Feb 23, 2016
Biofilm and structure
•What a biofilm is and structure of the biofilm is•How this biofilm works.
Fig. 1. Stylistic depiction of biofilm formation.
Biofilm properties
•Forms a protective layer •Allows organism to grow unhindered
Fig. 2. Life cycle of biofilm showing slime layer.
Psuedomonas Aeruginosa
• A bacterium that forms a bioflim• Forms biofilm, found everywhere•
• Add image from journal showing that A/B not effective
Previous studies on Pseudomonas Aeruginosa
Use of Heavy metalsMetal cations Cobalt, copper, nickel, silver.
• Need high concentrations of metal cations to kill populations
• Persister cells are killed at a slower rate
Use of antibioticsUse of Ciprofloxacin and Tobramycin
antibiotics
• Slow diffusion of tobramycin due to binding
• Ciprofloxacin ineffective • Oxygen may be limiting factor.
Results from the antibiotic experiment
Fig. 3. Killing of P. aeruginosa in biofilms in exposure to ciprofloxacin. Filled squares were the treatment and the unfilled were the controls (Walter et al.)
Fig. 4. Killing of P. aeruginosa in biofilms in exposure to tobramycin. Filled squares were the treatment and the unfilled were the controls.
Time (h)
Types of antibiotics used
Ciprofloxacin Tobramycin
Why the antibiotics didn’t work
From Walters,
•Lack of oxygen restricts bacterial metabolic activity
•Took long to penetrate through the biofilm
Fig. 5. Penetration of tobramycin (squares) and ciprofloxaicin (circles) in P. aeruginosa. Open symbols are in sterile controls (Walters et al., 2003)
Nanowire bundles
Wires with a diameter in the nanometer scale
•Conductive•Large surface area•Used as detectors in electrochemistry
Fig. 6. Transmission electron microscopy of Cu(OH)2 nanowires (Zhuang et al. 2007)
Fig. 7. Image of ordered nanowire in a microarray.
Why copper oxide
• Copper was on the effective metals in previous experiments
• Works well in biological settings from glucose and hemoglobin experiments.
Proposed experiment: Artificial neutriphil net
•Emulate a neutriphil net with nanowire bundles laced with antibiotics
•Use this net on biofilms to get through the slime layer more effectively.
Fig. 8. Image of a neutriphil net trapping bacteria
Follow experiments developed by
Synthesis of Biofilm Synthesis of Copper oxide nanoparticles
Expected results
• We expect to see no growth if the antibiotics are able to penetrate the biofilm layer effectively
Literature cited
How we can apply this study
• Cf– Pseudomonas attacks alveoli
• Burn