Development of a Cerium-Doped Titanate/Polyphenol Nanostructured Coating for Titanium Implants: Enhancing Antibacterial Properties through Ciprofloxacin Release

Titanium implants are widely used in orthopedics and dentistry; however, their long-term performance is challenged by bacterial colonization, lack of antioxidant activity, and mismatch in mechanical properties with bone tissue. In this study, we developed a hybrid nanostructured coating composed of cerium-doped titanate and a poly(tannic acid) layer, further functionalized with ciprofloxacin to enhance antibacterial properties. The coating was synthesized through sequential hydrothermal, ion-exchange, and polyphenol deposition steps, followed by antibiotic loading. Comprehensive characterization using SEM, AFM, XPS, FT-IR, and nanoindentation confirmed the successful formation of a uniform nanostructured coating with drug adsorption capability. Antioxidant activity studies demonstrated the material's ability to scavenge both free radicals and hydrogen peroxide. The obtained materials also exhibited the ability to neutralize intracellular reactive oxygen species (ROS). The scavenging of free radicals was facilitated by the polyphenolic component of the coating, whereas the decomposition of H₂O₂ was enabled by the presence of Ce³⁺ ions. Drug release experiments showed controlled ciprofloxacin release for up to 34 h, ensuring effective antibacterial action during the critical early stage after implantation. In vitro studies with osteoblasts confirmed the biocompatibility of the coatings, while antibacterial tests against <i>Staphylococcus aureus</i> and <i>Pseudomonas aeruginosa</i> revealed almost complete inhibition of bacterial growth. Importantly, the modified surface exhibited a Young's modulus closer to that of human bone, suggesting a potential reduction of the stress shielding effect. Overall, the developed cerium-titanate/polyphenol/antibiotic hybrid nanostructured coating represents a promising strategy to improve the performance and safety of titanium-based implants.