Electrochemical Corrosion Behavior and Antibacterial Performance of ZnO/TiO₂/CuO–Se Nanocomposite Coatings on Ti6Al4V Implants in Simulated Body Fluid

Antibiotic-resistant infections pose ongoing challenges and financial strain on healthcare, particularly for implantable devices. Although titanium alloys offer mechanical stability and corrosion resistance, their vulnerability to bacterial degradation underscores the need for enhanced protective strategies. In this study, we aimed to develop and evaluate a novel antibacterial and corrosion-resistant coating for Ti6Al4V implants using a combination of nanoparticles (NPs). The study utilized a coating composed of nanometal oxides (ZnO/TiO2/CuO) and selenium nanoparticles (NMOs/SeNPs) integrated into a polyacrylamide matrix. Treated Ti6Al4V was coated with the NMOs/SeNPs using various parameters of the dip coating method to investigate the corrosion rate in a body-simulated environment. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to measure the corrosion resistance, while antibacterial activity was quantified using colony-forming units (CFU) against E. coli and S. aureus. The electrochemical tests indicated that, under the optimal coating parameters applied to the implant, the corrosion rate decreased by more than ninefold to 0.016 mm/year (corresponding to a corrosion current density of 9.77×10⁻⁷ A/cm²), compared to 0.152 mm/year for the uncoated controls at pH 7.4 (containing corrosive ions). Consistent with these findings, the impedance measurements demonstrated a substantial increase in resistance, with the optimized sample exhibiting a resistance of 92,000 Ω, whereas the uncoated sample showed only 6,800 Ω. The results also showed a logarithmic increase in antibacterial activity of 2.46 and 2.52 CFU for Gram-positive and Gram-negative bacteria on modified surfaces (99.7% kill). However, the overall effectiveness of the coating varied with the type and concentration of NPs used, and the environmental conditions tested. The application of a polyacrylamide-based coating incorporating TiO2, CuO, ZnO, and Se NPs on Ti6Al4V implants could potentially improve their resistance to corrosion and bacterial colonization. These findings suggest that such coatings might contribute to the extended usability and safety of titanium-based implants in clinical settings.