infections. In this context, it is suggested to coat Ti-6Al-4V alloy implants with bioactive materials to enhance their osseointegration. These coatings can also provide a platform for the release of antimicrobial components. Polyether ether ketone (PEEK) is an increasingly investigated biocompatible material for orthopedic and spinal implants and is a potential candidate for implant coatings. Nevertheless, the lack of bioactivity of PEEK must be addressed, either by surface modification or the formation of a composite with bioactive materials, such as bioactive glasses (BG). The addition of bioactive materials improves the bone ingrowth of implants for biomedical applications. The presence of BG particles allows the coatings, to form an apatite-like layer upon immersion in simulated body fluid (SBF). This mineral phase is similar in composition to the hydroxyapatite in bone, confirming the possibility of achieving close bonding between bone and the coating surface. On the other hand, ionic silver is an established antibacterial agent and its incorporation in an implant coating has shown promising anti-pathogenic outcomes. If applied as nanoparticles (NP), silver antimicrobial properties are more significant. Chitosan, a natural biopolymer can be used both as a complexing and stabilizing agent to form uniformly deposited silver nanoparticles in the coating process. In this study, in-situ composite coatings of PEEK/BG/Ag NP were deposited by electrophoretic deposition (EPD) on Ti-6Al-4V substrate to produce bioactive and antibacterial coatings. These multicomponent coatings were physiochemically characterized. Field Emission Scanning Electron Microscopy (FE-SEM), and X-ray diffraction analysis (XRD) confirmed the deposition of PEEK/BG/Ag NP on the multilayer coating system. Energy dispersive spectroscopy (EDS) confirmed the presence of Ag, which was embedded in the chitosan matrix. Corrosion properties were evaluated by electrochemical polarization curves, indicating the enhanced corrosion resistance of the PEEK/BG/Ag NP coatings compared to the bare Ti-6Al-4V substrate. The results demonstrated that EPD is a low cost and efficient method to obtain homogeneous, robust, and bioactive PEEK/BG/Ag NP coatings on Ti-6Al-4V substrates to be further used for biomedical applications.