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 metals Metal cations Cobalt, copper, nickel, silver. Need high concentrations of metal cations to kill populations Persister cells are killed at a slower rate Use of antibiotics Use 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 CiprofloxacinTobramycin

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