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Pyrrole-hyaluronic acid conjugate for neural probe, stents, and sensor applications. Jae Y Lee and Christine E Schmidt June 19, 2009. Implantable electrodes. Loss of electrical sensitivity Increase in impedance Highly sensitive electrodes are required Nerve tissue reaction
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Pyrrole-hyaluronic acid conjugate for neural probe, stents, and sensor applications Jae Y Lee and Christine E Schmidt June 19, 2009
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 Neural electrodes a) GFAP-stained (3 weeks) b) a) J Neural Eng 2007 Williams CJ et al. b) Biomaterials 2003 Cui X et al. . Technology and properties • Electrochemical deposition of HA on conductive materials • - Electrically conductive • - Cytocompatible • - Stable • - Hydrophilic • - Resistant to protein fouling and cell adhesion
Electrochemical coating process Stable HA coating 0 – 1.0 V (vs SCE) Conductive substrate or electrode (e.g., ITO, PPy) HA coating solution
Surface characterization • Immunostaining of HA using bHABP, followed by PE-streptavidin Bare ITO HA caoted ITO Border ITO HA-coated ITO • Water contact angle measurement Bare ITO HA-coated ITO
Electrochemical Impedance Spectroscopy (EIS) Electrical properties of uncoated and HA-coated ITO are the same
In vitro astrocyte culture Immunostaining three days in culture Long-term culture Bare ITO HA-coated area 10 days 90 days Unmodified area HAase-treated HA-coated ITO • scale bars = 50 µm • GFAP (green), DAPI (blue), HA (red) • Images were taken at the same location for all time points. • Scale bars are 50 µm