Covalent Tethering of Beta-amyloid onto Titanium Reduces Bacterial Colonization

Dillon McCourt, Joseph Infanti, Denah Appelt, Brian J. Balin, Christopher S. Adams

Research output: Contribution to conferencePresentation


Introduction : A major complication in the use of surgical prostheses is periprosthetic infection (PPI). Bacterial colonization of a prosthesis may require its removal and is associated with significant disability, morbidity, and mortality. Considered a never event by insurance providers, reducing the incidence of PPI can increase the quality of life for patients, as well as lower the overall societal economic burden. Once bacteria are able to attach, replicate, and begin biofilm production, they can avoid immune system detection, as well as eradication by systemic antibiotics. Thus, we have focused on this initial colonization event as the critical stage of inhibiting PPI.

Objectives : The objective of this project was to demonstrate that covalently tethering an anti-microbial peptide (AMP), beta-amyloid (Aβ), to the surface of titanium can reduce bacterial colonization.

Methods : Aβ was tethered to the surface of titanium pins and mesh either with, or without, a Fmoc-aminoethoxyethoxyacetate (Fmoc-AEEA) linker via a modified, previously-established synthesis protocol. Immunostaining was used to confirm successful tethering with confocal microscopy. Upon verification of the surface modifications, the Aβ-titanium surfaces were challenged against Staphylococcus aureus , a Gram-positive coccus, and Escherichia coli , a Gram-negative bacillus. Antimicrobial effect is primarily determined by serial dilutions and colony counting on 3MTM PetriFilmsTM. Bacteriostatic or bactericidal effect is analyzed through staining with a Bacterial Viability Kit and visualization by confocal microscopy.

Results : Immunostaining of the Aβ-titanium surfaces demonstrated a significant increase in fluorescence in comparison to control surfaces, which only showed minimal background fluorescence. Bacterial colonization, as measured by colony counts, was normalized to untethered control titanium. Incubation in contact with both Aβ-titanium pins (both with linker and without) generated a statistically significant reduction in comparison to control surfaces. This reduction was similar that seen for vancomycin and tetracycline, two antibiotics included as positive controls. Visualization of adherent bacteria by use of the LIVE/DEADTM Bac LightTM staining revealed reduced colonization by both S. aureus and E. coli. These levels were also similar to those seen with our positive control surfaces.

Conclusion : Aβ can be covalently tethered to titanium surfaces. This tethered surface produces similar antimicrobial effects in comparison to tethered antibiotics. Thus, this research provides an early proof of concept that tethered antimicrobial peptides might be capable of reducing PPI incidence on titanium prosthetic implants.

Original languageAmerican English
StatePublished - May 8 2019


  • beta-amyloid
  • antimicrobial
  • covalent tethering
  • periprosthetic infection


  • Life Sciences
  • Medicine and Health Sciences

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