Abstract
Bioinspired nanotopography is a promising approach to generate antimicrobial surfaces to combat implant-associated infections. Whilst there have been considerable efforts to develop bactericidal 1D nanostructures, the antibacterial capacity of 2D nanostructures and their mechanism of action remains uncertain.This research project focused on the generation of antibacterial nanoflakes on titanium or titanium alloy, and exploration of the possible mechanisms by which these nanoflake surfaces
mediated antibacterial effects. Hydrothermal synthesis and alkaline etching/thermal annealing techniques were utilized to generate 2D nanoflake surfaces on pure titanium and Ti-6Al-4V substrates. Nanoflakes were then characterized using a range of analytical methods such as water contact angle, SEM and AFM, to quantify their physical properties. TEM and XRD were used to determine the crystal structures of the nanoflakes on both substrates.
The antibacterial performance of the nanoflake surfaces was assessed using a combination of viability assays, electrochemical and high-resolution imaging techniques. It was found that nanoflakes impair the attachment and growth of bacteria, and trigger the accumulation of intracellular reactive oxygen species, potentially contributing to the killing of adherent
bacteria.
Previous work proposed that the bactericidal capacity of nanotopographies can be strain dependent. To better understand the biological properties that modulate bacterial susceptibility to nanoflakes, two Escherichia coli appendages, type-1 fimbriae and flagella, were studied using knockout and complemented mutants. The data suggested that type-1 fimbriae confer a cushioning effect that protects bacteria upon initial contact with the nanoflake surface, whilst flagella-mediated motility can lead to elevated cell envelope abrasion.
Taken together, these data indicated the capacity for nanoflakes to mediate antibacterial effects, and identified parameters that can influence antibacterial efficacy and bacterial susceptibility. Such information can be applied to the design of antimicrobial nanoflake surfaces to optimize their potential for future use in medical and other applications.
| Date of Award | 1 Oct 2024 |
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| Original language | English |
| Awarding Institution |
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| Supervisor | Bo Su (Supervisor) & Angela H Nobbs (Supervisor) |