Joo-Woon Lee Department of Biomedical Engineering The University of Texas at Austin

1. Surface Structure and Reactivity of Conductive Polypyrrole with Oligopeptides Joo-Woon Lee Department of Biomedical Engineering The University of Texas at Austin Austin, TX 78712

2. Analytical, Organic, Polymer Chemistry Surface Science Materials Science Molecular/Cell Biology Biomedical Engineering Mechanical Engineering Sciences Engineering

3. Overview  Objective  Surface Modification of Conductive Polypyrrole (PPy) for Nerve Regeneration  Understanding Electrostatic Interaction of Oligopeptides to PPy  Facts: Summary from Archit’s Results  An Oligopeptide Ligand, T59 (12-mer): THRTSTLDYFVI, Specifically Bound to chloride-doped PPy (PPyCl) T59 as a Bi-Functional Linker for Surface Functionalization  What To Do  Detailed XPS Surface Characterization of PPyX (X = Dopants) : Doping Level, Surface Area, and Chemical Composition and Structure  Quantitative Assays for Structure-Reactivity Relationships of PPyX to T59  Synthesis of Functionalized PPyX  New Strategies for Covalent Immobilization of Biomacromolecules

4.  Polypyrrole (PPy) Black Powders Chemically Synthesized Stoichiometric Equation for the Synthesis of PPyCl nC4H5N + (2 + y)nFeCl3[(C4H5N)nnyCl] + (2 + y)nFeCl2 + 2nHCl y: Degree of PPy Oxidation (Doping Level) Experimental

5. 20m  Chemical Structure 1m PPy Surface Characterization  SEM Image of PPyCl Powders  Specific Surface Area Measurement As = 2.631  0.028 m2/g  Brunauer-Emmett-Teller

6. Fe2p XPS: PPyCl Surface Composition

7. (37.25 %) - - (36.14 %) NH (67.98 %) (15.05 %) Disorder-type i) C=N Defects ii) Non - Bonding (13.10 %) CN+ (7.98 %) Terminal C=O (10.84 %) C=N+ N=C (8.08 %) (3.58 %)   * HR XPS: PPyCl Surface Chemical Structure  C 1s Line  N 1s Line • Adjusted Cterminal C=O Atomic Conc. : 5.95 % (Surface Oxidation) • Oxidation States : NIox (+NC) & NIIox (+N=C)  Doping Level: 23.94 %

9. Specific Surface Area (As) and Doping Levelof PPy Variants

10. Q = VoHAtKB[L]/(1 + KB[L]) Q Total Heat Content VoVolume of PPy Powder Solution HEnthalpy of Binding per Mole of T59 AtTotal Surface Area (As  Sample Mass) [L]Unbound T59 Conc. F(x) = Fmin + (Fmax-Fmin)/(1 + 10^((logKD-x)*)) Quantitative Binding Characteristics

11. Arg-Tyr (R-Y) Interaction

12. Arg-Tyr (R-Y) Interaction

13.  Au Cys (C) CHRTSTLDYFVI or THRTSTLDYFVC (12-mer: T59 Variants) Au  Au-coated Si3N4 Chemisorption3 Thiolate Proposed Experimental PPyCl Pellet4 Mechanical Unbinding Force Analysis of PPy-T59 Interaction Background • Hydrophobic HSA-PPyCl Interaction (25  5 mg/g)1 • Steric Hindrance caused by Differences in the Structural Mass • Force Relaxation  Elongation Length2 • Dependence on PPy-T59 Binding Concentration Ref. 1. Azioune et al. Langmuir2002, 18, 1150. 2. Nakamura et al. Biopolymers (Peptide science) 2004, 76, 48. 3. Cavalleri et al. Phys.Chem.Chem.Phys.2004, 6, 4042. 4. Ruangchuay et al. Reactive & Functional Polymers2004, 61, 11.

14. *  Protein Immobilization + Functionalized Conductive Polypyrrole forCovalent Attachment of Biomacromolecules  Strategy  Synthesis of N-Succinimidyl Ester PPy Azioune at al. Langmuir 2004, 20, 3350. NHS: N-hydroxysuccinimide EDC: 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide