Preparation and Characterizations of Antibacterial Iodine-Containing TiO2 Nanotubes Composite Coatings on Pure Ti

A two-step electrochemical method was employed to fabricate iodine-containing TiO 2 nanotubes composite coatings on pure Ti, with the objectives of enhancing coating-substrate adhesion and antibacterial performance. TiO 2 nanotubes were synthesized via anodic oxidation followed by iodine electrodeposition in 0.2% povidone-iodine solutions without KI and with varying concentrations of KI, respectively. The samples were characterized via SEM, EDS, and XPS. The coating-substrate adhesion, antibacterial activity, and cytotoxicity were systematically evaluated. The results indicate that KI addition enhances the electrical conductivity of the electrolyte and thus accelerates iodine deposition, while excess I − leads to damage of nanotubular structure. The electrodeposited iodine species primarily exist in the forms of I 3 − , I 2 , and pentavalent iodine. The TiO 2 nanotubes retard the iodine release rate. With increasing KI concentration, the coating-substrate adhesion first increases and then decreases. The sample fabricated in the electrolyte with 0.05% KI achieves the maximum adhesion (28.7 ± 1.5 N). This optimal sample demonstrates antibacterial rates of 88.7% and 92.7% against E. coli and S. aureus , respectively while displaying negligible cytotoxicity. This two-step electrochemical approach for fabricating iodine-containing TiO 2 nanotubes composite coatings serves as a viable surface modification strategy for Ti implants, yielding antibacterial coatings with substantial clinical potential.