Biocompatible and Antibacterial PCL-TiO<sub>2</sub>@Ag/γ-CD MOF Nanocomposite Coating for Corrosion Resistance of Magnesium Alloy in Simulated Body Fluid

Magnesium alloys are promising candidates for bio-implant applications due to their biodegradability and biocompatibility. However, their rapid corrosion remains a critical limitation. This study presents the development of a multifunctional nanocomposite coating designed to enhance the corrosion resistance and antibacterial properties of magnesium alloy implants. The coating comprised γ-cyclodextrin metal-organic frameworks (γ-CD MOFs) decorated with TiO2@Ag core-shell nanoparticles, embedded in a polycaprolactone (PCL) matrix. Immersion tests in a simulated body fluid (SBF) revealed an initially higher corrosion rate for the PCL-TiO2@Ag/γ-CD MOF coating compared to the coating without TiO2@Ag nanoparticles; however, it demonstrated significant improvement over time. After five days, the corrosion inhibition reached 95.44%, with the corrosion rate decreasing to 1.70 mpy. Additionally, the composite coating exhibited strong antibacterial activity against Escherichia coli, Pseudomonas, and Staphylococcus aureus. Furthermore, MTT assays indicated that the coating facilitated the growth and proliferation of osteoblast-like MC3T3-E1 cells, confirming its nontoxicity and biocompatibility. These findings highlight the potential of the PCL-TiO2@Ag/γ-CD MOF nanocomposite as a biocompatible, antibacterial, and corrosion- resistant coating for biodegradable magnesium implants, offering a promising solution for biomedical applications.