Functionalization of Surfaces with Nisin in a Poly[ethylene oxide] brush layer Matt Ryder Dr. Joe McGuire – BioEngineering OSU HHMI Summer ‘07

Background – Instances of Infection 1  Infection in hospitals is the fourth largest killer in the US  2 million patients contract infections in hospitals each year…about 103,000 die as a result  228 infections/hour…12 deaths  Cost? $30.5 billion each year

Background  Three issues with implanted devices  Clot Formation  Bacterial Adhesion  Cell Proliferation  Currently, methods to counteract include:  Loading patients with heparin or antibiotics.

Background  These issues are directly related, both are initiated by adsorption events.

Hydrophobic Surface Background – Brush Layer  F108 creates brush layer that protects against protein adsorption.  Protein adsorption can result in very different outcomes, from benign surface coatings, to large clot formation (therefore risk of stroke).

Brush Layer – Protein Repellant A. F108 Coated SurfaceBare Surface F108 Coated SurfaceBare Surface B.

Background – Nisin Nisin is a small antimicrobial peptide produced by strains of Lactococcus lactis subsp. lactis. Nisin kills Gram positive bacteria through a multistep process that destabilizes the phospholipid bilayer of the cell and creates transient pores. The efflux of low molecular weight compounds from the cytoplasm and subsequent dissipation of membrane potential rapidly kills the targeted bacterium.

Nisin - Mechanism

Background – Nisin & Brush Layer  Goes against function of brush layer Hydrophobic Surface

Background – Product Activity

Hypothesis  If a surface can be chemically or functionally modified to adsorb and retain the Lantibiotic Nisin, antimicrobial activity and anti clotting function will be higher as compared to current coating methods.

Procedure overnight x # of days 2 days microspheres F108 Nisin Pediococcus

Results  Optimized concentrations of F108, Nisin and microspheres in solution.  Conducted serial dilution tests to find optimum concentration of Pediococcus.  Researched literature for background knowledge and future effectiveness  Standardized procedures to decrease variability.  Obtained valuable insight on Nisin activity from longevity testing.

Results dilution w/o Nisin dilution w/ Nisin Dilution optimized for colonies

Results

Future Research  28 day trials with current procedure  Blood serum studies to test longevity of Nisin in physiological conditions  Tests with EGAP rather than F108, a more clinically accepted polymer  in vitro studies using catheters

Acknowledgements  Special Thanks to:  Dr. Joe McGuire – Mentor  Dr. Christine Kelly  Karle Schilke  Dr. Jeff Tai – Protocols and instruction  Dr. Kevin Ahern – HHMI Program  The Howard Hughes Medical Institute

References 1. Committee to Reduce Infectious Diseases Pictures