Unraveling the complexity of surface antibacterial effects: A multifaceted evaluation of electrodeposited nanospikes

The intricate interaction between bacteria and surfaces, coupled with the complexity of biofilm formation, poses significant challenges in understanding and controlling microbial behaviour. To combat pathogen contamination and proliferation, bioinspired nanostructures as antimicrobial surfaces have gained prominence over the past decade. However, conflicting theoretical studies and experimental results have made it difficult to draw general conclusions about antibacterial mechanisms. To address these challenges, we have adopted an approach that provides access to deeper insights to characterize the performance of surfaces, by taking into account different modes of antibacterial action. To demonstrate the applicability of this strategy, nanostructured materials mimicking dragonfly wing, were evaluated. A gold electrodeposition process was optimized to create large-area, uniform nanospike arrays, ranging in height from 70 to 570 nm. Large sample area (12 cm²) was critical for ensuring statistically significant results in the analysis of antibacterial effects. Model surfaces with ∼150 nm high spikes were tested, demonstrating significant efficacy in reducing bacterial proliferation for Escherichia coli and Staphylococcus epidermidis . Moreover, striking differences between strains were observed in biofouling (surface detachment and release of bacteria). These findings underscore the relevance of such a protocol in precisely characterizing bacterial interactions with antimicrobial materials. By providing a standardized characterization method, this study aims to facilitate a deeper understanding of antimicrobial surface interactions with bacteria and contributes to the development of more effective antibacterial surfaces.