1. PEG Hydrogel Coating for Medical Devices PEG Hydrogel Coating for Medical Devices 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 Materials Client Specifications Problem Statement Motivation References Future Work Results Procedure Urinary Catheters Modify Staining Procedure Increase concentration of Eosin Y Change to Ethyl Eosin stain (more hydrophobic) Allow material to dry after Ethyl Eosin is applied Increase light application time during photopolymerization Focus on coating of latex and PVC Continue to test adhesion of hydrogel to substrate surface Test biocompatibility by exposing hydrogel coated material to bovine albumin solution Made of latex, PVC, silicon, PTFE (Teflon) Chance of failure 100% within weeks to months Catheter obstruction due to crystallization of proteins and bacteria collection Dependent upon patient and coating Silver nitrate, antibiotics, Norfloxacin 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. Uses: drug delivery matrix, biomaterial synthesis, food additives, wound dressings, soft tissue replacement PVC: Hydrophobic surface. Used as tubing for blood transfusion, dialysis, and feeding. Biologically inert, can be used as a negative control Polystyrene: Hydrophobic surface. Polar groups can be introduced to give the surface ionic or dipole-dipole bonding properties. Used to make Petri dishes and cell culture wells, good material for testing cell adhesion. Glass: Hydrophilic and negatively charged surface. Used for eyeglasses, chemical ware, thermometers, tissue culture flasks, and optics in endoscopy. All surfaces showed poor hydrogel adhesion Eosin did not adhere to surface All thicknesses were under 40 microns Client specifies 25-100 microns Non-uniform surface coatings Increased time in eosin Y solution did not affect hydrogel adhesion Increased rinsing of material before photopolymerization caused a decrease in hydrogel thickness but did not affect hydrogel adhesion Form a microlayer of PEG based hydrogel onto material surfaces in order to examine and improve upon their characteristics and biocompatibility. Our ultimate goal is to coat a urinary catheter with a uniform biocompatible hydrogel with sufficient material adhesion which we believe will improve upon the problems associated with existing long-term catheters. Create a detailed process for applying a hydrogel to surfaces Testing of thickness and adherence of hydrogel coatings Testing of fouling resistance of hydrogels in physiologically imitated environments bovine albumin solution, pH 7.35 Stain specimen in 50ppm Eosin Y solution from two hours to one week Rinse with distilled water: heavy, light, no rinse, bath Immerse specimen in macromer (PEG) solution and apply light from source for 40s Soak in saline to equilibrate any gel formed on surface View specimen under microscope to measure thickness by comparison to 6 micron polystyrene beads Used subjective test to measure adherence 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)