Effect of micropillar surface topography on the antibacterial performance of zinc oxide coated polymer films

In this study, nanoimprint lithography was employed to fabricate micropillars on the surface of a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) film. In the next step, a hydrothermal method was used to grow zinc oxide (ZnO) nanostructures on the PVDF-HFP film. The antibacterial properties of the resulting films were evaluated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The sharp ZnO nanostructures exhibited strong antibacterial activity through both physical membrane disruption and chemical interactions, including ion release and oxidative stress. The effect of micropillar structures on the antibacterial behavior of PVDF-HFP films was also investigated. The results show that the presence of micropillars enhanced the antibacterial efficacy. The increase in surface area enabled a higher concentration growth of ZnO nanostructures, which contributed to more efficient bacterial inactivation. ZnO-coated PVDF-HFP films with micropillars outperformed ZnO nanostructures grown on neat PVDF-HFP films, particularly against E. coli. Viability assays revealed a substantial reduction in bacterial survival, with only 3.80% of S. aureus and 1.36% of E. coli cells remaining viable on PVDF-HFP films with surface micropillars and ZnO. These findings highlight the potential of ZnO-coated, microtextured PVDF-HFP films as effective antibacterial materials for future biomedical and food packaging applications.