Sunday, October 3, 2010
18037

Optimization of Peripheral Nerve-Prosthetic Device Interface Conduction and Flexibility Using Electro-Chemical Polymerization of PEDOT On Decellular Nerve

Melanie G. Urbanchek, PhD1, Bong S. Shim, PhD2, Ziya Baghmanli, MD1, Benjamin Wei, MD1, Kyle Williams, HS3, Brent Egeland, MD1, Kirsten Schroeder, BA1, Nicholas B. Langhals, MSE1, Rachel M. Miriani, MSE1, Daryl R. Kipke, PhD4, David C. Martin, PhD2, and Paul S. Cederna, MD5. (1) Plastic Surgery, University of Michigan, 109 Zina Pitcher Place, BSRB, Room 2023, Stop 2200, Ann Arbor, MI 48109-2200, (2) Material Science and Engineering, University of Delaware, 201 Dupont Hall, Newark, DE 19716, (3) Engineering, University of Michigan, 109 Zina Pitcher Place, Room 2023 Stop 2200, Ann Arbor, MI 48109-2200, (4) Biomedical Engineering, University of Michigan, 2212 Lurie Engineering Center, Ann Arbor, MI 48109-2110, (5) 1500 E. Medical Center Drive, 2130 Taubman Center, Ann Arbor, MI 48109-340

Purpose: The purpose of this study is to optimize the process by which poly-3,4, ethylenedioxythiophene (PEDOT) is polymerized into decellular nerve scaffolding for interfacing to peripheral nerves. Our ultimate aim is to permanently implant highly conductive peripheral nerve interfaces connectors between amputee stump nerve fascicles and prosthetic electronics. We hypothesize that optimizing the polymerization of PEDOT onto DN significantly increases conductivity while minimizing incompatible PEDOT stiffness.

Methods: Decellular nerve (DN) scaffolds are an FDA approved biomaterial (Axogen™) with flexible extensile properties needed for successful permanent coaptation to peripheral nerves. DN is polymerized with biocompatible electro-conductive PEDOT (Fig 1) which has been shown to facilitate electrical conduction to biological materials 1, 2. New electro-chemical polymerization methods were used to vary PEDOT concentrations and to decrease dehydration. DN scaffolds were then tested for impedance and charge density (n ≥ 5 per 6 groups). DN scaffolds were also implanted as 15-20mm peripheral nerve grafts. Measurement of in-situ nerve conduction immediately followed grafting.

Results: PEDOT coated DN data show significant improvements in impedance and charge density for dehydrated concentrations as low as 10% and hydrated PEDOT concentrations as low as 1% when compared with DN alone (a ≤ 0.05). These measurements were equivalent to 100% PEDOT concentrations on DN.  In-situ, nerve conduction measurements demonstrate that DN alone is a poor electro-conductor while the addition of PEDOT allows DN scaffolds to compare favorably with the “gold standard” autograft nerve (Table 1). Surgical handling characteristics for highly conductive hydrated PEDOT DN scaffolds were rated 3 (pliable) while the dehydrated models were rated 1 (very stiff) when compared with autograft ratings of 4 (normal).

Conclusion: Low concentrations of PEDOT on DN scaffolds can provide significant increases in electro-active properties which are comparable to 100% PEDOT coatings. DN pliability is closely maintained by continued hydration during PEDOT electro-chemical polymerization without compromising any electro-conductivity. 

1.      Egeland BM, Urbanchek MG, Abidian MR, Kuzon Jr  WM, Cederna PS. A Tissue-Based Bioelectrical Interface has Reduced Impedance Compared to Copper Wire and Nerve. Plast Reconstr Surg, June 2009 123(6S), p 26.

2.      Urbanchek MG, Egeland BM, Richardson-Burns SM, Kuzon WM, Kipke DR, Martin DC, and Cederna PS. In Vivo Electrophysiologic Properties of poly (3, 4-ethylenedioxythiophene) PEDOT in Peripheral Motor Nerves. Plast Reconstr Surg, June 2009 123(6S), p 89.



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