Durable Antibacterial Performance of Au–Ag–Cu Thin Films Prepared by Magnetron Sputtering: Real-World Applications

The growing prevalence of bacteria resistant to antibiotics and conventional disinfectants is a cause for concern and underscores the necessity of developing new strategies to prevent the transmission of microorganisms. To this end, nanocrystalline Cu, Au, and Ag nanoparticles were employed to fabricate various coatings using the sputtering technique. Then, the antibacterial activity of the coatings against Gram-negative <i>Escherichia coli</i> and Gram-positive <i>Staphylocococcus epidermidis</i> was investigated. The coating obtained by co-sputtering of Au, Ag, and Cu exhibited the most pronounced antibacterial properties. This coating was applied to disposable BIC ballpoint pens, which were subsequently used by clients in two public institutions. After three months of regular use, the antibacterial properties of the coatings were re-evaluated. It was confirmed that this coating led to a significant reduction (log5 CFU/mL) in the bacterial presence on the treated surface within 0.5 h. These results support further investigation into the underlying mechanism, which is likely based on the synergistic interaction of the employed noble metal nanoparticles.