Abstract

Post-surgical implant-associated infections cause considerable patient morbidity and mortality. These infections are often caused by biofilm-forming bacteria such as Staphylococcus aureus and Pseudomonas aeruginosa. Bacterial biofilms are resistant to immune clearance and are a reservoir of antibiotic resistance. Implant materials that resist bacterial colonization may be able to improve patient outcomes. Carbon infiltrated carbon nanotubes (CICNT) are a potential surface modification for medical implants. The work presented in this dissertation focuses on characterizing the antibiofilm effect of the CICNT surface, better understanding its mechanism of action, and characterizing the enhanced antibiofilm effect of a copper-coated CICNT surface. S. aureus biofilms were grown on the CICNT surface in order to determine that the CICNT surface reduced their growth. A diameter of 150 nm was determined to be the most effective nanotube size. The antibiofilm effect remained in force for multiple isolates of S. aureus, though the effect size changed depending on the culture media used for biofilm growth. The antibiofilm effect of the CICNT surface is due to its texture, rather than its chemistry. It was also determined that the antibiofilm effect of the CICNT surface was not due to the surface killing the bacteria, nor was it because it prevented the bacteria from attaching. Rather, it may be because the surface reduces the growth of bacteria either through physical restriction of bacterial growth planes, or through mechanical signals transmitted to the cell that result in gene expression changes, slowing cell growth. However, the antibiofilm effect of the CICNT surface was somewhat modest, about a 3.6-fold reduction (70%). Copper is an antimicrobial material. The combination of a 5 nm thin film of copper with the textured CICNT surface resulted in a synergistic effect, resulting in up to a 6.9-log reduction after 12 hours of incubation. This was likely due to a contact killing mechanism. Understanding the role of nanotextured surfaces in preventing bacterial colonization and biofilm growth provides valuable insights into the development of antimicrobial surfaces and will guide future research on optimizing textured and copper-based bactericidal materials.

Degree

PhD

College and Department

Life Sciences; Microbiology and Molecular Biology

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2025-04-02

Document Type

Dissertation

Handle

http://hdl.lib.byu.edu/1877/etd13528

Keywords

Staphylococcus aureus, carbon nanotube, CICNT, biofilm, copper

Language

english

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