Biomedical polymers


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Biomedical polymers great interest in resarch and development.

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Biomedical polymers

  2. 2. CONTENTS • Introduction • Classification • Selection parameters for biomedical polymers • Applications • Conclusion 2
  3. 3. 3
  4. 4. Macromolecular compound obtained from natural origin. Chemical nature - polysaccharides, protein and bacterial polyesters. 4
  5. 5.  Flexibility;  Resistance to biochemical attack;  Good biocompatibility;  Light weight;  Available in a wide variety of compositions with adequate physical and mechanical properties and  Can be easily manufactured into products with the desired shape. Properties Of Biomedical Polymers 5
  6. 6. Classification Biomedical Polymers Natural Polymers Synthetic Polymers 6
  7. 7. Natural polymers, or polymers, derived from living creatures, are of great interest in the biomaterials field. Properties of natural polymers:  Biodegradable;  Non-toxic/ non-inflammatory;  Mechanically similar to the tissue to be replaced;  Highly porous; Natural polymers 7
  8. 8. Encouraging of cell attachments and growth; Easy and cheap to manufacture Capable of attachment with other molecules ( to potentially increase scaffold interaction with normal tissue). 8
  9. 9. Example of natural polymers A. Collagen B. Cellulose C. Alginates D. Dextrans and E. Chitosan 9
  10. 10. Collagen • Consist of three intertwined protein chains, helical structure • Collagen…..non-toxic, minimal immune response • Can be processed into a variety formats –Porous sponges, Gels, and Sheets • Applications –Surgery, Drug delivery, Prosthetic implants and tissue-engineering of multiple organs 10
  11. 11.  Derived from chitin, present in hard exoskeletons of shellfish like shrimp and crab  Chitosan desirable properties Minimal foreign body reaction Controllable mechanical biodegradation properties  Applications In the engineering of cartilage, nerve, and liver tissue, wound dressing and drug delivery devices Chitosan 11
  12. 12. Alginate • A polysaccharide derived from brown seaweed  Can be processed easily in water  Non-toxic  Biodegradable  Controllable porosity • Forms a solid gel under mild processing conditions • Applications in Liver, nerve, heart, cartilage & tissue- engineering 12
  13. 13. Synthetic Polymers  Advantages of Synthetic Polymers Ease of manufacturability process ability reasonable cost  The Required Properties  Biocompatibility  Sterilizability  Physical Property  Manufacturability 13
  14. 14. Applications: Medical disposable supplies, Prosthetic materials, Dental materials, implants, dressings, polymeric drug delivery, tissue engineering products 14
  15. 15. Synthetic Polymers Example of Synthetic Polymers :  (PTFE) Polytetrafluoroethylene  Polyethylene, (PE)  Polypropylene, (PP) Poly (methyl methacrylate), PMMA Materials in Maxillofacial Prosthetic 15
  16. 16. Synthetic Polymers Biostable Bioerodible Water soluble Other polymers Classification of synthetic polymers 16
  17. 17. • Polymers that are sufficiently biostable to allow their long term use in artificial organs blood pumps, blood vessel prostheses, heart valves, skeletal joints, kidney prostheses. • A polymer must fulfill certain critical requirements if it is to be used in an artificial organ.  It must be physiologically inert  The polymer itself should be stable during many years of exposure to hydrolytic or oxidative conditions at body temperature Biostable Polymers 17
  18. 18.  It must be strong and resistant to impact (when it is used as structural material to replace the bone).  The polymer must be sufficiently stable chemically or thermally that it can be sterilized by chemicals or by heat. 18
  19. 19.  Polymers that are bioerodible materials that will serve a short term purpose in the body and then decompose to small molecules that can be metabolized or excreted, sometimes with the concurrent release of drug molecules.  Mostly bioerodible polymers used as surgical sutures, tissue in growth materials, or controlled release of drug. Bioerodible Polymers 19
