AVS 53rd International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeA

Paper BI-WeA5
A Poly(Vinyl Alcohol)-Based Surface Coating for Implantable Electrodes

Wednesday, November 15, 2006, 3:20 pm, Room 2014

Session: Bio-Interfacial Modification and Bio-Immobilization II (Honoring Marcus Textor, ETH-Zürich for Substantial Contributions to the Field)
Presenter: E.R. Leber, University of Washington
Authors: E.R. Leber, University of Washington
B.D. Ratner, University of Washington
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Chronically implanted neural electrodes lose the ability to record or stimulate neural activity with time,@footnote 1@ generally within a few weeks.@footnote 2@ While there are numerous potential causes of this problem, most involve an unfavorable reaction or interaction at the electrode surface.@footnote 2@ Thus, the electrode surface is of paramount importance@footnote 3@ in improving the functionality and longevity of the electrode. Our laboratory has created a platinum (Pt) electrode surface modification platform that will allow for the incorporation of a biologic at the surface, with the goal of improving electrode performance. Thus far, our data demonstrates successful use of plasma deposition of acrylic acid on Pt to generate carboxyl functional groups. ESCA analysis of these samples consistently shows carboxyl groups to comprise around 17% of the surface carbon content. Soaking samples in H@sub 2@O at room temperature or 37° or under acidic or basic conditions does not significantly decrease carboxyl group content. EDC-activation of these carboxyl groups leads to the successful attachment of poly(vinyl alcohol) (PVA) to the Pt substrate in a concentration and temperature-dependent manner as verified by ESCA and TFAA+ESCA; this PVA layer will function as a hydratable and potentially soft intermediary layer between the Pt and the biologic. The hydroxyl groups of PVA will be activated using CDI chemistry to allow for the covalent attachment of a protein through its lysine residues; we plan to attach fibronectin. Impedance spectroscopy has been performed on bare Pt and Pt with attached PVA and preliminary results show the impedance did not increase significantly with the attachment of the PVA. @FootnoteText@ @footnote 1@ Cui X. J. Biomed. Mater. Res., 56, 261-272 (2001).@footnote 2@ Cui X. Biomat., 24, 777-787 (2003).@footnote 3@ Huber M. J. Biomed. Mater. Res., 41, 278-288 (1998).