Femtosecond-DLIP on tin-alloyed bronze: Effect of pulse fluence on surface topography for antibacterial application
Résumé
The rise of antibiotic resistance has prompted the exploration of other strategies, including the use of material surfaces, to prevent the spread of contagious microorganisms. Copper, renowned for its antimicrobial properties, holds potential in this area. However, its application is often limited from a materials perspective. Therefore, it is crucial to investigate copper alloys to assess their effectiveness in these promising new approaches. For that purpose, the surface of the bronze with 6 % tin content was modified using ultrashort-pulsed direct laser interference patterning (USP-DLIP) to produce 3 μm periodic line-like structures aimed at enhancing antibacterial properties. This study examines how pulse fluence impacts surface topography and subsequently, the killing of Escherichia coli (E. coli). The results show a variation in topography with varied peak-to-valley width ratios. Chemical analyses confirmed an increased copper content and the formation of tin-and copper-rich oxides. Subsequently, the flake-like oxide structures, formed due to laser treatment, were removed via etching with 5 % citric acid. The wettability tests showed increased hydrophobicity over 3 weeks, with etched surfaces exhibiting lower hydrophobicity than as-processed ones. Overall, the etched laser-processed surfaces demonstrated an E. coli killing rate of an order of magnitude higher than polished bronze and comparable to pure copper. This enhancement is attributed to the increased contact area and optimized topography achieved through USP-DLIP. This approach presents a promising strategy for antimicrobial surface design.
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