  20. 20.  Water-soluble polymers (usually bioerodible) that form part of plasma or whole blood substitute solutions or which function as macromolecular drugs.  Applications:  Improvement in the behavior of pharmaceuticals.  Used in synthetic blood substitutes as viscosity enhancers or as oxygen-transport macromolecules. Water Soluble Polymers 20
  21. 21. The design and selection of biomaterials depend on different properties – Host Response  Biocompatibility  Biofunctionality  Functional Tissue Structure and Pathobiology  Toxicology  Appropriate Design and Manufacturability  Mechanical Properties of Biomedical polymers Selection Parameters For Biomedical Polymers 21
  22. 22.  Host Response: The response of the host organism (local and systemic) to the implanted polymeric material or device.  Biocompatibility : The ability of a material to perform with an appropriate host response, in a specific application.  Toxicology: Should not be toxic.  Appropriate Design and Manufacturability: Biomaterials should be machinable, moldable, extrudable.  Mechanical Properties of Biomedical polymers: Tensile strength, yield strength, elastic modulus, surface finish, creep, and hardness. 22
  23. 23. Cardiovascular Applications Bones, Joints, And Teeth Contact Lenses And Intraocular Lenses Artificial Kidney And Hemodialysis Materials Oxygen-Transport Membranes Surgical Sutures Tissue Ingrowth Polymers Controlled Release Of Drugs Application 23
  24. 24. Heart Valves and Vascular Prostheses The Artificial Heart Heart pump designs 24
  25. 25.  Damaged heart valves, weakened arterial walls, and blocked arteries constitute some of the commonest cardiovascular disorders.  Silicone rubber is used because of its inertness, elasticity, and low capacity to cause blood clotting.  Poly(tetrafluoroethylene) 25
  26. 26. Artificial Heart  Artificial hearts are a mechanical device, they are typically used in order to bridge the time to heart transplantation, or to permanently replace the heart in case transplantation is impossible. 26
  27. 27. Artificial Heart  The heart is conceptually simple, it’s formed by synthetic materials and power supplies. A possible consequence it could be the body rejection. These complications limited the lifespan of early human recipients to hours or days 27
  28. 28. ABIO HEART  It’s the last artificial heart invented. It’s made by titanium and a special plastic in which the blood doesn’t stick. The heart has got flexible walls with silicon, a motor that moves it, and in the valve it controls the pressure.  5 years are the life of this hearts. 28
  29. 29. Heart Pump Designs 29
  30. 30. Bones, Joints, And Teeth  Occasionally repaired with the use of polyurethanes, epoxy resins, and rapid curing vinyl resins.  Silicone rubber rods and closed cell sponges- replacement finger and wrist joints.  Elbow joints- vinyl polymers and nylon  Knee joints- cellophane and, more recently, silicone rubber  Poly(methyl methacrylate) is the principal polymer used both for acrylic teeth and for the base material 30
  31. 31. Contact Lenses And Intraocular Lenses 31
  32. 32. • The function of a kidney is to remove low molecular weight waste products from the bloodstream. • Artificial kidneys have function by passage of the blood between the walls of a dialysis cell which is immersed in a circulating fluid. • Cellophane- Semipermeable dialysis membranes • The polymer is "heparinized" to prevent blood clotting-polycarbonate or cellulose acetate fibers. Artificial Kidney And Hemodialysis Materials 32
  33. 33.  Surgical work on the heart frequently requires the use of a heart lung machine to circulate and oxygenate the blood.  Poly(dimethylsiloxane) membranes are highly efficient gas transporters.  It is of interest that silicons rubber has approximately six times the oxygen permeability of fluorosilicones. Oxygen-Transport Membranes 33
