Accelerated biodegradation of FeMn porous alloy coated with ZnO: Effect on cytocompatibility and antibiofilm properties

Fe-based alloys are being studied as potential candidates for biodegradable implants; however, their degradation rates remain too slow. To accelerate biodegradation while simultaneously hindering biofilm formation, a ZnO coating was deposited onto porous equiatomic FeMn alloy discs by sol-gel method using dip coating. The effect of the ZnO coating on the microstructure, biodegradability, cytocompatibility, and antibacterial properties were investigated. Biodegradability experiments were performed by immersing the specimens in Hank's balanced salt solution and measuring ion release after up to 28 days of immersion. The experiments showed an increased degradation of the FeMn/ZnO sample due to Fe segregation towards the grain boundaries, formation of iron-manganese oxide, and limited formation of degradation products on ZnO. Further, indirect Saos-2 cell cytotoxicity testing in 24 h sample-conditioned media showed no significant cytotoxicity in concentrations equal to or below 50 %. In addition, the total biofilm biovolume formed by Staphylococcus aureus on the FeMn/ZnO surface was significantly reduced compared to the uncoated FeMn. Taken together, these results show that the ZnO coating on FeMn improves the degradation rate, maintains cytocompatibility, and reduces biofilm accumulation when compared to an uncoated FeMn alloy.