One-Step Pulsed Electrodeposition of ZnO/ZnP Composite Coatings on Titanium Implants for Enhanced Antibacterial Activity and Biocompatibility

Titanium implants are widely used in orthopedic and dental applications. However, bacterial adhesion and subsequent biofilm formation on Ti surfaces remain critical challenges, often leading to implant-associated infections. Although zinc oxide (ZnO) provides broad‑spectrum antibacterial activity, excessive Zn²⁺ release may induce cytotoxicity, and many zinc‑containing coatings still rely on complex multistep conversion routes or zinc‑based substrates. In this study, a ZnO/zinc-phosphate (ZnP) composite coating was successfully constructed on Ti substrates via a one-step pulse electrodeposition method. Compared with conventional multistep conversion routes, this method employs only two precursor salts and a single electrolyte bath to achieve rapid (15 min), one-step in situ deposition on Ti. By avoiding post-conversion reactions and repeated post-treatments, the process substantially simplifies the overall fabrication workflow. The composite achieves multifunctionality through a ZnO-ZnP synergy: ZnO delivers rapid antibacterial action, while the ZnP phase seals pores within the ZnO matrix and serves as a barrier, enabling controlled Zn²⁺ release (25% lower cumulative release at day 14). This densified composite structure delivered the highest corrosion resistance across all samples and promoted bioactivity, evidenced by dense apatite formation after immersion. In addition, ALP activity increased to 34.8 U/L at day 14 and CCK-8 assays showed the highest cell viability, demonstrating improved osteogenic potential and cytocompatibility. Furthermore, the coating showed effective antibacterial activity against Escherichia coli (E. coli) (96.2%) and Staphylococcus aureus (S. aureus) (89.8%), thereby effectively reducing the risk of clinical infections. This work provides a facile and efficient strategy for the one-step construction of multifunctional antibacterial coatings on metallic implants.