Incorporating Biodopants into PEDOT Conducting Polymers: Impact of Biodopant on polymer properties and biocompatibility
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Incorporating Biodopants into PEDOT Conducting Polymers: Impact of Biodopant on polymer properties and biocompatibility Paul J. Molino1, Anthony Tibbens1, Robert M.I. Kapsa1, Gordon G. Wallace1 1
ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia. ABSTRACT Poly(3,4-ethylenedioxythiophene) (PEDOT) was polymerized with the biological dopants dextran sulphate and chondroitin sulphate. Polymer physical and mechanical properties were investigated using quartz crystal microgravimetry with dissipation monitoring and atomic force microscopy, revealing polymer shear modulus and interfacial roughness to be significantly altered as a function of the dopant species. The adsorption of fibronectin, an important extracellular protein that is critical for a range of cellular functions and processes, was investigated using QCM-D, revealing protein adsorption to be increased on the DS doped PEDOT film relative to the CS doped film. PEDOT films have traditionally been doped with synthetic counterions such as polystyrene sulphonate (PSS), however the incorporation of biological molecules as the counterion, which has been shown to improve polymer biofunctionality, has received far less attention. In particular, there has been little detailed study on the impact of incorporating polyelectrolyte biomolecules into the PEDOT polymer matrix on fundamental polymer properties which are critical for biomedical applications. This investigation provides a detailed characterization of the interfacial and mechanical properties of biologically doped PEDOT films, as well as the efficacy of the composite films to bind and retain extracellular proteins of the type that are critical to the biocompatibility of the polymeric material. INTRODUCTION Inherently conducting polymers (ICPs) have attracted significant interest in the area of biomaterials research due to their biocompatibility and ability to perform a variety of biologically relevant functions such as the controlled release of growth factors and targeted drugs[1] and mechanical and electrical stimulation[2,3]. Of the ICPs, Poly(3,4ethylenedioxythiophene) (PEDOT) has attracted particular attention due to its favorable mechanical properties and chemical stability. During ICP synthesis, the positive charge on the polymer backbone is neutralized by the incorporation of an anionic species, a process known as doping. While PEDOT has typically been doped with a range of synthetic dopants, little attention has been directed to understanding the influence of the incorporation of large biological dopants on biologically relevant polymer properties, including polymer modulus and roughness, as well as the ability of the polymer surface to attract and retain proteins. It is widely accepted that artificial implanted surfaces may never directly interact with the cellular environment. Rather, proteins adsorbed to the material surface will interact with the surrounding environment and thus mediate subsequent cel
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