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Electroactive Polymers for Tissue Engineering of Nerve

Electroactive Polymers for Tissue Engineering of Nerve. Christine E. Schmidt Chemical & Biomedical Engineering. Digestive Tract. Vessel. Skin. Bone. Nerve. Tissue Engineering. Nerve Graft. Nerve Defect. Nerve Damage. Tumor. Nerve Fiber Elongation. Guide regenerating axons

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Electroactive Polymers for Tissue Engineering of Nerve

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  1. Electroactive Polymers for Tissue Engineering of Nerve Christine E. Schmidt Chemical & Biomedical Engineering

  2. Digestive Tract Vessel Skin Bone Nerve Tissue Engineering

  3. Nerve Graft Nerve Defect Nerve Damage Tumor

  4. Nerve Fiber Elongation

  5. Guide regenerating axons Prevent infiltration of scar tissue Increase concentration of intraluminal proteins Inhibit or permit diffusion of external macromolecules Nerve Guidance Channels (NGCs)

  6. The Ideal Nerve Conduit

  7. Enhancement of Nerve Regeneration

  8. Polypyrrole • Easy to synthesize • Inherently conductive • Flexibility in altering surface properties via dopant (X-)

  9. Pyrrole Polymerization Reference Electrode (Ag/AgCl) Working Electrode (ITO) Gold Wire Counter Electrode Aqueous Solution (0.1 M Pyrrole, 0.1 M Salt of Dopant)

  10. Stimulation Set-up (Constant i)

  11. In Vitro Electrical Stimulation A = PC-12 cells on PP B = PC-12 cells on PP + 100 mV

  12. Electrical Stimulation • 90%increase in the median neurite length observed with PP+V. • Only 20-40% increase seen on piezoelectric materials (PVDF).

  13. Protein Adsorption to PP

  14. Nerve Surgeries

  15. Nerve Surgeries

  16. Regenerated Nerve Cable 10 mm Distal Nerve Stump Regenerated Nerve Cable Proximal Nerve Stump sciatic nerve in rat, 8 weeks

  17. TEM of Regenerated Nerve Schwann Cell Nucleus Myelinated Axon Un-myelinated Axon

  18. Nerve Regeneration (6 wks)

  19. Nerve Regeneration with PP PP Regenerated Nerve Diameter (X1000) µm2 PP Silastic Silastic

  20. The Ideal Nerve Conduit

  21. Polypyrrole • Easy to synthesize • Inherently conductive • Flexibility in altering surface properties via dopant (X-)

  22. Hyaluronan (HA) HA is polyanion for use as dopant HA is important ECM component Degradation stimulates angiogenesis

  23. PP/HA Polymerization Reference Electrode Working Electrode (ITO) Gold Wire Counter Electrode Aqueous Solution Pyrrole, Na Salt of HA Viscous!

  24. Large nodules PP Thick Film Morphology PP/PSS PP/HA SEM images are at same magnification (20,000X). Films are 0.71 µm in thickness.

  25. PP/HA Bilayer Films Surface properties (HA activity) Bulk properties (roughness, conductivity, flexibility)

  26. PP Thick Film Morphology PP/PSS PP/HA Bilayer SEM images are at same magnification (20,000X). Films are 0.71 µm in thickness.

  27. PP Cyclic Voltammograms

  28. XPS Studies

  29. HA Present in PP/HA Films

  30. ~2-fold increase in blood vessels Stimulation of Angiogenesis PP/PSS (Control) PP/HA

  31. The Ideal Nerve Conduit

  32. Biodegradable Polypyrrole Synthesis flexible segment PPP PPP PPP degradable linkage electrically conducting unit

  33. conductivity maintained with 3-5 pyrrole units esters degraded by hydrolysis and enzymes flexibility imparted by aliphatic chain Biodegradable PP Design

  34. Final Polymer Structure

  35. NMR Supports Polymer Structure

  36. Biodegradability of Polymer

  37. New Polymer is Cytocompatible

  38. The Ideal Nerve Conduit

  39. Digestive Tract Vessel Skin Bone Nerve Tissue Engineering

  40. Thanks to... Early PP Studies: Prasad Shastri Robert Langer Joel Collier James Camp Terry Hudson Collaborative Laboratories (HA) Dr. Paraskevi Heldin (bHABP) NSF Whitaker Foundation Longenbaugh Foundation PP/HA Studies:

  41. http://www.che.utexas.edu/~schmidt

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