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    PolymersInMedicine.ppt PolymersInMedicine.ppt Presentation Transcript

    • Polymers In Medicine Jeremy C. Robinson Pierre M. Saint Louis Anoop Padmaraju
    • Overview
      • Introduction
      • Brief History
      • Applications
        • Cellophane
        • PGA, PLA, PLGA
        • Polydimethylsiloxane
        • Polyethylene and PMMA
        • Polytetrafluoroethylene
        • Polyurethane
      • The Future
    • 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.
    •  
    • History
      • Biomaterials not practical till 1860’s
      • 1900’s Biomaterials first used
      • WWII, PMMA used to replace damaged cornea
    •  
    • 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
    •  
    •  
    • PGA, PLA, PLGA
    • 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
    • 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
    • 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
    • Polydimethylsiloxane
      • “ Silicon”
      • Lubricants and Foaming agents
      • Pacemakers and Vaccine Delivery systems
    • 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
    • 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
    • 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
    • PMMA Fig. 4a PMMA disc over femoral window during the molding process Fig. 4b PMMA template after polymerization, showing molded plug
    • 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
    • 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
    • Polyurethane
      • Shoe soles, tires and foams
      • Thermoset, non-condensation step growth
      • Low molecular weight polymer (47,000)
      • “ Bridges” the gap between rubber and plastic
    • 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
    • Ventricular Assist Device
    • 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
    • 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
    • The Future
      • Opportunities are limitless
      • We as scientists and engineers are faced with big challenges
      • Potential and promise are tremendous
      • Questions!
    • 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
      •              
    • 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”)
    • 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
      •  
    • The End Thank You!