3D periodic microscale structures on binary copper-nickel alloys via fs-DLIP: impact on E. coli-substrate interaction

• Utilization of femtosecond pulsed direct laser interference patterning to modify surfaces of binary copper-nickel alloys. • Generation of periodic line-like and honeycomb structures, tailored to the size of an Escherichia coli cell. • Identification of the critical copper content range (70–90 wt-%) for effective contact killing in the presence of copper ions when laser structuring copper-nickel alloys. • The dimensional compatibility between the structured surface features and bacterial cells plays a crucial role in determining the antimicrobial effectiveness of the surfaces. In response to the rise of multidrug-resistant infections, researchers are increasingly focusing on modifying material surfaces through chemical or topographical changes to limit microbial spread. Copper and its alloys are particularly valued for their antimicrobial properties, playing a key role in combating pathogen transmission. To explore the potential of enhancing the antibacterial performance of copper-based alloys, this study focuses on surface modification of binary copper-nickel alloys. The goal is to create periodic microstructures at the scale of a single bacterial cell ( Escherichia coli ) and explore the bacteria-substrate interaction. Two copper-nickel alloy compositions with 10 and 30 wt-% nickel are selected to assess the impact of nickel on laser-material interaction. Additionally, two surface structures, lines and honeycomb, are fabricated to evaluate how structure type affects bacterial interaction. Results show that the line-like structures on the 10 wt-% nickel alloy enhance bacterial killing, while honeycomb structures show no improvement. Conversely, both laser-structured copper-nickel alloys with 30 wt-% nickel exhibit decreased bacterial killing, attributed to the reduced surface copper concentration (below 60 wt-%) as confirmed by chemical analyses. These findings highlight the importance of copper content and structural compatibility for effective contact-killing performance.