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BIODEGRADABLE POLYMER

BIODEGRADABLE POLYMER. Reporter: AGNES Purwidyantri Student ID no: D0228005 Biomedical Engineering Dept. Definition. Biodegradable

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BIODEGRADABLE POLYMER

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  1. BIODEGRADABLE POLYMER Reporter: AGNESPurwidyantri Student ID no: D0228005 Biomedical Engineering Dept.

  2. Definition Biodegradable  A “biodegradable” product has the ability to break down, safely, reliably, and relatively quickly, by biological means, into raw materials of nature and disappear into nature. Biomaterial  A biomaterial can be defined as a material intended to interface with biological systems to evaluate, treat, augment or replace any tissue, organ or function of the body [1].

  3. Degradation time Cotton rags 1-5 months Paper 2-5 months Rope 3-14 months Orange peels 6 months Wool socks 1 to 5 years Cigarette butts 1 to 12 years Plastic coated paper milk cartons 5 years Plastic bags 10 to 20 years Nylon fabric 30 to 40 years Aluminum cans 80 to 100 years Plastic 6-pack holder rings 450 years Glass bottles 1 million years Plastic bottles May be never

  4. What is Polymer Degradation? polymers were synthesized from glycolic acid in 1920sAt that time, polymer degradation was viewed negatively as a process where properties and performance deteriorated with time.

  5. BONE+PLATE Degradable Polymer Plate Mechanical Strength PLATE BONE Time Biodegradable Polymers as Medical Device Material • No need a second surgery for removal • More physiological repair • Avoid stress shielding • Potential as the basis for controlled drug delivery • Temporary sport during tissue recovery • Less invasive repair

  6. Natural Biodegradable Polymer 1. Polysaccharides  Starch  Cellulose  Chitin & Chitosan  Hyaluronic acid  Alginic acid 2. Polypeptides  Collagen  Gelatin 3. Bacterial Polyesters  EXPENSIVE  Poly-b-hydroxybutyrate (PHB)

  7. Synthetic Biodegradable Polymer • Polymer with hydrolyzable backbones • Poly-lactic acid (PLA) and its isomers &copolymers • Poly-glycolic acid (PGA) • Poly-lactide-co-glycolide (PLGA) • Poly-caprolactone (PCL)  long degradation time • Polydioxanone • Polymers with carbon backbones • Poly (vinyl alcohol) and poly (vinyl acetate) • Polyacrylates

  8. Biodegradable Polymers O N S Carbonyl bond to A. Where X= O, N, S Where X = O, N, S Ester Ester Amide Amide Thioester

  9. Biodegradable Polymers B. Where X and X’= O, N, S Carbonate Urea Urethane C. Where X and X’= O, N, S Imide Anhydride

  10. OH OH C C OH O OH H2O OH OH C C C + H2O C C C C C==O OH OH OH OH H Biodegradable Polymers • Acetal:Hemiacetal: • Ether • Nitrile • Phosphonate • Polycyanocrylate

  11. Degradation Mechanisms • Enzymatic degradation • Hydrolysis (depend on main chain structure: anhydride > ester > carbonate) • Homogenous degradation • Heterogenous degradation

  12. Degradation Steps Water-sorption Molar mass reduction Degradation Steps Loss of weight Reduction of mechanical properties (modulus & strength)

  13. Polymer Degradation by Erosion

  14. Degradation Schemes • Surface erosion (poly(ortho)esters & polyanhydrides) • Sample is eroded from the surface • Mass loss is faster than the ingress of water into the bulk • Bulk degradation (PLA,PGA,PLGA, PCL) • Degradation takes place throughout the whole of the sample • Ingress of water is faster than the rate of degradation

  15. Erodible Matrices or Micro/Nanospheres • (a)Bulk-eroding system • (b)Surface-eroding system

  16. Comparison [7]

  17. Factors Influence the Degradation Behavior • Chemical Structure and Chemical Composition • Distribution of Repeat Units in Multimers • Molecular Weight • Polydispersity • Presence of Low Mw Compounds (monomer, oligomers, solvents, plasticizers, etc) • Presence of Ionic Groups • Presence of Chain Defects • Presence of Unexpected Units • Configurational Structure • Morphology (crystallinity, presence of • microstructure, orientation and residue • stress) • Processing methods & Conditions • Method of Sterilization • Annealing • Storage History • Site of Implantation • Absorbed Compounds • Physiochemical Factors (shape, size) • Mechanism of Hydrolysis (enzymes vs • water)

