Background: Hundreds of thousands of titanium dental and orthopaedic implants are inserted annually in the UK but around a fifth will fail prematurely, with bacterial infection being the principal cause within the first year. Implant infection leads to chronic complications and with the development of antimicrobial resistance, current antibiotic-based treatments are rapidly becoming ineffectual. With inspiration taken from nanotopography observed on insect wings that can physically induce bacterial cell death, this project seeks to replicate these effects on titanium and further enhance their bactericidal performance with antimicrobial peptides (AMPs).
Aims and objectives: This project aims to fabricate titanium surfaces with synergistic bactericidal capabilities mediated by nanostructures and antimicrobial peptides (recognised as potential alternatives to current antibiotics) that will successfully graft (osseointegrate) into bone. Objectives include:
1. Generate nanotopographies on the surface of titanium.
2. Assess the bactericidal and anti-fouling potential of the surfaces using a variety of viability, metabolic and imaging assays.
3. Enhance and broaden the antimicrobial activity of the surfaces through coating with antimicrobial peptides.
4. Investigate the mechanical properties of the nanostructured surfaces and their correlation with osteogenic capabilities.
Results: Titanium dioxide nanostructures have been shown to cause a significant reduction in the vitality of Gram-negative bacteria (Escherichia coli, Klebsiella pneumoniae) and Gram-positive bacteria (Staphylococcus aureus). FIB-SEM performed at DESY has highlighted slight deformation of the Gram-negative bacterial cell membrane upon contact with the nanostructures. With AMP functionalisation complete inhibition of bacterial growth for 16 hours on flat surfaces but on nanostructures the AMP activity is impeded.
Significance of Research: This research promises to highlight methods of surface modification that could combat implant infections, and thus maximise the longevity of medical implants while minimising antibiotic use and maintaining osteogenic capabilities. This, in turn, could improve the wellbeing of millions of patients worldwide.