Superhydrophobic Copper-Composite Surfaces Exert Antibacterial Effects against Gram-Negative and -Positive Bacteria

Copper shows a high promise in developing biomedical materials with antibacterial effect. The antibacterial effect can be enhanced by nanostructured surfaces with superhydrophobic properties, which reduce the solid contact area available for bacterial adhesion and adherent growth. Here, three structured surfaces are fabricated to test the combined effect of copper and superhydrophobicity for antibacterial effects. One of the samples is superhydrophobic but does not contain copper, one contains copper but is not superhydrophobic, and the third is both superhydrophobic and contained copper. The antibiofilm and bactericidal effects of these samples are tested against medically important Gram-positive and -negative bacteria including Staphylococcus aureus (S. aureus), Staphylococcus epidermidis (S. epidermidis), and Pseudomonas aeruginosa (P. aeruginosa). The findings indicate that copper alone without superhydrophobicity, while decreasing the cell viability in most of the tested species, supports remarkably more biomass compared to the reference sample. The superhydrophobic and copper bearing samples, while allowing adherent growth to take place, provide the greatest bactericidal effect against two P. aeruginosa strains, and both the antibiofilm and/or bactericidal effects against S. aureus and S. epidermidis. Thus, this study reports that nanostructured materials, combining superhydrophobicity with copper, can be the method of choice to neutralize pathogens with different cell-wall structures and surface components mediating adherent growth.