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 BiofilmSynthesis 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

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