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  • 1. Polymers In Medicine Jeremy C. Robinson Pierre M. Saint Louis Anoop Padmaraju
  • 2. Overview
    • Introduction
    • Brief History
    • Applications
      • Cellophane
      • PGA, PLA, PLGA
      • Polydimethylsiloxane
      • Polyethylene and PMMA
      • Polytetrafluoroethylene
      • Polyurethane
    • The Future
  • 3. Biomaterials
    • What are they?
    • Substances other than food or drugs contained in therapeutic or diagnostic systems that are in contact with tissue or biological fluids
    • Why use Biomaterials?
    • Improve patient’s quality of life by replacing a defective body part with a substitute.
    • Physicians were limited to use off-the shelf supplies.
    • Novel biodegradable polymers and modified natural substances.
  • 4.  
  • 5. History
    • Biomaterials not practical till 1860’s
    • 1900’s Biomaterials first used
    • WWII, PMMA used to replace damaged cornea
  • 6.  
  • 7. Cellophane
    • “ Saran Wrap”, Rayon (fiber)
    • “ Regenerated” Cellulose
    • Invented 1908, Jacques E. Brandenberger
    • Kidney Dialysis
    • Invented 1959, William J. Kolff
    • Vegetable Parchment, Natural Casings early membranes
  • 8.  
  • 9.  
  • 10. PGA, PLA, PLGA
  • 11. PGA, PLA, PLGA
    • First synthesized by Dupont from Glycolic acid
    • PGA, originally Dexon, absorbable suture
    • 1963 Schmitt & Polistina Invents Biodegradable suture
    • PLA & PLGA Drug delivery systems
  • 12. PGA, PLA, PLGA
    • All polymers have low polydisparity index (PLA 1.6-1.9)
    • Depending on structure, polymers can be fit for different applications
    • Amorphous forms used in drug delivery systems
    • Crystalline forms good for scaffolding, or sutures
  • 13. PGA, PLA, PLGA
    • Two essentials in scaffolding: high surface to volume ratio, highly porous
      • Allows cells to easily proliferate for setup of pathways
      • Setup of pathways for nutrients
  • 14. Polydimethylsiloxane
    • “ Silicon”
    • Lubricants and Foaming agents
    • Pacemakers and Vaccine Delivery systems
  • 15. Polydimethylsiloxane
    • Discovered 1927, Dr. Frederick Stanley Kipping
    • Vulcanized rubber, can’t be melted or dissolved
    • Low glass transition
    • Produced by hydroxyl, groups through hydrolysis, replace the 2 Cl in the monomer
    • Ring opening polymerization, Higher MW
  • 16. Polydimethylsiloxane
    • Used in treatment of prostate carcinoma
    • Small biodegradable pellets (188 m) injected into area of body where needed.
    • Smaller doses, less toxic effects for patient
  • 17. Polyethylene and PMMA
    • Thermoplastics, exhibit moderate to high tensile strength with moderate elongation
    • Used for Hip replacement and Fracture Fixation
    • Annual procedures approaching 5 Million
    • Metal alternatives have corrosive problems
  • 18. PMMA Fig. 4a PMMA disc over femoral window during the molding process Fig. 4b PMMA template after polymerization, showing molded plug
  • 19. Polytetrafluoroethylene
    • High strength and Chemical resistance
    • High modulus and tensile properties with negligible elongation
    • Used for orthopedic and dental devices
    • Mechanical heart valve and implants
  • 20. Polytetrafluoroethylene
    • Excellent wear and fatigue resistance
    • Vascular grafts patch injured and diseased areas of arteries
    • Must be flexible to allow for the difficulties of implantation and to avoid adjacent tissue irritation
  • 21. Polyurethane
    • Shoe soles, tires and foams
    • Thermoset, non-condensation step growth
    • Low molecular weight polymer (47,000)
    • “ Bridges” the gap between rubber and plastic
  • 22. Polyurethane
    • One of the best load-bearing capacities
    • Discovered 1937, Otto Baker
    • Major medical uses Ventricular assist device
    • Developed by Dr. Liotta, Baylor, 1950’s
    • Redefined by Pierce and Donachy in 1971
  • 23. Ventricular Assist Device
  • 24. Polyurethane
    • VAD, used during open heart surgery, postoperatively and in case of extreme cardiac trauma
    • Pierce and Donachy used segmented polyurethane in their VAD
    • Safe contact barrier compressive properties made function similar to heart ventricle
  • 25. Polyurethane
    • Obtained through step-growth polymerization of diisocyanates and dihydroxl compounds
    • Injection molded
    • R.I.M.
    • Failures attributed to poor processing, not physical material properties
  • 26. The Future
    • Opportunities are limitless
    • We as scientists and engineers are faced with big challenges
    • Potential and promise are tremendous
    • Questions!
  • 27. References
    • Peppas, N., Langer, R. “New challenges in bio-materials”, Science, Vol. 263, March, 1994
    • Andreadis, S., “Applications of Biomaterials”, Tissue engineering handout, February 2001, University at Buffalo.
    • “ History and Development of Biomaterials”, www.bae.ncsu.edu/Courses/bae465
    • Fried, J. R., “Polymer Science and Technology.”, Prentice Hall, New Jersey 1995
    • “ Cellophane Invention”, http://inventors.about.com/science/inventors/library/inventors/blcellophane.htm
    • “ First Dialysis Unit”, www.ucl.ac.uk/uro-neph/history/dialysis.htm
    • “ Dialysis and the Artificial Kidney”, www.chemengineer.about.com/science/chemengineer/library/weekly/aa120897.htm
    • www.beyonddiscovery.com
    •              
  • 28. References
    • 9. Ikada, Y, Yoshihiko, S, “Tissue Engineering for Therapeutic Use 4.” Elsevier, 2000, New York
    •  
    • 10.          Pulverer, G., Schierholz, J. M., “Development of New CSF-shunt With Sustained Release of Antimicrobial Broad-Spectrum Combination.”, Baktercologie, Vol. 286, 107-123
    •  
    • 11.          Loomes, L. M., Jian Xiong, J., Brook, M. A., Underdown, B. J., McDermott, M. R., “Novel Polymer-grafted Starch Microparticles for Mucosal Delivery of Vaccines.”, Immunology, Vol. 56, 162-168, 1996
    •  
    • 12.          www.britannica.com, (keyword “polyethylene”)
    •  
    • 13.          “Uses of Polymehtylmethacrylate”, www.rcsed.ac.uk (Feb 2001)
    •  
    • 14.          www.britannica.com, (keyword “Polytetrafluoroethylene”)
  • 29. References
    • 15.          “Polyurethane – Features and Benefits”, www.elastchem-ca.com/poly.html
    •  
    • 16.          “Pierce-Donachy Ventricular Assist Device”, www.asme.org/history/Roster/H142.html
    •  
    • 17.          Liotta, D. “The Ventricular Assist Device”, www.fdliotta.org
    •  
  • 30. The End Thank You!

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