1. Pyrrole-hyaluronic acid conjugate for neural probe, stents, and sensor applications Jae Y Lee and Christine E Schmidt June 19, 2009

2. Implantable electrodes Loss of electrical sensitivity -Increase in impedance -Highly sensitive electrodes are required Nerve tissue reaction - Acute and chronic responses - Foreign body reaction - Glial scar tissue formation GFAP-stained (3 weeks) b) Neural electrodes a) a) J Neural Eng 2007 Williams CJ et al. b) Biomaterials 2003 Cui X et al.. Electrochemical deposition of HA on conductive materials - Electrically conductive - Cytocompatible - Stable - Hydrophilic - Resistant to protein fouling and cell adhesion Technology and properties

3. Electrochemical coating process 0 – 1.0 V (vs SCE) Conductive substrate or electrode (e.g., ITO, PPy) Stable HA coating HA coating solution

4. Bare ITOBorderHA caoted ITO ITO HA-coated ITO Surface characterization Bare ITOHA-coated ITO Immunostaining of HA using bHABP, followed by PE-streptavidin Water contact angle measurement

5. Electrochemical Impedance Spectroscopy (EIS)  Electrical properties of uncoated and HA-coated ITO are the same

6. In vitro astrocyte culture Immunostaining three days in culture scale bars = 50 µm GFAP (green), DAPI (blue), HA (red) HA-coated ITO HAase-treated Bare ITO HA-coated area Unmodified area 90 days 10 days Long-term culture Images were taken at the same location for all time points. Scale bars are 50 µm