1. PEG Hydrogel Coating for Urinary Catheters PEG Hydrogel Coating for Urinary Catheters B. Mulawka, B. Roedl, P. Schenk, D. Patel Advisor: Professor William Murphy, Client: Arthur J. Coury Ph.D, Vice President of Biomaterials Research, Genzyme Corporation Polyethylene Glycol Client Specifications Problem Statement Motivation References Future Work Results Hydrogel Formation Procedure Urinary Catheters Made of latex, PVC, silicon, PTFE (Teflon) Long term catheterization has many problems Catheter obstruction due to crystallization of proteins and bacteria collection Dependent upon patient and coating Silver nitrate, antibiotics Difficult to coat due to curvature of surface PEG: Nontoxic polymer. In water, helical structure, viscous, neutral, repulsive of charged molecules. Minimizes protein and cell interaction and decreases host response. Used in medicine delivery systems. Optimize a PEG hydrogel coating procedure on the surface of a latex catheter to achieve desired thickness, adherence, and protein resistance when exposed to a physiological environment. Catheter related infections cause 62,000 deaths and cost the healthcare industry an extra 1.8 billion dollars each year. Blockage caused by protein encrustation is prevalent in half of all urinary catheterizations. Catheter discomfort, failure, and infection can be reduced by coating the catheter with a microlayer of hydrogel that limits protein adsorption to the catheter surface. Create a detailed process for applying a hydrogel to surfaces Test thickness and adherence of hydrogel coatings Test fouling resistance of hydrogels in physiologically imitated environments bovine albumin solution, pH 7.35 Kenneth Messier, Genzyme Corp. McNair, Andrew M. "Using Hydrogel Polymers for Drug Delivery." Medical Device Technology (1996). Kizilel, Seda, Victor H. Perez-Luna, and Fouad Teymour. "Photopolymerization of Poly(Ethylene Glycol) Diacrylate on Eosin- Functionalized Surfaces." Langmuir (2004). Levillian, Pierre, Dominique Fompeyide. “Demonstration of Equilibrium Constants by Derivative Spectrophotometry. Aplication to the pKas of Eosin”. Anal. Chem. (1988). Cruise, Gregory. Scharp, David. Hubbell, Jeffrey. “Characterization of permeability and network structure of interfacially photopolymerized poly(ethylene glycol) diacrylate hydrogels.” Biomaterials. (1998) Wash.5”x.5” latex substrate with acetone Stain substrate with ethyl eosin of varying concentration Wash stained substrate with acetone Immerse substrate in PEG macromer Immediately apply four, 40 sec. light treatments Immediately place substrate in PBS to allow gel to equilibrate for a minimum of 12 hours Experimental Methods Thickness Sliced thin portion of coated substrate Measured under optical microscope with 6 um polystyrene beads Adhesion Measured using subjective 1-4 scale Protein Adsorption Place coated and uncoated substrates in 2 ml of 1% bovine albumin solution for 24 hours Wash substrates in 2 ml PBS for 24 hours, 3 times Place substrates in 1 ml vials of 1% SDS detergent solution and rotate for 24 hours Measure absorbance of vial solutions with UV spectroscopy Measure protein adherence using an alternative protein assay that is not based on UV absorbance. BCA Assay is an alternative Quantitative analysis of adhesion testing Test and alter process to further optimize thickness and adherence of hydrogel Coat Latex catheter using known process Begin experimental trials with latex catheter Hydrogel Thickness Data shows that thickness of gel varies with concentration of ethyl eosin stain used Altering the concentration of staining solution from 5ppm to 200ppm allows for gel thickness up to 30um Hydrogel Adhesion Adhesion of hydrogel to substrate varies slightly with gel thickness Best adhesion with 6 and 12 micron hydrogel layers Gel adhesion could still be improved upon Protein Adhesion 25 ppm ethyl eosin stain produced significantly lower protein adherence than an uncoated latex substrate, 50 ppm and 200 ppm ethyl eosin stains.