Thesis presented March 26, 2024

Abstract:
Microorganisms, ubiquitous and resilient, hold the undisputed title of the most persistent inhabitants of our planet. Present on Earth for approximately 4 billion years, their remarkable adaptive mechanisms have enabled them to colonize all environments, even the most extreme, and to play an essential role in them. Although their outstanding proliferation and antibiotic resistance capabilities have been established for at least a century, the end of the golden age of antibiotics in the 1960s has revived concerns. To address the resurgence of this resistance, new technological solutions have been explored to limit contamination in sensitive environments and surfaces, particularly in the medical field. Among these, the fabrication of actively antimicrobial surfaces is particularly relevant. Approaches involving chemical surface functionalization and the release of antimicrobial agents have been extensively explored in recent years but still suffer from disadvantages related to the durability of their activity. Newer approaches, such as the nanofabrication of bioinspired surfaces, also show promise and could complement existing methods. However, the interaction mechanisms between microorganisms and materials are complex, and for each approach, numerous parameters can influence surface effectiveness. Additionally, the lack of standardized protocols to characterize the full antimicrobial properties of surfaces complicates the sharing of knowledge and understanding of mechanisms. This thesis aims to highlight the impact of specific surface design parameters and the importance of taking them into account to design effective solutions, utilizing chemical functionalization with antimicrobial peptides and nanostructuring through electrodeposition. Drawing on the study of Escherichia coli and Staphylococcus epidermidis, two bacterial strains relevant for their impact on human health and their morphological differences, a comprehensive protocol for microbiological characterization of antimicrobial properties, accompanied by semi-automatic algorithms allowing faster data processing, has been developed. This protocol has been applied to assess the effectiveness of the approaches, whether individually or in combination. The obtained results contribute to a better understanding of the impact of the various studied parameters and emphasize key steps in comprehending and evaluating antimicrobial properties.

Keywords:
Chemical functionalization, Antimicrobial peptides, Nanostructuring, Antibacterial protection, Electrodeposition, Cell/surface interactions