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Hydrogels for Coating Medical Devices

Hydrogels for Coating Medical Devices. University of Wisconsin BME 400. Our Team. Benjamin Roedl – Team Leader Patrick Schenk – Communicator Darshan Patel – BWIG Brett Mulawka - BSAC. Client & Advisor. Client: Arthur J. Coury, Ph.D.

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Hydrogels for Coating Medical Devices

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  1. Hydrogels for Coating Medical Devices University of Wisconsin BME 400

  2. Our Team • Benjamin Roedl – Team Leader • Patrick Schenk – Communicator • Darshan Patel – BWIG • Brett Mulawka - BSAC

  3. Client & Advisor • Client: Arthur J. Coury, Ph.D. • Vice President Biomaterials Research Genzyme Corporation • Advisor: William Murphy, Professor of Biomedical Engineering

  4. Problem Statement • To form PEG based hydrogels on biomaterial surfaces in an interfacial photopolymerization process and to screen the coatings for interactions with cells and media that mimic physiologic fluids. It is hypothesized that these coatings will resist fouling and may be useful for implantable devices.

  5. Genzyme Corporation • One of world’s foremost biotechnology companies with the goal of applying the most advanced technologies to address unmet medical needs.

  6. Motivation • Development of blood compatible hydrogel could have many applications • Orthopedic applications • Urinary Catheter • Tissue Repair • Create a hydrogel application procedure that results in accurate and reproducible results

  7. Background-Hydrogels • Polymeric structures that absorbs water • Crosslinks, Polymer, Liquid (Water)

  8. Crosslinking • Covalent Bonds Linking One Polymer Chain to Another • Can be Caused by Heat, Pressure, Chemicals • Form free radicals • We use a chemical that is light initiated • By Crosslinking, Hydrogels are Capable of Remarkable Water Retention/Adsorption

  9. Polyethylene Glycol (PEG) • Properties • Clear, viscous, odorless, miscible in water, non-toxic • Uses • Wound dressing, soft tissue replacement, drug delivery.

  10. Eosin Y • One Part of a Two Part Photoinitiator System • Maximum Adsorption at 514 nm (visible) • Passes Free Radical to Triethanolamine Taken from OLMC.Ogi.edu

  11. Triethanolamine • Accepts Free Radical from Eosin Y • Combines with Macromer to polymerize reaction

  12. Procedure • Stain specimen with Eosin Solution • Immerse stained specimen in macromer solution • Apply visible light • An adherent, thin, hydrogel forms by polymerization of the macromer (PEG) • Expose specimen to cells to test for fouling

  13. Testing • Thickness • Need to maintain consistent thickness for reliable test data / Toughness • Adherence • Durability through many cycles • Fouling Resistance • Biocompatibility • Most important

  14. Thickness • Place fully swollen coated substrate on edge under optical microscope • Microscope with camera would be ideal • Hydrogel thickness goal: 25 – 100 microns • Alternate method: • Peel/slice piece of gel off at interface, cut to straight edge and measure with optical microscope

  15. Adherence • Using a pointed spatula or needle, one person (control) will estimate adherence on a specific scale • 0 = Has fallen off • 1 = Lifts off almost intact with mild force • 2 = Lifts off in large chunks with some force • 3 = Lifts off in small pieces with some force • 4 = Does not delaminate even by destroying gel with pushing force

  16. Fouling Resistance • Expose to proteins found in blood in solution • Stain with appropriate dye to view adhered proteins

  17. Future Work:Protein Adsorption • Determine the concentration of proteins we must measure • Establish the best protein assay method to use • Acceptable resolution • Ease of procedure • UV adsorption, BCA assay… etc

  18. References • Arthur J. Coury, Ph.D. • Kenneth Messier • 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).

  19. Thank you Questions?

  20. Hydrogel Preparation • Radical chain reaction used to form cross links • Initiated using electrons, gamma-rays, x-rays, UV light to excite polymer chain and form radicals • (We will use visible light 514nm for eosin) • Crosslinkers • Acrylate, double bond forms radical

  21. Polyethylene Glycol (PEG) • Non-toxic • Laxatives, Skin Creams, Lubricants

  22. Light Source • Using a xenon light source • Applied to sample for 40 Seconds at a Distance of One Inch • Light Source Supplies Energy to Remove Electron from Eosin Y • Leads to a propagation of crosslinking between the macromer and triethanolamine

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