  18. Poly(lactide-co-glycolide) (PLGA) [8]

  19. Factors for Polymer DegradationAcceleration • More hydrophilic backbone. • More hydrophilic endgroups. • More reactive hydrolytic groups in the backbone. • Less crystallinity. • More porosity. • Smaller device size.

  20. Medical Applications of Biodegradable Polymers • Wound Management • Staples • Sutures • Clips • Surgical Meshes • Adhesives • Dental Applications • Tissue regeneration • membrane • Void filler for after tooth extraction Cardiovascular applications Stents • Orthopedic Devices • Pins • Rods • Screws • Tacks • Ligament Intestinal Application Anastomosis Ring Drug, Gene Delivery System Tissue Engineering

  21. Tissue Engineering PLLA, PCL, PGA, poly(glycolide) & poly[d,l-(lactide-co-glycolide)] have excellent biocompatibility and good mechanical properties and have been licensed by FDA for in vivo applications for tissue engineering scaffolds [2]. Cells are cultured on a scaffold to form a natural tissue, and then the formed tissue is implanted in the defect part in the patients. In some cases, a scaffold or a scaffold with cells is implanted in vivo directly, and the host’s body works as a bioreactor to construct new tissues [3].

  22. Gene Delivery System [4] • Poly(l-lysine)-based degradable polymers • Poly(β-amino ester)s-based degradable polymers • Polyphosphoester-based degradable polymers • Polyethyleniminemodified with degradable polymers • Degradable polymers in siRNA delivery

  23. Gene Delivery System Barriers to gene delivery. Design requirements for gene delivery systems include the ability to (I) package therapeutic genes, (II) gain entry into cells,(III) escape from the endo-lysosomal pathway,(IV) affect DNA/vector release,(V)travelthrough the cytoplasm and into the nucleus, and (VI) enable gene expression [5]. TSP50 was immobilized onto biodegradable polymer fibers.ThenTSP50-immobilized polymer fibers could selectively adsorb the anti-TSP50 [6].

  24. Conclusion • Synthetic biodegradable polymers  no immunogenicity  easier to be chemically modified &functionalized. • The developing trends in the functionalization of synthetic biodegradable polymers (1) Easier functionalization processes with mild reaction conditions and without harmful effects on bulk properties of polymers are pursued (2) Functionalization will be related to biomimetics (3) Promising potential for in vivo applications.

  25. References 1. Nair LS,Laurencin CT. Biodegradable polymers as biomaterials. ProgPolym Sci. 2007;32:762–98 2 Rezwan K, Chen QZ, Blaker JJ, Boccaccini AR. Biodegradable and bioactive porous polymer/inorganic composite scaffolds for bone tissue engineering. Biomaterials 2006;27:3413–31 3. Place ES, George JH, Williams CK, Stevens MM. Synthetic polymer scaffolds for tissue engineering. Chem Soc Rev 2009;38:1139–51. 4. H. Tian et al. Progress in Polymer Science 37 (2012) 237–280 5. Wong SY, Pelet JM, Putnam D. Polymer systems for gene delivery—past, present, and future. ProgPolymSci 2007;32:799–837 6. Shi Q, Chen X, Lu T, Jing X. The immobilization of proteins on biodegradable polymer fibers via click chemistry. Biomaterials 2008;29:1118–26 7. Mobley, D. P. Plastics from Microbes. 1994 8. Robert A. Miller, John M. Brady, Duane E. Cutright. Degradation rates of oral resorbable implants (polylactates and polyglycolates): Rate modification with changes in PLA/PGA copolymer ratios. Journal of Biomedical Materials Research. Vol 11 issue 5 pages 711–719, September 1977

  26. Thank you

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