Title

Surface modification of a perfluorinated ionomer using a glow discharge deposition method to control protein adsorption and fibroblast inflammatory response

Date of Completion

January 2005

Keywords

Engineering, Biomedical

Degree

Ph.D.

Abstract

Current biomaterials follow a standard cascade of inflammatory events which, upon implantation, can significantly decrease the lifetime of implantable biosensors. In particular, uncontrolled protein adsorption and the subsequent formation of a fibrous capsule can limit the transport of analytes to and from the sensor. Creating a non-fouling surface would prevent the random adsorption of proteins but would also render a substratum impervious to cellular attachment. If a material could be resistant to random protein adsorption while concomitantly presenting specific cell adhesion ligands, surfaces could induce healing, reduce encapsulation, and consequently prolong the functionality of a sensor. The perfluorinated ionomer (Nafion™) is currently being used in the development of implantable biosensors. The Nafion surface is modified here via a plasma deposition method of a combination of two different monomers; tetraethylene glycol dimethyl ether (tetraglyme) and 2-hydroxyethyl methacrylate (HEMA). Different combinations were characterized via contact angle, atomic force microscopy (AFM) and electron spectroscopy for chemical analysis (ESCA, or XPS). Once Nafion was rendered non-fouling with regard to protein adsorption, the adhesion peptide Arg-Gly-Asp Acid (RGD) was covalently linked to the surface in order to attract desired mammalian cells. After the preparation of the various base and modified Nation substrata, the attachment kinetics and short-term physiological responses of normal human dermal fibroblasts are quantified in the presence and absence of known inducers of the fibrotic capsule and byproducts of sensor function, such as IL-1, H2O2, and glucose oxidase. ^