Abstract: Zinc and its alloys have emerged as promising candidates for the next generation of biodegradable metals due to their moderate degradation rates, good biocompatibility, and absence of harmful gas release during degradation. However,the uncontrolled degradation rate can easily lead to a sudden increase in local ion concentration, thereby triggering cytotoxic reactions and tissue inflammation, which compromise the material’s biocompatibility. Surface modification of zinc alloy with biocompatible metal-organic frameworks (MOFs) provides a scalable method to address these critical issues. In this study, we report the rational design of Zn-based MOF coatings on zinc alloy. Specifically, we selected organic ligands with different polarities (imidazole, 2-methylimidazole, and imidazole-2-carbaldehyde) for the design, which self-assembled into ZIF-4, ZIF-8, and ZIF-90 coatings upon coordination with Zn²⁺. In addition to having various-sized micro/nanochannel structures, the ZIF coatings create a rough surface and a more hydrophobic chemical environment, which protects the hydrophilic substrate. The variation in micro/nanostructures arising from the chemical functionality control leads to an increase in the roughness of the ZIF coatings, which reduces the bacterial adherence. Moreover, in short-term antibacterial tests, Zn²⁺ release is high enough to kill the viability of the bacteria. Therefore, all three coatings demonstrate excellent antibacterial properties against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In addition, ZIF-4 and ZIF-8 coatings showed good cell compatibility and met the standard of low cytotoxicity at 25 % extract concentration. This study provides new insights into the application of MOF-functionalized implants and promotes the innovative use of MOF coatings in metallic biomaterials for medical applications.

Key words: Zinc alloy, Molecularly engineered MOF, Degradation behavior, Cytocompatibility