  34. 34. Poly(glycolic acid), or condensation copolymers of glycolic acid with lactic acid. A high tensile strength and is compatible The polymer degrades by hydrolysis to nontoxic glycolic acid. 34
  35. 35. Drug release by diffusion  Early encapsulation and entrapment systems released the drug from within the polymer via molecular diffusion ◦ When the polymer absorbs water it swells in size ◦ Swelling created voids throughout the interior polymer ◦ Smaller molecule drugs can escape via the voids at a known rate controlled by molecular diffusion (a function of temperature and drug size) Add water Add time 35
  36. 36. Drug release by erosion • Modern delivery systems employ biodegradable polymers – When the polymer is exposed to water hydrolysis occurs – Hydrolysis degrades the large polymers into smaller biocompatible compounds – Bulk erosion process – Surface erosion process mer Polymer mer mer mer mer mer mer mer mer Water attacks bond mer mer mer mer mer mer mer mer mer mer mer mer mer mer mer mer mer mer 36
  37. 37. Bulk erosion (e.g. poly lactide, polyglycolic acid) ◦ When the polymer is exposed to water hydrolysis occurs ◦ Hydrolysis degrades the large polymers into smaller biocompatible compounds ◦ These small compound diffuse out of the matrix through the voids caused by swelling ◦ Loss of the small compounds accelerates the formation of voids thus the exit of drug molecules Add water Add time 37
  38. 38. Surface erosion (e.g., polyanhydrides) –When the polymer is exposed to water hydrolysis occurs –Hydrolysis degrades the large polymers into smaller biocompatible compounds –These small compound diffuse from the interface of the polymer –Loss of the small compounds reveals drug trapped within –Note these polymer do not swell. Add water Add time 38
  39. 39. 39 Biomedical polymers are essentially a biomaterial, that is used and adapted for a medical application. Biomedical polymer can have a beginning functional, such as being used for a heart valve and more interactive purpose such as hydroxyapatite coated in implant and such implants are lunching upwards of twenty year. Many prostheses and implants made from polymers have been in use for the last three decades and there is a continuous search for more biocompatible and stronger polymer prosthetic materials.
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  41. 41. H.C.Paul, Textbook Of Polymer Chemistry(The Basic Concept), Marcel Dekker , Inc, pp-199-505. H.R.Allcock, F.W.Lampe, Textbook Of Contemporary Polymer Chemistry, 2ndEdition, Prentice Hall, INC, pp-575-589. J. H. Ward, R. Bashir, N.A. Peppas, Micropatterning Of Biomedical Polymer Surfaces By Novel UV Polymerization Techniques, 2001, John Wiley & Sons, Inc.,pp-351-360. M.A.Ward And T.K.Georgiou, Thermoresponsive Polymers For Biomedical Applications, 2011, Www.Mdpi.Com/Journal/Polymers, Polymers 3, pp-1215-1242. M.R.Aguilar, C. Elvira, A. Gallardo, B. Vázquez, And J.S. Román, Smart Polymers And Their Applications As Biomaterials, 2007, Topics In Tissue Engineering, Vol. 3 Eds, pp-1-27. N.K.Jain, Textbook Of Pharmaceutical Product Development, 1st Edition, CBS Publication, pp-585-618. 41
  42. 42. N. R. Patel, P.P.Gohil, A Review on Biomaterials:Scope, Applications& Human Anatomy Significance, April 2012, Int J Emerging Technology and Advanced Engineering (ISSN 2250-2459, Volume 2, Issue 4), pp-91-101. N. Saha, A. Saarai, N. Roy, T. Kitano, P. Saha, Polymeric Biomaterial Based Hydrogels for Biomedical Applications, 2011 , Sci Res. J Biomaterials and Nanobiotechnology2, pp-85-90. Report On Radiation Synthesis And Modification Of Polymers For Biomedical Applications, 2002, International Atomic Energy Agency, pp-1-199. S. Brocchini, Combinatorial Chemistry And Biomedical Polymer Development, 2001, Elsevier Science, Advanced Drug Delivery Reviews 53, pp- 123 –130. T.J.Peter, Textbook Of Polymers For Controlled Drug Delivery, CRS Press, pp-99-148.  polymer as a biomaterial. 42
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