PEG Hydrogel Coating for Medical Devices B Mulawka

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 Problem Statement Form a microlayer of PEG based hydrogel onto material surfaces in order to examine and improve upon their characteristics and biocompatibility. Motivation 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. Client Specifications Procedure • Stain specimen in 50 ppm 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 40 s • 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 • 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, p. H 7. 35 Urinary Catheters • 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 Results • 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 Future Work Materials • 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. • 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 References • Kenneth Messier, Genzyme Corp. • Mc. Nair, 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 p. Kas 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)